钢管高强混凝土组合柱的受剪性能及承载力计算

Shear behavior and bearing capacity calculation of high strength concrete-encased concrete-filled steel tube composite columns

为了研究钢管混凝土组合柱的受剪机理及承载力,以剪跨比、箍筋形式、体积配箍率、轴压比和钢管尺寸为变化参数,设计了12个钢管高强混凝土组合柱进行受剪性能试验,分析组合柱的破坏过程及形态、荷载-位移曲线、荷载-应变曲线、变形以及承载力等受力性能的变化规律。研究表明:组合柱破坏形态受剪跨比和箍筋形式的影响显著,除剪跨比1.5的井字形箍筋组合柱发生剪切黏结破坏外,其余均发生斜压破坏;体积配箍率在1.63%~1.93%和试验轴压比在0.1~0.2之间时,组合柱具有较强的变形能力和承载能力;在体积配箍率相同的情况下,井字形箍组合柱拥有更好的剪切延性而八字形箍组合柱受剪承载力更高;相比普通钢筋混凝土柱,钢管混凝土组合柱的变形及受剪能力显著提高。试验基础上,基于修正压力场理论,提出了钢管混凝土组合柱受剪承载力计算方法,计算结果与试验结果吻合良好。

To study the shear behavior of high strength concrete-encased concrete-filled steel tube(CFST)composite columns,12 specimens were designed with shear span ratio,stirrup types,volume-stirrup ratio,axial compression ratio and steel tube size as variable parameters.The failure process and patterns,load-displacement curves,loadstrain curves,deformation and bearing capacity of specimens were analyzed.Test results shown that the failure patterns of specimens are affected by the changes of shear span ratio and stirrup types.Shear adhesive failure occurs in wellshaped stirrup composite columns with a shear span ratio of 1.5,diagonal compression failure occurs in the rest of the composite columns.When the volume-stirrup ratio is between 1.63%and 1.93%and the axial compression ratio is between 0.1 and 0.2,the columns have larger shear bearing capacity and better ductility.With the same volumestirrup ratio,the specimens equipped with well-shaped stirrup have better shear ductility while those equipped with octagonal stirrup have larger shear capacity.Compared with ordinary reinforced concrete column,the ductility and shear bearing capacity of high strength concrete-encased CFST composite columns are significantly improved.Based on the experimental research and modified compression field theory,a formula for calculating the shear bearing capacity of high strength concrete-encased CFST composite columns were presented.It is proved that the calculated values of shear bearing capacity are in good agreement with the test results.