Standardization Design Of Medium Span Steel Box Girder Bridge

At present,in order to resolve the serious situation of excess domestic iron and steel production capacity and achieve the goal of capacity reduction,the State Council,the Ministry of Transport and the Chongqing Municipal Government have all issued guidelines for the steel industry to reduce excess production capacity and accelerate the construction of steel bridges.This measure will inevitably Accelerating the pace of the design and construction of steel bridges in China can be expected to be a period of highspeed development of steel bridges,especially steel box girder bridges,in the coming years.China has compiled a standard drawing of a reinforced concrete T-beam bridge spanning 25 to 40 meter span and a standard design atlas of the plate girder bridge and the 48,64 and 80 meter single-lane railway undercarriage beam bridge,but in the aspect of the highway flyover bridge.There is no widely accepted standard design atlas and reasonable structure for steel box girder bridges.Therefore,it is of great engineering practice guidance significance to standardize the design of medium span steel box girder bridges,study their economic and reasonable structural forms,reduce project cost and improve the quality of project construction.The main research contents and results are as follows:(1)The design parameters of thousands of bridges were investigated separately,and the representative spans,spans,and lane widths were selected to conduct the structural arrangement of the steel box girder,and the chambers,webs,and flange plates were studied.Structural designs such as stiffeners and diaphragms are reasonable.(2)Four standard sections of 4×30 meter,4×40 meter and 4×50 meter continuous steel box girder bridges with high-to-span ratios of 1:15,1:20,and 1:25,respectively,are divided into four standard sections using parametric analysis methods.The standardized design of the top plate,bottom plate and web of the standard beam section,and optimization of the spacing between the stiffeners and diaphragms in both longitudinal and transverse directions,and the optimum plate thickness design values and minimum steel consumption for the steel box beams satisfying the strength and stiffness requirements are obtained.(3)The advantages and disadvantages of cross-section structures were evaluated in terms of the amount of steel used,the deflection of live load,the ease of welding construction and maintenance,etc.,and the most economical and reasonable structural layout was selected.In engineering practice,the cross-section of 2.0 meter beam height should be preferred for 4×30 meter continuous steel box girder,2.0 meter beam height should be preferred for 4×40 meter continuous steel box girder,and 2.5 meter for 4×50 meter continuous steel box girder.m beam high section.(4)The effects of three different beam setting methods on the stress behavior of steel box girders are summarized.All the steel girders are arranged with large beams,which not only can effectively reduce the mid-span deflection value and improve the stress of the roof,floor and web,but also increase the deflection and stress with the increase of the span,beam height and the number of off-load lanes.The larger the reduction,the more obvious the stress improvement of the bottom plate and the web at the fulcrum.