摘要
采用外套薄壁U形钢板、内灌无收缩灌浆料加固受火后钢筋混凝土梁,该加固技术能有效避免灌浆材料脱落,具有长效的加固功能。为验证该加固方法的有效性,进行了14根混凝土梁的静载试验,研究了U形钢板厚度和受火时间对加固RC梁受弯性能的影响,以及U形钢板厚度和剪跨比对加固RC梁受剪性能的影响。借鉴常温下组合梁承载力的计算方法,给出了薄壁U形钢板加固受火后RC梁受弯和受剪承载力的计算公式。结果表明:受火1.0、1.5 h后混凝土梁的受弯承载力分别降低了9.4%、10.4%,剪跨比为1.74、2.58的混凝土梁受火1.5 h后受剪承载力分别降低了19.5%、10.6%。薄壁U形钢板加固受火后RC梁的受弯、受剪承载力相比未受火RC梁分别提高了127.4%~151.7%、21.3%~56.7%。在薄壁U形钢板内侧和上翼缘焊接角钢形成的内隔环能保证薄壁U形钢板和混凝土共同工作,加固后试件可作为完全剪切连接的组合梁。加固试件发生受弯破坏时内隔环承受的纵向剪力较大,而发生受剪破坏时内隔环承受的纵向剪力较小。
Reinforced concrete （RC） beams after fire can be strengthened by installing external thin-walled U-shapea steel plate and filling non-shrinkage grouting material inside. It has the advantages of effectively avoiding the shedding of the grouting materials to ensure a long-term reinforcement effect. In order to verify the effectiveness of the reinforcement method, the static loading tests of 14 concrete beams were carried out. The effects of U-shaped steel plate thickness and fire exposure time on the bending performance of strengthened RC beams, and the effects of U-shaped steel plate thickness and shear span ratio on the shear performance of strengthened RC beams were investigated. The calculation formulas for the flexural strength and the shear strength of the strengthened beams were developed by referring to the calculation formulas for the capacity of composite beams at ambient temperature. The results show that the flexural strength of concrete beam decreases by 9.4% and 10. 4% after experiencing fire for 1. 0 h and 1.5 h, respectively. After experiencing fire for 1.5 h, the shear strength of concrete beam with the shear span ratio 1.74 and 2.58 decreases by 19.5% and 10. 6% , respectively. The flexural strength and the shear strength of concrete beams firstly exposed to fire and then strengthened with thin-walled U-shaped steel plate is about 127.4% - 151.7% and 21.3% -56.7% of that without fire, respectively. The spaced ring formed by welding angle steel in the inner side and above the flange of thin-walled U-shaped steel plate can ensure the U-shaped steel plate and concrete work together. The strengthened specimens can be seen as full shear connection composite beams. The longitudinal shear force of the spaced ring is larger when the flexural failure occurs in the strengthened beams, and is smaller when the shear failure occurs in the strengthened beams.
作者
徐玉野
郑顺盈
董毓利
罗漪
XU Yuye ZHENG Shunying DONG Yuli LUO Yi(College of Civil Engineering, Huaqiao University, Xiamen 361021, China)
出处
《建筑结构学报》
EI
CAS
CSCD
北大核心
2017年第3期58-66,共9页
Journal of Building Structures
基金
国家自然科学基金项目(51578255)
福建省科技计划重点项目(2014Y0033)
华侨大学中青年教师科研提升计划(ZQNYX204)
关键词
混凝土梁
薄壁U形钢板
加固
火灾后
静力试验
受力性能
concrete beam
thin-walled U-shaped steel plate
strengthening
after fire
static test
mechanical performance
