| With the progress of economy and technology,it not only makes higher demands for the safety of bridge structures,but also has new needs of the modeling design of bridge.Due to its large span and aesthetic advantages,arc bridges nowadays have obtained widely use in many cities and have gradually became a landmark building.However,facing to the increasing road capacity,vehicle volume and overload phenomenon in recent years,many old bridges were damaged with the frequent accidents.Therefore,doing load test to the existing old arch bridges to has become an essential and vital work.The load test can comprehensively examine the performance and safety of the existing old bridge so as to fully reflect the bridge's safety performance and load capacity.There's no doubt that this kind of analysis about load test has a great significance to the continuous usage of old arc bridges.In this paper,by analyzing the load test to concrete-filled steel tube(CFST)arch bridge,the theoretical analysis and research focusing on the deformation,dynamic characteristics and cable force detection of the bridge are deep studied.Based on the research of the Third Bridge on Wo River,this paper detailed the historical development both on tied arch bridge and load test.And then analyzed the basic theory of dynamical and static load test and cable force detection.Finally,the real working state of the bridge is evaluated by comparing the finite element calculation model with the field measured data.The research contents are as follows:(1)Using the finite element software MIDAS or Civil,the refined model to the main bridge of The Third Bridge on Wo Rriver is set up.And by applying self-gravity on the model with lane load combinations which according to the design specification of bridge,to run the analysis then obtain its controlled section and the loading condition,also to check the security situation of the bridge under the dynamic and static load,so as to obtain its bending moment diagram and deflection deformation diagram under the dynamic and static load.(2)On the static loading test,by doing medium and unbalance loading experiment in L/2 and L/4 section of the bridge to collect the strain of bridge structure and the change of deflection curve under static load test.By comparing the measured value which collected with the theoretical value,it can be full understand of the actual operating conditions of bridge structure.(3)On the dynamic load test,according to the dynamic characteristic test and dynamic response test of the bridge,the micro-strain time-history curves of the main control section of the bridge under the condition of sports car,brake and environmental excitation were recorded.Based on the analysis of the micro-strain time-history curve and the first six modes,the impact resistance of the bridge is evaluated.(4)Testing the cable force of the boom.The variation of the cable force of the boom at the L/2 section of the bridge under medium load was observed,and the frequency analysis of the frequency spectrum was carried out.By comparing and analyzing the theoretical and measured values of the bridge boom,the overall safety of the boom and the bridge structure is judged.Figure [86] table [25] reference [70]... |
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