Theoretical Analysis And Application Research Of The Support System Of The Flat Arched Steel Truss Roof

Planar tubular arch truss structure as one of the most important tubular truss structures which has appealing design,light weight and advantage of simple construction.Being the arch structure,planar tubular arch truss not only needs to maintain it's in-plane stability but also to keep it's out-of-plane stability by setting up supporting system. As a general rule,planar tubular arch truss should maintain it's out-of-plane stability mainly by setting supporting system and purline. Therefore evaluating the impact on different kinds of supporting system needs to be further study.In this paper,Planar tubular arch trusses with span of 24 meters and 36 meters are the main research object and the roof model were constructed by the finite element software under different depth-span ratio and rise ratio,then linear and non-linear buckling analysis were made with the all model. It could be find out the rules between the factors and the ultimate capacity by Comparing the size of the buckling load in linear and non-linear bucking about the model which were under different rise ratio and depth-span.The analysis shows that when the span depth-span ration are certain,the rise-span ratio have obvious effect on stability bearing capacity as well as the stability bearing capacity of the model is reduced with the falling of the rise-span ratio.it also proved out that when the span and rise-span ratio are in steady,the stability bearing capacity of the model with connecting bars goes up as rise-span ratio increased.However, the buckling strength of the model adopted with knee-bracing decreases with the increasing of depth-span ratio. Model adopted with knee bracing of the 24 meters span has much higher bearing capacity than the model adopted with connecting bars,however,the buckling bear capacity of the model adopted with connecting bars of the 36 meters pan tends to be better. The buckling modes show that the lower chords near the bear of the model which is adopted with connecting bars has modes of local buckling failure out-of-plane while the upper and lower chords of the planar truss in model which is adopted with knee-bracing lead to out-of-plane mode.The research results of the paper show the different effect about two kinds of support system which were in different span,rise-span ratio and depth-span ratio. System of bracing designed inthis kind of structure would refer to the research conclusion in this paper.