Abstract: To improve the anti-deformation capacity of bridge structure, prestressed Reactive Powder Concrete (RPC)-Normal Concrete (NC) composite beam is proposed and ten prestressed RPC-NC composite beams and one NC beam were designed. Experiments of the mid-span deflections of the composite beams are conducted and the calculation method of the reflection is proposed. The influence of the degree of prestress, height of RPC and concrete degree of NC are considered in the experiments. The results show that the developing process of the deflection of composite beam can be divided into three stages, the elastic stage before cracking, cracking stage, rapid increasing stage after the yield of reinforcement. The higher the degree of prestress is, the longer the elastic stage is before cracking of the mid-span load-deflection, and the faster the stiffness yield and strength phase fall. The formulas of code for design of concrete structure and code for design for design of reinforced and prestressed concrete structure of railway bridge and culvert are modified based on the testing results. The calculated results by the modified formulas are in good agreement with the testing results.

Key words: road engineering, reactive powder concrete(RPC), normal concrete(NC), composite beam, equivalent stiffness, bending deflection