The Stability Analysis For Large-span Reactive Powder Concrete Box Girder

Reactive powder concrete (RPC) is a type of ultra-high performance material, which has the advantages of high strength, high toughness and high durability. The box girder made of reactive powder concrete is thinner and lighter than that of the ordinary concrete box girder, which may cause the unstable failure before reaching its ultimate strength under the condition of satisfying the normal use of the strength and deflection. Therefore, the problem of RPC box girder stability has been paid attention. The main contents of this paper include:(1) Stability analysis of RPC rectangular plate. In order to obtain the maximum width-to-thickness ratio of RPC plate under different boundary conditions, the limit values of the plate width to thickness ratio are analyzed by using the elastic stability theory and ANSYS software respectively. The numerical solution of the buckling coefficient is compared with the theoretical minimum. And the result shows:the numerical solution is close to the theoretical minimum at a/b≥3, while the former is much larger than the latter at a/b<3.Compared with the theoretical minimum of the buckling coefficient, the numerical solution is fully considered the influence of the aspect ratio and the actual constraint on the critical buckling stress.(2) Based on the lateral buckling theory of thin-walled beams, the formula for lateral buckling under of RPC box girder uniform load is derived, which is used to solve the critical load of box girder global instability. According to the theory of web buckling, the critical load of box girder web buckling is calculated. Then the stability analysis of the box girder is carried out by using ANSYS. The results show: the stability failure forms of box girder are web buckling failure, and buckling failure load of box girder is much larger than that under normal using condition. At the same time, the application of the lateral buckling theory and the web buckling theory in the RPC box girder are verified.(3) Analysis of influencing factors on the RPC box girder stability. The effect of the web height-to-thickness ratio, the roof width-to-thickness ratio, the arrangement of the diaphragm, the prestress and the load type are analyzed. The analysis results show that the web height-to-thickness ratio and the roof width-to-thickness ratio has great influence on the box girder stability, while the influence of the number and thickness of diaphragm plate is limited, the prestress has little effect and partial load will reduce the stability of the box girder.