Bending Test Research And Shear Lag Effect Analysis On 24m RPC Precast Segmental Simply-Supported Box Girder

Reactive Powder Concrete(RPC)has the high compressive strength and tensile strength.And its impermeability,frost resistance,and corrosion resistance are better than ordinary concrete's.Therefore,the use of RPC instead of using ordinary concrete is an efficient way to promote the development of bridges to large spans,thin-walled,and high durability.Recently,a number of theoretic studies on RPC precast segmental beams have been conducted,while lacking the research of large-scale model tests.Based on this,the bending test and numerical simulation were performed on a 24 m RPC precast segmental simply-supported box girder in this paper.The pipe friction and deformation characteristics of the RPC thin-walled simply-supported box girder have been studied.Meanwhile,the stiffness parameters and failure modes have been obtained.Moreover,the shear lag effect of the test beam and its influencing factors have been analyzed.The main contents and conclusions are as follows:(1)A bending test has been performed on a 24 m RPC precast segmental simply-supported box girder to measure the friction coefficient between prestressed steel and pipes as well as to study the tensile effect of prestressed steel on RPC girder.Moreover,the load-deflection curve,the distribution law of stress,cracking time,crack distribution,and the failure mode of the test beam have been studied under the conditions of normal loading,eccentric loading,cracking and Re cracking loading.(2)A finite element model of the 24 m RPC precast segmental simply-supported box girder was built.And its stress and deformation under static loading have been analyzed with the comparison of the numerical simulation and test results.Based on the specifications,the prestress loss,cracking moment and crack spacing of the RPC precast segmental simply-supported box girder have been calculated.Combined with the test phenomena and numerical simulation data,the failure mode of the segmental assembled box girder has been analyzed.(3)By using the energy variation method.the formulas for calculating the shear lag coefficient in the mid-span cross section under concentrated loading and uniformly distributed loading were deduced.Furthermore,the impacts of self-weight,prestress,shear lag effect during operation stage,the geometric factors of box girder and the joint type on the shear lag effect of the test beam have been analyzed.The analysis shows that the length of the cantilever plate,the width ratio of the web,the span width ratio have certain effects on the shear lag effect.The glue joints can improve the overall performance of the segmental beam and also have a certain effects on the shear lag effect.