| Masonry pagodas are outstanding representatives of ancient building construction skills and have significant cultural relics value.Nevertheless,under the action of multiple factors,majority of the ancient masonry pagoda structures are in varying degrees of destruction.The ancient pagoda,which was situated on a hilly terrain,frequently sustained more severe damage when an earthquake occurred.Thus,it is of great engineering significance for studying the effect of hill topography on the seismic response of ancient masonry pagodas.In this work,the Zhongjiangnan Tower located at the summit Tongyu Mountain in Zhongjiang County,Sichuan Province was utilized as the prototype,and the acceleration time history collected by Zigong Xishan Park array during the Wenchuan earthquake was selected as the base input.The old masonry pagoda was subjected to an earthquake damage test using a small shaking table,and quantitative results were obtained about the influence of topographic effect on the ancient pagoda’s earthquake response.Simultaneously,the dynamic elastic-plastic analysis of the tower under the same ground motion is conducted by finite element model,and the results have been compared with the test results.Moreover,the effects of hill height,horizontal distance between structure and top of slope,horizontal distance between structure and foot of slope,soil layer effect and slope on seismic response of masonry ancient pagoda have been discussed by finite element model.Based on the research outcomes,engineering solutions for increasing the performance of masonry old pagoda are presented.The primary work completed is as follows:(1)Small shaking table testThe similarity ratio of each physical quantity had been determined,and then two similar models were designed.The findings of the modal analysis revealed that the dynamic properties of the two related models were the same.Zigong array records had been used as base input to execute shaking table tests.The results demonstrate that with the increase of the input PGA,the acceleration amplification coefficient of the ancient tower at the foot of the mountain decreases from 2.465 to 2.107.The ancient pagoda at the summit of the mountain’s acceleration amplification coefficient falls from 3.216 to 2.918.The peak acceleration of the historic pagoda at the top of the mountain is 1.820～3.243 times that of the ancient pagoda at the foot of the mountain.The maximum relative displacement of the ancient pagoda on the top of the mountain is 1.444～18.742 times that of the ancient pagoda at the foot of the mountain.The maximum understory displacement Angle of the ancient pagoda at the top of the mountain is 1.330～18.742 times that of the ancient pagoda at the foot of the mountain.(2)Finite element numerical simulation analysisA finite element numerical model consistent with the experimental model was established,and the elastic-plastic dynamic response analysis was conducted with the base input used in the experiment.The results show that with the increase of the input ground motion PGA,the acceleration amplification coefficient of the ancient pagoda decreases from 2.465 to 2.108.The acceleration amplification coefficient of the ancient pagoda at the foot of the mountain decreases from 3.159 to 2.867.The maximum relative displacement of the ancient pagodas on the top of the mountain is 1.643～23.622 times that of the ancient pagodas at the foot of the mountain,and the maximum inter-story displacement of the ancient pagodas are all greater than that of the ancient pagodas at the foot of the mountain.Ancient pagodas at the mountain’s peak have an angle that is 1.264～23.622 times greater than those at its base.The numerical simulation results are close to the experimental results.(3)Analysis of the influence mechanism of terrain effectThe numerical model of the Zhongjiangnan Tower prototype is established,and the effects of the hill’s height,it’s horizontal distance from the slope’s top,and its horizontal distance from the slope’s foot,and its horizontal distance from the slope’s foot on the on the structure’s seismic response are discussed.The findings demonstrate that the topographic effect have a substantial impact on the seismic response of the structure.When the horizontal distance is more than 3.5H,the influence of topographic effect could be avoided.When the distance between the ancient pagoda and the foot of the mountain is less than H,the impact of topography on the ancient pagoda at the foot of the mountain is crucial,and the effect of topography could be avoided in other cases.Although the peak displacement of the old pagoda at the top of the hill is enormous,it has no regular impact on the peak displacement of the pagoda at the foot of the hill.Moreover,in contrast to soil layer amplification,slope topography has a more obvious effect on seismic response of structures. |
PDF Full Text Request