Static Analysis On Slanting Type CFST Arch Bridges

Han River North Bridge is a five-span tied rigid-frame concrete-filled steel tube arch bridge without any lateral braces. The maximum span of the bridge is 160 meters, which is the largest arch bridge without lateral braces in the world. In order to raise the lateral rigidity, a hollow steel tube side arch is set as an out-of-plane brace for the vertical arch rib. The vertical arch rib is mainly used to carry the vertical loads, and the side arch rib to increase the stability. They are together to become a stable structures. Based on the practice of Han River North Bridge, this dissertation has carried out the following research:(1) The mechanical behavior of this slanting type Concrete-filled steel tube (CFST) arch bridge has been systematically studied, including the internal force distribution between the vertical and side arch ribs under vertical loads, the force-transfering mechanism of the whole arch under horizontal loads, and the influence of the V-shaped component and tie bars on the arch ribs.(2) In order to inspect the actual status and performance of Han River North Bridge, the loading test was carried out. The test contents covered the deflection and stress of the main sections, natural frequency, impact coefficient and damping ratio, etc. The results indicated that the bridge is satisfactory both on the working performance and on mechanical behavior; and they all meet the requirements of the design codes.(3) The stability behavior of the'A'span (maximum span) was predicted by means of three methods, i.e., the eigenvalue buckling analysis, the geometric nonlinear analysis, and the dual-nonlinear analysis considering the nonlinearity of both the materials and the geometry. The differences of the predicted results using above methods were compared and the failure reason under ultimate loads was analyzed. At last, Parameter study was carried out to investigate the bridge stability, including the number and locations of the wind braces, loads with uncertain direction from the suspenders .