Seismic Vulnerability Analysis In The Construction Process Of High-speed Railway Concrete Continuous Rigid Frame Bridge With Double Thin-wall Piers

Taking a prestressed concrete continuous rigid frame bridge with double thin-wall piers of a high speed railway as the engineering background,the spatial finite element model is established by software OpenSEES,and the dynamic time history analysis of the system is conducted by the incremental dynamic analysis(IDA)method.The change law of seismic vulnerability in the construction process,and the influence of pile-soil interaction and cantilever effect on seismic vulnerability have been studied.The main work and conclusions are as follows:(1)The concrete double thin-wall piers has obvious dynamic axial force effect under horizontal longitudinal ground motion.In view of this dynamic characteristic,the applicability of various damage indexes is discussed.A single damage index,which considers the dynamic axial force effect and can be used to do regression analysis of the seismic demand and the ground motion intensity parameters,is put forward,that is,the compressive strain ductility ratio of the outer edge of the confined concrete,and the division of the damage state and the applicable conditions of the index,and the corresponding analysis method of the index are also given.(2)Several representative construction stages were selected for research.The probability of cracking damage at each stage of construction is not sensitive to the construction process.For cracking damage,the middle construction stage is more dangerous.The maximum cantilever state is relatively not the most dangerous stage,and the zero-block construction stage is the most secure.The probability of slight damage,medium damage and complete damage is gradually increasing with the increase of construction progress,and the sensitivity of these three kinds of damage to the construction process is increasing in sequence.(3)Without considering the effect of pile-soil interaction,the probability of each damage state will be overestimated,especially for the probability of cracking damage and slight damage state.Whether considering the pile-soil interaction or not has little influence on the probability of moderate damage and complete damage.(4)When the zero-block system considering the mass of cantilever is used to replace the maximum cantilever system for seismic vulnerability analysis,the probability of each damage state will be overestimated,especially the cracking damage and the slight damage state.The probability of damage in medium damage state and complete damage state is not sensitive to cantilever effect.