Research On Distortion Effect Of Reactive Powder Concrete Thin-walled Box Girder

Reactive powder concrete(RPC)is a new type of cement-based composite material with excellent properties,such as high strength,high toughness and high durability.It has broad application prospects in engineering.The excellent properties of RPC structure can reduce its self-weight,increase the span,reduce the size,and make the structure thinner.Compared with ordinary concrete box girder,the thickness of the box wall of the RPC box girder under the same bearing capacity becomes thinner,and the longitudinal warping moment of inertia and the transverse flexing moment of inertia are lower.Therefore,it is necessary to consider the deformation of the cross-section of the RPC box girder under the eccentric load.This paper focus on the distorting effect of RPC thin-walled box girder.The main contents are presented as follows:(1)The active powder concrete thin-walled simply supported box girder with 24m,48m and 72m spans are taken as the research objects.Based on the plate beam frame method,the differential equations of the box girder distortion with the distortion angle as the basic displacement parameter are derived.The initial parameter solution and the additional load of the differential equation have been obtained by the elastic foundation beam comparison method.The influence of the mid-section distortion effect of the active powder concrete thin-walled box girder and the distortion effect of box girder without considering the shear deformation have been obtained.Based on the energy variational principle,the differential equations of distortion considering shear deformation are derived,and the distortion effect of RPC thin-walled box girder considering shear deformation is obtained.(2)Based on the 48m RPC thin-walled box girder,the effects of span ratio,high span ratio,box wall thickness and flange width on the distortion of box girder are analyzed.As the span ratio increases,the curvature of the box beam distortion effect curve increases.As the high-span ratio increases,the cross-section distortion effect value of the box girder decreases.As the thickness of the box wall increases,the distortion of the box girder decreases,and the thickness variation of the top plate,the bottom plate and the web only affects the warping stress of the section near it.The effect of the width variation of the flange plate on the distortion of the box girder can be ignored.(3)The numerical method is applied to analyze the distortion effect of the RPC thin-walled box girder.The distortion and warping stress of the box girder are obtained.The numerical values well agree with the theoretical calculations through the comparision.