| Aimed at considering the influence of ambient temperature on the frequency of civil engineering during modal identification, based on the damage detection method of the modal parameters, 3 concrete model beams were tested considering the ambient temperature changing and different damage, the experimental modal were extracted and analysis, the curves of frequency of the beams changing with the ambient temperature and crack were obtained , it is shown that the frequency of concrete beam is sensitive to the environmental temperature, one concrete footbridge was monitored under ambient vibration at different temperatures, the modal frequencies extracted from the monitoring data basically correspond with the experimental results. The temperature has a certain impact on the frequency and should be taken into account during the dynamic test of the concrete bridge.The mainly work in this paper as follows:1) The modal parameter of the concrete model beams and the concrete footbridge were analyzed by the software of Midas/civil software to get its modal frequency and damping.2) The DASP2006 acquisition and analysis system is used to sample and analyze modal parameter and hammering method is used. Eigen-system realization algorithms and stochastic subspace identification in DASP2006 are used to analysis, and result of it analysis compare with the Finite element analysis, it shows that the results of the measured and simulation of finite element are within acceptable agreement at 10℃.Then modal parameter of beam is sample and analyze under different ambient temperature, it found that the temperature has a certain impact on the modal parameter concrete beam.3) In order to verify the result of the analytic, one concrete footbridge was monitored under ambient vibration at different temperature; the modal parameter extracted from the monitoring data basically correspond with the experimental results, it shows that the temperature has a certain impact on the modal parameter of concrete footbridge during the dynamic test. |
