Inversion Analysis Of Earthquake Damage And Research On Protection Measure To Haibao Pagoda In Yinchuan

Ancient masonry pagodas is widely distributed,and has a long history,it is an important part of heritage building in our country.The characteristic of ancient masonry pagoda structure is itself heavy,low material ductility,Sensitive to uneven settlement of foundation.The earthquake damage is very common,so,the earthquake mechanism and the reinforcement and protection measures need to be studied urgently.The earthquake disaster of Haibao pagoda was analyzed by the method of numerical simulation and in situ test,combined with the investigation,archaeological achievements and historical seismic damage data,the relevance of the earthquake mechanism and the existing structure disease were confirmed,and the seismic capacity of damaged structures were evaluated,finally the reinforcement and protection measures of the structure integrity were discussed.The main researches in the paper are as follows:(1)The elastic modulus of four ancient masonry pagodas were calculated by the rebound method,according to theoretical formula;At the same time,the dynamic performances of three ancient masonry pagodas were tested by the method of pulse method,the inverse analysis is carried out by using the finite element model of space,and the measured period as the target value,the equivalent elastic modulus of ancient masonry pagodas was obtained.Based on the comparative analysis,The feasibility of equivalent elastic modulus was discussed.(2)Combined with historical seismic damage data,the earthquake disaster of Haibao pagoda was analyzed by response spectrum method and time-history analysis method,and the seismic damage mechanism was discussed,the results show that,the calculation results and actual damage is similar.(3)The effects of high pedestal on the dynamic characteristics of the tower structure was studied.The results show that,the high pedestal not only affects the natural cycle and vibration modes of the tower structure,but also affects the earthquake response of upper part of the tower structure.High pedestal shorten the frequency range of the tower structure,causing the frequency between the modes is more intensive and the deformation of high modes is higher under earthquake.(4)Combined with the earthquake mechanism and the existing structure disease,the reinforcement measures of the structure integrity were given.And the effectiveness of reinforcement is discussed.