Studies of In-Plane Ultimate Loads of the Steel Truss Web–RC Composite Arch

This paper describes an experiment on the in-plane mechanical behaviors of the steel truss web–RC composite arch subjected to the unsymmetrical concentrated loads applied simultaneously at the $2\text{/}3$ and $5\text{/}6$ span points of the arch. The experimental results show that loads were transmitted as shear forces through the steel truss webs. The maximum measured strain in two steel tubes near the cross section at the $5\text{/}6$ span point was less than the yield strain, and punching shear failure was observed at the loading sections. Using the experimental model, the authors developed and performed a finite-element simulation. They found that double N-shaped webs might be the most conducive to the stiffness and bearing capacity of the composite arches and require comparatively less steel. The critical wall thickness of the web tubes at which punching shear failure occurred was 3.5 mm for this arch model. Given the same wall thickness, the ultimate bearing capacity of the composite arch decreased as the incline angle of the web members increased. In the composite arch, there is no substantial difference in terms of bearing capacity between the steel truss webs and the corrugated steel webs, but both types of webs are better than the flat steel webs in relation to bearing capacity and steel consumption.