Seismic Damage Simulation And Collapse Resistance Strategies Of Typical RC Frames During The Great Wenchuan Earthquake

In this paper, typical RC frames in Xuankou School which is near to the epicenter of the earthquake are chosen and the nonlinear time history analysis and the IDA based collapse analysis is implemented to study their collapse procedures, damage mechanisms and collapse resistance differences. Corresponding strengthening strategies are proposed to increase the collapse resistance. The main achievements of this dissertation are as follows:(1) Development of nonlinear analysis models for RC frames. Problems in common design computational models are discussed. With the secondary development user subroutines of general purpose FE software of MSC.MARC, micro-macro-hybrid model and macro model considering the foundation and slab are proposed according to the actual damages, which is more accurate than the common design computational models.(2) The study on the damage mechanism of school building A and office building H. The collapse progress of school building A is simulated with nonlinear time history analysis and IDA based collapse analysis is implemented to study their collapse procedures, damage mechanisms and collapse resistance differences. By analysis of the collapse mechanism, the key parts that influence structure's collapse resistance are found, which is very helpful to the strengthening strategies for collapse resistance.(3) The study on the collapse resistance of RC frames considering the confinement of hoops. Several currently used stress-strain models for confined concrete are introduced and tested for accuracy. The most accurate models are chosen to analyze the collapse resistance of school building A and office building H confined with hoops.(4) Strengthening and design strategies are proposed to improve the collapse resistance of RC frame structures. Strengthening strategies include strengthening with braces, strengthening with BRB and strengthening with dampers. Design strategies include increasing the column sections,increasing the confinement of hoops, and increasing the seismic fortification intensity. IDA based collapse analysis and pushover analysis are implemented for each strategy and the results are compared.