PBL剪力键混凝土榫在特定破坏模式下的应力状态分析

Analysis of stress state of PBL shear connectors' concrete tenon in specific failure mode

根据实验建立3个PBL剪力键有限元模型,结合荷载—滑移曲线,对不同破坏模式下混凝土榫的应力状态进行分析。研究结果表明:剪切破坏下混凝土榫上半圆环处于主应力相差较小的三向受压状态;压碎破坏下混凝土榫上半圆环处于主应力差值较大的三向受压状态,前两者均仅在下半圆环有拉应力出现;割裂破坏下混凝土榫主应力相差较大、三向受压区域相对较小、上半圆环与贯穿钢筋接触部分存在拉应力。可通过适当加大钢板厚度、内设横向钢筋、加强外包混凝土底座等措施使PBL剪力键发生剪切破坏,从而提高其承载力。

Based on the experimental data,three finite element models of PBL shear connectors are established.Combined with load slip curve,the stress state of PBL shear connectors’concrete tenon under different failure modes is analyzed by ANSYS.The results show that the upper half of the concrete tenon in the shear failure mode is in the three-way compression state with small difference in principal stress,and only in the lower half of the ring there is tensile stress.In the crushing failure mode,the upper part of the concrete tenon is in the three-way compression state with large difference in principal stress,and tensile stress only exists in the lower half of the ring.In the splitting failure mode,the concrete tenon has a large difference in the principal stress,and the three-way pressure region is relatively small,and tensile stress exists in the part where the upper half of the ring is in contact with the throughout reinforcement.The shear failure mode can be germinated by increasing the thickness of the steel plate,adopting transverse reinforcement and strengthening the outsourcing concrete base,so as to improve the PBL shear connectors’bearing capacity.