Building Pathologies and Acoustic Performance

The urban foot-over-bridges are part of everyday life of citizens which provide access to transportation. In Mumbai, India on September 26, 2017 a major stampede happened on a railway foot over bridge. In many cities, the old foot-over-brigades are heavily damaged which may cause a fatal accident. How can we analyse a foot-over-bridge to understand level of safety? Which NDT techniques can provide us accurate analysis? How can we make a planning for a common policy to make our cities safer? It is indeed important to investigate the damages of foot-over-bridges to make our cities safer to avoid stampede. Some of the important aspects of the investigation of these foot-over-bridges are the strength of the concrete, damages of the steel element and severity in damages in the steel connections which causes the failure. Further in this research, a case study is illustrated of railway foot-over-bridge deteriorated with passage of time. The investigation found that the foot-over-bridge was completely damaged and need an urgent demolition for the safety of the citizens.

Reinforced concrete structures present in the marine environment are subject to the chloride penetration in the different marine aggressive zones. These chlorides penetrate through the concrete cover layer and, when reach the reinforcement, create favorable conditions for the beginning of the corrosion process, leading to several problems as the progressive reduction of the mechanical strength of the reinforcement. At this point, considering the existence of port infrastructures in operation, playing a key role in trade relations between nations, this chapter presents a case study regarding chloride attacks on reinforced concrete structures present in different marine aggressive zones under natural degradation for more than 40 years. The objective of this chapter is to inform managers responsible for the maintenance and rehabilitation of these structures about the aggressiveness of chloride attacks in the context of reinforcement corrosion through a case study presentation, thus demonstrating that the lack of maintenance strategies and rehabilitation plans can lead to loss of functionality and safety of the structure, where total or partial collapses are likely to occur.

Corrosion is the most inevitable issue in the reinforced concrete structures. Assessing the corrosion resistance and corrosion rate of the rebar becomes essential to predict the service life of the structure and also to take necessary precautionary measures. This chapter discusses about the various field and laboratory techniques available to assess the corrosion resistance and corrosion rate of the steel embedded in concrete. The various experimental techniques such as half-cell potential, impressed voltage, electrical resistivity, macro cell, AC impedance, and polarization resistance tests are discussed below.

Ingression of chloride is a most devasting phenomenon in the concrete. Especially the concrete structures present at the coastal regions are highly vulnerable to the salt ingression and rebar corrosion. Therefore, it becomes essential to develop a durable cementitious composite which can withstand in the aggressive environments. Various researches and field experience have shown that the usage of blended cements can supress the ingression of chloride ions into the concrete. Blending the portland cement with the mineral additions like fly ash, ground granulated blast furnace slag, silica fume and metakaolin makes the concrete more impermeable and enhances its chloride resistance. The present chapter discusses about the possibility of improving the chloride resistance and chloride binding capacity of the concrete using various mineral additions.

Acoustic forecasting models from computational simulation (SC) has been the tool used to evaluate the acoustic behavior of the building, even before the work is done, thus enabling the reduction of post-adaptation costs. This research aims to evaluate the reliability of computational simulation by analyzing data from simulations and field measurements (MC) of 14 case studies, in relation to horizontal partition systems (SVH). For the 228 SVH data, of which 116 were for SVH-RA and 102 for SVH-RI, the comparative study showed 38% acceptability between SVH-RA measurement and simulation; and 46% for SVH-RI. This acceptability refers to the values within the ±2 dB range of the aforementioned uncertainty. The data also showed variation between SC and MC, sometimes presenting larger SC, sometimes larger MC. The predicted hypothesis was that SC would always be higher due to the ideal conditions of the simulation, which do not occur in the field. However, where situations of MC greater than SC occurred, it was deduced that deciding on the simulation means choosing to work in favor of safety, since the minimum level of the standard is projected and better results are obtained in the field. It was also verified, through variation of the input data, that the fidelity with the technical specification of the designed systems reproduces reliable values, and the opposite, results in doubtful and discrepant data. In general, the results of the comparative analysis point to the use of computer simulation as positive, since part of the percentage that is not acceptable in this study represents doubtful measurements, and therefore, the simulation is an effective predictive tool and useful in the search for acoustic quality in residential buildings.