Research On The Seismic Performance Of 800 Meters Span Kiewitt Type Mega-latticed Structures

With the progress of the times,more structure forms appear,span is also constantly growing in the direction of development.Under the background,Kiewitt reticulated mega structure was proposed as in the static condition,it with a small amount of steel and good mechanical properties.However,the performance of the structure under earthquake has not been studied in depth.Taking into account the frequent earthquake in China in recent years and seriously endanger the lives and property of the people,it is necessary to carry out an in-depth analysis of the seismic performance of the structure.In this dissertation,Kiewitt reticulated mega structure with 800 m span as the research object,the research was mainly focused on the following aspects:1.The modal analysis was carried out,according to dense property of frequency spectrum,a coefficient was proposed,which was based on the weight of displacement and internal force.The physical significance of coefficient is clear and easy to implement,improving the computation method of Rayleigh damping.The ground motion screening program based on Matlab was compiled,and 5 actual strong earthquake ground motion records which meet the requirements were selected.2.The displacement and internal force responses of structures under different dimensions were calculated by time history analysis method.The results showed that the Kiewitt reticulated mega structure had high coupling degree in three direction,vertical earthquake and horizontal earthquake response in the same order.3.According to the characteristics of Kiewitt reticulated mega structure with a large number of members and nodes,response envelope data processing method was proposed.The displacement and envelope of equivalent stress in structure under earthquake were similar to that under the static force,and the amplification factor at the control point and control member is not more than 1.2.4.Calculated the internal force coefficient of Kiewitt reticulated mega structure in 5 horizontal ground motion and 5 vertical seismic.The distribution characteristics of the internal force coefficient under different parameters were analyzed,found that horizontal earthquakes act as control rather than vertical earthquakes.5.The displacement and internal force response of the member were calculated by multidimensional response spectrum method,and the calculation results were compared with the time history analysis method.The comparison results showed that the accuracy of the multidimensional response spectrum method can be used in the preliminary design of the structure.6.The space truss substructure and the Tensairity substructure were designed.By comparing the Kiewitt reticulated mega structure with the substructure and that without the substructure in the static and dynamic characteristics,the substructure has improved the overall stiffness of the structure.Through the comparison of displacement and internal force envelope of the Kiewitt reticulated mega structure with grid and tensairity substructure under static and seismic,found that the amplification coefficient at the control point and the control rod is around 1.2.