| The use of all-frame-thick-plate conversion tower structures in urban rail transit systems has become increasingly prevalent.However,research on the dynamic characteristics and dynamic response of this structural system under earthquake loads is limited both domestically and internationally.In order to investigate the aforementioned characteristics of the all-frame-thick-plate conversion tower structure,this study conducted reduced-scale vibration table tests and finite element analysis parameter analysis on a structure located in Shenzhen.Elastic-plastic analysis of the all-frame-thick-plate conversion multi-tower structure was carried out under a rare seven-degree earthquake using finite element software.Furthermore,the wavelet packet signal energy damage assessment method was introduced to investigate the development of damage in the structural system under large earthquake loads.The specific work carried out in this study is described as follows:1.In order to investigate the dynamic response of a full-scale thickened frame structure with infill walls under seismic excitation,shaking table tests were conducted.Analysis of the resulting data indicates that the acceleration response of the model structure varies consistently with height across different levels of seismic activity.Notably,the distribution of the upper tower along the height direction changes gradually from an approximately linear distribution under small seismic excitation to an "S"-shaped distribution.This can be attributed to the discontinuity of vertical stiffness in the upper tower,which induces a certain whip effect at the top.Additionally,the floor displacement angle of the structure exhibits an increasing trend followed by a decreasing trend as height increases.2.In order to investigate the safety of the lower frame support layer under earthquake loads,a comparison was made between the experimental results of the full-frame support layer and the upper tower.The results show that the dynamic amplification factor and floor displacement angle response at the thickened plate layer of the lower frame support layer are both smaller than those of the upper tower.The maximum floor displacement angle of the lower frame support layer is 1/751,indicating that the lower frame support layer is basically in an elastic state under the seismic design level of 7 degrees.The strain data of the components shows that the strain response at the thickened plate is smaller than that of other components.3.Through parameter analysis using finite element software,it was found that the dynamic characteristics and dynamic response of the all-frame-thick-plate conversion structure are greatly influenced by the height of the conversion layer and the number of towers on the conversion plate,but less affected by the thickness of the conversion plate.4.To explore the elastic-plastic damage development of the all-frame-thick-plate conversion structure under rare seismic loads,SAUSAGE finite element software was used to conduct damage assessment on the three-tower structure under a 7-degree earthquake.The data showed that most of the concrete columns in the lower frame support layer suffered from slight to moderate damage,while most of the concrete beams in the structure suffered from slight to mild damage.The damage to the shear walls of the upper tower was relatively small.5.The damage assessment of the structure through wavelet packet decomposition showed that most of the floors of the structure were in a moderate state of damage after experiencing the 7-degree earthquake,but the structure was still repairable.The most severely damaged part of the structure was located between the 3rd and 20 th floors,which is consistent with the SAUSAGE finite element damage assessment results and verifies the accuracy of using wavelet packet decomposition for structural damage assessment. |
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