A Comparative study on nonlinear modeling of structural walls

Dursun, Süleyman Eren
The need for tall buildings increases day by day because of many reasons such as increase in population. Representing the behavior of tall buildings under seismic loads is a complicated problem. Thus, in structural engineering, performance based analysis and design approach is generally used for tall buildings which may require nonlinear analysis of buildings. In such an analysis, however, modeling of structural walls has several challenges especially for the ones with irregular cross sections. Therefore, this study mainly focuses on the comparison of different nonlinear modeling approaches for the structural walls. First, a calibration study was conducted. For this purpose, typical wall layouts were modeled with different modeling approaches and elastic linear analysis results were compared with the theoretical solutions. Results showed that finite element modeling approach is good enough for the elastic analysis of structural walls. Then, walls were modeled as distributed inelasticity (fiber) model with Perform3D and ETABS and also continuum model were created utilizing TNO Diana. The analyses results were compared with experimental results for rectangular and T-shaped walls. Results indicated that both modeling approaches can capture the behavior of planar walls under cyclic loading but fiber model over-estimate the capacity of the flanged walls. As a final step, 4 (squat wall) and 15 (slender wall) story buildings having a core wall were modeled elastically with ETABS and designed according to ASCE7-10 and ACI-318. These buildings were modeled nonlinearly with both Perform3D and TNO Diana. Behavior of the buildings was compared according to pushover and time history analyses. With this comparison it was seen that fiber modeling approach cannot capture the effect of shear cracks in concrete. Moreover, fiber model cannot correctly calculate the behavior of wall flanges under tension.