Analysis Of Dynamic Characteristics And Dynamic Response Of Liaocheng Guangyue Tower Under Traffic Excitation

The vibration caused by traffic excitation is long-term and repeated. When the dynamic stress induced by vibration reached a high level, it will cause the fatigue damage of ancient buildings, reducing structural strength, appearing crack and harming the structure safety. The current traffic excitation has become one of the most serious threats to ancient buildings, the correct evaluation of the influence of traffic excitation on ancient buildings is particularly important. Liaocheng Guangyue tower is the national key cultural relics protection unit. The vibration for it was performed in this paper, and 3 kinds of modal identification method was used to analyze the test data. The dynamic response of Guangyue tower under traffic excitation was simulated numerically, which was analyzed as with dynamic characteristics. Then safety evaluation was performed based on the test data and the results of numerical simulation. The main research contents are as follows:(1) The vibration test of dynamic response under traffic excitation for Guangyue tower was conducted. After smooth processing, eliminating tendency and digital filtering, the vibration of Guangyue tower high pedestal was analyzed, so was the head of column vibration velocity of erch layer.(2) The cross-correlation function between responses was achieved by natural excitation technique, then the modal parameters of Guangyue tower was identified by ITD and STD. The dynamic characteristic was ansyszed by Op.polylscf algorithm under the modal analysis software. The results by the above 3 methods were very close.(3) The dynamic analysis model of Guangyue tower after the repair and reinforcement was established based on equivalent modulus of elasticity, and its correctness was verified. The three-dimensional finite element model of timber structure-high pedestal-annular foundation was established. Considering randomness of vehicle load, vehicle loading mode of roundabout was put forward to simulating the worst case of vehicle load, based on which the dynamic response of Guangyue tower was analyzed when driving at different speeds. The elastic wave velocity of timber parallel grain was tested according to the national standard(GB/T50452), by which the permissible value of horizontal vibration velocity of the top column was got. The dynamic response of test and the numerical simulation results was assessed about security. With neither of them greater than the permissible value, Guangyue tower is in a safe state under the current traffic excitation.