Experimental Study Of Oblique Section Strength Of Compression Members

The weakness of reinforced concrete frame is the cross section who suffers the combined loadings of compression, bending and shear. Therefore, under the seismic action, the reinforced concrete frame column’s inclined section damage phenomenon comes earlier than the frame beam. This dissertation make a exploratory research of the problem of inclined section bearing capacity of the reinforced concrete frame column under compression and the main research contents and conclusions are as follows:1. This project has carried on experiments with six reinforced Z-shaped concrete column specimens with same section size and reinforcements.Experiments results show that the reinforced concrete members inclined section under the effect of compound forces have a correlation among bending resistance, crush resistance and shear resistance capacity and that the main factor of members failure pattern are compression-shear ratio and shear span ratio. The presence of bearing has an extinction effect on capacity of the column’s compression bearing capacity as large as45%; the smaller the shear span ratio, the larger influence on flexural bearing capacity of column, reaching the biggest weaken degree up to43%.2. Combined with previous analysis, the article thought that:1) For small bias column component, the variation coefficient of inclined section bearing capacity is significantly greater than that of normal section. That is to say the partial coefficient of inclined section bearing capacity has to be greater than the normal section small bias bearing capacity.2) For large bias column component, the presence of shear force not only enhanced the variation coefficient, but also makes the original ductile failure to become brittle failure. The reliability index of the brittle failure is greater than the ductile failure so that the partial coefficient of inclined section bearing capacity has to be greater than the normal section large bias bearing capacity.3) Both the two factors above make the partial coefficient of frame column inclined section to be greater than the bias component and graeter than the original safety factor when calculate based on bias component.3. the weakness of normal section bearing capacity and the small partial coefficient might be the reason that the frame column defected earlier than the frame beam. 4. In this paper, on the basis of experiment, we used the ANSYS finite element analysis software to simulate the experiment process, getting a calculated bearing capacity in a reasonable range of error compared with the experiment results. It is shown that the results composited the experimental phenomenon well through force-displacement curve, stress nephogram and crack distribution calculation. Therefore, the numerical model in this paper can simulate the reinforced concrete frame columns under combined loadings of compression, bending and shear bearing capacity and mechanical laws.5. This paper collected51inclined section bearing capacity of reinforced concrete components test data for comparing with bias bearing capacity physical model when shear force is0. The statistical analysis of test results show that shear force have an adverse effect on compression member bias bearing capacity, which is negatively related with shear span ratio. The average of extinction effect on the large bias column component and small bias column component is19%and11%, respectively. In conclusion, the negative impact of the shear force must be considered when inclined section bearing capacity of reinforced concrete components is calculated.