Reseaurch On Ultimate Load Carrying Capacity Of Strengthened Steel Tubular Trusses

The hidden welds of joints in the steel tubular truss which gets welded directly usually aren’t to be welded. To facilitate the construction and the ultimate bearing capacity isn’t reduced a lot, it needs getting strengthen treatment. This paper bases on the Warren truss, making four prototype trusses with different strengthen treatments. This paper studies the static performance of four Warren steel tube trusses by experimental research and FEM. The main research work and outcomes are as follows.1. Prototype experiments:Of those four trusses were carried out with the vertical load on the symmetrical four points along the span of the whole truss. The main parameters were that the hidden weld line welded or not, being strengthened with concrete into chord, being strengthened with half circle plate on joints. The experiments studied the influences of different strengthened ways to trusses’ failure modes and ultimate bearing capacity. The results showed that both of the above two strengthened trusses can improve the structural performance, stiffness and ductility. The truss with concrete-filled steel tubular chord and steel tubular brace is a better strengthened way to get improving, because the core concrete can produce better synergistic effects with steel tubular chord.2. Numerical analysis:Full-range analysis on load-versus deformation relations of those four trusses was performed base on the finite element models established by ANSYS. The accuracy and rationality of the ANSYS models were verified by the collected experimental results. Based on the ANSYS models, the stress and strain distributions and developments at different characteristic points of the full-range process were analyzed, and the typical failure modes of those trusses members were illustrated. The mechanical transmission path was also analyzed. Parametric analysis was conducted on the influences of static performance of those two strengthened trusses. The parameters included the core concrete of chord, the length ratio and the thickness ratio between half circle plate and the chord.The main creative points of this paper are as follows:1. The prototype experiment of the strengthen Warren truss with hidden welds unwelded was conducted the first time, revealing the failure mode.2. The finite element models of trusses with hidden welds unwelded was established, making a certain amount of primitive accumulation on the numerical analysis instead of prototype experiment.