Study On Mechanical Properties Of Loaded Double-layer Reticulated Shell Structures In Service

With the continuous development of society,the use of large-span space lattice shell structures has become more widespread.Compared with the traditional structure,the reticulated shell structure is simple in structure,reasonable in force,and regular in layout.It is convenient for production,transportation and installation.Therefore,the development speed is unusually rapid.Over time,some reticulated shell structures have to be restructured due to damage or social needs.This may lead to sudden changes in the structural forces and damage.The failure of local components often causes the collapse of the entire structure,resulting in more Big accident.This article combined with the LED screen lifting and reconstruction project of Tianjin Stadium to study the overall safety of the structure due to the sudden increase in load caused by the sudden change of the load,so as to determine whether the structure needs to be reinforced and repaired,so as to provide the basis for further research.This article combines the double-layer reticulated shell structure renovation project of Tianjin Stadium,the main research contents and conclusions are as follows:(1)Under the condition that the initial stress and initial displacement of the structure are unknown,the static load test on site can be used to obtain the change of the internal force and joint displacement of the structural member,and the preliminary judgment of the working condition of the structure under the static force can be obtained.The follow-up study of this paper lays the foundation.(2)Set up the finite element model of the reticulated shell structure by means of finite element,and simulate the change of stress and joint displacement of the double-layer reticulated shell after the load changes,and verify the accuracy of the finite element simulation.Then through the finite element simulation structure in the actual load conditions,the absolute value of the rod stress and node displacement.Through comparative analysis,it was found that the reason that the structure satisfies the requirements of the 88 th edition of the "Steel Structural Design Code" and does not meet the requirements of the 2003 version of the "Steel Structural Design Code" is that the new and old specifications are different for the steel intensity grouping.In response to this situation,it is proposed that the structure of the structure should be reviewed in accordance with the new regulations,and a method of casing reinforcement should be adopted to solve such problems.(3)The state after the completion of the transformation by the finite element simulation.The time-history analysis method was used to analyze the seismic performance of the structure.It was concluded that the displacement response of the structure at the quarter-span was the largest,and the response of the internal force near the load change position was the largest,providing a certain basis for further research.(4)A suspended finite element model was established to simulate the swing state of the suspended screen under seismic action after completion of the lifting transformation.The stress and joint displacement of the structure under the action of the earthquake under the swinging state and the static state of the suspended screen were comparatively studied.In the situation,it was concluded that the influence of hanging screen swing on the seismic performance of the structure itself is small.