Browsing by Author "HASAN, Ghadeer"
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Item EVALUATION OF MODIFIED AND EXTENDED PUSHOVER METHODS FOR RC BUILDINGS HAVING SETBACK IRREGULARITY(2022-09-12) HASAN, Ghadeer; MERTOL, Halit CenanIrregular configurations of reinforced concrete buildings were frequently identified as one of the main causes of failures during previous earthquakes. The setback irregularity which occurs due to abrupt reduction of the lateral dimension of the building at specific levels of elevation may be catastrophic for buildings having various heights. Engineers are more likely to adopt simplified nonlinear static analytical procedures such as pushover analysis when evaluating the seismic performance of reinforced concrete buildings due to its ease in application. The use of conventional pushover analysis methods provides acceptable results low-rise buildings. However, these methods do not provide sufficient results for mid- and high rise buildings whose behavior under seismic actions is not only governed by the fundamental mode shape. To overcome this problem, some advanced methods considering the effects of higher mode shapes were proposed by various researchers. However, the applicability of these methods to three dimensional high-rise buildings having setback irregularity was not addressed in the literature. In this study, a total of 6 mid- and high-rise building models having setback irregularity at various locations were analyzed using nonlinear pushover analysis methods namely the Inverted Triangular Lateral Load Pattern (TLP) according to ASCE 7-22, First Modal Shape Lateral Load Pattern (FLP), Uniform Lateral Load Pattern (ULP), Modified Upper Bound Method (MUB), and Extended Upper Bound Method (EUB), to evaluate the applicability of these methods. The results obtained using these methods were compared to the Nonlinear Time History Analysis Method (NLTHA) which provided benchmark solutions to the problems. Three of the building models had 6 stories and the other three had 12 stories. The story heights of the models were all 4.5 m at the ground story and 3.2 m for the rest of the stories. All models had four bays in both plan view directions with a typical length of 6 m each. One model of each height level was a regular building and used for comparison purposes. Other two models of each height level had setback irregularity in various locations of the elevation in one direction. The results were assessed for seismic demand variables such as lateral displacements, interstory drift ratios, and plastic hinge rotations. The EUB method also provided more accurate results of interstory drift ratios of all irregular building models compared to those of the conventional pushover analysis procedures (TLP, FLP, and ULP). Conventional pushover methods were not sufficient to predict the plastic hinge rotations at the upper stories of the 6 and 12 story building models, whereas the EUB method provided reasonable estimates of these plastic hinge rotationsfor irregular buildings.