The Emley Moor Television Tower, by A

THE ARUP JOURNAL

MARCH 1972

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ro»rott [<'i 1 ii in a Vol. 7 No. 1 March 1972 Contents Published by Ove Arup Partnership THEARUP 13 Fitzroy Street. London. W1 P 6BQ

Editor: Peter Hoggett Art Editor: Desmond Wyeth FSIA JOURNAL Editorial Assistant: David Brown Future problems facing the designer, by Ove Arup

The Emley Moor television tower, by A. Bartak and M. Shears

Building 14 1 3 Russell Offices Canberra, by M. Lewis and D. Ryan

The raising of 16 The Wellington Inn, by J. Charge

Front Cover: The Emley Moor television tower (Photo : Geoff Rooke) Back Cover: Early 19th Century print of Manchester Market Place.

It would not do. however, to limit the discus• in turn on sophisticated hardware. Both are Future sion to structural design only, using the word complex mental activities, set in motion by a in its narrower sense, for whereas everything stated objective, and based on a stock-in- problems we build or make must have structure to keep trade of knowledge and experience, its intended shape, the structure itself is only augmented by fact-finding, classification, facing a means to an end; its merit cannot be interpretation, analysis and synthesis in judged without reference to the thing of which various proportions — a process where the designer it forms part. imagination, intuition and invention are of Designing - and we could add planning - vital importance. However, the two differ in which is roughly the same thing, on a larger their objectives. scale - plays a central and increasingly The scientist wants to explore nature, to find Ove Arup crucial role in technology; it is the key to out how it works. He is looking for general everything which is made or built. For in laws. The motive may be pure curiosity - This paper was given at the Royal Society modern construction everything is thought when we call it pure science - or he may hope Discussion Meeting. Building technology in out beforehand, no unauthorized action is that the acquired knowledge will help him to the 1980's, on 4 November. 1971. allowed. So any feature of the finished job run the machinery himself. In this case it is which is not purely accidental must be due not so pure, and approaches the kind of to a decision by somebody. As a matter of research which may form part of designs I am aware of. and grateful for. the honour convenience, I call these decisions design breaking new ground. you show me by asking me to address you decisions, and the sum of them the total The designer wants to change nature to suit on the subject of 'Future problems facing the design. The total design is seldom recorded his convenience. He is trying to solve a designer'. in toto, it is more an idea than a reality. But practical problem here and now. But his I am afraid, however, that you may have the idea of total design implies that sufficient problem is underdefined. There is not just overestimated my powers. Like the Danish decisions have been made and recorded to one, but many solutions, good, bad and cartoonist Storm-Petersen I find it very enable others skilled in organizing such work indifferent. He must choose. The bad solutions difficult to prophesy - very difficult indeed - to carry it out. The total design must, by come easy to hand, the good he must search and especially about the future. But I can tell definition, be viable, i.e. it must be possible for, and work for. And that is the designer's you straight away what I fear may happen : to carry it out as intended. And it completely real metier, that is his real problem, to find the that designers in the future will even more defines the finished job. best solution. Or, as you can never be sure than now be working under constraints which This cannot be said of all so-called designs. that there isn't a better solution, to find at will make it impossible for them to give of These are often only preliminary designs, least a good solution, a solution of quality. their best. And I could add that even more sketches, plans or architectural perspectives And this is a problem in more than one sense- than now their best may not be good enough showing certain aspects of the intended total for what is quality? What is goodness? because it is too narrowly based. This I think design, but one cannot always be sure that The 'goodness' of a total design must be the is by far the gravest problem facing designers, they are viable, or practical, before the details same as the goodness of the finished structure, and it is a problem for all of us, unless present have been worked out and all the implications for the total design completely defines the trends are reversed. considered. This leads to the often lamented latter. And the goodness of a structure, using This is a somewhat pessimistic answer, and gap between vision and embodiment. It is a this term about any product of the building probably not what you expected. My opinion wise precaution to bring the design to a industry, must be related to its purpose, and is of course based on my own experiences as stage when you know for certain that it can the consequences flowing from its being a designer of sorts, and it is therefore a very be built and what it will cost, before embarking constructed in this particular location. The personal one. Let's hope I am wrong. on work on the site or in the factory. structure must obviously be fit for its purpose Our designs, as executed, make our environ• to be good. But that is not all that is implied Meaning of design ment, and this in turn makes us. partly at by quality, as I hope to explain. The purpose The word 'design', used as a noun or verb, least. Designing therefore assumes an import• behind the whole undertaking does not can mean many different things. Here we are ance not far short of that which belongs to emanate from the designer, and may not even concerned with design as a link in the process scientific enquiry. In fact the two are intimately be disclosed to him. As far as he is concerned, of building and construction. Incidentally intertwined, one of them would get nowhere it takes the form of a brief given him by his I make no distinction between the two; without the other. The whole of our technology client and telling him in more or less general such distinctions have become obsolete is based on scientific knowledge, and terms what is wanted. The designer then with growing mechanization and factory scientific observation, and research depends digests this information and disgorges it again production. close line valves until the last point has in a form which will enable the builder to be dangerous if too narrowly based. Designers Brief, design, execution reached the required lift. Timing the closing of construct what the client wants. - besides knowing their metier - must have The brief cannot define quality. But it can the valves gives the error in level during lifting This is the highly simplified version of the an understanding of what other people need, prevent quality being produced by the which restricts the maximum following lift and building process which is generally used and not just of what they want to give them, designer, and often does, either by being so indicates the necessary vernier adjustment on when writing or talking about the subject. and sometimes perhaps what they need is a vague that the designer has not really under• the flow control valves if an increase in lift is The reality is infinitely more complicated and chance to build their own shacks - disregard• stood the client's needs and therefore comes desired. we will come to that later. ing aesthetics. up with the wrong answer, or more often by being too detailed, thus pre-empting design Design in practice 63 mm was the maximum continuous lift used Formula for excellence decisions which ought to be taken by the I am aware that all this must sound a bit but it was as efficient to maintain 25 mm lifts. The brief, supplemented by reference to the designer, or which at least ought to be high-falutin' to you. What has all this to do The latter gave better control than that which client if necessary, is obviously a very integrated with the other design decisions was specified, and became the standard lift. important document. If it could really explain with the client? He doesn't necessarily want and modified as a result. The average rate was 10 minutes for 25 mm. exactly what was wanted, the question of an architectural or other kind of masterpiece. It is wrong to treat brief and design as The slight accumulation of variations in lift quality would be solved. The best design Maybe his object is to sell out quickly. Let's separate documents. The brief and the basic were corrected as required by taking levels at would simply be the cheapest of those say a rural council wants a water tower. They design decisions should result from a the six points after each retraction and packing Fig. 15 Fig. 16 satisfying the brief. The formula measuring have not much money - but they are in a collaboration between client and designer. sequence, and then levelling by jacking All jacks on pier location No. 1 in position Control panel in foreground showing a group efficiency or excellence would be : hurry - for the matter has been debated for You cannot decide what to build without individual points. and first three packed against pier. of six lines, valves and gauges. In the C several years. They know what they want: so finding out what can be built for the money Note Tentest board, angle support grillage, background is pier No. 4 with its jack group they go to an engineer who has designed The extension of jacks prior to retraction and E = — available, what the options are. The client's night rings, and continuity reinforcement. and manifold, during jacking. water towers before and say: re-packing was limited to approximately P job is to explain his situation and his needs as (Photo: Martin Koretz) (Photo: Stan Parkinson) One of these, please, so high, so many gallons, 115 mm. allowing for a 100 mm pack and where C stands for commodity as defined by fully as possible to his professional advisers, for so much money, or less. And we would mortar bed. A typical retraction and packing the brief and P stands for cost in pounds. And but not to propose, or at least not to dictate like the tenders to go out in six weeks time. sequence was as follows. this is in fact what the whole of the modern the solution. Just as a patient should explain Fig. 17 Fig. 18 It can be done. A sketch design, approximate obsession with cost-efficiency is based on . . . his symptoms to the doctor, but should not Using a hand pump, sufficient pressure was Water level control weir. Water level tube and control box for All possible factors, even such imponderables quantities which can be modified later, the suggest the cure, far less prescribe it, the fed into the jack group to enable the night (Photo: Stan Parkinson) pier 8. and levelling tape. as a saving in time for busy executives, are contractor starts digging. But he hasn't had very thought is preposterous in this case. The rings on up to a maximum of -j of the jacks (Photo: Stan Parkinson) evaluated in money terms, and optima are the working drawings yet. And so on. in that group to be released. The pressure was relationship should be one of openness and produced by the computer and used as a The water tower stands in this village for a trust in both cases. then released using the vent valve. By basis for what are in effect political decisions. long time. It is its most prominent feature. The same intimate relationship should exist applying physical pressure, the free jacks were This is very crude, and potentially very danger• You cannot avoid seeing it. A pity - but we retracted, the jacks remaining being sufficient ,'•: between design and execution. The designer ous, for it entirely ignores the quality of the must have water. to carry the total load at that point, both under must know where he is going, he cannot product, which we do at our peril. Even the This is, on a small scale, what happens most pressure and on their night rings. The new best of briefs cannot begin to define quality. design unless hecanjudge whether his design packs under the retracted jacks were bedded of the time, more or less. But it is not the way can be built, how it can be built and roughly The brief can be satisfied both by good and to get the environment we like. onto the previous pack and load applied mm bad designs. You can specify that you want how much it costs, at least enough to enable again to the jack group by hand pump, thus Of course most designs are more or less him to compare the cost of alternative solu• an elegant structure or a friendly house, or a routine designs. They must be. we can't loading up the new packs and enabling the town hall which is the envy of neighbouring tions. Otherwise he proceeds blindfold. To next set of night rings to be released. This invent