Understanding the cracking behaviour of reinforced concrete elements subjected to the restraint of imposed strains

了解受外加应变约束的钢筋混凝土构件的开裂行为

• 批准号: EP/T004185/1
• 负责人: John Forth
• 金额: $ 85.56万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FT004185%2F1
• 关键词: Understanding; cracking; behaviour; reinforced; concrete

Concrete is the most widely used construction material and is essential to the global programme of infrastructure updating (global estimate ~$100tn including UK National infrastructure plan £400bn) (www.oxfordeconomics.com/publication/open/283970). Excessive cracking due to restraint in poorly designed reinforced concrete (RC) structures is a widespread problem in the concrete construction industry and leads to many instances of costly remedial measures and delays. For example, a recent project in England was delayed due to excessive cracking caused by the restraint of imposed strains (from early thermal and shrinkage actions). Subsequent changes recommended by the applicants during the construction programme to limit the edge restraint of early thermal and shrinkage strain produced a real cost saving to the client of approximately £1.75M. The design guidance developed in this research will increase the performance and efficiency of new RC infrastructure as well as prolong the life of existing infrastructure through improved understanding of cracking. There are many situations when cracking due to the restraint of imposed deformations may be difficult to avoid. In fact, cracking from the restraint of early thermal movements (often referred to as 'non-structural' cracking) is the most common form of restraint induced cracking. In design, cracking is managed by the provision of reinforcement intended to distribute internal strains in such a way as to control the cracking pattern and limit crack widths. Current UK/EU design guidance on restraint induced cracking is encapsulated in EN1992-3:2006 and CIRIA report C660/766. The underlying design methodology in these documents has been used for over 30 years and is flawed. This is reflected in field observations identifying cracking patterns contrary to - and crack widths in excess of - those predicted by EN1992-3:2006. It is apparent that such 'non-compliance' cases result from erroneous basic assumptions; in particular; the boundary (restraint) conditions play a more significant role in determining the crack pattern than assumed in the current design guidance. The outcome of this research will provide practising engineers with the ability for the first time in three generations of UK/EU codes to correctly design RC elements for the restraint of short and long-term imposed strains. Planned dissemination routes will significantly aid the reduction in frequency and overall number of non-compliance cases, which currently result from the poor understanding of restraint induced cracking and affect all aspects of concrete construction in the UK.

混凝土是使用最广泛的建筑材料，对全球基础设施更新计划至关重要（全球估计约为100万亿美元，包括英国国家基础设施计划4000亿英镑）（www.oxfordeconomics.com/publication/open/283970）。由于设计不良的钢筋混凝土（RC）结构中的约束而导致的过度开裂是混凝土建筑行业中的一个普遍问题，并导致许多昂贵的补救措施和延迟的情况。例如，最近在英格兰的一个项目由于施加的应变（来自早期的热和收缩作用）的限制而引起的过度开裂而被推迟。在施工计划期间，申请人建议进行后续变更，以限制早期热应变和收缩应变的边缘约束，为客户节省了约175万英镑的真实的成本。在这项研究中开发的设计指南将提高新的钢筋混凝土基础设施的性能和效率，以及通过提高对开裂的理解延长现有基础设施的寿命。在许多情况下，由于施加变形的约束而导致的开裂可能难以避免。事实上，早期热运动的约束开裂（通常称为“非结构性”开裂）是约束诱导开裂的最常见形式。在设计中，通过提供钢筋来控制裂缝，钢筋的作用是分散内部应变，从而控制裂缝模式并限制裂缝宽度。关于约束诱导开裂的现行英国/欧盟设计指南包含在EN 1992 -3：2006和CIRIA报告C660/766中。这些文档中的基本设计方法已经使用了30多年，并且存在缺陷。这反映在现场观察中，发现裂纹模式与EN 1992 -3：2006预测的相反，并且裂纹宽度超过EN 1992 -3：2006预测的。很明显，这种“不符合”情况是由错误的基本假设造成的;特别是，边界（约束）条件在确定裂纹模式方面比当前设计指南中的假设发挥更重要的作用。这项研究的结果将提供执业工程师的能力，第一次在三代的英国/欧盟规范，以正确地设计钢筋混凝土元件的限制短期和长期施加的应变。计划的传播路线将大大有助于减少频率和不符合规定的情况下，这是由于目前的限制诱导开裂的理解不足，并影响在英国的混凝土施工的各个方面的总数。

项目成果

Understanding the cracking behaviour of reinforced concrete elements subjected to the restraint of imposed strains

了解受外加应变约束的钢筋混凝土构件的开裂行为

• 发表时间: 2021
• 作者: Elwakeel;A

Imposed loading effects on reinforced concrete walls restrained at their base

对钢筋混凝土墙施加的荷载效应在其底部受到限制

• DOI: 10.1680/jstbu.17.00179
• 发表时间: 2020
• 期刊: Proceedings of the Institution of Civil Engineers - Structures and Buildings
• 作者: Shehzad M

Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems

结构系统力学、建模和设计的当前观点和新方向

• DOI: 10.1201/9781003348443-204
• 发表时间: 2022
• 作者: Ridley I

INDUCED CRACKING IN EDGE RESTRAINED WALLS - FEA PARAMETRIC STUDY

边缘限制墙中的诱发裂纹 - 有限元分析参数研究

• 发表时间: 2022
• 作者: Elwakeel A

Predicting the influence of restraint on reinforced concrete panels using finite element models developed from experimental data

使用根据实验数据开发的有限元模型预测约束对钢筋混凝土板的影响

• DOI: 10.1080/15376494.2023.2248600
• 发表时间: 2023
• 期刊: Mechanics of Advanced Materials and Structures
• 影响因子: 2.8
• 作者: Shehzad M