State of Repair of Marquees on Buildings in Recife, Brazil: Case Study and Quantitative Analysis
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State of Repair of Marquees on Buildings in Recife, Brazil: Case Study and Quantitative Analysis João Ribeiro de Carvalho 1 Thiago de Oliveira Chaves 1 Eudes de Arimatea Rocha 1 Antonio Carlos de Albuquerque Melo 2 Kalline Almeida 2 Eliana Cristina Barreto Monteiro 3 ABSTRACT In Brazil, the practice of undertaking periodical repairs to buildings still unfortunately seems tenuous for owners and the technical sector proper. Since no building was designed or built to last forever, each day more buildings appear with a shorter service life due to lack of maintenance. In this sense, the marquees, isostatic structures in balance, which have little connection with the rest of the structure, become slabs quite vulnerable to the action of pathological expressions, such as corrosion, efflorescence, mildew and damp. To assess the state of repair of the marquees of the buildings in downtown Recife, a visual inspection with photographic report follow-up and later quantitative analysis of the pathological expressions found were proposed. The qualitative conservation of marquees was analyzed in three case studies that were chosen in earlier inspections because of their poor state of repair, their peculiar or representative interventions, and pathologies that would primarily allow easy access for their inspection. This paper is even more relevant when the collected data herein give a general idea of the state of repair of marquees of buildings in downtown Recife, and could be used to repair the degraded marquees, thus preventing accidents. KEYWORDS Marquee, Inspection, Pathologies, Repair. 1 Undergraduate in Civil Engineering – University of Pernambuco, Pernambuco, Brasil, [email protected] ; [email protected] ; [email protected] . 2 Currently undertaking Master’s course in Civil Construction – University of Pernambuco, Pernambuco, Brazil, [email protected] ; [email protected] . 3 PhD Professor in Civil Construction – Department of Civil Engineering at the Catholic University of Pernambuco, Pernambuco, Brazil, [email protected] João Carvalho, Thiago Chaves, Eudes Rocha, Antonio Melo, Kalline Almeida and Eliana Monteiro 1 INTRODUCTION Reinforced concrete structures not only undergo mechanical but also biological, chemical and physical actions that contribute to the deterioration of concrete and reinforcement over time. It is essential to consider in the design stage all those degradative actions involved during the structure’s service life and plan strategies for their preventive maintenance. One of the methods for analysing the quality of buildings was to undertake qualitative and quantitative studies on the group of degraded marqueemarquees. According to Castro (1994), studies on damage to buildings have been performed in several countries through public or private agencies. Among the existing structural elements, it was decided to study the state of repair and durability of the marquee, bearing in mind that this structural element is a common feature of buildings in the centre of Recife. Its role is to protect and shelter the population but because of the typical lack of care with maintenance it has a high rate of accidents. 2. INSPECTION METHODOLOGY There are many techniques involved in the inspection of concrete structures, namely detecting, identifying, assessing, characterising and monitoring the pathologies. These techniques are very valuable for control of the phenomenon, whether in preventive operations or in solving the problem. According to the parameters mentioned by Clímaco; Nepomuceno (1994), who indicate that the methods recommended for a structural appraisal must be adopted in stages in order that no problem or pathological expression goes unnoticed. The flowchart in ‘Fig. 1’ shows the routine of an inspection on the concrete structure. Preliminary Checklist Detailed Diagnosis Qualitative Study & Inspection Inspection Quantitative Study Figure 1. – Activities involved in the inspection routine. Qualitative studies of the state of repair of the marquees were performed on three (3) different locations, each being a separate case study (investigation); these were chosen from a set of previously maintained marquees because they were in a poor state of repair, and with pathological expressions of interest to the overall study, or peculiar or representative interventions that had been put in place following previously prescribed maintenance actions. The case study of the marquee on Marquês de Olinda Avenue was also performed; this structure had partially collapsed in February, 2009 and this accident had repercussion in the media since it occurred close to the city’s carnival centre (Marco Zero do Recife) , and only two days following the end of the yearly festivities. By adopting a predefined inspection methodology, a survey was carried out along the main streets in the centre of Recife and 121 marquees were inspected to comprise the sample of the quantitative study, and on which was based the state of repair of marquees in