our technique afresh every time we complicate the execution through ignorance cities, but that does not help you much. The build. But even if the bulk of what is built process was repeated at each jacking point —• or neglect of the ways and means of construc• client buys the cat in the bag. All he can do is relies on previous experience slightly adapted until retraction and packing was complete. to choose a good designer. That is why it is tion is bad design. True economy demands The next extension of jacks was then begun. i to present circumstances, it is the fresh look that the design indicates a practical way of tempting to hold a competition for the best at the evidence which initiates progress and design, except that the submitted designs building. Where only two jacks formed the total I o improves quality. The natural instinct of a true number in a group, two additional independent necessarily must be in the form of sketch- designer is to ask himself: How can I do this I hope I have explained the need for integra• jacks were used to carry the load whilst both designs, which may not fulfil what they thing better than it has been done before? tion of brief, design and execution. But there lifting jacks were retracted and packed. promise, and the assessors may not recognise Let's forget how it is normally done. By is much more integration to be done. nascent quality when they see it. concentrating on the essence of what is If we look at the real situation we find that To maintain stability during jacking the As the Danish author Piet Hem has said : Art needed and the most direct of all the ways jobs are getting larger and more complex and number of packs allowed under extended is solving problems that cannot be formulated of achieving it. perhaps I can find a simpler, that the total design is split between dozens jacks prior to stabilizing was limited to three. before they have been solved. The shaping cheaper and a better solution, fitting into of different professions, experts, manufac• Therefore, each time a third set of unrestrained of the question is part of the answer.' And surroundings better, pleasing the people I turers and contractors, each at best pursuing packs was placed a further section of pier designing is essentially an artistic process. Of am serving. If these aims clash - as they will - his own particular kind of quality. Communica• was concreted. It course collection of data, research, analysis, perhaps if I try harder, some insight, some tion between them is inadequate, and not calculating, quantifying, costing, etc.. and idea, will come to me in the middle of the much concerned with a rational appraisal of especially previous experience, play their the design. But although the quality of the The process of jack extension, retraction and night. important part, and in engineering structures overall planning services, the structural packing, and pier extension was continued perhaps the most important part - and some It may quite likely happen, of course, that the design, the architectural conception and until the required lift of 1.46 m had been of these activities can be eased by computer• designer, after such an excursion, falls back detailing and the economic efficiency are all reached within the specified tolerances. ized information processing, analysis and on a traditional solution because it is in fact important, it is the synthesis of all these Finally the levels were checked from the • --J mathematical simulation. But the essence of the best in the given context. He has wasted partly conflicting aims which constitutes the bench mark and the required adjustments to designing is to effect a harmonious synthesis time and effort. But he has gained the quality of the whole job. We need all-round level were calculated for each pier position. ?33 of partly conflicting aims and obstinate facts. satisfaction, valuable to any designer, of or comprehensive quality, wholeness, which Employing the hand pump the jacks were It is largely to find the right spatial arrange• knowing that he has chosen rightly. is really nothing else than a closer adaptation : then used to finally correct all beam levels as ment of parts. Designing can be likened to the The brief, and the formula : to human needs. 3nS required. solving of a gigantic three-dimensional jig• C Sufficient jacks were then removed at each Total Architecture saw puzzle - except that there is not one but E = — pier to enable final underpinning to be many solutions, and not one but many But who is going to do the integration ? The 1 P constructed. This underpinning consisted of job is too big for one man. Team work is the designers. And they have got to find or shape cannot even settle the dispute between an in situ pier cast in rapid hardening Portland answer, but is difficult when the members of the parts themselves, keeping always the alternative solutions, if they happen to cost cement of sufficient area to carry the full the team so to speak live in different countries object in mind. the same. For instance, if the brief can be jacking load at each pier, cast to within 75 mm and speak different languages. It requires satisfied by using either structural steel, of the beam soffit. The gap was then dry- teamwork of a much higher order, whose A designer has his own standards. He is a reinforced concrete or aluminium as the basic packed using a 1 :3 mix beneath a separating members collectively embrace the experience professional, a craftsman, and if he is good structural material, the three schemes will layer of polythene. When this underpinning needed for the job, understand each other and himself, he knows when he has done a good differ in many respects which cannot be had attained its required strength sufficient have the same desire to create what I elsewhere job. It must be all of a piece, have wholeness, measured with the same yardstick. Durability, pressure was put on the remaining jacks to have called Total Architecture. In such a team clarity, it must not be too strong at one point thermal conductivity, ease of effecting altera• allow their night rings to be released. The enthusiasm can survive, and can even spread and too weak at another - but, as I said, it is tions, cost of upkeep, weathering, suitability load was then transferred to the underpinning and flourish. useless to try to define quality. All we can say by releasing the pressure on the jacks, which for possible mass production, use of local is that its emergence results from the Total Architecture does not mean that cost is were finally removed. resources and labour and many more, all involvement of the designer, from his passion will vary. Even the shape would be affected, neglected. It only means that quality is not The final extension of the piers up to the for perfection, from the fever which grips him and they would certainly look different. We forgotten. The only hope I see of combining beam and casting of remaining slabs followed, when he sees the chance of producing a really would have to modify our formula to: low cost with quality is to spend more time thereby containing the final underpinning. good job, and which makes him sustain the C plus EC plus D over the design. By more constructive Although the development will represent all effort involved. I believe, perhaps naively, forethought the time and money spent on the that is most modern, functional and attractive E = that such enthusiasm is a pre-condition for site can be reduced. Saving money is done in architecture, it will have an indissoluble P creating a structure or an environment which by better design, better job organization and link with the past. where EC stands for commodity in excess of is not as cold and inhuman as much of our that required, but still of some value, and D less waste, not by more accounting. The Old Shambles is to stay and those using modern environment, but in which we can stands for delight, the artistic quality. EC and Post-design costing can be a useful check on the centre, whilst reflecting on the modernity feel at home. D cannot be objectively measured in money a design before work is put in hand - but it Fig. 19 of the city and the forward thinking of its But enthusiasm is not enough. It can even terms, yet they cannot be ignored either. comes too late - it means re-design if the View from north after main contract excavation had been completed people, will also be reminded of its centuries- (Photo: Stan Parkinson) old traditions. design is loo expensive. And in any case the Naturally designers should work as efficiently You may object that the formula gets less had a line on-off valve followed by a flow re-levelling, the flow control valve verniers above each jacking point. Immersed into the present over elaborate Bills of Quantities are as possible - but to prevent them from useful for every addition, and you are right, control valve and its by-pass on-off valve for being adjusted as part of the process, until tube are two electrical contacts completing a a clumsy and time-wasting instrument for this designing in the true sense is counter• for it is very difficult to put a value on EC. D single line operation and finally a pressure the first full jack extension was reached. The circuit containing a light. When the water purpose, as progressive quantity surveyors productive, to put it mildly. and SP. But we have to do it, or at least we gauge with a maximum capacity of 40N/mm2. jacks were then retracted and packed using falls below the level of the upper contact, the will admit. have to make decisions which take account The rate of lift possible from the supply was a pre-designed sequence. This process was circuit is broken and the light goes out. The client of these items, and the sooner the better, if 25 mm in 2J minutes. The flow in the line maintained for a further three 6 mm lifts The water level acts as a control to the lifting But the present vogue and esteem for pre- The 'client' has changed as well. He has lost design cost estimation, where definite sums we can believe the prophets. was however reduced by losses in the system following the initial full extension, but with in the following manner. his identity and accessibility, being replaced and by use of the flow control valves, the are allocated to various parts of a non-existing This is a matter for politicians rather than the water level in operation. The latter was The upper contacts are lowered by means of a by a board of directors responsible to their actual average working flow achieved being design, rests on a curious delusion. Where designers; it directly affects only the brief, checked during these three lifts for accuracy screw on a threaded rod until they just make shareholders, or by government departments 25 mm in 10-12 minutes. does the estimator obtain his superior and therefore the client's right to build what and found to be functioning correctly. Lifts contact with the water and complete the administering directives from on high, both At each of the six jacking points the supply knowledge of what the right design should he wants. But. as I hope I have made clear, were then increased to 25 mm in 6 mm electrical circuit. All lights are now on. The represented by agents who can only administer was fed into a jack group manifold via a cost? It is really an insult and an obstacle to brief and design cannot be separated, and increments. weir is raised by the amount needed for the official policy, no matter how inappropriate to non-return valve. Each manifold had a designers; their work is dismissed as of no scientists and designers must be brought in as The water level forthcoming lift and time is allowed for the the situation. But are these the true clients? hydraulic line to each jack in that group, the importance. advisers, to decide why we build and what The water level had one vertical level tube water to flow through the system and come Do we not design for the people who use minimum being two and the maximum nine. to build. fixed above each of the six jacking positions. to rest. The amount of lift can then be seen Of course, designers may not be good the structures and live in the environment? At the end of each manifold were two valves This was supplied by two tubes, one down as the distance between the level of water and enough - if you are strict you can say that of This view has certainly been gaining ground This is a much more difficult and controversial for hand operation when levelling, and each of the long sides of the building, which the highest immersed contact. The jacks are most designers. But before you bring in among designers; it was one of the planks question than how to build. To get strong and retraction and packing of jacks during lifting, were in turn connected to a control weir at operated and the building lifted. As the weir somebody else to do their job for them, you in the programme of the Modern Movement concerted action by independent national one valve for the hand pump and one for a