| Collapse mechanism and the design of collapse resistance are the most prominent topics in Structural Engineering.A great number of RC frame structures collapsed in the past several mega-earthquakes,left tremendous casualties.This fact indicates that the present understanding on collapse mechanism of RC frame structure is far beyond correct.In this dissertation,the relationship between loads and the resistances of the RC frame structures in the critical state before collapse was calculated in correspondence to shaking table test of a three stories model.Results from analysis and test provided a better reference for the understanding of the collapse mechanism.Major achievements of the dissertation are summed up as follows.1.With the increase of earthquake intensity,the damage characteristics of the RC frame structures are of obviously difference.During initial steps,inclined cracks appear on the infill walls and the edges are crushed.Then plastic hinges emerged at the top and bottom of the column,finally one story of the structure or even the whole collapsed.2.One RC frame structure in the Great Wenchuan Earthquake was chosen as the analytical prototype here.According to the similarity ratio of 1:4,we reproduced the columns,beams and floors of this building.Shaking table model test was conducted to study the seismic performance of the structure and the whole process of collapse was recorded.3.According to “decomposition movements” pattern,the quantities such as strain,displacement and acceleration of each layer and their interrelation of critical columns at the moment before the collapse of the model were analyzed.4.In this paper,the equation which describes the critical stability of the RC frame structure was established by considering the material strength and size of the representative columns.Thus,once we know the reinforcement,strength and size of the column,we can calculate the maximum story-drift angle of the structure at critical moment of collapse. |
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