Seismic Analysis With Second Order Effect Of Reinforced Concrete Frame Structures Subjected To Near-field Earthquake Ground Motions

Recently, both foreign and domestic scholars have researched extensively about near-field earthquake and the second order effect. But until now the most researches are about the steel frames and combinated structures. The second order effect can be neglected in our current code if the ratio of stiffness to weight satisfies certain condition when referring to the reinforced concrete frame. Nevertheless, suffering with near-field earthquake, the structure will act beyond common imagination. So the consideration of the second order effect of the reinforced concrete frame under near-field earthquake is necessary. Focused on these problems, this thesis involves the following work:1. The hazard and the characteristics of near-field earthquake is introduced, and then, the second order effect and the related design methods is summarized. Two kind of elasto-plasitc analysis method are compared.2. With the method of nonlinear time history analysis, the behavior of a tall reinforced concrete frame is studied under the action of far-field ground motions and near-field ground motions with pulse and without. It is found that the requirement of base shear, top displacement and story drift is magnified under near-field earthquake. This phenomenon is more remarkable under the pulse ground motion. With the PGA becomes larger, this amplification effect increase. The second order effects enlarge the requirement of top displacement and story drift and diminish that of base shear. This influence goes big when the PGA arises. The effect under near-field earthquake with pulse is more prominent than near-field earthquake without pulse and far-field earthquake by sequence. The similar phenomenon appears on the residual top displacement and the residual story drift of the structure.3. The theory of the incremental dynamic analysis and the vulnerability analysis is described in this paper. The IDA curves and the vulnerability curves are taken from the analysis of a tall reinforced concrete frame. Combined with the seismic hazard curve, the MAF of the structure's each limit state can be calculated. Also, the influence of the second order effect on the IDA results is obtained.