Research On Analysis And Evaluation Method Of Ant-progressive Collapse For Large-span Single-layer Spatial Grid Structures

In recent years,frequent collapse of large-span spatial grid structures show that,although it has high degrees of statical indeterminancy,failure of the key members may develop catastrophic progressive collapse.The research on progressive collapse of large-span single-layer spatial grid structures is extremely imperative,compared with multi-layer spatial grid structures,due to the characteristics of small redundancy,more sensitive to defect and large influence of construction effect.Therefore,analysis and evaluation method of ant-progressive collapse for large-span single-layer spatial grid structures based on local failure are researched in this paper.the main research contents and conclusions are as follows:(1)The selection method of important members suitable for single-layer spatial grid structures was introduced,known as multiple responses based on primary scope.This proposed method was implemented in the mechanical analysis of three typical single-layer spatial grid structures.The results have shown that the novel analysis approach is suitable for the evaluation of important members of large-span spatial grid structures.The deficiency of current methods that single structural response is only considered has been made up.The problem that the members to be removed for spatial grid structures are not given unified standard in progressive collapse analysis has been solved.(2)Novel improved nonlinear analytical method known as alternate load path method considered construction effect was introduced.Due to considering the construction effect for subsequent analysis,the dangerous fact caused by construction process is avoided.The model of single degree of freedom was built to analysis dynamic effect of progressive collapse.The principles of dynamic magnification was derived,the load dynamic magnification factor decreases and the displacement dynamic magnification factor increases respectively with the development of plastic area.The simplified simulation method of dynamic effect suitable for single-layer spatial grid structures was put forward.On this basis,the value ranges of the load dynamic magnification factor were given,it should be 1.7~1.9 when DCR<0.7 and 1.4~1.6 when DCR>0.9.(3)Based on incremental dynamic analysis,the novel evaluation method of progressive collapse was introduced.The proposed method established a unified evaluation criterion is not restricted by the structural form,and the anti-collapse behavior can be evaluated quantitatively.The initial geometrical imperfection cannot be ignored,otherwise the dangerous evaluation results may be obtained.(4)The above analysis methods were applied in the main stadium for the Universiade Sports Centre.The distribution of the important member for folded-plane latticed shell structures was established.The initial condition considering the construction effect was gained.After that,the evaluation result can be concluded that the roof of the main stadium for the Universiade Sports Centre has good resistance to progressive collapse,the collapse margin ratio is 1.68.