Recife. The marquees chosen from the sample space are located in the busiest pedestrian streets, since in those streets there is greater risk to causing an accident of great proportions given the possibility of a structural collapse. In this research study, the inspection methods were based on those studies carried out by Jordy (2006), given the success achieved from results of inspection of marquees in the city of Rio de 2 XII DBMC, Porto, PORTUGAL, 2011 State of Repair of Marquees on Buildings in Recife, Brazil Janeiro. The work of Jordy (2006) offered a inspection methodology typically focusing on the inspection of marquees. Accordingly, some of the main points described in this methodology were adopted, and in which the essential elements for defining the state of repair of the structure were given,, such as: location and description of marquee, geometrical survey, general waterproofing status, status of the drainage system, hazards and, the reinforcement layout. 3 PROGNOSIS AND SOLUTION OF CASE STUDIES The aim of the study that is described in this paper was to quantify the recurrence of pathological expressions, maintenance and repair interventions completed and acquire any other relevant data in regard to the condition state of the marquees. Such information provided a general idea of their state of repair that was in fact referenced by quite a representative sample size. The criterion for choosing the structures for analysis was based on: (i) the potential risk that the marquees represented for the population in case of collapse; (ii) accessibility to parts of the marquee; (iii) its environmental zone, and; (iv) the level of pathological expressions that were evident. Four case studies have been carried out where they had construction failures, concrete pathologies and faults referring to earlier repairs. 3.1 Case Study 1 (M1) The first case study performed was on a marquee located on Bom Jesus Street in the neighbourhood of Recife Antigo, Recife. The marquee, forming part of the first floor slab, is 100 metres long, 1.5 metres wide, with an average thickness of 12.5 cm and is located at a height of 2.80 metres above ground level. This marquee was built about forty-three years earlier and is included in the concrete environmental aggressivity class III (standard NBR 6118 (2007)) and had had no routine maintenance. Consequently various different pathological expressions were evident. For example, these included: dampness (moisture uptake); crumbling of concrete and of the protective coating; longitudinal and transversal cracking; exposed and corroded reinforcement. For the marquee in question (M1), the side view of which is shown in ‘Fig. 2’, the reinforcement of the support beam can been seen exposed at several points. Shown in ‘Fig 3’ an area of the marquee where exposed reinforcement is evident. Figure 2. – Side view of M1 Figure 3. – Measuring M1’s rated cover It is apparent, therefore, that it is advisable to repair marquee M1 as an emergency corrective action, in which the defects evident in respect to waterproofing, drainage and structural repair will be corrected. 3.2 Case Study 2 (M2) The second marquee investigated (M2) located in the Boa Vista neighbourhood, was supported by beams and was located in a zone of environmental aggressivity of class II. This marquee showed XII DBMC, Porto, PORTUGAL, 2011 3 João Carvalho, Thiago Chaves, Eudes Rocha, Antonio Melo, Kalline Almeida and Eliana Monteiro signs of repair intervention to its’ structure but had not undergone any routine preventive maintenance. On the date of inspection of marquee M2 the following pathologies were evident: dampness; vegetation growth in the top part of the marquee; a break in a portion of the marquee due to the presence of a lamp post; an opening in the slab through which rainwater drainage pipes ran from the roof; and transversal cracking in the slab. The stains from the dampness of the slab were caused by blocked drainpipes in the marquee, the pipes being used to drain rainwater from the roof. Dampness was also likely caused and by flaws in the waterproofing, mainly in the areas close to the drainage pipe ‘Fig. 4’. It was also found that an intervention to place a public lamp post in M2, part of which was demolished with no planning, suppressed existing reinforcement bars and was not reinforced. This caused structural damages to the marquee, giving rise to cracks around the affected area, with crosswise and radial clefts around the demolished area ‘Fig. 5’. Figure 4. – M2 pipes and Figure 5. – Cut made in M2 Figure 6. – Vegetation damp stains for a lamp post growing out of M2 Another pathology found when inspecting the marquee was the proliferation of vegetation growth and the growth of fungi; lack of maintenance aggravates such situations. This problem is quite common among marquees in Recife and cities with high rates of relative humidity. As well, the presence of a large number of birds also exacerbates the situation and. Birds, namely pigeons, for example, are responsible for carrying seeds that are dropped onto the slab surfaces, where plants and fungi begin to grow, as shown in ‘Fig.