A1 Administrative matters related to the research Following the publication in the Official Journal of European Communities C series n° 170/20 June 14 1996 of the “Notice of public contract - Open procedure” for a research activity aimed at “providing the scientific basis for harmonised definition of models for determining the actions of snow applied to the structural parts of construction works”, the present research group co-ordinated by Prof. Sanpaolesi - University of Pisa (IT), on July 1996 presented a tender referring to the technical specification document “General invitation to tender n° 96/C 170/13”. The research group comprises the following institutions: 1. BUILDING RESEARCH ESTABLISHMENT LTD , CONSTRUCTION DIVISION (UNITED KINGDOM ) 2. CSTB , CENTRE DE RECHERCHE DE NANTES (FRANCE ) 3. ECOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE , (SWITZERLAND ) 4. ISMES STRUCTURE ENGINEERING DEPARTMENT (ITALY ) 5. JOINT RESEARCH CENTRE, ISIS (EU ) 6. SINTEF , CIVIL AND ENVIRONMENTAL ENGINEERING (NORWAY ) 7. UNIVERSITY OF LEIPZIG, INSTITUTE OF CONCRETE DESIGN (GERMANY ) 8. UNIVERSITY OF PISA , DEPARTMENT OF STRUCTURAL ENGINEERING (ITALY ) In the tender the research work was divided into two consecutive phases. Each phase deals with two specific items and technical co-ordination of the research activity for each item is carried out by a member of the research group: Phase I task Ia: “Development of models for the determination of snow loads on the ground” Co-ordinator Dr. Gränzer (University of Leipzig - DE); task Ib: “Development of models for exceptional snow loads” Co-ordinator Mr. Sims (BRE- UK); Phase II task IIc: “Definition of criteria to be adopted for serviceability loads” Co-ordinator Prof. Holand (SINTEF - N); task IId: “Analytical study for the definition of shape coefficients” Co-ordinator Mr. Stiefel (EPFL - CH); The contract (banco n° 500269) between the European Commission and the research group was signed on Dec. 16 1996. Prof. Sanpaolesi signed the contract as Co-ordinator of the group, on behalf of all participant. This contract covers only phase I of the research. During the reference period, fixed as 14 months after the signature, the group has strictly followed the administrative, formal and technical indications enclosed in the contract and in its annexes. Technical specifications were given in Annexe III of the contract. The research activity started on Feb. 1997, the interim report and final report were required to be sent to the Commission within 9 months and 12 months respectively after the signature of the contract. As a result of a delay in starting the works the Co-ordinator, on behalf of the Partners, asked DGIII for an extension of three months to the contract duration. This was approved in the 55 letter to the Co-ordinator from the Commission dated 20 June 1997 and article two of the contract was amended as follows: "La tâche confiée au contractant devra être accomplie au plus tard 17 mois à compter de la date de signature du contrat (phase I)". Therefore the timetable for the submission of official deliverables iwas as follows: - interim report 16th December 1997; - draft final report 16th March 1998. The interim report was submitted to the Commission on December 11 1997, according to the revised timetable. Now the final report is being submitted to the Commission in accordance to the timetable. Only in the case of comments coming from the Commission, within one month after the submission, will the group have one further month in order to revise the document taking into account the Commission’s observations. To date seven meetings among Partners have taken place, - in Brussels on 12 th February 1997; - in Zurich on 29 th April 1997; - in Ispra on 3 rd /4 th July 1997 (with the presence of National Technical Contacts); - in Pisa on 19 th /20 th September 1997 (with the presence of Mr. Jean); - in Frankfurt on 11 th 12 th December 1997; - in Brussels on 29 th January 1998; - in Oslo on 3 rd and 4 th March 1998. The development of the research work has been completely in accordance with all requirements of the contract and no particular difficulties have been encountered during the development of the study. An information and communication protocol between Partners was agreed. Both fax and e-mail are used. When e-mail was used Partners were asked to acknowledge receipt of message within 24 hours otherwise non-receipt was assumed. The standard for documents was WORD6 and spreadsheets is EXCEL5 operating in the Microsoft Windows environment. All Partners carried out the work in accordance with the existing QA procedures at their respective organisations. For the present research work a liaison with CEN/TC/250/SC1 has been established. This liaison was approved by SC1 with the resolution n° 76 dated May the 23 rd 1997. According to the Annexe 2 to the tender each participant had contacts with the National Meteorological Offices of specific European countries, in order to collect snow data and to receive their comments. As for the NMO, contacts were made , according to Chapter 4 of the tender, with National Technical Contacts, who were also formally invited to the meeting held in Ispra on 4 th of July 1997. 