Implications of the embedded through-section technique for improving the resilience and sustainability of existing reinforced concrete infrastructure

嵌入式贯穿截面技术对提高现有钢筋混凝土基础设施的弹性和可持续性的影响

• 批准号: EP/L010364/1
• 负责人: Samir Dirar
• 金额: $ 12.56万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FL010364%2F1
• 关键词: Implications; embedded; through; section; technique

The strength enhancement of structurally deficient concrete infrastructure is an application of considerable economic and strategic importance, particularly in the case of bridges. In the United Kingdom alone, it has been estimated that there are approximately 10,000 bridges on the strategic road network and 150,000 bridges on local roads, of which a considerable number need strengthening or replacement. The estimated cost of assessing and strengthening such structures is in excess of £4 billion. Other countries, e.g. the United States, are faced with the same challenge, so emphasising the global significance of the issue.During the past two decades, fibre reinforced polymer (FRP) reinforcement has gained acceptance as strengthening systems for existing reinforced concrete (RC) structures. The use of FRP strengthening systems is advantageous due to their excellent mechanical and durability properties. Extensive research has resulted in approved FRP flexural strengthening methods for RC structures. In contrast, FRP shear strengthening of RC structures is not yet fully understood.To date, FRP shear strengthening systems for existing RC structures have primarily been applied as externally bonded (EB) or near-surface mounted (NSM) reinforcement. In order to utilise these systems, both sides of individual beam webs must be accessible. However, it is difficult to provide such an access in several practical situations. Moreover, laborious and time-consuming surface or groove preparation is required to ensure adequate bond between the concrete and the EB or NSM systems respectively. Furthermore, unless proper anchorage is provided, both the EB and NSM systems debond from the concrete at a stress level of 20% to 30% of the ultimate strength of the FRP reinforcement.The embedded through-section (ETS) technique is a recently developed shear strengthening method for existing RC structures. In this method, vertical holes are drilled upwards from the soffit in the shear spans of existing RC beams. High viscosity epoxy resin is then injected into the drilled holes and FRP bars are embedded into place. The ETS technique provides higher strengthening effectiveness than that provided by the EB or NSM systems. Other advantages of the ETS technique include higher protection against fire and vandalism, less epoxy consumption, and no need for access to the top slab or time-consuming surface preparation.Research investigating the shear behaviour of RC beams strengthened with ETS FRP bars has been limited. All beams tested to date had effective depths of less than 400 mm. This is unrepresentative of several practical situations where RC bridge beams have significantly higher effective depths. Moreover, the effect of other parameters that influence the structural behaviour of the strengthened beams, such as the shear span to effective depth (a/d) ratio and FRP bar type, has not been sufficiently investigated. A proper understanding of the effect of the above-mentioned parameters on the strengthened behaviour is vital for the best utilisation of the ETS technique.This project will investigate, experimentally and numerically, the effect of a/d and FRP bar type on the behaviour of realistically sized RC beams strengthened in shear with ETS FRP bars. The combination of experiments and numerical techniques will ensure an integrated modelling approach that will inevitably lead to a better understanding of the strengthened behaviour. The experimental results will be used to check the accuracy of current design standards and improve their predictions where needed. The insight gained from this project will enable the utilisation of FRP reinforcement for improving the sustainability and resilience of existing RC infrastructure. The concepts encompassed in this work will underpin our understanding of the behaviour of FRP-strengthened concrete structures and thus have parallel implications in a variety of other areas of concrete construction.

