Study On Dynamic Response Of Continuous Rigid Frame Bridge To Blasting Seismic Wave

With the wide application of blasting in the project,more attention has been paid to the effects and the security risks of blasting seismic wave on the structures.Therefore the response of structures under blasting earthquakes and its safety assessment research are important research topic.Because of the characteristics of high pier and long span,the safety problems of long-span continuous rigid frame bridge should be taken seriously.However,the researches on dynamic response and safety assessment of bridges under blasting seismic waves were studied rarely.Therefore,it is necessary to conduct comprehensive research on this aspect.The main work and results of this paper are as follows:(1)Discussing the related theory of blasting seismic wave in detail,and compared blasting seismic wave with natural seismic wave.The dynamic response analysis of the response spectrum and time-history analysis of the theory were described in detail,which provided the theoretical basis for the following dynamic response analysis.(2)Establishing the pile-free model and pile model by finite element software considering pile-soil effect.Here XuKengKou main bridge was taken as the research object.The pile-soil effect was discussed through the analysis of the dynamic characteristics of the bridge.Huo Yongji response spectrum was selected to analyze the response spectrum of bridge dynamic response.The influence of near far zone,amplitude and input direction on the upper dynamic response of bridge was analyzed by different combination conditions.The distribution of the displacement response of the bridge under different construction stages was analyzed,which was also compared with the bridge under the state of the bridge.(3)Studying the method of simulating blasting seismic wave.The appropriate spectral density function and acceleration envelope function were selected.A set of program of simulating blasting seismic waves was compiled by using Matlab software.Different amplitudes,frequencies,durations of the simulated artificial blasting seismic wave and the measured seismic wave were then captured.By changing the input of these three elements blasting seismic data,their influence of on the dynamic response of bridge were discussed in terms of the peak response value of the bridge.(4)Carrying out the safety assessment.The common methods of safety assessment under blasting earthquakes were studied.The safety assessment combined the current assessment methods with dynamic response results.The bridge in the state of finished and statemaximum cantilever was assessed.At last,the measures of bridge safety protection were studied.The research results were of great significance to control and predict the safety problems of bridges which under blasting seismic waves,the research can also improve the existing safety assessment methods.