SEISMIC RESPONSE ANALYSIS OF SUPER HIGH-RISE FRAME-CORE TUBE STRUCTURE USING IMPROVED NONLINEAR LAYERED SHELL MODEL

An attempt is made to develop a modified layered shell element model specialized in simulating reinforced concrete (RC) shear walls in super high-rise buildings. Due to its deficiency for shear walls with significant variation of thickness-to-length ratio from along the structural height of general super high-rise buildings, a quadrilateral flat shell element NLDKGQ is improved in the model by the replacement of a thin-thick plate element TMQ, which is based on the generalized conformation theory, as well as by a membrane concrete material developed previously. The improvement with the TMQ endows the NLDKGQ element by capability to simulate efficiently the out-of-plane performance of shear walls with variable thickness-to-length ratios. The shear locking is avoided by the utilization of reduced integration scheme and then its accuracy is demonstrated by the test results of a RC concrete slab, four in-plane RC shear walls, and a frame-shear wall structure. The adoption of shell elements with out-of-plane performance is recommended when the structure possesses obvious shear effect and large number of shear walls with relative large thickness-to-length ratios. Afterwards, the improved model is incorporated into a self-developed program to carry out a nonlinear dynamic time history analysis on a 250m+ frame-core tube super high-rise building. The significance of studying the shell elements for super high-rise building indicates itself as the shear deformation of shear wall components has little influence on overall structural responses but in-negligible impact on the shear walls in structural bottom stories.