Seismic Performance Analysis Of Long-span Steel Truss Arch Bridge During Construction

Steel truss arch bridge has beautiful shape,large span capacity and high bearing capacity.It has been widely applied.China located between the Pacific Rim seismic belt and the Eurasian seismic belt.Frequent earthquake disasters will seriously damage bridges and cause huge economic losses.Therefore,it is necessary to conduct a comprehensive study on the seismic performance of steel truss arch bridges.However,almost all previous studies on the seismic performance of bridges assumed that the bridge structures were in the completion stage,i.e.the analyses were normally performed during the service life of the bridges.The seismic performance of the bridges during construction is rarely investigated.The primary aim of the present research is to investigate the seismic performance of a steel truss arch bridge during its construction period.In this thesis,the development status of long-span steel truss arch bridges is introduced firstly.The characteristics of the bridge type are introduced in detail from three aspects: structure,stress and construction.At the same time,the current aseismic design and research status of bridges are discussed,which provides a theoretical basis for the subsequent analysis.Then,a bridge model is established by finite element software MIDAS/CIVIL,and two key construction stages are selected to analyze their dynamic characteristics.On this basis,the seismic performance of the bridge in different construction stages is analyzed by response spectrum analysis method and time history analysis method respectively.Finally,some calculation results are compared and analyzed to verify the accuracy of the research.Through the investigation,it is found that in the construction stage,the main component materials of the bridge did not yield under the earthquake action,while the displacement response was obvious.The torsion and lateral stiffness of cantilever bridges are poor.The main arch closure can greatly enhance the torsion resistance of the structure,improve the stress distribution,and improve the seismic performance.Temporary structures such as cable tower and prestressed cables are more likely to be damaged by earthquakes.