钢-正交胶合木组合梁浆锚栓钉连接件受剪性能

Shear performance of grouted stud connections for steel-cross laminated timber composite beams

为研究钢-正交胶合木(CLT)组合梁浆锚栓钉连接件(GSC)的受剪性能,设计8组GSC和2组浆锚螺栓连接件(BCGP)进行推出试验。试验参数包括栓钉直径(16~22 mm)、栓钉排数(单排、双排)、开槽方式(单向、双向)、开槽倾斜角度(0°~30°)、连接件类型(栓钉、螺栓)和灌浆料是否添加钢纤维。试验结果表明:GSC破坏模式为栓钉弯曲或剪断,同时伴有灌浆体转动与开裂;BCGP破坏模式为螺栓剪断,同时螺栓根部灌浆料被压溃;随栓钉直径从16 mm增加至19 mm, GSC受剪承载力与剪切刚度近似呈线性增长;相比于矩形槽口,随着楔形槽口倾斜面的增加,连接件受剪承载力降低,剪切刚度有所提高;槽口倾斜角度由0°增加至30°时,受剪承载力呈先下降后上升的趋势,剪切刚度呈先上升后下降的趋势,相较于矩形槽口,楔形槽口灌浆块体转动现象更为明显;受群钉效应的影响,双排与单排栓钉连接件的总承载力和总剪切刚度并不呈两倍关系。理论推导了GSC槽口处CLT板表层局部压溃破坏时的受剪承载力计算式,计算结果与试验结果吻合较好;针对栓钉剪切破坏情况,已有受剪承载力计算式的计算结果与试验值之间存在一定误差,最高达50%以上。

To study the shear performance of steel-cross-laminated-timber(CLT)composite beams with grouted stud connections(GSC),eight groups of GSC specimens and two groups of bolt connectors in grout pockets(BCGP)specimens were designed for push-out tests.Test parameters included stud diameter(16-22mm),row of studs(single and double),slotting mode(single-way and double-way),angle of groove surfaces(0°-30°),connection type(studs and bolts)and whether steel fibers were added to the grout or not.The test results indicate that the GSC fail primarily by bending or shear failure of studs combining with cracking and rotation of grout blocks,while the main failure modes of BCGP include bolt shearing failure and grout blocks crushed at the root of studs.The shear strength and shear stiffness of GSC increase linearly with the stud diameter increasing from 16mm to 22mm.Compared with the rectangular notch,the bearing capacity of the connections with wedge-shaped(WS)notch decreases,while the stiffness of the connections with WS notch increases with the number of sloping surfaces of the notch increasing.As the angle of the sloping surfaces of the WS notch increasing from 0°to 30°,the shear capacity decreases initially and then increases,while the shear stiffness increases at first and then decreases.Compared with the rectangular notch,the rotation of grout blocks in the WS notch is more obvious.Due to the group effect of studs,the total shear capacity and the total shear stiffness of double-row stud connections are not in a linear relationship with the number of stud rows.A shear capacity formula is proposed for the GSC in case of local crushing of the CLT panel,and the calculation results are in good agreement with the experimental results.Finally,for the shear failure of stud,the predictions from exiting formulas for shear capacity in relevant specifications differs from experimental results with a maximum difference up to more than 50%.