Experimental Research On Shear Performance Of T-Shaped R.C Frame Column With Broad-Limb

Special-shaped columns is peculiar structure in our country which are used widely. Special-shaped columns are RC columns with T-shaped, L-shaped and +-shaped. The ordinary special-shaped columns, whose ratio of section height to section thickness is not beyond 4, are used in little housing building. The special-shaped columns, which is called special-shaped columns with broad-limb, are inevitable used in buildings because of the limit of axial compression ratio, and the ratio of section height to section thickness is between 4 and 5.Since 90's last century, ordinary special-shaped columns have been studied already. But, few researches are conducted to study special-shaped columns with broad-limb, specially in its shear capacity. In this paper, the following work has been done.On the basis of experimental data of T shape RC columns with broad limb which are designed to fail in shear , the influence of primary factors on bearing capacity under low cyclic load are analyzed; Based on experimental data of T and L shape columns with broad-limb and other ordinary T and L shaped columns which are designed to fail in shear, the shear bearing capacity of T and L shaped-column with broad-limb and ordinary T and L shaped-column are investigated. The truss-arch model with softened concrete stress-strain relationship is extend to special-shaped columns with broad-limb. The simplified tri-linear analytical method is used to calculate the bi-directional shearing strength of special-shaped columns with broad-limb. The factors affecting the bi-directional shearing strength are analyzed by grey relation analysis theory.Through the analysis of the experiment and theory, the conclusion can be gotten as followed: the lower limit proposed formula for calculating the shear-bearing capacity of T and L shaped-column are provided, considering the effects of shear-span ratio, stirrup ratio and axial compression ratio, the theoretical results are in better agreement with the test results. The formula which is given from truss-arch model with softened concrete stress-strain relationship, can reflect preferablly the influence of shear-span ratio, steel bar, flange and axial load. The theoretical results of formula of the simplified tri-linear analytical method are in better agreement with the test results. The result grey relation analysis of revealed that the most important influence factors are axial compression ratio, stirrup ratio, ratio of section height to section thickness and tensile strength of concrete.