增强结构缺陷的混凝土基础设施的强度是一种具有相当大的经济和战略重要性的应用，特别是在桥梁的情况下。据估计，仅在英国，战略公路网就有大约 10,000 座桥梁，地方道路上有 150,000 座桥梁，其中相当多的桥梁需要加固或更换。评估和加固此类结构的估计成本超过 40 亿英镑。其他国家，例如美国也面临着同样的挑战，因此强调了该问题的全球重要性。在过去的二十年中，纤维增强聚合物（FRP）加固作为现有钢筋混凝土（RC）结构的加固系统已获得认可。由于其优异的机械和耐用性能，FRP 加固系统的使用是有利的。广泛的研究已获得批准的用于 RC 结构的 FRP 抗弯加固方法。相比之下，RC 结构的 FRP 抗剪加固尚未完全了解。迄今为止，现有 RC 结构的 FRP 抗剪加固系统主要用作外部粘合 (EB) 或近表面安装 (NSM) 加固。为了利用这些系统，各个梁腹板的两侧都必须是可接近的。然而，在一些实际情况下很难提供这样的访问。此外，需要费力且耗时的表面或凹槽准备，以确保混凝土与 EB 或 NSM 系统之间的充分粘合。此外，除非提供适当的锚固，否则 EB 和 NSM 系统在 FRP 加固极限强度 20% 至 30% 的应力水平下都会与混凝土脱粘。嵌入式贯穿截面 (ETS) 技术是最近为现有 RC 结构开发的抗剪加固方法。在这种方法中，从现有 RC 梁剪跨的拱腹向上钻垂直孔。然后将高粘度环氧树脂注入钻孔中，并将玻璃钢棒嵌入到位。 ETS 技术比 EB 或 NSM 系统提供更高的强化效果。 ETS 技术的其他优点包括更高的防火和防破坏保护、更少的环氧树脂消耗以及无需进入顶板或耗时的表面处理。对用 ETS FRP 筋加固的 RC 梁的剪切性能进行研究有限。迄今为止测试的所有梁的有效深度均小于 400 毫米。这并不代表钢筋混凝土桥梁具有明显更高的有效深度的几种实际情况。此外，影响加固梁结构性能的其他参数的影响，例如剪跨与有效深度（a/d）之比和FRP筋类型，尚未得到充分研究。正确理解上述参数对加固行为的影响对于 ETS 技术的最佳利用至关重要。该项目将通过实验和数值研究 a/d 和 FRP 筋类型对使用 ETS FRP 筋进行剪切加固的实际尺寸的 RC 梁的行为的影响。实验和数值技术的结合将确保集成的建模方法，这将不可避免地导致对强化行为的更好理解。实验结果将用于检查当前设计标准的准确性，并在需要时改进其预测。从该项目中获得的见解将能够利用 FRP 加固来提高现有 RC 基础设施的可持续性和弹性。这项工作中包含的概念将巩固我们对 FRP 强化混凝土结构行为的理解，从而对混凝土施工的各种其他领域产生类似的影响。

项目成果

Bond performance of the deep embedment shear strengthening method

深埋剪切加固法的粘结性能

• 发表时间: 2016
• 作者: Caro M

Experimental Behavior and Design of Exterior Reinforced Concrete Beam-Column Joints Strengthened with Embedded Bars

• DOI: 10.1061/(asce)cc.1943-5614.0000883
• 发表时间: 2018-08
• 期刊: Journal of Composites for Construction
• 影响因子: 4.6
• 作者: Ridwan Rahman;S. Dirar;Yaser Jemaa;M. Theofanous;M. Elshafie

Finite element parametric study of reinforced concrete beams shear-strengthened with embedded FRP bars

• DOI: 10.1016/j.compstruct.2016.04.017
• 发表时间: 2016-08
• 期刊: Composite Structures
• 影响因子: 6.3
• 作者: Michael Qapo;S. Dirar;Yaser Jemaa

Deep embedment strengthening of full-scale shear-deficient reinforced concrete beams

• 发表时间: 2015-12
• 作者: Yaser Jemaa;Connah Jones;S. Dirar

Effect of transverse and longitudinal reinforcement ratios on the behaviour of RC T-beams shear-strengthened with embedded FRP BARS

横向和纵向配筋率对嵌入 FRP 筋抗剪加固 RC T 梁性能的影响

• DOI: 10.1016/j.compstruct.2021.113622
• 发表时间: 2021
• 期刊: Composite Structures
• 影响因子: 6.3
• 作者: Sogut K