考虑低弹模泡沫的抗拔不抗剪连接件力学行为精细化分析

Refined Analysis of Mechanical Behavior of URSP Connectors with Low Modulus Foam

为探究抗拔不抗剪(URSP)连接件滑移与拉拔过程中连接件与混凝土力学行为的分布规律,考虑栓钉四周包裹的超弹性低弹模泡沫,对URSP连接件的滑移演变与拉拔性能进行精细化分析。通过与试验结果对比,验证模型可靠性,分析URSP连接件滑移演变与拉拔过程中栓钉应力与混凝土损伤分布规律,揭示URSP连接件受力特征,进一步探究连接件形式对螺帽最大应力与混凝土最大主应力影响。结果表明,采用ABAQUS可压碎泡沫模型模拟弹性泡沫棉,其计算值及分布规律与试验结果吻合较好,验证建模方法有效性;URSP连接件滑移过程主要包括弹性初始阶段、向弹性泡沫棉滑移阶段以及滑移受混凝土约束应力增大3个阶段,当处于滑移阶段时,栓钉竖向拉应力为87.6 MPa,纵向剪应力为9.8 MPa,表征URSP连接件抗拔不抗剪特性;由于弹性泡沫棉存在,螺柱内部整体Mises应力降低24.2%,其附近混凝土受压损伤与受拉损伤分布有所减弱,对混凝土开裂起到抑制作用;在螺帽四周布置弹性泡沫为栓钉螺帽Mises应力与竖向拉应力减小的主要因素,螺帽顶设置弹性泡沫混凝土主压应力明显增大,连接件形式对混凝土主拉应力影响较小,建议URSP连接件设计与施工过程中保留螺帽位置低弹模泡沫。

This study investigated the distribution patterns of mechanical behavior between connectors and concrete during the slip and uplift processes of uplift-restricted and slip-permitted(URSP)connectors.By considering the super-elastic low modulus foam encasing the bolts,a refined analysis of the slip evolution and uplift performance of URSP connectors was conducted.The reliability of the model was verified by comparing it with experimental results,analyzing the distribution patterns of bolt stress and concrete damage during slip evolution and uplift processes of URSP connectors.This research revealed the force characteristics of URSP connectors and further explored the influence of connector design on the maximum stress of the nuts and the maximum principal stress in the concrete.The results showed that the ABAQUS crushable foam model effectively simulated elastic foam,with computational values and distribution patterns aligning well with the experimental results,thereby confirming the validity of the modeling method.The slip process of URSP connectors mainly consisted of three stages:the initial elastic phase,the slip phase towards elastic foam,and the constrained slip phase under increased concrete stress.During slip phase,the vertical tensile stress in the bolts reached 87.6 MPa,while the longitudinal shear stress was 9.8 MPa,highlighting the uplift-restricted and shear-permitted properties of URSP connectors.The presence of elastic foam reduced the overall Mises stress in the bolt by 24.2%,diminishing both compressive and tensile damage in the adjacent concrete,thereby mitigating cracking.The arrangement of elastic foam around the nut was the main factor for the decrease in Mises stress and vertical tensile stress in the bolt,while the main compressive stress in the concrete at the top of the nut increased significantly.The design of the connector had a minor impact on the main tensile stress in the concrete,leading to the recommendation that the low modulus foam at the nut position should be retained during the design and construction of the URSP connectors.