Stability Analysis Of Long Span CFST Arch Bridge Under Static Wind Load

The CFST arch bridge is widely used in the construction of our country's transportation by virtue of its high bearing capacity,good stability and good economic benefit.The bridge gets greater in span and more gentle in quality with the development of bridge design theory,manufacturing technology and new construction materials.Among them,the effect of wind load on bridge construction and operation becomes more and more obvious.Based on a large CFST arch bridge with a span of 300 meters in western China,this paper establishes a structural model using the finite element software Midas Civil,and analyzes its stability under static wind load.On the basis of the Code for Code for Wind and Bridge Design(JTG / T D60-01-2004)and the General Code for Highway Bridge Design(JTG D60-2015),the main research work includes the following points:(1)Simulate the displacement of the maximum cantilever state,the arch state and the bridge state under the static wind load by the finite element model,pointing out that the maximum displacement deformation occurs in the maximum cantilever state.Meanwhile,make recommendations for the wind protection in the construction process.(2)Analyze the dynamic characteristics of the cantilever state and the bridge state,obtaining the first ten order vibration response graph.By analyzing the vibration response diagram,it is found that the in-plane vibration modes of the arch ribs in the bridge state appear later than the out-of-plane modes,indicating that the stiffness of the in-plane stiffness is out-of-plane stiffness.Then the symmetrical modes appear later than the anti-symmetry,each component can form a unified whole,playing a coordinating role.However,due to the longer bridge operation period,it should focus on strengthening the wind protection at this stage.Besides,by analyzing the maximum cantilever state vibration pattern,it is found that the maximum amplitude occurs in the main top of the arch ring,while the cantilever arm maintains a balance only by stabilizing arch and cable,it is easy to lose stability under the effect of wind load,so strengthening the cable wind is necessary.(3)Expound the stability of vibration,galloping and vortex-induced resonance stability,and carry out the engineering examples supported.The results show that the CFST arch bridge has strong stability and on the basis of the analysis,the control measures of wind and vibration are discussed in detail.(4)Analyze the stability of the maximum cantilever state before the joint,and put forward the relevant measures to optimize the arrangement of the arch ribs and the angle of the wind wave.