Effects of Soft storey Irregularity on RC building Response

Abstract

Albanian building stock is composed of reinforced concrete and masonry buildings. Most of these buildings are designed with Old Albanian Codes (KTP Codes) and some of them are constructed without any project. Considering these facts and the observations done in Albanian construction industry, presence of structural irregularities is very common in these buildings. Irregularities are weak points in the building which may cause fail of one element or total collapse of the building during an earthquake. Irregularities encountered in Albanian construction practice consist of short column, large and heavy overhangs, reinforcement details and soft story irregularity. Since Albania is a high seismic country which has been hit many times from earthquakes of different magnitudes establishes the need to study the effect of irregularities. Among all these irregularities in this study is taken in consideration the soft story effect under seismic loads in low and mid-rise buildings of Albanian construction practice. In order to get the effect of soft story irregularity in RC buildings several number of Nonlinear Static (Pushover) Analyses are done for regular frames, frames with soft story because of higher height and lack of masonry infill walls in ground story or because of the presence of both cases for the two types of structures, 3 and 6-story frames representing low and mid-rise buildings respectively. The analysis has been performed by ETABS software. The results of the analyses indicate that low and mid-rise structures with soft story irregularity due to absence of infill walls and higher height of ground story are more vulnerable during earthquakes.