Thongchom Chanachai, Hu Lili, Sanit-In Penpichcha Khongpermgoson, Kontoni Denise-Penelope N, Praphaphankul Nitipong, Tiprak Koravith, Kongwat Suphanut
Department of Civil Engineering, Faculty of Engineering, Thammasat School of Engineering, Thammasat University, Pathumthani 12120, Thailand.
State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Polymers (Basel). 2023 Jul 1;15(13):2925. doi: 10.3390/polym15132925.
Glass fiber-reinforced polymer (GFRP) rebars are commonly used as an alternative to conventional steel reinforcement in a variety of structural applications due to their superior low cost, strength-to-weight ratio, and durability. However, their mechanical properties after exposure to elevated temperatures, particularly in fire-prone environments, remain a significant concern. To address this concern, the present study focuses on investigating the residual tensile behavior, specifically the tensile strength and elastic modulus, of GFRP rebars exposed to high temperatures that are realistically encountered during fire incidents. The temperature range considered in this analysis spans from 100 °C to 400 °C, with a heating rate of 20 °C/min. The fire duration of 1 h is used. This comprehensive analysis is essential for enhancing our understanding of the performance and applicability of GFRP rebars in fire-prone environments. Based on their actual application in the construction industry, five specimens of three different rebar sizes (16, 20, and 25 mm) were examined for the effect of rebar size on tensile behavior after fire exposure. In addition, the effects were investigated of air- and water-cooling methods on residual tensile behavior. The nominal tensile strength, elastic modulus, and ultimate strain of GFRP rebars at ambient temperature are 930 MPa, 50.2 GPa and 1.85%, respectively. The test results indicated that as the temperature increased to 400 °C, the ultimate tensile strength of the GFRP bars decreased by up to 55%, while the ultimate strain increased by up to 44%, regardless of the cooling method. In addition, when rebars of sizes 16-25 mm were subjected to a 400 °C fire treatment, the smaller the rebar, the greater the percentage of ultimate tensile and strain reduction. These findings hold great significance for the utilization of GFRP bars within the construction industry. This study offers valuable insights into the design of fire-resilient structures, emphasizing the importance of considering rebar size and cooling methods due to their impact on the post-fire tensile strength and strain of GFRP rebars.
玻璃纤维增强聚合物（GFRP）钢筋由于其成本低、强度重量比高和耐久性强等优点，在各种结构应用中通常被用作传统钢筋的替代品。然而，在暴露于高温后，尤其是在易发生火灾的环境中，其机械性能仍然是一个重大问题。为了解决这一问题，本研究重点调查了GFRP钢筋在火灾事故中实际遇到的高温下的残余拉伸行为，特别是拉伸强度和弹性模量。本分析中考虑的温度范围为100℃至400℃，加热速率为20℃/分钟。采用1小时的火灾持续时间。这种全面的分析对于增强我们对GFRP钢筋在易发生火灾环境中的性能和适用性的理解至关重要。根据它们在建筑行业的实际应用，对三种不同钢筋尺寸（16、20和25毫米）的五个试件进行了火灾暴露后钢筋尺寸对拉伸行为影响的研究。此外，还研究了风冷和水冷方法对残余拉伸行为的影响。GFRP钢筋在常温下的名义拉伸强度、弹性模量和极限应变分别为930兆帕、50.2吉帕和1.85%。试验结果表明，随着温度升高到400℃，无论采用何种冷却方法，GFRP钢筋的极限抗拉强度最多降低55%，而极限应变最多增加44%。此外，当尺寸为16 - 25毫米的钢筋进行400℃的火灾处理时，钢筋尺寸越小，极限抗拉强度和应变降低的百分比就越大。这些发现对建筑行业中GFRP钢筋的使用具有重要意义。本研究为耐火结构的设计提供了有价值的见解，强调了考虑钢筋尺寸和冷却方法的重要性，因为它们会影响GFRP钢筋火灾后的抗拉强度和应变。
