| With the continuous development of transportation construction in China,steel truss bridges have been widely used and promoted due to their beautiful appearance,large span capacity,strong bearing capacity,and ease of construction.For long span steel truss bridges,the launching method is a common construction method,especially in the construction environment of crossing rivers,valleys,and existing lines,which has obvious advantages.However,in recent years,with the continuous increase in bridge span and weight,and the increasingly complex construction environment and conditions,higher requirements have also been put forward for the launching construction of steel truss bridges.Therefore,it has important practical significance and engineering value to conduct in-depth research on the launching construction of steel truss bridges.This paper takes the 100 m simply supported steel truss beam jacking construction of Laowei Bridge on Qidong 6th Road of Binzhou Xiaoqing River Navigation Resumption Project as the engineering background,and studies the stress,deformation,and lateral anti overturning stability during the jacking construction process using the finite element software Midas/Civil,aiming at the problem of the narrow spacing slideway of the bridge.The main research contents are as follows:(1)Through the analysis and comparison of the construction process of the pushing method,in order to save construction time,a dragging pushing construction plan is adopted;In order to make reasonable use of the old bridge,a narrow spacing sliding track scheme based on the old bridge deck was proposed,using Bailey beams and steel pipe columns as the sliding track support system to support the pier position within the scope of the old bridge,reducing construction costs and improving construction efficiency.(2)According to the construction process,the construction stages are divided,and a finite element simulation model for the space of steel truss bridge launching construction is established.The forces and deformations of the steel truss bridge,slide beam,and support during each construction stage are analyzed,providing a theoretical basis for temporary structure design and construction monitoring.The analysis results indicate that the stress and deformation of the steel truss beam and temporary structure components during the construction of the top push can meet the requirements and are within the safe range.(3)A parameterized analysis was conducted on the lateral anti overturning stability of steel truss bridges during incremental construction from the perspectives of wind load,spacing between sliding block supports,lateral displacement,lateral eccentric load,and uneven settlement of temporary piers.It was found that the increase in wind load,lateral displacement,lateral eccentric load,uneven settlement of temporary piers,as well as the decrease in spacing between sliding block supports,have a significant impact on the lateral anti overturning stability of steel truss bridges;Through the orthogonal experimental design,the sensitivity analysis of the above factors is carried out by using the analysis method of range and variance,and the significance judgment of each factor is made by using the F-test method.The analysis shows that the wind load is a highly significant factor,the spacing of sliding block supports and the lateral eccentric load are significant factors,the lateral deviation is a general significant factor,and the uneven settlement of temporary piers is not significant factors.(4)The stress,deflection,and lateral displacement of the main components during the steel truss beam pushing construction process were monitored on site.The theoretical data and monitoring data were in good agreement,and the stress and deformation were within a safe range,providing good guidance for on-site construction. |
