Study Of Mechanical Properties Of The Ultimate Bearing Capacity Of Steel Pipe Of Reactive Powder Concrete

Based on the basic principles of densified systems containing homogeneously arranged ultra-fine particles (DSP) and Reactive Powder Concrete (RPC) adopted by foreign researchers specialized in building materials, silica rume,ultra-fine fly ash, quartz powder,52.5-class Portland cement and superplasticizer were selected and mixed, the theoretic of mixed steel fiber reinforced cement-based composite materials and of micro-aggregate filling voids were applied, the composition was adjusted, the mixture ratio of RPC was optimized, a suitable curing schedule was adopted, in the result, an ultra-high performance concrete designated RPC was successfully prepared by normal technology methods.The mechanical properties on one-directional loading of two kinds of mixture ratio RPC materials with or without steel fiber and of hollow steel tubes were studied. Three kinds of loading format were analogized and the working mechanism of RPC filled in steel tube short columns. The specimens of RPC filled in steel tube short columns were studied, and their characters of deflection were analyzed. The tested cures of loading-displacement relationship of RPC filled in steel tube short columns were given and the characters were discussed. A formula for predicting the ultimate bearing capacity of RPC filled in steel tube short columns under axial compression was derived from the limit equilibrium method. Compared the test results of the ultimate bearing capacity with computation of formulae provided by Good C D and et al, the slightly modified Cai-shaohuai formula was most accurate to calculate the ultimate bearing capacity of RPC filled in steel tube short columns. The influence of the strength of core concrete, the ratio of steel content, confinement coefficient and loading format on the mechanical properties of RPC filled in steel tube short columns.The specimens of RPC filled in steel tube slender columns were studied, and test results showed that the ultimate loading capacity and maximum displacement decreased as the slender ratio L0/D increased, the relative loading when the lateraldeflection increasing fast decreased as the L0/D increased.Such parameters as in-service function, construction technique, construction speed, earthquake resistance behaviour and fire resistance behaviour were analyzed, the results showed that RPC filled in steel tube columns had advantages over other columns in the respects. From the economical analysis of different columns supporting similar loading, it can be seen that the material price of RPC filled in steel tube columns was the lowest. Considering outstanding durability of RPC material, themacro-price of RPC filled in steel tube columns should be the lowest and the economical benefit should be the best.RPC filled in steel tube columns was an ideal construction material and had abroad application prospect.