Research On Composite Damage Index Of Reinforced Concrete Pier Based On Dynamic Test

China is located at the junction of several seismic zones,and earthquake disasters occur frequently.The seismic damage of viaducts,sea-crossing bridges and other bridge structures poses a serious threat to traffic safety and the safety of life and property.As the main component of bridge structure,piers are very vulnerable to earthquake and difficult to replace.It is of great significance to study the seismic performance of piers and to evaluate the damage degree of piers.The traditional damage assessment based on the failure state of bridge pier needs to be further improved,and performance-based structural damage assessment has become a trend of development.Among them,the damage index which can fully and accurately reflect the damage performance of piers has become a hot spot of relevant research.At present,the research and analysis of pier damage performance are mostly limited to numerical simulation and the damage index used is relatively single.The evaluation of pier damage is not sufficient,and the damage performance of piers can not be fully and accurately described.Therefore,it is necessary to use reasonable damage index to evaluate the damage status of pier effectively.The main research works of this paper are as follows:(1)According to the existing displacement damage index and elastic-plastic energy dissipation difference damage index,a combined damage index was proposed.Based on the finite element software,the pier model was established and pushover analysis was carried out.According to the numerical simulation results and the relevant research conclusions,the damage evaluation limit range of damage index was further determined.(2)Nine specimens of reinforced concrete rectangular hollow piers were set up for shaking table test.According to the test data,the corresponding three damage indexes of each test piece were calculated.Combined with the actual damage of the test pier,the evaluation results of the three damage indexes were compared and analyzed.In order to further verify the applicability of the composite damage index,17 seismic records were introduced for numerical simulation through the finite element software,and combined with the results of three seismic waves in the test,so as to verify the applicability of the composite damage index under the action of multiple seismic waves.(3)Using the composite damage index,the influence of the three parameters ofreinforcement ratio,axial compression ratio and reinforcement ratio on the damage performance of hollow piers was investigated.(4)The further research and improvement of composite damage index were prospected.The conclusion shows that this study has a certain reference value for the seismic performance analysis of high pier bridges.