再生混凝土装配式节点剪切性能仿真分析

Simulation Analysis on Shear Performance of Prefabricated Joints in Recycled Concrete

摘要: 为探究再生混凝土(RAC)与超高性能混凝土(UHPC)组合结构在装配式建筑中的界面剪切性能，本文基于ABAQUS建立含不同数量三角形剪切键的S1k-S6k试件三维有限元模型，模拟界面剪切加载过程，分析荷载–位移曲线及损伤分布特征。模型采用C3D8R单元、T3D2单元，界面采用考虑粘结与损伤的接触–分离模型，通过加载获取力学响应与损伤规律。结果表明：各组试件荷载–位移曲线形态一致；剪切键个数不超过3个时，试件抗剪性能接近，位移约0.38 mm达极限荷载(约44 kN)，个数大于3时，极限承载能力与最大位移显著提升；压缩损伤集中于RAC与UHPC上下表面接触棱边并向内扩散，拉伸损伤位于上下粘结平面及RAC外侧中间部位，且损伤范围与程度随剪切键个数增加而扩大；峰值荷载下应力沿试件中线对称扩散，剪切键数量增加可提升最大应力值、扩大应力分布范围并使其贴合UHPC外轮廓，优化剪力传递。研究为RAC-UHPC组合结构设计与绿色建筑发展提供参考。

Abstract: To investigate the interfacial shear performance of the composite structure of recycled aggregate concrete (RAC) and ultra-high performance concrete (UHPC) in prefabricated buildings, this study established three-dimensional finite element models of S1k-S6k specimens with different numbers of triangular shear keys based on ABAQUS. The interfacial shear loading process was simulated, and the load-displacement curves as well as the damage distribution characteristics were analyzed. The model adopts C3D8R elements and T3D2 elements, and the interface uses a cohesive-separation model that accounts for bonding and damage. Mechanical responses and damage patterns are obtained through loading. The results show that: the load-displacement curves of all groups of specimens have the same shape; when the number of shear keys is no more than 3, the shear resistance of the specimens is similar, and the ultimate load (approximately 44 kN) is reached at a displacement of about 0.38 mm; when the number exceeds 3, the ultimate bearing capacity and maximum displacement are significantly improved; the compressive damage is concentrated on the contact edges of the upper and lower surfaces of RAC and UHPC and spreads inward, while the tensile damage is located on the upper and lower bonding planes and the middle part of the outer side of RAC, and the damage range and degree expand with the increase in the number of shear keys; Under peak load, the stress spreads symmetrically along the midline of the specimen. An increase in the number of shear keys can improve the maximum stress value, expand the stress distribution range, make it fit the outer contour of UHPC, and optimize shear transfer. This study provides a reference for the design of RAC-UHPC composite structures and the development of green buildings.