【作者】 李建伟；

【导师】 严佳川；

【作者基本信息】 哈尔滨工业大学 ， 土木工程， 2025， 硕士

【摘要】 钢筋U形环扣连接是一种基于上下U形环扣钢筋间混凝土粘结作用传递荷载的装配式混凝土节点连接技术,通过将构件中的受力钢筋预制成规定形式,在工厂进行构件模块化施工后,运输至现场进行拼接,实现高效便捷施工。在面向核工程的装配式结构中,该技术可以通过无热影响区的连接方式减少焊接残余应力对构件连接性能的不利影响,利用预制工艺的精准性保障模块拼装的整体性,降低施工现场人工操作需求。此外,其灵活适配复杂钢筋节点的特点进一步提高了核工程异形构件的装配效率,为面向核工程的混凝土结构模块化施工提供了创新性技术路径。本文针对核工程中钢筋连接节点在单向拉伸和双向拉伸工况下的力学性能展开系统研究,系统考察了钢筋U形环扣连接的破坏模式和失效机理,在此基础上建立了单向拉伸和双向拉伸工况下钢筋U形环扣连接性能的精细化有限元数值分析模型,系统考察了钢筋U形环扣连接主要设计参数对连接性能的影响规律,推导并提出了钢筋U形环扣连接基本锚固长度计算公式以及搭接长度计算公式。本文主要工作如下:(1)针对核工程结构特点,提出了面向核工程的钢筋U形环扣连接构造方式,设计并开展了共计45组129个钢筋U形环扣连接试件单向拉伸试验,定义了钢筋拉断破坏、混凝土劈裂破坏、钢筋拔出破坏三种典型破坏模式,系统分析了不同破坏模式的破坏机理,获得了环筋扣合高度、混凝土强度、环筋横向间距、钢筋直径、钢筋牌号、横向插筋位置、环筋弯折形式对钢筋U形环扣连接力学性能的影响规律。(2)针对钢筋连接组数较少时可能存在的双向拉伸工况,设计了钢筋U形环扣连接双向拉伸试验的加载方案,系统进行了共计49组147个钢筋U形环扣连接试件双向拉伸试验,定义了钢筋拉断破坏、偏心受拉破坏两种典型破坏模式。通过正交试验方案的设计,定量获得了不同影响因素对钢筋U形环扣连接力学性能的影响程度。在偏心受拉破坏模式下,混凝土强度、环筋扣合高度影响高度显著,置信度为99%;钢筋直径对力学性能影响显著,置信度95%;环筋横向间距影响较显著,置信度为90%;横向插筋位置、钢筋牌号对钢筋U形环扣连接力学性能的影响较小。(3)基于ABAQUS有限元分析软件,针对单向拉伸和双向拉伸两种工况,分别建立了钢筋U形环扣连接性能精细化有限元数值分析模型,该模型可以考虑材料非线性和钢筋与混凝土之间界面滑移效应。通过参数分析,获得了核心区混凝土强度、构件截面尺寸、保护层厚度、群接效应等因素对钢筋U形环扣连接力学性能的影响规律。(4)结合试验及数值模拟分析结果,提出了钢筋U形环扣连接在单向拉伸和双向拉伸下的承载力计算方法,验证了其适用性,提出了钢筋U形环扣连接的基本锚固长度和搭接长度计算公式。更多还原

【Abstract】 The U-shaped rebar loop connection is a prefabricated concrete joint technology that transfers loads through bond anchorage between upper and lower U-shaped loop bars and surrounding concrete.In nuclear power engineering,this method involves prefabricating load-bearing rebars into specified configurations,followed by modular factory casting and on-site assembly to achieve efficient construction.For nuclear prefabricated structures,this welding-free technique eliminates heat-affected zones,thereby mitigating adverse effects of welding residual stresses on joint performance.Precision-controlled prefabrication ensures module integrity while reducing on-site labor requirements.Its adaptability to complex rebar configurations further enhances assembly efficiency for irregular nuclear components,providing an innovative approach for modular construction of nuclear concrete structures.This study systematically investigates the mechanical behavior of U-shaped rebar loop connections under uniaxial and biaxial tension in nuclear engineering.Failure modes and mechanisms were analyzed,and refined finite element models for uniaxial/biaxial tension scenarios were developed.Key design parameters influencing connection performance were evaluated,with formulas proposed for basic anchorage length and splice length.The main contributions are as follows:(1)A U-shaped rebar loop connection configuration tailored for nuclear engineering was proposed.Uniaxial tension tests were conducted on 45 groups(129specimens)of U-shaped rebar loop connections.Three failure modes were identified:rebar fracture,concrete splitting,and rebar pull-out.The failure mechanisms were analyzed,and the influences of loop height,concrete strength,lateral loop spacing,rebar diameter,rebar grade,transverse insert position,and loop bending configuration on mechanical performance were quantified.(2)For potential biaxial tension scenarios in nuclear engineering with limited connection groups,a biaxial tension loading protocol was designed.Biaxial tension tests were performed on 49 groups(147 specimens).Two failure modes were defined:rebar fracture and anchor eccentric tensile failure.Orthogonal experimental design quantified the impact hierarchy of influencing factors,revealing concrete strength and loop height as dominant parameters,with transverse insert position and rebar grade showing minimal effects.(3)Abaqus-based finite element models incorporating material nonlinearity and rebar-concrete interface slip were developed for uniaxial and biaxial tension.Parametric analyses elucidated the impacts of core concrete strength,component thickness,concrete cover thickness,and group effects on mechanical performance.(4)Load-bearing capacity calculation methods for uniaxial and biaxial tension were proposed based on experimental and numerical results.Their applicability was validated,and formulas for basic anchorage length and splice length were derived.更多还原