point away from the building. is away from the building the water level in had better be sure that these others are in architecture. This means that the critical governments in this matter seems beyond venting off oil during retraction. At each The absolute water level is maintained by each tube lowers in relation to the tube, better designers, for it is better designs we look at the brief, for which we felt the need the reach of man, at least not until disaster jacking point a tape was rigidly fixed to the water constantly flowing over the weir, the staying constant with the weir, the actual need, not better costs. A feasibility study by in the interest of wholeness, must penetrate stares us in the face. But at least people and beams for levelling and control of lift. designers is the way to get an idea of costs deeper. When the client is the public, the governments have begun talking. level of which is manually controlled by a change at each point being the actual lift at beforehand. brief must defend public interests. That means screw mechanism. The use of a weir eliminates that point. As each upper contact breaks from But that we must stop glorying in waste Lifting procedure No, costing must be an integral part of that we must take into account the wastage problems associated with expansion or the water the light at the position goes out seems obvious. Waste can be glorious - but The first lifting sequence was to release the designing. We need cost-conscious design. of scarce resources, the cost of preventing evaporation. The system is bled of air prior to and the on-off line valve to that point is it leads to waste land. We must preserve our beams from the ground stiction. The weight of And that is in fact what all engineering design pollution, the spoliation of our environment, use. Each of the six level tubes is rigidly fixed closed. Hence the slowest point during lifting heritage, conserve our resources, build for the building and its new supporting beams is or ought to be - to find the cheapest the harm done to fauna and flora - in fact all to the building alongside the levelling tape catches up with the fastest by continuing to permanence, not for scrap. We must reduce had to be transferred totally from the ground, solution to a given problem. This can be the things people have warned us about, and our production of unnecessary gadgets, where the beams were acting simply as over• said to be the definition of engineering, and which are the pet theme of our more serious simplify our lives where possible so that size footings, onto the lifting jacks, with the everything we build is engineering of one publications. We cannot afford to neglect something is left over for those in need. beams spanning freely. This was done by kind oranother. them, even if only partly well founded. The lifting all points together and measuring the total design must be truly comprehensive. Does this invalidate the quest of quality in Cost-conscious design is the way as I see it - extension at each jacking position simultane• We must add to our formula another factor: design ? I don't think so. To do one's job well but the situation is not propitious for its ously, the line to each of the six jacking SP - the social price we have to pay. if we is good for one's self respect and good for adoption. Spending more on design goes positions being closed when a 3 mm lift execute this design, and we had better put it one's fellow beings, and it can't do any harm against the whole trend, against official could be measured, until all six lines were below the line this time : as far as I can see even if it doesn't solve all policy. We are trying to reduce the cost of closed. The pressures during this initial lift the problems of mankind. design by mechanizing it. applying cost C plus EC plus D exceeded later pressures, as anticipated, due efficiency techniques, which cannot distin• E = After all, it only means using our resources to ground stiction. The pressures during the guish between good and bad design. P plus SP wisely. initial lift were restricted to the maximum beam reaction design pressures. After all points had been raised a nominal 3 mm, the six permanent levelling tapes were checked in pairs using three fixed quickset levels and the five jacking points individually aerial supporting masts because: taken at this time. This was to erect the aerial raised to the sixth and highest lift above The (i) The local planning authority requested supporting steel mast within the tower at the datum. This process was repeated until the that any new guyed structures be located ground level, together with the aerials and pressures of consecutive lifts were more Emley Moor not nearer to public roads and dwellings than upper section cladding, and hoist the consistent and it could be seen that the their height; the resulting increase in the assembly into its final position at the top of beams were all clear of the ground. (Five television tower distance from the existing station buildings the concrete structure. The reasoning behind 3 mm lifts were used). The lifts were increased making a guyed mast solution unacceptable. this decision was the desirability of eliminating to 6 mm and the process repeated, including the risk of delay which could result if conven• (ii) It was believed that cantilever structures tional methods of erection were attempted, made entirely of steel could not be realized Andre Bartak and especially taking into account that the site within the available time. had a history of severe weather conditions. Mike Shears (iii) Past studies had indicated that steel Fig. 12 left cantilever structures did not have a definite Also, in order to save time, it was decided to First stage underpinning This article first appeared in the February 1972 cost advantage over concrete for the contem• eliminate the period required for tendering and Wellington facade to Market Place complete issue of The Structural Engineer and is plated height range. negotiate instead with a selected contractor. and ready for reinforcing and concreting reproduced here by kind permission of the Six contractors possessing the necessary (Photo : Martin Koretz) In order to optimize the overall cost, estimates specialized experience were approached and Council of the Institution of Structural were prepared for three alternative heights of Engineers. after a series of interviews the choice was the proposed tower as follows : made. From this time onwards the contractor Height of Height of Total made available to the design team his Introduction concrete aerial overall considerable construction experience, thus The collapse of the guyed structure at Emley structure super structure height making a very important contribution towards Moor on 1 9 March, 1 969 resulted in the loss 213 m 55 m 268 m the development of the design which of both the ITA and BBC programmes in a 244 m 55 m 299 m necessarily had to evolve around the mode large and densely populated area of Yorkshire. 274 m 55 m 329 m of construction. Although VHF monochrome services were As previously indicated, time was a major quickly restored by various emergency In each case, the steel superstructure to carry factor governing the evolution and develop• measures including the erection of a temporary the aerials was to consist of approximately ment of the design. A short list of dates 216 m high guyed mast, full coverage of the 30.5 m of triangular section with 1.98 m sides which follows illustrates this point: area previously served by the UHF BBC2 and the top 24.4 m of triangular section with colour transmissions could not be re• 0.99 m sides. The whole of the aerial super• Initial briefing : Mid-May 1969 established by these means. structure was to be surrounded by fibre glass At the time, the Independent Television cylinders of 3.66 m in diameter around the Site investigation start: End of May 1 969 Authority were themselves in the midst of a 1.98 m triangular section and 1.52 m in Commencement of Beginning of programme of conversion to colour trans• diameter around the 0.99 rm triangular section. work on the design : June 1969 mission, the opening of the new service These estimates were incorporated into the being originally scheduled for the end of parallel studies made by the Authority's Contractor on site: August 1969 Figs. 13 & 14 1969. and therefore it is not surprising that engineers, who concluded that the best Third stage underpinning when the ITA authorized a feasibility study overall solution was provided by the structure Foundation excavation Sinclair's facade to the Old Shambles: for a new structure to support the aerials at of the maximum height, i.e. 329 m. (Fig. 1.), start: August 1969 2 m deep underpinning from inside The brief specifically excluded the provision with reinforcement being fixed. Fig. 1 3 Emley Moor, they specified that the UHF Concrete structure for any public facilities such as a viewing shows cross beam second stage transmissions from the new structure should completed: September 1 970 commence, if possible, by the end of 1970. platform or restaurant. underpinning with formwork stripped and The initial briefing given on 16 May, 1969 Early decisions and developments Aerial mast in position : November 1 970 cross bracing and shoring. Another decision which profoundly influenced requested solutions based on cantilever (Photos: Martin Koretz) the further development of the design was UHF aerials in operation: January 1971 concrete structures surmounted by steel 21 future beam soffit level which in turn rests main development contract sub-structures using a hand pump, were extended to the top upon a temporary underpinning foundation, and drainage. Where the ground conditions of the packs. Pressure was then applied up or, where available and suitable, upon existing were suitable, concrete was cast against the to 3.4 N/mms. This initial application of foundations or cellar walls. The location of excavation with the exception of the top pressure was to compress and bed the stools and details of temporary foundations sections of each pier and the two piers on the Tentest board, to bleed and test the jacks were such that pre-underpinning ground party line of the buildings, which were and jacking circuit beyond the group manifold, pressures were maintained as near as practi• required to be fair-faced. Each pier was cast and to relieve the temporary increase in local cally possible. Each stool was finished with up to the level required for jack installation. ground pressure associated with pier construc• a concrete cover block, the top of which was The jacks were located in predetermined tion by taking load down the final support. at the future beam top level, and the under• groups and positions, and held upside down Each jack has a screw-threaded mechanical pinning was completed with 1 :3 dry mix by their baseplates at each pier with a light stop called a night ring. This is used to guard mortar packed to the brickwork above. steel angle grillage bolted to the underside of against leaks or failure of the non-return valve All concrete for the underpinning beams was the beam. This method enabled jacks to be when pumping ceases. supplied ready-mixed and placed throughout retracted when fully extended without the On completion of the piers and installation by pump, due to the difficulties of access. need to man-handle the jacks themselves. and pinning of the jacks, the remainder of The largest pour was in the 1.98 m deep A 1 3 mm pack of Tentest compression board the hydraulic jacking circuit and control was Shambles facade beam of Sinclair's, which was placed between the underside of the set up and bled free of air. The total hydraulic took 45 m3. On completion of the underpinning beams and the jack baseplates. When all system was then tested. Power was supplied beams, pier construction and jack installation jacks were in position in any one group the by a 1.5 kW motor driving a positive displace• were carried out in four stages, two piers at a pier was extended up to a level approximately ment pump, the rate of flow of the pump being time, remote from each other in order to 1 50 mm below the jack, reinforcement being 4.5 litres per minute at 960 rpm. At this flow minimize as far as possible the temporary left projecting to provide continuity in the maximum theoretical pressure which increase in ground pressure accompanying, subsequent pier extensions. 230 mm square could be developed by a 1.5 kW motor was and adjacent to, pier excavation. 2 precast concrete packs were placed and 30 N/mm . The output was fed, via the mam The excavation of piers was by hand down bedded into the spaces between the jacks and hydraulic line on-off valve, into a manifold to a minimum of 305 mm into bunter sand- the extended pier. The jacks were then with six hydraulic lines, one to each jacking sandstone, or lower as required by the future connected up to their group manifold and. point. Each of the six lines at the control panel

