EFFECT OF REDUCED MATERIALS STRENGTH DUE TO POOR EXECUTION OF CODE COMPLIANT STRUCTURE AND TO STUDY THE INCORPORATED REDUNDANCY AFTERWARD

Abstract

Pakistan is facing a population increase at a high rate. This increase in Population has urbanized many areas. Not only the people are constructing buildings, but high-rise building is a new trend, as they cover lesser area and provide maximum space to live. But current construction practices in Pakistan are not up to the mark because of poor quality control and the work is done manually keeping chances of human error which cause variation in the concrete compressive strength. This study is focused to find out the variation in the concrete compressive strength due to poor execution practices on site and its effects on overall building response. For this purpose, a case study region i.e., the Islamabad region is considered. Being the capital of Pakistan, it consists of high-rise buildings and buildings of national interest. As this is an earthquake-prone region, so it is necessary to perform a seismic Vulnerability Assessment of these high-rise buildings, influenced by the variation in material strength. Structures in the Islamabad region are designed according to the Building Code of Pakistan (BCP 2007), so this study is only focused on the code-compliant structures in the study region. Compression test results were required to study the variation in the concrete compressive strength. So, the test results from the different structural labs truly representing the region were taken. Data were organized and analyzed using MS Excel and origin Pro. An average, Standard Deviation, Upper bound, and lower bound compressive strength for various structural members were concluded. Considering the variation in Structural Members' compressive strengths, sample buildings (representing the major classes of the buildings) from the Islamabad region were modeled on CSI ETABS18. All the buildings were designed according to BCP 2007. Each structure is modeled 3 times, for design strength, for design + SD, for design - SD, and nonlinear static pushover analysis are performed on the models to get the response of the building. Results are plotted against design strength and varied strengths to study the response of the building due to the poor execution practices in the field This study will provide a general trend for the redundancy present in the code-compliant structure after variation in concrete compressive strength due to poor execution. However, Structure in field is compliant with code and have redundancy to bear the variation in compressive strength of concrete.