采用装配式栓钉的钢-UHPC组合板的抗弯性能

Flexural behavior of steel-UHPC composite slabs with demountable shear connectors

为提高钢-UHPC组合结构的延性,本文提出一种采用装配式栓钉连接的钢-UHPC组合板。设计并完成了不同抗剪连接程度的组合板的抗弯性能试验,分析了组合板试件破坏形态、极限承载力、刚度、裂缝发展规律和板端滑移,并与采用焊接栓钉的钢-UHPC组合板进行了对比分析,讨论了组合板试件的可拆卸性,最后对其极限抗弯承载力和抗弯刚度进行了理论分析并推导了计算公式。结果表明:装配式栓钉连接的钢-UHPC组合板破坏模式为纵向水平剪切黏结破坏;降低栓钉间距能提高组合板的协同变形能力,从而提高组合板结构的极限承载力、弹塑性阶段的刚度和裂缝控制能力;与采用焊接栓钉连接的钢-UHPC组合板对比,其在发生较大变形的情况下钢板和UHPC板仍然可较容易地拆卸分离;推导了装配式栓钉连接的钢-UHPC组合板的极限承载力计算方法和抗弯刚度计算公式,提出了抗弯刚度计算时应对UHPC板高度进行折减,折减系数(βU)在正常使用阶段建议为0.85,理论计算结果与试验结果吻合良好。本文研究成果可为采用装配式栓钉的钢-UHPC组合板的设计和应用提供理论依据。

To improve the ductility of steel-ultra-high performance concrete(UHPC)composite structures,we proposed a type of demountable steel-UHPC composite slab based on demountable shear connectors.The flexural tests for demountable steel-UHPC composite slabs with different shear connection degrees were designed and completed.The failure mode,ultimate capacity,stiffness,cracking behavior,and relative slip of demountable steel-UHPC composite slabs were analyzed and compared with those of steel-UHPC composite slabs with welded shear connectors.The demountability of demountable steel-UHPC composite slabs was discussed.The ultimate flexural capacity and flexural stiffness of demountable steel-UHPC composite slabs were theoretically analyzed,and related calculation formulas were deduced.Results showed that the failure mode of demountable steel-UHPC composite slabs was longitudinal horizontal shear bonding failure.Reducing the stud spacing could enhance the cooperative deformation capacity of demountable steel-UHPC composite slabs,resulting in the improvement of their ultimate flexural capacity,stiffness at the elastic-plastic stage,and crack control ability.Different from the steel-UHPC composite slabs with welded shear connectors,the steel slab and UHPC slab of the demountable steel-UHPC composite slabs could be easily disassembled even in the condition of large deformation.The formulas for the ultimate flexural capacity and flexural stiffness of demountable steel-UHPC composite slabs were derived.It was proposed that the height of UHPC slab should be reduced when calculating the flexural stiffness,and the reduction coefficient(βU)was suggested to be 0.85 in serviceability state.The theoretical calculation results were in good agreement with the test results.The research results can provide theoretical basis for the design and application of steel-UHPC composite slabs with demountable shear connectors.