MOSCOW EMLEY MOOR HAMBURG HILLBROW VIENNA BRIXTON W BERLIN LONDON 508m E BERLIN 330m MUNICH 271m JOHANNESBURG 260m JOHANNESBURG DORTMUND 212m STUTTGART 201m 360m 290m 266 m 233m 219m 211m

Fig.1 above m Emley Moor Tower and other similar structures

Fig. 2 left Fig. 10 View of completed tower Close-up of precast concrete underpinning (Photo: Greaves (Photographers) Ltd.) stools (Photo: Stan Parkinson)

330 m (1084 I BEAM v CLAY AT FINAL LEVE 3-3 STONE COAL Final beam MUDSTONE soffit 305m 11000) SANDSTONE

BEAM INTERMEDIATE JACKING LEVEL BEAM SUPPORTING JACKING LOA DS ONLV BEAM MUDSTONE AT ORIGINAL UNDERPINNING LEVEL - ACTING AS TRADITION Al Shell diameter HalJITI FOUNDATION thickness 350mm(l'li") Rising beam i II 263 6m 1865 I soffit level 52-10 GREEN LANE COAL Tentest compression board

Inrtial bearr soffH T PLAN AT 274 3m Light steel angle grillage Jack take-up of MUDSTONE Jack night ring Park Initial top of piei 1 1 ! 1 I - •— — — —• — J_ —'

PIER 107-6 NEW HARDS COAL

Fig. 8 MUDSTONE Jacking sequence

Fig. 9 General Market Place Development: view prior to any contract work showing the site as it has basically been since the war (Photo : Stan Parkinson) The demolition of immediately adjoining SANDSTONE PLAN AT TURRET FLOOR LEVEL property followed on completion of the bracing, after which the underpinning works commenced. The underpinning was in four pre-planned stages ensuring overall and local stability at all times, each stage being com• pleted before commencement of the one MUDSTONE following. Lightly loaded posts were dead shored prior to being underpinned. Heavily loaded small lengths of brickwork and brick 200-0 piers, where normal brickwork underpinning would cause unacceptable temporary stresses on the adjacent brickwork and foundations, Fig. 3 above were needled to relieve the load during the Geological succession underpinning of that particular section. The work was done from within the old cellars where they existed. There were two basic types of underpinning; the type used for standard depth beams being the contractor's standard, built-up. precast, concrete underpinning stool and, for under• pinning beams in excess of 0.9 m deep, specially designed steel section underpinning stools. Both types of stool allowed reinforce• ment to pass through where required by the quantity of steel or by the variation in line of the supported brickwork relative to the PLAN AT FIRST PLATFORM LEVEL Shell diameter, 24 4 t'80 I centreline of the beam. Each stool is bedded thickness 533mmll'9"l onto a precast block, which gives the required Fig. 4 right cover to the steel stool. All underpinning was Cross section and plans showing the general arrangement of the tower in pre-designed positions, the cover blocks being placed upon a separating medium at support lines, indicating that jacking off Design rate of flow depending upon the valve The bottom 10.67 m has plate webs and diameter over the upper mast and 3.66 m it during the hoisting, can be seen in Fig. 6. cellar walls may not be feasible. (Prior to this, The design and control of the total free calibration and variations in the system beyond above that the structure is latticed (Fig. 5). over the lower portion. Because of the high At intervals of 46 m the framework is braced access to the building was not available to jacking system (that is after initial separation the valve. The total area of jacks at each All connections were made with HSFG bolts rigidity of the cylinders, all horizontal joints to the concrete shell by platforms which also the client). from the ground) was based upon the jacking point was determined from the and the steelwork was fully galvanized. between units were designed to accommodate give access to the aircraft obstruction lights. principle that all jacking points should lift at Considerable thought was given to the movement and the units were individually The scheme to include all the final beams and estimated jacking load, assuming a fairly Aerial platforms the same time and at a constant rate, as far as uniform working pressure for all jacks. The problem of developing the friction in the supported by the steelwork. The joints were supports prior to jacking, and thereby Four external platforms near the base of the possible and therefore within specified flow control valves were calibrated to allow faying areas. These areas were grit-blasted sealed with one part polysulphide sealant. eliminating a planned sequence of construc• tower, as shown in Fig. 7. will carry 3.66 m tion, would clearly reduce both construction tolerances of variation in level. for the variation in jack area at each point. at the fabricator's works in order to remove Internal structure diameter microwave dish aerials. The plat• time and areas of possible doubt and delay. A pin joint was designed into the end of each the zinc but not to penetrate the alloy layer. A basic system using on-off valves alone Inside the concrete shell, a rectangular, forms were cast on to steel beams projecting In the light of these factors it was decided to longitudinal beam at the party wall where the No masking was used. After assembly of the would only achieve this by an uneconomical latticed steel framework forms a shaft for a through the shell wall and braced internally. investigate further the original principle of Wellington beams are supported on a corbel steelwork at the site, the areas surrounding and lengthy process of lifting each jacking Pockets which can be broken through were jacking all final structure off piers down to off the main Sinclair's supporting beams. the connections were cleaned by further maintenance lift and supports the aerial point separately. left in the concrete so that similar groups of bedrock. Under The Wellington the beams are of such blasting and then painted. feeder cables, the tower lighting, power and Various methods of control were investigated stiffness that the pairs of supports to each For the protection of the aerials and of the telephone facilities and incorporates an platforms can be constructed in the future at A second scheme was therefore drawn up. by the contractor and the method finally longitudinal beam act as one support during men servicing them, the mast was enclosed emergency cat ladder with rest platforms. any of the first three internal platform levels. This gave more calculable design conditions adopted was to introduce a hydraulic flow jacking at the centre of pressure of their jacks. in electrically translucent, cylindrical glass This framework which had also been designed Doorways were also formed in the shell to during jacking. Results of research and control valve into each of the six hydraulic The resulting beam system is very simple, fibre reinforced plastic cladding 1.52 m in to accommodate the aerial mast and to guide give access to these platforms. development work on a jacking system for lines to the individual jacking points. When being basically a pair of simply supported this application led to this scheme being calibrated and located to their best advantage beams in the east-west direction of each adopted as the basis of final design and these valves will maintain a uniform flow of building, each carrying two cross-beams, pre-site planning. Fig. 5 right hydraulic fluid regardless of varying pressures with the party wall and two gable beams The aerial mast partially assembled during The depth of beam was, for practical reasons, at each side of the valve. As used, they spanning basically onto the supporting piers. trial erection (Photo: British Steel kept within the cellar depths below ground ensured that there would be a flow in all lines, Free rotation is allowed to a large degree by Corporation. Teesside Photographic Unit) floor and became 1.98 m maximum. not simply the line with least resistance, the the supporting jacks.

As the final structure is also the jacked structure, deformations within each building were less during jacking than at completion. The junction of the two buildings is the critical point during jacking, due to the possible effects of variation in level between jacking points. Owing to the flexible nature Fig. 6 below t*B Of otl of the timber frame this possible distortion Lift cage and internal platforms (Photo OAACIO AMO n*o **« 70 Ctots was considered acceptable, within specified Geoff Rooke) tolerances, on the variation in level from datum. The area of each pier had. for practical purposes, to be 1.83 m square. They were formed by hand excavation down to bedrock 5 some 7.6 m below. Their exact location, following basic positioning from planning requirements, had to provide an off-set from the jacking beams in order that excavated material could be removed, and sufficient area off which to jack, as there were a maximum of nine jacks on any one pier. •fcp //ttvcArts tfe*rrcAL toeAr/o/v or ufr/tAt jAucf. The two vertical supports on the party wall line could not be 1.83 m square due to the circulation requirements beneath, the one on the north facade being restricted to 0.76 m x Fig. 6 0.46 m. At this position the jacks were on Section AA. showing supporting structure before lifting operation temporary supports founded on bedrock within the base excavation. In the maximum exposed condition, during the main contract when the site excavation down HYDRAULIC CIRCUIT to rock isolates the building, it will be approximately 21.3 m to the highest point JACK GROUPS HYDRAULIC SUPPLY UNIT from the excavated level. The pier sizes and positions are ideal for stability during this

BODO p.n time. The contract work

Flow control vel The work on site started on 11 November 1 970 VFS 1-300 30O0 p and was executed in seven principal stages, as follows:

Positive displacement 1 Internal bracing and shoring Dump EL 75 g 0 m at 960 rym up 4300p 2 Demolition of adjacent properties

FUM relief valve 3 Stage underpinning and casting of TO502-1 to 3000 p.* supporting beams, in four phases 4 Stage excavation and casting of final 3 h p l4SOr p m. TO PIER 3 motor TO Hlfctt 4 6 HQ TOTAL JACK vertical supports in four phases GROUPS 4 MANIFOLDS 277 cu me./min mai AS ABOVE 5 Stage jacking and extension to piers Theoretical max. rat* ot lift ro PIER 9 6 Removal of jacks and final underpinning 7 Final casting of ground floor slabs. The internal shoring and bracing was

