Analysis Of The Second Order Aerostatic Stability For Long-span Steel Truss Arch Bridge

Steel truss arch bridge with its beautiful structure and large spanning capacity become one of the most widely used type of city bridges across the rivers.With the increasing span and vector height of steel truss arch bridge,the stability problem in construction is especially prominent,as the bridge designers are one of the focus of attention.Based on the basic theory of second-order static wind stability,this paper analyzes the second-order static wind stability analysis by the finite software ANSYS.Taking a(70+240+70)m through steel truss arch bridge-Suling Mountain Bridge as an example,study the second-order static stability of the bridge in the construction.The main contents of the paper are as follows:(1)This paper reviews the history of arch bridge development at home and abroad,and makes a systematic overview of the development of arch bridge research theory.It briefly introduces the representative theory of arch bridge stability calculation,including analytic method and numerical analysis.With the continuous improvement of electronic computer performance and the development of large-scale engineering software,the finite element software has been used as the main means to analyze engineering problems.This paper focuses on the concrete analysis method by ANSYS finite element software for two kinds of stability problems,the double nonlinear theoretical basis and realization approach.(2)Establish the spatial nonlinear model of the Suling Mountain Bridge.Analyze the first order stability of the dead load and the construction load and the static wind load under four working conditions.The results show that: When the static wind load is not taken into account,the overall stiffness of the pre-construction structure is large,and the buckling mode is the external buckling of the local member.As the sections are assembled,the cantilever increases and the overall stiffness decrease.The overall instability is preceded by the local buckling of the rod.Considering the first-order stability of the static wind load,the buckling form of the structure is manifested as the out-of-plane instability of the wind brace member.(3)Revealing the failure mechanism of the failure bar,analyze the second-order static wind stability of the Suling Mountain Bridge by considering the double non-linear.The results show that: The failure of the whole bridge is caused by the increase of the local bar in the plastic zone,and the loss of the whole stiffness.Flexion of the prominent parts manifested in the diagonal bar under the first wind support.(4)Analyze the second-order static wind stability of the arch bridge by considering the influencing factors,including the boundary condition at the arch,the cable tension change,the non-linear and the non-directional loads of hanger rod.Have the following conclusions: Boundary form and the cable tension change have little effect on wind stability.Geometrical nonlinearity and material nonlinearity have different effects on them,and the material nonlinearity is most significant.Considering only geometric nonlinearity tends to overestimate the structural wind resistance.Mainly depends on the physical properties of the material.The effect of the non-directional loads of hanger rod can't be neglected,and the effect on the structural integrity is significant.