Study On Vertical Bearing Capacity Of Double Square And Circle High-strength Stirrups Concrete

In order to predict vertical bearing capacity of double stirrup constraint concrete columnand to provide theoretical basis for axial compression test loading force per level,this paperadopts the single spiral stirrups constraint concrete circular column as the theoretical basis.Inthis paper, a plain concrete, three concrete columns with single stirrups and nine concretecolumns with double stirrups are tested by axial compression.The results show that:the bearing capacity of double stirrup constraint concrete can beincreased by about30%than single stirrup constraint concrete,promotion effect is verysignificant. Double stirrup constraint can improve the ultimate bearing capacity and ductilityof concrete material.Outer stirrup has no obvious influence on compression of concrete.Withthe increase of inner stirrup characteristic value,the duration of compression will be longerand more balance.Based on the experimental data,the equation is established betweenincreased value of peak strength or peak strain and stirrup ratio.A formula between typicalstrainε0.85,ε0.5and the stirrup character values under the condition of0.85fccand0.5fccis also set up.The formula for ductility coefficient of columns is acquired with generalagreement between calculated results and experimental data.