Calculated Actual Recorded installed prior to demolition due to the more PbK Nfl Jacks Total area Flow of tack! ratio toad kip* pre** 1*4.1 load kips preea p.**. exposed condition which the demolition 1 8M V4B8 388 2480 298 2000 creates. The bracing of The Wellington -ri - 3 8W M8-8 194$ 394 2850 394 2650 4 9M 1872 443 2850 393 2350 consists of two cross-braced steel towers for 5*6 7L 72 t 179 2480 159 2200 the full height, giving resistance to lateral 1910 142 230O a 5 „ 7*8 6L 6TB 118 418 2500 loads only. V 9 9M 167 2 tt# 449 2680 KEY PLAN OF PIERS Spar, P L U ( G E Total. T3L .MM 7*50 1949 k 1604k In Sinclair's the ground floor crosswalls and gable wall openings only were cross-braced and dead shored. The external walls were tied at ground floor level across the building's Fig.7 above Fig. 7 width during the 1.98m deep underpinning GPO platforms (Photo Geoff Rooke) Hydraulic circuit and plan of piers of the Shambles' facade to give stability to the brickwork in this temporary condition. The temporary change of external environ• 4 ment during the course of the lifting and main contracts required the building to be fully braced. This bracing was installed as the H-II6 o first operation and is internal, as it had to be I07 5 •in lifted along with the building. Sinclair's, although not in such a poor structural condition as The Wellington, relied -• upon the Victoria Street terrace of buildings for lateral stability, its ground floor having no SO iI cross walls and the Victoria Street gable wall -I3I O I26 0 being largely window and doors. All ground floor openings under cross walls at 1st floor level, and the window and door openings in III the Victoria Street gable, were cross-braced and dead shored off the jacking beams. I—I—(—I—I—\—\—I—r—I—1 The contractor, Pynford Midlands Ltd., was July AMU S*tM Do Nov 0»c J»n Frt M»i Apr M.v J«n. l l v v chosen at the initial design stage in order that full advantage could be taken of their experience in the specialized field of under• Fig. 8 pinning, jacking and moving of buildings. Plot of predicted monthly wind velocities MARKET STREET The planning as described dictated the possible maximum depths for horizontal structure and the basic number and positions of vertical supports down to bedrock, for the Fig. 9 right r permanent works. First four natural vibration mode shapes of Mode Number 1 Fig. 3 The premise was made that the final structure the tower Frequency Hi 1)22 0 58 a HI. 183 Plan of Market Place Development would be the structure used during jacking, and on that basis, the contractors were Turret nantly wind loaded and likely to be sensitive to maximum gust windspeed predicted by the asked what their requirements for temporary At the top of the tower an enclosed turret wind gust fluctuations. Since the nature of estimated extreme gust distribution was 46 works would be. The contractor indicated will house outside broadcast dish aerials wind loading is known to be highly variable, m/s. as indicated by the basic windspeed that this principle would in many instances and associated equipment. It was designed it followed that the estimation and description map in CP3: Chapter 5: Part 2: 1970. require underpinning depths far in excess of to be constructed after the aerial mast had of the wind forces, and the prediction of the Dynamic analysis procedure normal practice, and considered the use of a been brought into service. The structure resulting structural performance, could be The calculation of the structural responses, maximum underpinning beam depth in the forms a collar around the tower so that only best assessed by statistical design procedures. i.e. bending moments, direct forces, deflec• order of 0.9 m as more usual, and more unbalanced live loads generate horizontal Furthermore, the possible sensitivity of the tions, etc.. of the Emley Moor tower due to feasible. The underpinning beams would shear forces in the tower wall. It consists of tower to windspeed fluctuations suggested a the action of wind drag forces, was carried then be used to jack the buildings against 20 steel trusses, placed radially and cantilever- statistical-dynamic, ultimate design proced• out using a statistical, dynamic analysis existing foundations and cellar walls and. ing from a concrete compression ring and a ure, rather than a quasi-static approach. It has procedure. This procedure has been described where these were not sufficient, against 1 steel plate tension ring. The roof is carried been shown * that the more usual code type in more detail elsewhere' 2 but is outlined temporary 'high' level pad foundations. by steel beams supported by mullions carried design based on a windspeed of return period briefly as follows: This principle of jacking was also consistent at the ends of the trusses. The roof and floor equal to the design life can lead to inconsis• with standard practice, giving foundation are both of in situ concrete cast on permanent tent results for this kind of structure, since the 1 The wind velocity is assumed to be com• pressures during jacking consistent with the shuttering. The face is clad with insulated risk of failure is not logically included in the posed of a steady, mean component and a pre-underpinning conditions, this being aluminium sandwich panels and the soffit is design process and the resulting actual load superimposed randomly fluctuating com• achieved by correct jack distribution. also clad in aluminium. The basic dimensions factors against the assumed 'failure conditions' ponent to represent the gustiness. The total dead load of the existing Wellington of the structure were determined by the need will not only be different according to the 2 The steady, mean component is the design structure was calculated as 81 tonnes, with to provide 1.8 m square windows so that real exposure conditions of the site, but will mean hourly windspeed obtained from the the new supporting structure giving a total dish aerials of that diameter could be used in also vary throughout the structure. estimated extreme windspeed distribution of 149 tonnes to be lifted. The maximum outside broadcast links. Spectrafloat glass The decision to use a statistical-dynamic, with a probability of occurrence chosen to allowable number of supports to the final was chosen for the windows to reduce solar ultimate design procedure is particularly gain. The client carried out tests to ensure appropriate in the case of a tall concrete structure under The Wellington was six. and calculations showed that the preferred under• that this glass would not degrade the aerial tower, where the stresses in the shaft are not 330 0 performance. To maintain the temperature linearly related to variations in the wind pinning beam depth was suitable for the final within the range which can be tolerated both forces, due to the effect of the high precom- design conditions. by personnel and equipment, heating and pression in the tower shaft under self weight. The total dead load of Sinclair's existing ventilating equipment is housed between the Additional design checks were made, however, structure was calculated as 31 8 tonnes which,

