Modeling Methods And Programming Of High-rise Building During Strong Earthquake

Along with the acceleration of China’s urbanization process, aseismicdesign of high-rise building becomes the research focus in the field of urbandisaster prevention and mitigation. The earthquake damage data indicates thatthe some of the high-rise building may collapse or severely damaged in strongearthquakes, which would directly result in huge casualties and property losses.In order to enhance the reliability and the safety of the high-rise building, wemust establish a reasonable and effective capacity design of these buildings, andthe research on seismic response simulation of high-rise building is the only wayto achieve this goal. However, the current methods of seismic responsesimulation is not perfect in many ways, such as the shear wall nonlinear analysismodel is immature; the dimensional stress state needs further understanding; thenonlinear iteration is not likely converge which would lead to calculationsuspension without a result, etc. In order to build a practical high-rise buildingsimulation method and analysis platform, the research in this thesis are asfollow:1.In order to improve a reliable and computationally efficient beam-columnfinite element model for the analysis of high-rise building during strongearthquake, force-based beam-column elements is used which will greatlyreduce the amount of degrees of freedom. Further more, integration methodfixing integration point at the ends of the element is proposed in this paper andimplemented into OpenSees program. The case study shows that the result ofGauss-Radau integration (an integration point at only one end of the element)and Gauss-Lobatto integration (two integration points at both ends of theelement) are more accurate than the result of Newton-Cotes (also twointegration points at both ends of the element), but they all perform better thanthe result of Gauss-Legendre. The force-based beam-column element withintegration method fixing integration point at the end is thus recommended forthe nonlinear analysis of frame structures.2.Force-based fiber element is the most commonly used for the nonlinearanalysis of reinforced concrete structures, it ignores section shear deformation,and assumes the section is plane. However for shear wall structures, the sectionis much wider than beam and column, thus plane section assumption and section shear deformation ignorance will cause greater error. Based on this background,a modified force-based fiber element (MFBFE) which consider section sheardeformation is proposed in this paper. The cross section is no longer planesection but curved surface in modified force-based fiber element. In the presentpaper, the MFBFE elements is first formulated and then implemented in a finiteelement program OpenSees. Numerical analysis for low-cyclic loading test of agroup of nine shear wall specimens based on MFBFE element. Analytical resultsshow that the MFBFE element is capable of accurately predicting the entirehysteretic loops of these shear walls, including the initial stiffness, yield strength,ultimate strength, unloading stiffness, residual displacement, ductility andenergy dissipation. And the trend analysis under variable axial compression ratio,variable aspect ratios and variable concrete strength, variable longitudinalreinforcement ratio, variable constraint zone length, variable stirrup ratio showsthat the MFBFE element has broader applicability.3.The implicit method and explicit method is researched. Numericalanalytical results shows that both implicit and explicit methods have goodprecision. For small structure with few degrees of freedom, implicit method ismuch more efficiency than explicit method, but explicit method is much moreefficiency than implicit method for large structure with large degree of freedom.It is recommended explicit analysis method is used for the nonlinear analysisof high-rise building with large degree of freedom.4.A finite element program called ViPSea (Visual Interaction Program forstructural engineering analysis) is developed based on on TCL/tk language. It isan interactive graphical modeling and displaying, invoke the OpenSees solver tocalculate, so it can real-time dynamic display the structure responseanalysis.Further more, it is a cross-platform software. ViPSea provides a newplatform for nonlinear analysis of high-rise building.5.Nonlinear seismic response analysis on a high-rise building withdamaged heavily in Wenchuan Earthquake in Dujiangyan is done using ViPSea.Analysis results show that the maximum value of inter-story drift appears atthe first floor, and the damage is serious, which agrees well with the damageinvestigation results.