Simulation for the Collapse of RC Frame Tall Buildings under Earthquake Disaster

China is a country that suffers a lot from the earthquake disaster. The major reason for the human death and property losses in earthquake is the collapse of the tall buildings. Hence, correct simulation for the failure modes and accurate prediction for the collapse of the tall buildings under earthquake disaster is very useful for studying the safety of buildings and evaluating losses during earthquakes[1]. However, a lot of simplifications must be carried out in the existing simulations to overcome the numerical problems because the grave nonlinearity exists when collapse happens. This may lead to the results away from a real phenomenon. In this study, a fiber model for reinforced concrete (RC) structures (referred as THUFIBER) is developed, which is based on the general-purpose finite element package of MSC.MARC that carries significant capacity of solving nonlinear problems. In this model, the concrete and the reinforcement inside the structural elements are modeled respectively with different fibers as shown in figure 1 so that the cyclic behavior of material can be properly simulated. Pushover and dynamic time-history analysis for a RC frame tall building are carried out to illustrate the capacity of the proposed model. And dynamic time-history analysis is emphasized in this paper to discuss the collapse modes of the structure. The results show that THUFIBER can simulate the collapse and failure process of the structure under the dynamic loads such as complicated seismic loads, including the softening and fracture behaviors of structural elements, and further the program shows good convergence in the non-linear cases. So THUFIBER has a strong and promising ability for nonlinear analysis including collapse numerical simulation. Figure 1 Section dicretization of the fiber model Figure 2 Simulation for the Collapse of the frame