trusses beneath the floor. to establish the working load stresses and to ZM 3 with the new supporting structure, gave 712 compare the results with traditional design tonnes total to be lifted. The maximum Lightning protection methods. ••••IT ITffEfl allowable number of piers to the final structure Four of the vertical reinforcement rods were under Sinclair's was four, giving a maximum welded continuously through the height of Meteorological investigation Fig. 4 span of 13.7 m. The preferred underpinning the tower to provide the down conductors for The first problem in the design procedure was Market Place Development: plan below ground beam depth was not suitable for the final the lightning protection system. External to establish an adequate description of the design conditions. The contractor therefore copper bands around the tower at 91.1 82 and wind structure at the site in terms of the proposed that the final structure under The Sinclair'* Oyster Bar Old Wellington Inn 274 m are connected to the down conductors appropriate windspeed profiles and other Working load Icooal - sialic Wellington only should be used during jacking and all steelwork and doors are bonded to the ground roughness parameters required to and that standard depth jacking beams and system. The aerial mast has lightning finials define the gustiness of the wind, and to obtain standard jacking procedure be used under on top. a steel section of cladding at the working load - dynamic estimates of the distributions of both extreme Sinclair's. This meant introducing the final change in section, and copper bands at the and regularly occurring windspeeds. supporting beams, where required in addition mid-height of each section. The system is A statistical analysis was made of windspeed Ultimate lead dynamic to the jacking beams, into the space which earthed by four probes driven outside of the data recorded at several meteorological would be provided by the building being tower. stations close enough to Emley Moor to be lifted 1.46 m above its original position. The Other provisions considered representative of the general wind remaining supports down to bedrock were Electrical control gear for the tower lighting, climate and suitable for the assessment of finally to be installed and pinned to the lifted power, telephone and lift is accommodated conditions likely to be encountered at the site. structure. The first scheme was based upon in a room within the base. A separate room is The available windspeed data was of varied this principle. provided to house GPO transmitting equip• quality and duration but allowed fairly After finalizing this preliminary scheme, ment in the base of the tower. reliable predictions to be made of monthly considerably more information concerning the Other transmitting equipment is housed in and annual extreme mean hourly and development as a whole was available, and the buildings remote from the site. Feeders to the maximum gust windspeeds for the site at establishment of the required contract time, aerials run underground to the tower perimeter various return intervals (Fig. 8). Windspeed together with additional items of work which and from there in a concrete duct to the 0 800-U)1 1600.i03 frequency distributions required for the J Sl.g. had to be carried out in that time, necessitated central steel lift cage. consideration of functional design require• Bending moment! LtNml a review of the construction sequence and I I Stag. 3 General design considerations ments and problems associated with fatigue programme. From considerations of the size and general Fig. 10 were also estimated, but with less confidence A survey of the buildings was also now avail• proportions of the structure it was clear that Distribution of bending moments Fig. 5 than for the extreme windspeeds. able, which showed that the inner line of 8 the Emley Moor tower would be predomi• Sinclair's and The Wellington underpinning stages As a comparison check, the once in 50 years cellar walls was well within the superstructure suit the particular design requirement. The The structural damping values assumed for shedding of vortices from the various wind forces due to the design windspeed are the various dynamic design conditions for the cylindrical portions of the structure. The raising applied to the structure in the normal manner, tower are given below for the lowest modes; Although vortex shedding over part of the using appropriate force coefficients and damping was allowed to increase for higher concrete shaft was theoretically possible, of The taking account of windspeed variation with modes. consideration of the influences of shaft taper, height. The resulting bending moments, Concrete shaft 0.01 - 0.02 Critical the turret and end effects at the shaft head Wellington Inn direct forces and deflections are the mean Steel aerial mast 0.005 - 0.01 indicated that shedding would not be well responses of the structure. The total probable peak (ultimate) bending correlated and cross-wind oscillations, if any, 3 The structure is assumed to vibrate about moment distribution for the tower is shown would be relatively insignificant. The more John Charge the mean deflected position due to the action in Fig. 10. flexible steel aerial mast was expected to be more prone to aerodynamic instability, of the fluctuating component of the wind, and Working load design particularly in view of the lower structural an analysis is made to obtain the natural mode To ensure that permissible material stresses Historical background damping inherent in the system. Furthermore, shapes and frequencies of vibration. are not exceeded under working load 'When Queen Elizabeth I came to the throne due to the operational requirements of the 4 The random nature of the fluctuating gust conditions, and to satisfy functional design in 1558. this building, now known as The aerials themselves it was important to ensure Wellington Inn, was 230 years old. Long live component and the vertical distribution of requirements, a full dynamic analysis was wind gusts over the structure are assumed to carried out using the once in 50 years mean the absence of regularly occurring, large Queen Elizabeth II.' This laconic claim appears amplitude oscillations of the mast. on a poster on the outside wall of The be adequately represented by Davenport's hourly windspeed. After the dynamic behav• 3 Investigation of the vibratory behaviour of the Wellington Inn. Documentary evidence shows cross-spectrum of longitudinal turbulence . iour of the structure had been established, it was found possible to 'factor down' the mast showed that the natural frequencies at it to have been built in 1462 as three shops 5 The dynamic contributions to the bending ultimate load responses, i.e. moments, forces which vortex shedding effects would be most and dwellings, part of the meat market at the moments, direct forces deflections, etc. are and deflections, for the working load designs. significant were 0.58 and 1.83 Hz, correspond• centre of old Manchester, then known as evaluated using standard random vibration The wind loads acting on the tower were also ing to modes 2 and 4 respectively, of the The Flesh Shambles. methods, the dynamic response value obtained derived from BRS Digests 99 and 101, and complete structure. The inn was the birthplace of John Byrom in being the largest peak value likely to occur later from CP3: Chapter 5: Part 2: 1970. and A series of wind tunnel tests was performed 1692, author of Christians Awake and during the design wind storm. applied as static forces for working load to study the aerodynamic stability of the inventor of a phonetic shorthand, and was 6 For a linear structure, the total design value design comparisons using a building life aerial mast and the effectiveness of spoilers said to have been used as a recruiting office of any response quantity is then obtained by factor (S,) = 1.0. in suppressing any excitation. The tests were by Bonnie Prince Charlie during the 1745 direct superposition of the mean and peak The values for the drag coefficients used in carried out at the National Physical Laboratory Jacobite rebellion. fluctuating components. 4 the ultimate load analyses were retained for under the direction of Mr. D. E. Walshe using When first licensed as an inn in 1830, it was Ultimate load design the working load design checks. The distribu• an aeroelastic model of the aerial mast called The Vintners Arms. It is now owned For the overall design for structural safety of tion of working load bending moments over mounted in the atmospheric wind tunnel by Bass Charrington and is the only timber the tower it was decided to accept a 1% risk the tower is also shown in Fig. 10 for (Fig. 11). the model being designed so that box-framed building in Manchester. Fig. 1 that the design windspeed would be exceeded comparison with the ultimate load moments. the fundamental and second modes of the The larger part of Sinclair's Oyster Bar, Bowens: The Wellington Inn in the late 1 9th century in a period of 50 years, equivalent to a design model were representative of the expected furthest from The Wellington, dates back to the wind return period of 5000 years. The Aerodynamic stability of aerial mast full-scale mast behaviour in modes 2 and 4 1 5th Century. Known as John Shaw's Punch- resulting extreme mean hourly design wind- In addition to considerations of the effects of respectively. House in the 18th Century, it was a regular speed estimated from the calculated extreme wind drag, the circular plan shape and very meeting place for the cotton merchants of Fig. 2 value distribution was 36 m/s at ground level, slender proportions of the tower made it Fig. 11 Lancashire. The part adjoining The Wellington The Wellington Inn and Sinclair's Oyster Bar before raising (Photo : Stan Parkinson) the variation with heignt being taken to be necessary to study the aerodynamic stability Model of the aerial mast in the wind tunnel was only built in 1 925. represented by the £ power law. A partial of the tower as influenced by fluctuating (Photo by courtesy of the National Physical load factor of unity was taken for the ultimate aerodynamic forces that may result from the Laboratory) Both buildings had remarkable escapes from load design at this extreme wind condition. the extensive bombing in the area during the last war, when such buildings as The Bull's The steel aerial mast at the top of the tower is Head, outside of which once stood the stocks, essentially a structural appendage, which may / and The Slip Inn, were destroyed, leaving only in principle have a different design classifica• this terrace of early buildings remaining from tion to the concrete tower. Considerations of the old centre of Manchester. the function of the aerial mast and the *2 The Wellington Inn was scheduled as an economic consequences of failure, however, ancient monument by the then MPBW, now led to a comparable design basis for the entire the DOE. and Sinclair's was listed as of structure. historic interest. This being the case, the The tower structure was analyzed for this and present development had their retention as other wind loading conditions of interest in the focal point of the scheme. the drag direction, using a static and non- The development and planning deterministic dynamic numerical procedure, The development is by CWT Developments. all computations being performed on a CDC (Manchester) Ltd., a subsidiary of Central & 6600 computer. In the computer program, the District Properties Ltd., in conjunction with tower was represented by an assembly of one- Manchester Corporation. It covers 2 hectares, dimensional beam-column elements inter• will cost £10m, and will contain shops, offices, connected at nodal points, utilizing a lumped two supermarkets, car parking for 700 cars, mass idealization for the dynamic analysis. and includes a pedestrian walk system In calculating the structural responses the designed to link the development on both secondary effects resulting from the elastic I sides of Deansgate with future surrounding deformation of the structure were included in developments and with Market Street, which the analysis and the effect of cracking of the is to be pedestrianized. The Wellington Inn concrete under the extreme design load and Sinclair's Oyster Bar are situated in the checked separately. centre of the east side of the development. The drag coefficients were selected on the I. An underground road will service the entire basis of the high Reynolds Number involved : scheme on the east side which, due to the Circular tower and mast sections 0.7 road systems surrounding the development Turret structure 1.0 and overall planning, has only one available Mast sections with helical strakes 1.3 entrance and exit position. The Wellington I The first four natural vibration mode shapes and Sinclair's lie in a direct line with the new - and frequencies obtained from the frequency- \ access position and are consequently above The largest span of new supporting structure The supporting beam positions are dictated mode analysis, and shown in Fig. 9, illustrate the best service road position. over the service road is 13.7 m which could by the existing ground floor vertical structure an interesting feature of the Emley Moor As previously mentioned, the pedestrian walk be accommodated within the available depth. layout, and are generally central under the tower in that the second and fourth modes are system is designed to link Market Street with The decision to jack the buildings to the new mean centreline of the existing ground floor essentially motions of the aerial mast portion. the upper levels of the scheme. This planning levels and span over the service road was supports and the new supports. These beams It was found in fact that these modes of requirement necessitates a change in level of therefore accepted, being the only fully are carried on eight 'piers' founded on vibration corresponded very closely to the 1.46 m to the old buildings being retained, in integrated and uncompromising solution to bedrock, the number and basic positions first and second modes respectively of the order that their integration into the new the many requirements. This was to be carried being fixed by the underground service road aerial mast alone. This clearly indicated that immediate environment can be achieved. out prior to the main contract. beneath Sinclair's and the access stairs and the fundamental mode of the tower, although The required service road levels dictated by cellars beneath The Wellington. The development providing the predominant contribution to the new ground floor levels and general of the structural scheme The Wellington, although not obtaining the dynamic stresses of the concrete shaft, construction depths, combined with a clear The planning requirements leading to the physical support from the adjacent buildings, would not be sufficient to represent the height requirement of 5.1 m in the road, gave jacking up and spanning of the buildings as was sheltered by them. Its structural condition overall oscillatory behaviour. Indeed, the a possible construction depth of 2.44 m under described were the major considerations in is very poor, particularly in respect of its second mode provided the most important \ the buildings. design. stability. contribution to the stresses in the aerial mast. Although there was evidence of excitation of the mast within the concrete tower. It factor) is plotted for the Emley Moor founda• each cylinder at both frequencies, pronounced appeared that such devices could be designed tion in Fig. 1 3. The foundation dimensions instability occurred only in the fundamental to provide sufficient damping to effectively were chosen so that: mode, due to excitation of the upper cylinder reduce the mast oscillations resulting from (a) Under working load conditions the within the critical windspeed range. This vortex excitation. In the event, however, it was pressure under the windward toe is zero. condition produced regular and well main• found impossible in the time available to (b) A load factor greater than 2 against tained oscillations and resulted in the largest ensure that the theoretical performance of overturning is achieved with a maximum amplitudes. It was found, however, that the the dampers would be realized in practice. bearing pressure under the leeward toe addition of helical strakes to the top third of Since construction, the aerial mast has been 2 of 1190 kN/m . the upper cylinder suppressed this instability instrumented with anemometers and accelero- to an acceptable level. meters in order that the actual vibratory The bending and torsional reinforcement was determined, after computer analysis, as an Investigations were also made into the behaviour of the mast may be studied, and it is hoped that data thus obtained will lead to a equivalent grid framework under ultimate possibility of increasing the damping of the conditions. aerial mast structure by means of block better understanding of full-scale structures dampers located at the support bearings of of this kind. Allowance was made in the reinforcement at Icing the base of the shaft for the foundation deformations. Experience on site had shown that severe PIAN ON FOUNDATION Concrete shaft design icing could occur and it was necessary to demonstrate that it was unlikely that large As mentioned earlier, design at ultimate load is the logical procedure for overall safety, pieces of ice could become dislodged from The main column section of the frame unit is bush hammered to form part of the external Fig. 5 particularly in view of the large precompres- the new structure. With conventional latticed 267 x 256 mm tapering to 216 mm. The wall treatment. The Russell complex. Canberra. sion resulting from the self-weight of the and guyed steel structures this has presented design allows for a reduction of 6 mm on Building 1 4 is on the right tower. Indeed the ultimate load requirements All floor units, frame units and typical balcony at times a serious hazard to the users of the three sides for bush hammering. The columns (Photo : Harry Sowden) proved to be the most onerous conditions in units and external roof beam units were cast roads and buildings adjoining the site. are reinforced with four 16 mm structural determining the vertical reinforcement in the in steel moulds. In special cases units were Although the proposed solution, having grade bars welded at each end to plates concrete shaft. cast in timber moulds where no more than mainly concrete surface and no exposed which transfer the load from the pin to the wall of the entrance lobby are two vertical The dynamic analysis of the concrete shaft and 1 2 were required. steelwork at all, was inherently more satisfac• floor units. The section was designed to cope panels representing the traditional colours of supported steelwork determined the envelope tory in this respect, the designers made every with the axial loads and moments induced by Manufacture was based on a one-day cycle. the naval flag, executed in brilliant red and bending and shear force diagrams under effort to maintain a clean contoured silhouette, the maximum eccentricity possible at the Units were lifted in the morning, the forms blue Duco paint, each with two tones of the ultimate wind imposed loadings. Additional and to avoid incorporation of any features extreme of construction and erection toler• cleaned out, checked for trueness of profile, one colour, making a vivid and interesting moments were included to allow for the which could constitute future ice traps. ances. A cage of galvanized high tensile mesh reinforcement placed and concrete poured in composition contrasting with the neutral secondary effects of eccentric dead weight Additionally, tests were conducted in the surrounded the main reinforcement in order the afternoon. The units were steam cured colours of the concrete and natural timbers in the deflected form under cracked conditions. Climatic Test Chamber of the British Aircraft to give a two hour fire rating. overnight for an average of six hours steaming used in the foyer. Corporation at Weybridge to simulate various The vertical reinforcement necessary to External balcony units sat on the projecting at peak periods. freezing and thawing conditions. Sections of provide the ultimate bending capacity was Russell 14 is a very happy addition to one of beams of the floor units with the front face The large proportion of fines and the nature GRP cladding and concrete pipe (both determined in accordance with the commonly Canberra's more important groups of buildings. bush hammered and in line with the top of of the granite used in the mix caused some 1.52 m in diameter) were used and it was used assumptions for reinforced concrete It complements the group and the sense of the frame unit. These serve as fire barriers minor problems in steel trowelling the concrete clearly demonstrated that with the structure under ultimate conditions. The governing cohesion is further emphasized by the between floors. in the forms. The suitable time for trowelling envisaged, the ice was more likely to thaw in equations for an eccentrically loaded annular extension of the existing security walls of the varied largely with weather conditions and it place than fall off in lumps. section have been expressed in a convenient 64 mm thick bush hammered blades were site to tie in with the base of the building. was found that a constant watch had to be form for design purposes by Greiner" and used for additional sun protection on the Credits Foundation design kept. they and the resulting design curves were north facade. They were attached to the frame Client: The National Capital Development 2133 m The foundation form as a reinforced concrete used as a basis for the design of the vertical units after erection by site drilling threaded Great care was exercised in supervision at the Commission. gravity annulus was adopted primarily in the reinforcement. fasteners and bolting. casting yards and the extremely high degree interests of speed, both in design and con• Architects: Collard. Clarke and Jackson. Load-bearing wall panels are used at each of finish obtained proves the worth of this struction time. The cross-sectional profile, Two reinforcement meshes, one at the outer Quantity surveyors: Rider Hunt and Partners. end of the building at typical floor levels. operation. with sloping underside surfaces to provide and the other at the inner face of the annulus, Main contractor: Mainline Constructions Pty. These are 3 m x 2.1 m x 1 50 mm and weigh adequate horizontal key to the bed-rock while were used throughout the height of the In the mam entrance to Russell 14, mounted Ltd. 3 tonnes. They are bush hammered on the minimizing the rock excavation, and with structure. The vertical reinforcement was on an armour plate glass security screen, there Precast concrete: Monler Ltd. (Canberra) external face and joints are sealed with an sloping top surfaces to increase the concrete detailed in lengths of two lifts of 4.6 m plus a is a representation of the traditional Naval elastomeric compound. They carry a 0.9 m volume without the use of formwork. is lap length, half the required amount being Fouled Anchor designed by the architect Max strip of floor loading as the end floor units are Collard. It is formed of a series of brass rods Fig. 6 5 486 m 2743m placed eccentrically to the wall springing in placed in each lift to achieve a staggered lap supported continuously on these units. The order to minimize the concrete volume distribution. of different diameters, welded and polished. Building 14 : general view external face of the floor unit edge beam is Immediately behind this screen on the rear required to provide the necessary overturning In terms of the steel area expressed as a (Photo: Harry Sowden) TYPICAL SECTION Fig. 12 resistance. The 'lozenge' section has a high percentage of the gross concrete area, a Foundation layout and section torsional strength to absorb the forces created minimum value of 0.35% was considered to be by the eccentric configuration. The general appropriate for a structure of this kind. This arrangement, including a typical cross-section, value exceeded the strength requirement at Beannn Pressuie is shown in Fig. 12. both the base and top sections while the The equations used to determine the bearing maximum value of 1.11% was reached at a pressure distribution below an annular gravity height of 1 28 m. footing, subject to an increasing overturning moment, were those developed on a previous projects. The variation of extreme bearing Fig. 14 pressure with applied moment (expressed as Foundation under construction (Photo; a proportion of the working moment - load Greaves (Photographers) Ltd.)

