“Review of structural irregularities on Albanian RC buildings with a case study

Abstract

Almost, all Albanian buildings are composed of masonry and reinforced concrete, and just a few of them, like industrial buildings are composed of steel. Unfortunately, the quality of building stock in this country is low in performance and not properly designed according to building codes. Considering that Albanian building code has not been updated since 1989, and many of these buildings are constructed without any structural engineering plan, there is a large presence of structural irregularities. It is of great importance to focus on structural irregularities due to the hazards they cause. Irregularities vary from the less hazard one, those of damaging structural elements, till to those of causing total collapse of buildings. As Albania is an area prone to high seismic hazard with different magnitudes, it is a must to be aware and take actions while talking about structure irregularities. Therefore, a typical residential R-C frame- building, 6 story height, was taken in evaluation through this study. This kind of building is mostly representative of latest - 90 buildings typology due to their same construction method, period and quality. The structural design model consists of irregularities such as: soft story because of difference in height and soft story due to non-presence of masonry partition walls for open space commercial purposes, poor reinforcement details, structural additions represented as heavy overhangs, semi infilled frames and short column effects. The seismic performance assessment will be displayed by analytical method consisting of iv pushover analysis, which is an easy way to explain the non-linear response of building. The results provided by pushover demand, capacity spectrum and plastic hinges formation give us a real understanding of structural behaviour. What observed from analysis shows that every structural irregularity in RC building, affect the structure by decreasing its performance level considering bearing stiffness and deformation capacity. When comparing the presence of irregularities some of the such as combination of soft story with height difference – absence of infill walls – short column due to semi infilled frames, - and overhangs, results in serios damages leading to total loss of stiffness in structure.