Prefabricating Technique And Mechanical Properties Research Of RPC-NC Hybrid Beams

Reactive powder concrete and normal concrete(RPC-NC)hybrid beam is a new type of high performance composite structure.It has excellent performance,good economic benefit,and excellent durability.It is obvious better than reinforced concrete structure in the crack resistance,because steel fiber in the RPC can hinder the crack propagation.The requirements of safety and durability to engineering structure are becoming higher,and this new type of hybrid beam can meet the requirements,so it will obtain good development.In the thesis,based on the mechanical properties test of the RPC-NC hybrid beam,the preparation technology of RPC and the fabrication process of RPC-NC beams are researched.Based on the test result and finite element analysis and basic structural calculation theory,the mechanical properties of RPC-NC hybrid beam are studied.Preparation of RPC is the most important step to guarantee the quality of RPC-NC hybrid beams.By the studying on the influence factors of RPC strength,the influence law of different components rate are obtained,and the first mix proportion are given.The strength value of first test is below the design strength,and there are many pores in the RPC.Then,the mix proportion is adjusted to increase water cement ratio and high power vibration equipment is used,the result is satisfied.The fabrication process of RPC-NC hybrid beam is similar to the normal concrete beam.The features of fabrication processes are to ensure the height of the prefabricated section,and to ensure the surface roughness and shear strength,and to design the correct pouring time by the RPC and NC shrinkage performance.The experimental results about the mechanical properties of RPC-NC hybrid beams are given and analyzed in detail,and some characteristics of the normal section cracking and failure are obtained.Initial positive crack may appear at the NC bottom from the interface,may appear rat the top of the RPC.The bearing capacity of the normal section is greatly influenced by the steel ratio,and is influenced less by the relative height of RPC.Based on the finite element analysis,the stress distribution laws of hybrid beams and normal section failure characteristics are researched.Then,the influence of different reinforcement ratio to crack resistance and bearing capacity of normal section was studied...