Jlnmale capacity annulus ot [oundaTion leinloicement oovernsi A..I * my load

ZO 2I4

Fig. 13 The variation of extreme bearing pressure and its relation to load factor 10 for the perimeter columns and internal in situ The horizontal steel was determined by GRP cladding surface spread of flame (Class 1 to BS476: columns. The construction cycle allowed for considering each section as an independent The data relating to the GRP cladding panels, Part 7). Normally this is achieved by the a lift to be completed every three or four days. ring, loaded principally by positive and and the mechanical properties assumed, are incorporation of large amounts of fire On completion of the core walls the large negative wind pressures according to the given in Table A. The design requirements retardant fillers. However, these tend to have perimeter columns were constructed, which Roshko distribution. Additional loads were were stringent and careful analysis was an adverse effect on strength and to increase 10 marked the end of the 'wet' construction. included where appropriate, arising from the required to obtain the optimum balance the variability between panels, due to the fact These were cast to their full three storey height horizontal component of the bending forces between face thickness and depth of ribbing. that the resin material is more difficult to in one pour with reinforcement left projecting due to the vertical curvature of the shaft wall. It was considered more economical to employ handle. Instead, on this project a new for the intermediate slabs to avoid horizontal The horizontal steel was detailed as closed a single skin with polyurethane foam-filled intumescent coating was applied to the inner construction joints. rings, each made up of a number of standard stiffening ribs, than to use a complete face of the panels. This coating had been developed specifically for use with glass fibre At the heads of these columns, haunchings mill lengths with a closing bar as necessary, sandwich panel. all provided in straight lengths and sprung reinforced plastics. extend 1.1 m from the face of the columns. The panels were made in GRP moulds formed into position. At the end of these haunches 230 x 230 mm from two timber master moulds. Very careful Foundation construction pockets and pins carry the precast column In the outer layer of reinforcement, the attention to panel edge details was required, Excavation for the foundations down into frames above. Tolerances on these in situ horizontal steel was placed outside the as accuracy of fit on site was important. the weathered sandstone was carried out columns in all planes were ± 3 mm. vertical steel torestrain the latterfrom springing between two mass concrete retaining walls. Quality control tests were carried out on The quality of the plasticized plywood column outwards due to the vertical curvature when This minimized the amount of excavation and 460 mm square panels formed at the same formwork and concrete mix design was con• subject to bending tension. Similarly, in order enabled ready mixed concrete trucks to time as. and in step with, the main panels. trolled strictly at all times to give a strip that to restrain pull-out tendency of the horizontal discharge the concrete directly into place. The tests included tensile strength, cross- ensured a high quality of finish. steel of the inner layer of reinforcement, the Lorry mounted pumps were used for the breaking strength, elastic modulus in bend and Concrete was placed using a series of three horizontal steel was placed outside the remainder. Fig. 14 shows the foundations resin/glass ratio. tremmies and the mix showed no sign of vertical steel. The cover at the outer face was under construction. segregation. Compaction was by internal 50 mm and, at the inner. 40 mm. The panels were required to have a very low Reinforced concrete shaft vibration. Faces were bush hammered 10 to The shaft was cast in lifts of 2.3 m using 28 days after placement and a very high Table A: GRP Panel data specialist equipment designed and developed standard of finish was achieved. While by the contractor for chimney construction. construction of the in situ slabs was proceed• Panel data UHF cladding VHP cladding The basic elements are illustrated in Fig. 15. —Bridge ing, precasting had commenced and a The steel derrick was cruciform in plan and sufficient number of units were stockpiled in No. of rings of panels 13 9 G Li-1, I I . -LLU hung from inserts cast into the concrete. A readiness for erection. ! No. of panels per ring 3 6 rigid angle ring hanging from the head of the Lower Court derrick supported the external scaffold and LG The basic ribbed floor unit is 3.7 m wide by Nominal height of ring 1.88 m 3.05 m 7 m long and weighs 6.6 tonnes. Two main the external shutters. It was also used to adjust beams span 5.94 m at 1.83 m centres with an Ring diameter 1.52 m 3.66 m the diameter of the external shutter. Two internal working platforms hung from the integral 64 mm slab. The main beams project Face thickness of panel 8 mm 1 0 mm 1.1m beyond the slab. The overall depth of the derrick and these were served by three high i Depth of stiffening ribs 6 mm 127 mm iT TO unitis320mmand the depth of the projecting speed rope guided hoists. The derrick was lifted for each new lift of concrete and from beams 254 mm. Intermediate beams between Depth of flanges 76 mm 1 27 mm the main beams span between transverse time to time both it and the working platforms beams coinciding with the window wall and No. of ribs per panel 4 4 were cut down to suit the reducing diameter of the tower. SECTION A-A corridor partition. These intermediate beams at 0.9 m centres provide for soundproofing Mechanical properties of GRP laminate (BS 2782) A single set of steel shutters was used for the the demountable partitions. whole of the shaft. The external one was Tensile strength 125 N/mm2 The main beams of the floor units sit within composed of a series of plates tensioned pockets boxed out of the core walls and on the Crushing strength 103 N/mm2 together and overlapping at intervals around precast column frame. The seating detail at the circle to take care of the variations in Cross-breaking strength 180 N/mm2 the core line was kept the same for all support diameter and taper. The internal shutter was conditions. The support pin detail at the other Elastic modulus in bend 5.5 x 103 N/mm2 sprung towards the outer by a number of high end of the unit varied in size depending on the tensile steel spirals clipped on to it. Adjust• Offices floor height, column loads being transferred ment for changing diameter and taper was through the pin. Three different pin sizes were made by interchanging sheets of different I used, 64 mm mild steel, 70 mm and 76 mm sizes (Fig. 1 6). high tensile steel. To limit the variation in diameter which the derrick had to accommodate, the bottom 23 m Insita slab Offices of the shell was cast from scaffold using ready mixed concrete and lorry mounted pumps. From 23 m up to 46 m the derrick was used TYPICAL FLOOR in conjunction with the site batching plant, but the working platforms were provided by further scaffolding. During the winter months shutters were insulated with polystyrene and the water for mixing concrete was heated. Construction continued in all weather conditions, only about 60 working hours being lost as a result Offices n Working platform of high winds and low temperatures. The full height of the tower was cast in 1 22 f • entry Hanging 8 lifts over a period of 44 weeks, the highest ^— scaffold mm rate of casting achieved being five lifts per Offices week. The concrete portion of the structure was topped out in September, 1970. 0 In all. the tower contains 7000 m3 of concrete Shutter stripping Lower r-Access tunnel platform to other buildings

