Evaluation of P-delta effect on the performance of high rise structure

Nowadays the increasing population of cities has increaesed the tendencey for the construction of high rise buildings. On the one hand, the fact that the behavior of the structure becomes more complex with the increasing height, on the other hand, the fact that the building reaches larger dimensions in terms of modeling and the relatively more realistic construction and evaluation of the structural analysis makes it very important. Therefore, idealizations to be used in the analysis of such structures, which have many unknown numbers and loading conditions, and the assumptions to be made to shorten the solution time become important and critical for engineering. In this context, it is clear that the P-delta effect, which can be neglected in standard structures in most cases, is effective in the behavior of high rise structures and is one of the parameters that should be evaluated in the structural analysis. The P-Delta effect is a secondary effect called a nonlinear geometric effect. Therefore, the importance of the P-Delta effect in the behavior of the structure may vary depending on the rigidity of the structure, the fragility of the structural elements, the amount of axial load, the building height, seismicity of the region or wind speed. In this study, the earthquake performance of three high-rise buildings were evaluated separately for cases where the P-Delta effect was taken into consideration and neglected. In limiting the P-Delta effect, increasing the strength of the structural system is offered as an option by codes and standards. In this study, the limitation of P-Delta effects by using different concrete strengths was investigated. The building models were analysed by assuming that they were built in an earthquake zone with moderate seismic hazard for the different situations indicated. In addition, the variation of the P-Delta effect depending on the earthquake hazard has been investigated for moderate, high and very high earthquake hazard situations. The evaluation was made on the basis of the Göreli Kat Ötelemesi Oranı, the maxsimum displacement, bending moment and shear values in the critical elements, deformation based damage limits for reinforced concrete members. Evaluation of the results shows that high rise buildings, that designed according to 2018 Turkish Building Earthquake Code, P-delta effect of the seismic behavior can be significantly higher.