钢-UHPC组合结构中栓钉剪力键力学性能研究

STUDY ON MECHANICAL PROPERTIES OF STUD SHEAR CONNECTORS IN STEEL-UHPC COMPOSITE STRUCTURES

为深入研究栓钉在超高性能混凝土(ultra-high performance concrete,UHPC)和普通混凝土(normal concrete,NC)中的力学特性及破坏形态,对8个栓钉剪力键试件进行了推出试验,详细探讨了混凝土类型、栓钉直径及长度对栓钉剪力键极限抗剪承载力的影响规律;基于有限元模型,进一步分析栓钉的极限抗拉强度、直径、长径比及混凝土强度对抗剪性能的影响,并详细研究栓钉直径、长度及混凝土强度对栓钉剪应力有效分布长度的影响。结果表明:栓钉根部附近的剪切断裂是主要的破坏形式;与NC试件相比,UHPC试件的抗剪承载力和抗剪刚度更高,但延性较低;栓钉剪应力在根部出现峰值,并沿钉帽方向迅速衰减;栓钉直径对剪应力有效分布长度影响显著。最后,根据试验结果提出了栓钉剪断破坏模式下的荷载-滑移曲线及抗剪承载力计算公式,计算结果与试验结果吻合良好,可为工程设计提供一定的参考价值。

In order to further study the mechanical properties and failure modes of studs embedded in ultra-high performance concrete(UHPC)and normal concrete(NC),a total of eight stud push-out specimens were tested and the influences of concrete type,diameter and length of stud on ultimate shear capacity were discussed.Based on the finite element model,the effects of ultimate tensile strength,diameter and length diameter ratio of stud and concrete strength on shear performance were further analyzed.The effects of diameter and length of stud and concrete strength on the effective distribution length of shear stress of stud were studied.The results show that the shear fracture near stud roots is the leading dominant failure mode.The shear capacity and shear stiffness of studs embedded in UHPC are higher than that of ordinary concrete,but the ductility is lower.The shear stress of stud peaks at the root and decreases rapidly along the direction of the nail cap.The diameter of stud has a significant effect on the effective distribution length of shear stress.Finally,according to the test results,the load-slip curve and a formula for the calculation of shear capacity under the stud shear failure mode are put forward,and the calculated results are in a good agreement with the test results,which can provide a reference for pertinent engineering design.