SCALE ^OWOAOM FEET

GROUND FLOOR

Fig 3 Fig 4 Section through Building 14 Close-up of precast units Fig. 15 Fig. 16 and floor plans (Photo: Harry Sowden) The general arrangement of the climbing derrick and working platform Working platform (Photo: David Aldred) and 660 tonnes of reinforcement. The lowest and nine jacks were employed, three on each winds. The mast was then raised so that lifts of waM each contained approximately face of the mast, mounted on the slab at approximately 30 m projected and a steel 76 m3 of concrete and were poured at the 269 m. The capacity of each jack was 12 transition section in the cladding was fitted Building 14 rate of 9 m3/hour. The topmost lifts contained tonnes and one in each group of three was below the 1.52 m diameter GRP. The following approximately 15 m3 each and the rate of used as a working spare. All jacks were day the mast reached its final position and Russell Offices, pouring was 4 m3/hour. controlled from a central console and could brackets were bolted to each face above the The centre of the tower was set out for each be operated independently to level the load. 273 m slab. The mast was lowered back on to Canberra lift by using an autoplumb stationed at ground The lifting procedure is illustrated in Fig. 19. neoprene bearings, levelled in beneath the I level and sighting an illuminated target. By the The wire ropes were attached to a lifting brackets. III time construction reached 183 m. significant framework beneath the mast and stability was The permanent horizontal restraints at the two Mick Lewis and I solar movements could be detected and achieved by fixing rope guides to the mast at top slabs are provided by two laminated setting out was usually carried out in early the centre and top. These were removed in rubber bearings placed between the mast and Dan Ryan III I morning. Fig. 17 shows one plot which was turn as they reached the jacks. the edge of the slab on each face at both made of this movement. Guidance through the lift cage was provided levels. Load was induced into each of the III by timber skids. On the top slabs, heavy steel bearings by inflating a Freyssi flat jack placed This is an edited version of an article which iiiiiiiii!! Hoisting aerial mast rollers were provided to bear on the corners of behind it. Resin was used in the jacks and first appeared in Constructional Review. 44(2). HI i The mast was first assembled into 6.1 m the lower section of the mast and to resist they were left to harden in position. pp. 18-23. 1971. lengths outside the tower and these were wind forces. The timber skids immediately When the mast had been fixed, the ITA's •IIIIll mi i lifted by mobile crane into the central lift cage below the top slabs were strutted back to the aerial contractors raised the feeder cables and The Russell offices are located at one of the ! (Fig. 18). When the mast was complete, the concrete since they were also required to the UHF aerials came into service on 21 points of the National Triangle, the basis of till i Minimi ITA's aerial contractors fitted the UHF aerials resist wind forces. January. 1971. The lower VHF aerials and Canberra's Central Area planning. The focal and GRP cladding. GRP cladding were erected from the outside uniiii •HI li i! i II 11! i nKuluuiHI Hoisting began on 18 November, 1970 and point of the Russell group is the American minimi of the tower using a cradle running on guide "w. ,III II in i in mm The method of hoisting the mast, by means of the mast was at the top by the evening of War Memorial. Sited at one end of the group bonds. The work took three months and these minimi I 11IIII MUM;urin hydraulic jacks of Swedish origin which act 20 November. During the following two days of buildings. Building 14 dob no. A164) is mi ] aerials came into service on 21 April, 1971, on special wire rope, was developed in close the strakes were fitted to the GRP cladding an important visual component creating a just over two years from the collapse of the co-operation with the main contractor. whilst it emerged slowly through the top of climax to the group particularly when viewed original mast. The total weight to be lifted was 62 tonnes the tower. The third day was lost due to high from the Kings Avenue axis. It is also the first building of significance to be seen as the city is approached from the airport. Distant sitings Omm - 25mm Fig. 18 from points such as the proposed Parliament 5 10 15 20 I 30 The aerial mast prior to the hoisting operation House site and the opposite shore of the I I I 1 I I 1 (Photo: Geoff Rooke) eastern basin led to the design of a structure taller than the existing buildings which in no way detracts from the prominence of the War 13 30 Memorial. Fig. 1 20 00 Building 14 : Model 13-8-701 The existing Russell offices are all clad in (Photo: David Moore. Sidney) • 18 00 grey granite and their facades are fairly flat in appearance. Precast concrete frame units were chosen to form the structural envelope of Building 14, with care exercised in the choice of surface finish to ensure harmony with • 12 15 existing buildings. The strong pattern of light and shade produced by the windows being Credits recessed behind the precast frames contrasts The client for the project was the Independent with the smaller scale modelling of the 05 15 Television Authority. Permission for the adjoining buildings in the group. The recession 14-8-70) publication of this paper was obtained from of the window wall also provides sun protec• DITAIl I Mr. Howard Steele B.Sc. (Eng.). ACGI. the tion and window cleaning facilities. Director of Engineering to the Independent The building comprises 1 3 storeys, the first II oo • Television Authority. three containing offices, plant and computer Main contractor: Tileman & Co. Limited. centre with nine typical office floors above Structural steelwork sub-contractor: J. L. Eve and the main plant room on the 13th floor. 8 00 hrs BOOhr? Construction Co. Ltd. The building's users are subject to security Advice on problems of vibration and fatigue, classification and required a large number of provided by Dr. T. A. Wyatt of Imperial small offices with no false ceilings and a high College, London and the assistance received degree of acoustic privacy. In order to fulfil these requirements a rectangular plan form from the Meteorological Office at Bracknell Inulu ilipformed in matters of weather information and wind was selected 50.3 x 1 7.4 m with a central core icrvica

27.4 x 5.5 m. The core contains toilets, lifts, Pr«c*it floor unit! data, are also acknowledged. D.l.il A Fig. 17 stairs and strong rooms. A corridor surrounds Plot of solar movement at 257 m (840 ft) level SUN'S PROGRESSION References the core leading to individual offices 4.1 m Precast balcony umri (1) WYATT, T. A. The calculation of structural deep and planned on a 0.9 m module using Precast column units response. Proceedings of the CIRIA seminar demountable timber partitions. temporal ply braced on the modern design of wind-sensitive 10 12 3 4 t* Hoof untt during Precast ribbed floor units with a soffit finish ICAU FEET erection AERIAL MAST ERECTION SEQUENCE structures, 1970. Paper 6. pp. 83-93. CIRIA. straight off the steel form were selected as the 1971. most satisfactory and economical means of (2) SHEARS. M. Problems in the application fulfilling these requirements and providing a of statistical design methods. Ibid, Paper 7, pleasing and uniform ceiling finish which could pp. 95-104. CIRIA. 1971. provide easy soundproofing of partitions. (3) DAVENPORT. A.G. The response of The central core is cast in situ and provides slender line-like structures to a gusty wind. the stiffening for all lateral loads and also the

Proceedings of the Institution of Civil vertical support for the surrounding floors Precast column unit Engineers. 23 (November), pp. 389-408. which consist of precast units. The precast Service COr* well Verticil adiustment 1962. Dry pick mortar column frames to the external walls transmit 2 base pUt. tack welded to adjusting nut when levelled t'/j tceed plus I topping on (4) WALSHE. D. E. The effect of strakes and vertical loads but none of the precast elements : precast floor unit Adjusting nut with head machined shrouds on the aenoelastic stability of a model are designed to resist the transverse loads on to slight radiui U d