Experimental Study Of Combined Force Of Reinforced Concrete Column Under Eccentric Compression

The cross section which are under compressive stress, flexural moment and shearing force under seismic action is the weakness of reinforced concrete member. When reinforced concrete construction was under combined loadings,as the correlations of comading,the form of damage, the fracture morphology and the ultimate bearing capacity of the member are more complex. This dissertation makes an exploratory research of the correlation between the forces of the members under combined loadings. The main contents and perorations are as follows:1.This paper summarized many domestic and foreign theoretical research results which about the reinforced concrete member under combined loadings, and a calculation model of the ultimate bearing capacity of the member under combined loadings.2.This paper contained an experiment of five reinforced concrete columns under different eccentric flexural loading. The experiment scheme make full use of the property of HPB300,and applied initial moment on members through prestressed technique.The test results of member Z-1 and Z-4 show that the flexural moment is relevant to the shear action, with the increasing of the flexural moment,the shear capacity will increase about 30%;In addition four members(Z-1、Z-2、Z-3、Z-4) occur bending shear failure.Member Z-0 occurs typical large eccentric compression failure.3.The process of reinforced concrete column with eccentric compression under combined forces had been simulated by the ABAQUS method(finite element analysis). With the simulation results and test results bad been compared respectively. A conclusion was obtained, the simulation results’ errors were reasonable. The combined loading model had been built by changing the parameters with an extend simulation analysis. when the axial compression ratio was low, the axial compression ratio shearing action had increased, and then, the flexural bearing capacity of the specimen was reduced; when the axial compression ratio was not less than 0.2, the shearing action had increased, and then, the flexural bearing capacity of the specimen increased.4. According to the results of the experiment and finite element analysis, the laws of the relevance between the compressive stress, flexural moment and shearing force of the member under combined loadings are:1) The correlation between compressive stress and shearing force. When the axial compression ratio was less than 0.8, the axial compression ratio had increased, and then, the shear capacity of the specimen increased; when the axial compression ratio was larger than 0.8, the shear capacity of specimen decreases rapidly2) The correlation between compressive stress and flexural moment. When the axial compression ratio was less than 0.6, the axial compression ratio had increased, and then, the flexural bearing capacity of the specimen increased; when the axial compression ratio was larger than 0.6, axial compression ratio had continually increased, the bending bearing capacity of specimen was reduced.3) When the bending moment or shearing action is little,there is no relevance between them.When the bending moment of the specimen reached about 60% of their bending strength, the shear capacity of specimen declined slightly; when the shearing action of specimen reached about 60% of their ultimate shear capacity, the flexural bearing capacity of the specimen fell slightly.5.According to the influence of axial force,shear and bending moment when members are under combined loadings, this paper amend the formula of bending shear calculation was given by Xu Zipeng[15]. By the calculation, the results presented a better fit to the practical test results.It can express the property of the member under combined loadings better.