薄层UHPC中MCL形组合榫连接件力学性能研究

Research on mechanical properties of MCL-shaped composite dowel connectors in thin-layer UHPC

抗剪连接件正常使用阶段的力学性能是影响钢-混组合梁桥结构变形的关键因素。针对薄层超高性能混凝土(Ultra-high Performance Concrete,UHPC)及改进螺旋线(Modified Clothoide,MCL)形组合榫连接件组合形式中组合榫连接件力学性能研究不足的问题,研究UHPC对MCL形组合榫连接件抗剪刚度的影响,探索适用于薄层UHPC中MCL形组合榫连接件的抗剪刚度计算方法。设计并开展薄层普通混凝土(Normal Concrete,NC)以及薄层UHPC中的MCL形组合榫连接件推出试验;建立精细化的ABAQUS有限元数值模型,并通过试件试验结果验证所建立的有限元数值模型的适用性和有效性;基于推出试验数据及有限元数值模拟结果,采用组合榫三弹簧刚度模型,推导出薄层UHPC中MCL形组合榫连接件的抗剪刚度计算公式。研究结果表明:1)UHPC试件中的组合榫连接件抗剪刚度较NC试件有大幅提高;2)MCL形钢榫厚度的增加将使组合榫连接件抗剪刚度显著增大;3)提出的抗剪刚度计算公式能够准确计算薄层UHPC中MCL形组合榫连接件的抗剪刚度。研究成果可为带有MCL形组合榫连接件的UHPC组合结构的推广和应用提供理论支持。

The mechanical properties of shear connectors in normal service phase are the key factors affecting the deformation of steel and concrete composite structures.Aiming at the problem of insufficient research on the mechanical properties of composite dowel under the combined form of Ultra-High Performance Concrete(UHPC)and Modified Clothoide(MCL)connectors,the influence of UHPC on the shear stiffness of MCL-shaped composite dowel was studied,and the method for calculating the shear stiffness of MCL-shaped composite dowel in thin layer UHPC was explored.Push-out tests of MCL-shaped composite dowel in thin layer Normal Concrete(NC)or UHPC were designed and carried out.Refined finite element models were established by using ABAQUS software,of which the applicability and validity were verified by comparing against the test results.Based on the push-out test and finite element results,the formula for calculating the shear stiffness of the MCL-shaped composite dowel connectors in thin-layer UHPC was deduced.The results show that:1)the shear stiffness of composite dowel connector is significantly improved in UHPC compared with that in normal concrete;2)the shear stiffness of composite dowel connector increases with the thickness of steel dowel;3)the proposed formula for calculating the shear stiffness of the composite dowel can accurately calculate the shear stiffness of the MCL-shaped composite dowel connector in the thin-layer UHPC.This study provides useful theoretical support for the promotion and development of UHPC composite structure with MCL-shaped composite dowel connector.