Evaluation and Prediction of the Mechanical Behavior and Durability of FRC for Optimization of Design Criteria at Serviceability Limit States for Bridges

评估和预测 FRC 的机械性能和耐久性，以优化桥梁正常使用极限状态下的设计标准

• 批准号: RGPIN-2015-06694
• 负责人: Charron, JeanPhilippe
• 金额: $ 1.6万
• 依托单位: École Polytechnique de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614303
• 关键词: Evaluation; Prediction; Mechanical; Behavior; Durability

Large proportion of infrastructures, particularly bridge decks, are exposed to severe environmental conditions and present an early deterioration. Thus, some materials and design criteria used in construction do not allow reaching the expected lifetime of structures (over 75 years) without intervention. Promising methods to extend significantly the durability of infrastructures are to revise design criteria in service conditions for normal strength concretes (NSC) and promote utilization of Fibre Reinforced Concretes (FRC). Compared to NSC, FRC presents significant improvements in terms of mechanical properties and durability. However, a crucial lack of adapted design criteria in service impedes full exploitation of these materials in Canada. The general objective of the research program is to evaluate the mechanical behaviour and the durability of cracked NSC and FRC structural components to establish efficient design criteria in service conditions. The specific objectives are to: (a) evaluate water permeability of reinforced concrete under representative conditions of bridges, (b) reproduce the water transport and mechanical behavior of reinforced concrete under these conditions, (c) propose admissible crack widths and rebar stress levels applicable to various concrete categories to ensure durability of structures. The novelty of the scientific approach is to evaluate water permeability of concrete in the most representative conditions of bridges, which means on reinforced concrete sustaining permanent loads and randomly cracked. A unique experimental device developed recently will be used and improved; it allows accurate evaluation of water permeability, crack widths and rebar stresses in a reinforced concrete component simultaneously to the application of static, constant or cyclic loadings. The research program involving mainly 14 HQP will include experimental studies to evaluate the impact of FRC composition, design conditions, loading conditions, and environmental conditions on water permeability. Based on mechanical and permeability results obtained, nonlinear finite element analysis will also be conducted to reproduce crack patterns and water penetration in reinforced concrete structures in service, and to propose admissible crack widths and rebar stress levels for NSC and FRC in service conditions. In many cases current design criteria in service for reinforced concrete structures do not allow reaching their expected lifetime. Experimental and numerical studies of this research program will provide efficient admissible crack widths and rebar stress levels adapted for NSC and FRC to ensure long-term durability of structures. These design criteria in service will be proposed for introduction in construction codes. Their utilization will improve durability of infrastructures, thus lowering their maintenance and repair costs.

大部分基础设施，特别是桥面，都暴露在恶劣的环境条件下，并且会出现早期退化，因此，在没有干预的情况下，施工中使用的一些材料和设计标准不允许达到结构的预期寿命（超过 75 年）。为了显着延长基础设施的耐久性，需要修改普通强度混凝土（NSC）使用条件下的设计标准，并促进纤维增强混凝土（FRC）的使用。与 NSC 相比，FRC 在机械性能方面取得了重大改进。然而，由于缺乏适用的设计标准，阻碍了这些材料在加拿大的充分利用。 该研究计划的总体目标是评估高效开裂 NSC 和 FRC 结构部件的机械性能和耐久性，以建立使用条件下的设计标准。具体目标是： (a) 评估代表性条件下钢筋混凝土的透水性。桥梁，（b）再现这些条件下钢筋混凝土的水输送和机械行为，（c）提出适用于各种混凝土类别的允许裂缝宽度和钢筋应力水平，以确保结构的耐久性。 该科学方法的新颖之处是在最具代表性的桥梁条件下评估混凝土的透水性，这意味着将使用和改进最近开发的独特的实验装置来准确评估承受永久荷载和随机裂缝的混凝土的透水性。在施加静态、恒定或循环载荷的同时，测量钢筋混凝土构件中的透水性、裂缝宽度和钢筋应力。 主要涉及 14 个 HQP 的研究计划将包括实验研究，以评估 FRC 成分、设计条件、加载条件和环境条件对透水性的影响，基于获得的力学和渗透性结果，还将进行非线性有限元分析以重现。使用中的钢筋混凝土结构的裂缝模式和水渗透，并提出使用条件下 NSC 和 FRC 的允许裂缝宽度和钢筋应力水平。 在许多情况下，当前钢筋混凝土结构的设计标准无法达到其预期寿命。本研究项目的实验和数值研究将提供适用于 NSC 和 FRC 的有效允许裂缝宽度和钢筋应力水平，以确保结构的长期耐用性。这些正在使用的设计标准将被提议引入建筑规范中，它们的使用将提高基础设施的耐用性，从而降低其维护和维修成本。