The Ultimate Bearing Capacity Research Of A Leaning-type Arch Bridge

The leaning-type arch bridge is composed with two pieces of vertical mainarches and two pieces of leaning stable arches located on the both sides of the mainarches, with no transverse braces between the main arches, and it is one of thecompetitive power bridges in the urban bridges. The notable space effect of this typeof bridge requires a complex design of the structure and loadings. Thus the furtherdevelopment of the bridge is confined with the design of ultimate bearing capacity. Inthis paper, studies on ultimate bearing capacity of the leaning-type arch bridge arecarried out:(1) Arc-length method is employed to investigate the system of the leaning-typearch ribs. The process of its lateral instability is tracked and analyzed, and the extremevalue point of the lateral instability is obtained. Geometric nonlinearity, materialsnonlinearity and the double nonlinearities effects on the ultimate bearing capacity ofthe system of the leaning-type arch ribs are illustrated. The impacts of changes of thestable inclination angle, stiffness, central angle and the length of top transverse brace, thebending stiffness of transverse brace, rise-span ratio, the main arch boundary conditionsand the horizontal wind load are revealed.(2) The influence of non-directional load and deck on ultimat bearing capacity ofthe leaning-type arch bridge is considered. The load-displacement curve is obtainedthrough the tracking of the equilibrium path of arch bridge, which reveal thedeformation process of the nonlinear instability and failure, instability modes and thefailure mechanism.The effect of geometric nonlinearity, materials nonlinearity, doublenonlinearities and the various design parameters of bridge on the ultimate bearingcapacity of the system are illustrated.(3) With the linear elastic eigenvalue analysis and the double nonlinear extremevalue point analysis, the stable arch influence coefficient1, the influence coefficientof suspender and deck2, the influence coefficient of ultimate bearing capacity3and the confidence interval of the lateral instability critical load are obtained underdifferent bridge design parameters. Based on these analyses, the simplified calculationmethod is proposed for the ultimate bearing capacity of this leaning-type arch bridge.