Studies On In-Plane Stability And Design Of Web-Opened Steel Arches

In this paper,a new kind of web-opened steel arch(WOSA)is studied.The WOSA consists of two chord members that are interconnected discontinuously through multiple flat-batten-plates.As it combines the advantages of arches and web-opened members,its application in the future can be expected.The in-plane stability and design method are studied by theoretical and finite element analysis(FEA)in this paper.By means of structural mechanics or the first order elastic analysis to the simplified beam element model of the WOSA,the formula to calculate the strength of the components in the WOSA has been derived.The elastic local buckling performance of flat-batten-plate is also studied to calculate the upper limit of its height-to-thickness ratio according to the principle that the local buckling of the plate won't happen before it yields.The sectional shear stiffness of the WOSA is calculated,and with this consideration the elastic buckling load of the WOSA is derived.Further theoretically derived elastic buckling loads are validated by finite element analysis(FEA)by changing the rise-to-span ratio,the slenderness and other parameters of the WOSA.The elasto-plastic load resistance of the WOSA under pure axial compression is studied through FEA,and accordingly a?-?_n curve is then established.The load resistance,failure mode and instability mechanism of WOSA under full-span uniform vertical load,half-span uniform vertical load and their combinations are also studied.With the numerical results obtained by FEA,the design equations for predicting the load resistance of the WOSA are established.The formulas are also validated by FEA,indicating that they give a lower boundary of the in-plane load resistance of the WOSA.When the height-to-thickness ratio of the webs is above its upper limit,the web local buckling will happen before the global buckling.It concluded that the instability mechanism of the WOSA may be predominated by either a combination of the global instability and the web failure or web failure alone.