Research On Mechanical Performance Of Ultra-wide Simply Supported Hollow Slab Channel-beam Bridge

Prestressed concrete channel-beam(hereinafter referred to as channel-beam)is a through bridge structure composed of main beam,track bed slab and end beam.It has the advantages of low building height,large clearance under the bridge,and good sound insulation and noise reduction effect.It is widely used in highway,railway and urban rail transit bridge construction.In the past,the channel-beam bed slabs were mostly made of concrete solid slabs,and the selfweight effect of the structure was prominent,which restricted its development to long-span bridge structures.Under the premise of ensuring the safety of the force,hollowing the concrete solid slab can effectively reduce the structural self-weight of the channel-beam and increase its spanning capacity.At present,there are few researches on prestressed concrete hollow slab channel-beam bridges at home and abroad,and there are few research reports on the reasonable structure and design method of channel-beam hollow slab.Based on the engineering background of the newly-built double-track super-wide simply supported channel-beam bridge of the Guangzhou-Shenzhen Third Line in Guangdong Province-the Xifu River Bridge(32m span),combined with its nonlinear numerical analysis model and mechanical performance calculation results,four different structural forms of concrete hollow slab channel-beam are proposed,and studied its basic mechanical properties and key design parameters.The specific work completed is as follows:(1)The calculation theory of bending,torsion and shear lag of the channel-beam is summarized,and then a nonlinear finite element analysis model of a channel-beam is established by ABAQUS,and the calculation accuracy of the model is verified by the test results.The results show that the finite element modeling method considering material nonlinearity can better simulate the spatial force characteristics of prestressed concrete channel-beam.(2)Aiming at problems such as the prominent self-weight effect of the channel-beam concrete solid slab,based on the engineering background of the Xifu River Bridge on the Guangzhou-Shenzhen Third Line,the hollow slab design principle of the channel-beam bridge is proposed.Based on this principle,four hollow slab structures with different structural forms are designed,ABAQUS is used to numerically analyze its bending,torsion and shear lag effects.The results show that the stress and deformation of the sawtooth-box hollow slab and the sawtooth-sawtooth hollow slab under static load are relatively small,followed by the sawtooth hollow slab,and the box-shaped hollow slab has relatively large stress and deformation.The shear lag effect is basically the same.Comprehensive consideration of factors such as construction difficulty and structural response,when the channel-beam adopts sawtooth hollow slab,the construction is simple,the structure has high bending and torsion resistance,and the strength and rigidity under the design load meet the requirements of the specification.(3)Taking the prestress,the height of the main beam and the slope of the corner of the main beam and the track bed slab as the basic parameters,the influencing factors of the mechanical properties of the hollow slab channel-beam are further studied.The results show that the transverse prestress has a greater influence on the transverse stress and vertical displacement of the hollow slab channel-beam,and the longitudinal prestress and the height of the main beam also affect the longitudinal normal stress and vertical displacement of the main beam of the hollow slab channel-beam significantly.(4)The applicability of the current code formula to the stress calculation of the hollow slab channel-beam is evaluated.The results show that the maximum error of the main beam stress between the finite element calculation results and the formula calculation results is 2% during the bridge completion stage,and the maximum error of the main beam stress during the operation stage is 1%.The current code formula can be better applied to the calculation of the stress of the main beam of the hollow slab channel-beam during the bridge completion stage and the operation stage.