Study on Ultimate Shear Strength and Shear Design Equation for the Spirally Reinforced Concrete Columns

The purpose of this study is to The following items，according to the cyclic loading tests on 28 （divided into 2 series in each 14）scale is about 1/3 of full-size) column specimens with spiral hoops.1) To determine quantitativelycertain factors' influences on the ultimate shear strength of reinforced concrete octagonal columnswith spiral hoops.2) To review the suitability of the experimental equations and several countries'code equations for shear strength of reinforced concrete columns based on the recent test date.Theresults are summarized as follows (1) the phenomena of cracking and shear failure for the octagonalcolumns with spiral hoops are similar to the normal columns with square hoops.(2) theultimate shear strength of the spirally reinforced concrete columns increased with the increasing ofconcrete strength (Fc), axial load (N)spiral reinforcement ratio and longitudinal reinforcement ratio. The ultimate shear strengthdecreased with the increasing of…More column height. These strengths are similar to those of square columns.(3) The shearoctagonal columns strength of octagonal columns can be calculated conservatively using the存在的shear strengthreplacing the octagonal sections with squares having the same gross area and same(4) The test results indicate that The shear carried by truss mechanism involving精神描述（Qut）是很好的描述，由45个truss模型和描述shear可以expressed by the (1+<eta>_0) times ofthe shear carried by arch mechanism (Qua). Where <wta>_0 isaxial compressive stress factor （=N/A Fc）A is the cross-sectional area of column . the shear strength equation for reinforced concretecolumns, Qu(=Qut+Qua), is the same as the B methodwhich is the one now under consideration for a new shear design equation in the架构Institute of Japan.(5) The current empirical equations and several countries' code equations forshear strength are investigated according to 118 available date of the most recent experimentsmentioned in (4)，the modified shear design equation of the AIJ [Qu=Qut+(1+<eta>_0)Qua] is better agreement withtest date. Less

The purpose of this study is to clarify the following items, according to the cyclic loading tests on 28 (divided into 2 series in each 14, scale is about 1/3 of full-size) column specimens with spiral hoops.1) To determine quantitatively certain factors' influences on the ultimate shear strength of reinforced concrete octagonal columns with spiral hoops.2) To review the suitability of the experimental equations and several countries' code equations for shear strength of reinforced concrete columns based on the recent test date.The results are summarized as follows:(1) the phenomena of cracking and shear failure for the octagonal columns with spiral hoops are similar to those of the normal columns with square hoops.(2) The ultimate shear strength of the spirally reinforced concrete columns increased with the increasing of concrete strength (Fc), axial load (N), spiral reinforcement ratio and longitudinal reinforcement ratio. The ultimate shear strength decreased with the increasing of … More column height. These strengths are similar to those of square columns.(3) The shear strength of octagonal columns can be calculated conservatively using the existing shear strength equations by replacing the octagonal sections with squares having the same gross area and same reinforcement.(4) The test results indicate that the shear carried by truss mechanism involving spiral reinforcement (Qut) is well represented by the 45゜ truss model and the remainder shear can be expressed by the (1+<eta>_0) times ofthe shear carried by arch mechanism (Qua). Where <wta>_0 is the axial compressive stress factor (=N/A・Fc, A is the cross-sectional area of column). The shear strength equation for reinforced concrete columns, Qu(=Qut+Qua), is as the same as the B method, which is the one now under consideration for a new shear design equation in the Architectural Institute of Japan.(5) The current empirical equations and several countries' code equations for shear strength are investigated according to 118 available date of the most recent experiments. As mentioned in (4), the modified shear design equation of the AIJ [Qu=Qut+(1+<eta>_0)Qua] is in better agreement with test date. Less