Saingam Panumas, Gadagamma Chaitanya Krishna, Hussain Qudeer, Ejaz Ali, Hlaing Hnin Hnin, Suwannatrai Rawirot, Khan Kaffayatullah, Suparp Suniti
Department of Civil Engineering, School of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand.
Structural Engineering, School of Engineering and Technology (SET), Asian Institute of Technology (AIT), Thailand.
Heliyon. 2024 Oct 24;10(21):e39675. doi: 10.1016/j.heliyon.2024.e39675. eCollection 2024 Nov 15.
The hybrid confinement system combines various fiber types within a single matrix, allowing for the adjustment of volumetric ratios to optimize confinement performance. Synthetic FRPs are more expensive and have a higher carbon footprint due to significant CO emissions during production. In response, this study presents an innovative hybrid confinement approach using two natural materials: cotton ropes and FSMS (CFS) to improve concrete strength and ductility. Specimens, standardized at 300 mm height and 150 mm diameter with longitudinal steel bars and stirrups, were divided into two groups based on CFS configurations. The stress-strain response of CFS-confined concrete displayed distinctive behavior: an initial parabolic phase leading to peak compressive stress (ultimate strength), followed by a linearly degrading phase. Across all subgroups, CFS confinement significantly enhanced ultimate strength and corresponding compressive strains, with Subgroup 2A achieving the highest improvements of 246 % in ultimate strength and 1477 % in strain. Moreover, the ductility gain was reported as high as 20 for CFS-confined concrete. A non-proportional enhancement in the compressive behavior was observed with the increase in confinement ratio. Predictive models were developed for the idealized two-branch response of CFS-confined concrete, encompassing expressions based on nonlinear regression for ultimate strength, corresponding strain, ultimate strain, and elastic modulus. Two existing models were modified to trach each branch of the response. Integrating these two adjusted models closely replicated the experimental compressive curves.
混合约束系统在单一基体中结合了多种纤维类型，从而能够调整体积比以优化约束性能。合成纤维增强复合材料（FRP）成本更高，并且由于生产过程中大量的碳排放，其碳足迹也更大。作为回应，本研究提出了一种创新的混合约束方法，使用两种天然材料：棉绳和废轮胎钢丝（CFS）来提高混凝土的强度和延性。试件高度为300毫米，直径为150毫米，配有纵向钢筋和箍筋，根据CFS配置分为两组。CFS约束混凝土的应力-应变响应表现出独特的行为：初始抛物线阶段导致峰值压应力（极限强度），随后是线性下降阶段。在所有子组中，CFS约束显著提高了极限强度和相应的压缩应变，2A子组的极限强度提高幅度最大，达到246%，应变提高幅度达到1477%。此外，据报道，CFS约束混凝土的延性增益高达20。随着约束比的增加，抗压性能出现了非比例增强。针对CFS约束混凝土的理想化双分支响应开发了预测模型，包括基于非线性回归的极限强度、相应应变、极限应变和弹性模量的表达式。对两个现有模型进行了修改，以跟踪响应的每个分支。将这两个调整后的模型结合起来，能够紧密复制实验抗压曲线。
