Research On Mechanical Behavior And Design Method Of Rectangular Steel Tube Truss Arch Bridges With Chord Concrete-inside

Supported by the Program for West Transport Construction Science and Technology, and Applied Basic Research Programs of ministry of transport of China (2006319812130), the mechanical behaviors and design method of the rectangular steel tube truss arch bridge with the concrete-filled in chord,which is a novel kind of structure,were studied in this paper.The research work aims at solving basically that calculations and analyses of the new construction applied practical projects. The main research works were concluded as follows:Three partially concret-filled rectangular steel tube trusses tests are completed.The comparing tests show that:the concrete-filled in chord trusses have the higher bearing capacity of the overall truss and joints. The concrete-filled in compression chord can help compression chord members very well, and reduce the steel tube strain; The concrete-filled in tension chord do not effect the tension chord members obviously at start state, but can prevent the contraction deformation of tension steel tube at late stage. The concrete-filled in chords do not effect the overall deformation and the branchs obviously,but the concrete-filled in chord changed the failure mode.Based on the practical project, the finite element model of rectangular steel tube truss arch bridges with the concrete-filled in chord was built up, and the mechanism of this type bridges were studied. Studies show that the concrete-filled in chords lead to the steel tube stress slightly increased.The stress of arch rib in varying cross-section would be the control factor in design.The bending behavior of foot arch and the axial behavior of the vault are obviously differ form the typical steel truss arch. The concrete-filled in rib chords do not effect the the web members obviously.Considering the stress and deflection factors,the concrete in tube filled to L/4-L/2 is preferable.The concrete-filled in chords avoid tube wall crippling,it is better for reducing the section size,simplifying the construction of joints,saving investment.