Axial compression behavior and stress–strain modeling of CFRP-confined square RC columns with varying anchor configurations

IF 6.4 1区工程技术 Q1 ENGINEERING, CIVIL

Engineering Structures Pub Date : 2025-09-29 DOI:10.1016/j.engstruct.2025.121456

Zhengxie Zhang , Yonglai Zheng , Tanbo Pan , Chenyu Hou , Xin Lan , Xubing Xu , Liangqin Wu , Chao Yang , Yubao Zhou

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引用次数: 0

Abstract

Carbon fiber reinforced polymer (CFRP) has emerged as an effective material for strengthening reinforced concrete (RC) structures due to its high tensile strength, corrosion resistance, and ease of installation. However, in square or rectangular RC columns, stress concentrations at corners hinder the development of uniform confinement, thereby reducing strengthening efficiency. This study presents a comprehensive experimental and theoretical investigation into the performance of CFRP-confined RC square columns with varying anchor configurations. Six full-scale column specimens were tested under monotonic axial compression, each externally wrapped with one layer of CFRP sheet and installed with zero to four CFRP anchors. All columns were chamfered with a 30 mm radius to mitigate corner stress concentrations. The experimental results demonstrated that CFRP anchors significantly enhanced load-bearing capacity and ductility, improved lateral confinement, and modified the failure mechanisms. The specimen with three anchors exhibited optimal performance, with a 51.5 % increase in peak load (from 879.9 kN to 1333.2 kN) and a 29.9 % improvement in ductility index compared to the unconfined control. The failure mode transitioned from brittle global instability to ductile localized damage, accompanied by more uniform hoop strain distribution. However, excessive anchoring introduced stress interference and local cracking, leading to performance degradation. To characterize the mechanical response, a modified stress–strain model was developed, incorporating a reduction factor to account for confinement weakening caused by anchor installation. The model exhibited strong agreement with experimental data (R² > 87 %) in predicting both peak and ultimate stresses. This study provides valuable insights into the mechanical enhancement mechanisms of CFRP anchoring systems and offers a rational design basis for strengthening non-circular RC columns in structural rehabilitation.

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不同锚杆配置cfrp约束方柱轴压特性及应力-应变模型

碳纤维增强聚合物（CFRP）因其高抗拉强度、耐腐蚀和易于安装而成为增强钢筋混凝土（RC）结构的有效材料。然而，在矩形或方形混凝土柱中，角部的应力集中阻碍了均匀约束的发展，从而降低了加固效率。本研究对不同锚杆配置的cfrp约束RC方柱的性能进行了全面的试验和理论研究。在单调轴压条件下对6个原尺寸柱试件进行试验，每个柱试件外包裹一层CFRP片材，安装0 ~ 4个CFRP锚杆。所有柱都以30 mm半径倒角，以减轻拐角应力集中。试验结果表明，CFRP锚杆显著提高了承载力和延性，改善了侧向约束，改变了破坏机制。与无侧限对照相比，有三个锚杆的试件表现出最佳性能，峰值荷载增加51.5 %（从879.9 kN增加到1333.2 kN），延性指数提高29.9 %。破坏模式由脆性整体失稳向延性局部损伤转变，环向应变分布更加均匀。然而，过度锚固会引入应力干扰和局部开裂，导致性能下降。为了描述力学响应，开发了一个改进的应力-应变模型，其中包含一个折减因子，以考虑锚杆安装引起的约束弱化。该模型在预测峰值和极限应力方面与实验数据（R²> 87 %）具有较强的一致性。本研究为CFRP锚固体系的力学增强机理提供了有价值的见解，并为结构修复中非圆形RC柱的加固提供了合理的设计依据。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Engineering Structures 工程技术-工程：土木

CiteScore

10.20

自引率

14.50%

发文量

1385

审稿时长

67 days

期刊介绍： Engineering Structures provides a forum for a broad blend of scientific and technical papers to reflect the evolving needs of the structural engineering and structural mechanics communities. Particularly welcome are contributions dealing with applications of structural engineering and mechanics principles in all areas of technology. The journal aspires to a broad and integrated coverage of the effects of dynamic loadings and of the modelling techniques whereby the structural response to these loadings may be computed. The scope of Engineering Structures encompasses, but is not restricted to, the following areas: infrastructure engineering; earthquake engineering; structure-fluid-soil interaction; wind engineering; fire engineering; blast engineering; structural reliability/stability; life assessment/integrity; structural health monitoring; multi-hazard engineering; structural dynamics; optimization; expert systems; experimental modelling; performance-based design; multiscale analysis; value engineering. Topics of interest include: tall buildings; innovative structures; environmentally responsive structures; bridges; stadiums; commercial and public buildings; transmission towers; television and telecommunication masts; foldable structures; cooling towers; plates and shells; suspension structures; protective structures; smart structures; nuclear reactors; dams; pressure vessels; pipelines; tunnels. Engineering Structures also publishes review articles, short communications and discussions, book reviews, and a diary on international events related to any aspect of structural engineering.