Analysis Of Large-span Reticulated Domes For Progressive Collapse

With the rapid economic development, the large-span reticulated domes are usedmore and more widely. The safety of structures is the key. Therefore, the analysis ofthe resistance to collapse of large-span reticulated dome is of great importance.This paper is focused on a large-span roof with two different structural layouts.One is a large-span single-layer Schwedler Monoclinal dome, the other is a large-spandouble-layer reticulated dome. The static nonlinear buckling analysis and dynamicearthquake resistance analysis are conducted. Firstly, the progressive collapsepotential of large-span reticulated domes is evaluated based on AP method understatic loads and the progressive collapse mechanism of the structures is exploredaccording to stability and strength failure criteria. Furthermore, the time-historyanalysis is employed to evaluate the dynamic performance, the resistance to collapseand collapse mechanism of the structures under severe earthquakes withthree-dimensional Elcentro Wave and three-dimensional Tianjin Wave as earthquakeinput. All the analysis aim to provide the theoretical basis for engineering design.Thus the conclusions are as follows.(1)The structural layout applied, which is the large-span single-layer reticulateddome, has a certain redundancy. When10key elements or3key nodes were removed,the single-layer reticulated dome under the service load would cause progressivecollapse. Therefore the protection of key elements, especially key nodes of thisstructure should be strengthened. However, the redundancy of the other structurallayout applied, which is the large-span double-layer reticulated dome, is good and it is7to13times that of single-layer reticulated dome. When10key elements or3keynodes were removed, the double-layer reticulated dome under the service load wouldnot cause progressive collapse. Hence, the resistance to progressive collapse oflarge-span double-layer reticulated dome is better than that of large-span single-layerreticulated dome.(2)The security of single-layer reticulated dome is controlled mostly by itsstability under static loads. While the strength analysis results of the large-spandouble-layer reticulated dome by increasing loads show that the double-layerreticulated dome without any local damage has instability failure; progressive collapse of the structure with minor local damage is a result of both instability failure andstrength failure; progressive collapse of the structure with severe local damage is aresult of strength failure.(3)The resistance to collapse of large-span reticulated dome is good under severeearthquakes and the dynamic failure critical load of these two kinds structures is35m/s2to48m/s2. The resistance to earthquakes of large-span double-layer reticulateddome is slightly better than that of large-span single-layer reticulated dome.(4)In dynamic time-history analysis, the plastic element ratio and thedispacement of key joints increase in pace with the increasing seismic inputacceleration. It means that the structural stiffness is gradually weakening. The offsetof the equilibrium position of the joints vibration increases but not much and thetime-displacement curve does not have a sudden point of divergence. So the effect ofmaterial nonlinearity is more significant compared with geometric nonlinearity.Plastic-depth development leads to the plastic inner force redistribution and then mostrods reach the yield strength so that the structure lost carrying capacity. This is typicalstrength failure. Hence, the large-span reticulated domes mostly have strength failureunder severe earthquakes.