Dynamic Responses Of A Space Grid Structure To Explosion Seism And Air Shock Wave

From the damage and collapse accident of the space grid structure of Donghai Road Station,it can be seen that there were four characteristics in the explosion accident of Tianjin: large equivalent,large scale distance,multiple explosions and accompanied with explosion seism.However,most of the researches were aimed at the small equivalent and close range explosion at home and abroad.Therefore,it is necessary for the new characteristics of the explosion to research the laws of dynamic responses of space grid structure under it,and to summarize the targeted measures of anti-explosion.Numerical simulation of dynamic responses of the column-supported space grid structure was carried out based on ABAQUS finite element software under multiple blast loads.The results show that after the first explosion,partial bars enter the yield stage,and there is a large residual deformation in the structure,so the structural damage aggravates the destruction of the structure under the second blast loads.Because of the serious deflection of the space grid,when designing large-span roof structures under the similar blast loads,the blast loads on the roof must be paid more attention.The shear-resist ability of bearings of space grid is a weak link in the column-supported space grid for blast resistance.Finally,some measures to improve the shear capacity of the bearings are listed.Numerical simulation of dynamic responses of the space grid structure was carried out based on ABAQUS finite element software under only explosion seism,only air shock wave and both of them simultaneously.And the influences of the three load conditions on the dynamic responses of the space grid structure were contrastively analyzed.And the spectral characteristics of explosion seismic wave and natural vibration characteristics of the space grid were analyzed.The results show that the explosion seismic waves have the characteristics of wide frequency range and rich high-frequency contents.The impact on the internal force of the supporting columns and the bars of space grid is significant under only explosion seism.Considering combined actions of explosion seism and air shock wave,dynamic responses of the structure under separate explosion seism and air shock wave cannot be combined by superposition.And the impact of air shock wave on the structural dynamic responses is dominant,but the explosion seism’s contribution to the structural dynamic responses cannot be ignored.The three finite element models were established for a space grid structure by the midas Gen software,which were non-isolated structure,traditional horizontal isolation structure and three-dimensional isolation structure.Natural vibration characteristics of the three models were analyzed.And dynamic responses of the three models were compared under explosion seism and natural seism respectively.The results show that the explosion seismic waves have the characteristics of wide frequency range,rich high-frequency contents and short duration.The responses of displacement and internal force of the space grid structure under natural seismic waves are larger than the structural responses under explosion seismic waves.The natural vibration period of the structure is obviously prolonged by using horizontal and three-dimensional isolation bearings.And three-dimensional isolation bearings can more effectively prolong the natural vibration period of high order.Compared with the horizontal isolation bearing,the three-dimensional isolation bearing has better isolation effect and wider applicability.According to the results of finite element analysis and the scene of the explosion,the concept of design and the anti-explosion protection measures were summarized in this paper from two aspects of air shock wave protection and explosion seism wave protection.