| Light-weight steel portal frame structures have been widely used in actual industrial buildings. However, as light-weight steel portal frame structures are commonly light-weighted, flexible and light-damping, they are highly subject to strong winds destroying. For exploring the wind-resistant loading behavior and the ultimate bearing capacity of3D portal frame including weight-bearing structure and Support system out of plane under ultimate-state, nonlinear finite analyses of a large-spanned portal frame industrial building located at the eastern coastal area of China were performed.Firstly, the overall wind-resistant safety levels of light-weight steel portal frame structures under the plane positive wind load were investigated. Taking an actual project as an example, a refined three-dimensional finite element model was established with shell element and truss element out of plane. Considering the spatial effect of longitudinal component, the initial geometric imperfections and also material nonlinear, the ultimate bearing capacity and wind-induced ultimate limit-state failure modes under the positive wind load were investigated, and meanwhile were compared with the result of the plane model. The result displayed that the failure modes of two kinds of models were shown as the buckling of beam-column joint of the second frame. However, stress of spatial model into the buckling was obviously smaller than that of the plane model and buckling modes were also clearly different. Meanwhile, the effects of the longitudinal supporting system such as the rigidity and location changing of tie rod, purlin and brace on the wind-resistant ultimate load-capacities of the overall frame are discussed.Secondly, considering the effect of the diagonal wind load space action of light-weight steel portal frame structures, the ultimate bearing capacity and wind-induced ultimate limit-state failure modes under the diagonal wind load were studied, and meanwhile were compared with the state of the plane positive wind load. The result displayed that under the action of the diagonal wind load, the spatial effect of the overall light-weight steel portal frame structures were more obvious. The overall out-plane buckling was the main failure mode of the light-weight steel portal frame and meantime connecting parts of the main frame structures and vertical support systems easily performed stress concentration resuting in local buckling. |
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