56 All financial aspects have been regularly fulfilled by the contractor and by the Commission in respect of terms foreseen by the contract. A2 Snow loads/depths data base / density models This Annex presents summary information on the sources, the nature and the availability of snow data in each country. A2.1 Austria The annual (partially monthly) maxima of snow depth (m), measured at 7 o’clock in the morning, were purchased, for this contract, from the Austrian Meteorological Office. In Austria the snow depth is measured by means of a ruler. There were 2-4 measurements per station and the final value of snow depth is the mean of these. Period of measurements: 1947 – 1997. Total number of stations is 160. The minimum period of observations is 30 years. 80 stations have a record period of 50 years. All data were available in electronic format as ASCII data. Additional information for the stations is: the number (according to the Austrian meteorological office), geographical co-ordinates, and altitude. A2.2 Belgium and Luxembourg Thirteen meteorological stations were selected in Belgium and one in Luxembourg. Unfortunately, there is only a short period available on computer (12 years, from 1985 to 1996), but there are several complete samples from the data used by R. Sneyer (data from 1947 to 1965). 6 stations have an altitude lower than 100 m, 3 stations have an altitude included between 100 and 200 m, 3 stations have an altitude included between 200 and 500 m and 2 have an altitude greater than 500 m. The statistical sample for each station is constituted by the annual maximum of daily maximum snow depths. For several stations there are some years without snow; a year is considered without snow, if the annual maximum snow depth is lower than 1 cm. To evaluate snow load from snow depth, an average density of 1,5 kN/m 3 was used. A2.3 Denmark The Danish Meteorological Institute records snow depth and snow cover on a routine basis. Simultaneous measurements of snow density and relevant climatic parameters were performed for the period 1971-80 at one station in Southern Jutland. To estimate water equivalents from other known meteorological parameters, a simulation model was used, that simulates the development of a snowpack. Simulations have been made for seven synoptic stations in the period 1971 – 79. Unfortunately, the detailed data have been lost and are not available for further analyses. However work on snow loads is in progress in Denmark, but results were not available for incorporation in Phase I of this research. 57 A2.4 Eire and United Kingdom Measurements of snow depth are taken by ruler at 0900 GMT and recorded to the nearest whole centimetre on a daily basis, whenever snow is lying on the ground. Prior to 1971 measurements were made to the nearest inch. This alters the discrimination in recorded snow depth values for stations with records starting before 1971. Water equivalent of lying snow is recorded at some stations in the UK, also at 0900GMT, on days when the total snow depth is at least 2cm. The average snow water equivalent value from at least three samples is recorded along with the corresponding depth of snow cover. Water equivalent records for Eire are not available. The computer records of snow depth data for the network of 14 synoptic stations in Eire were purchased from Met Eirreann. All these stations have records in excess of 30 years which are quality checked. The UK Met Office supplies data without quality assurance. A preliminary pilot study for a small region of the UK revealed some stations with a significant number of errors in the data. Given the relatively small data set for the UK and the type of errors found, the inclusion of erroneous data would significantly affect results. This must have occurred during the previous determination of characteristic snow loads in the UK and therefore questions the reliability of snow loads given in both the UK snow loading standard BS6399 Part 3 and in Annex A of ENV 1991-2-3 [Ref. 1]. Hence data quality is particularly important for UK and all data therefore had to undergo a thorough programme of quality checking prior to analysis. Checking programs developed by BRE highlighted potential errors where there were exceptionally large snow depths or large differences in snow depth on consecutive days. These data were then checked against the original daily records in the Archive and also against alternative sources of information. Many transcription errors were discovered and corrected.