GFRP Stirrup Confinement对GFRP-RC梁的结合强度的影响
Zahid Hussain1, Jesús D Ortiz1, Seyed Arman Hosseini2
1Civil and Architectural Engineering Department, University of Miami, Coral Gables, FL 33146 USA.
International journal of concrete structures & materials
|December 16, 2024
概括
这项研究表明,杆封闭显著提高了玻璃纤维增强聚合物 (GFRP) 条在混凝土梁中的粘合强度. 结合杆效应可以改善GFRP钢筋混凝土结构的发展长度规定.
科学领域:
- 土木工程 土木工程是指土木工程.
- 材料科学 材料科学 材料科学
- 结构工程 结构工程
背景情况:
- 当前的ACI 440.11代码规定,用于玻璃纤维增强聚合物 (GFRP) 增强混凝土 (RC) 的发展长度,不考虑杆封闭对结合强度的影响.
- 现有的拼接长度要求带来了实际实施的挑战.
- 在GFRP材料属性的进步需要更新的设计规定.
研究的目的:
- 为了研究涂沙GFRP条的粘合强度,考虑到杆的封闭效应.
- 建议在债券强度条款中包含一个新的因素,以考虑杆封闭.
- 评估GFRP条的现有设计规范 (ACI 440.11,CSA S6,CSA S806) 的性能.
主要方法:
- 一个实验项目涉及16个GFRP-RC梁,受四点负荷.
- 测试参数包括不同长度 (40,60,80巴直径) 和脚间距 (100毫米,200毫米).
- 实验结果与ACI 440.11,CSA S6:25,CSA S6:19和CSA S806:12的预测进行了比较.
主要成果:
- 杆封闭显著增加了粘合强度,减少了纵向条的滑动,并增强了分裂应力阻力.
- 带有60db连接长度和100mm杆间距的梁与没有杆的梁相比,显示出57%的更高容量.
- 在ACI 440.11方程中,过高估计了涂沙GFRP条的结合强度,但在距离较近的杆上,它是保守的.
结论:
- 杆封闭对于准确预测混凝土中GFRP条的粘合强度至关重要.
- ACI 440.11 代码需要修订,以整合杆封闭效果,以提高准确性和实用性.
- CSA S6:25提供了与实验结果最接近的债券强度预测.
相关概念视频
01:22Fiber Reinforced Concrete
68
Fiber-reinforced concrete significantly enhances the structural and nonstructural properties of traditional concrete by incorporating fibers like steel, glass, and polymers. These fibers, varying from natural ones such as sisal and cellulose to manufactured ones like polypropylene and Kevlar, are mixed into hydraulic cement with aggregates. Steel fibers, often preferred for their robustness, contribute to improved ductility, toughness, and post-cracking performance. The concrete is classified...
68
01:25Reinforcements in Concrete
70
Reinforced concrete is a composite material used extensively in construction, combining the compressive strength of concrete with the tensile strength of steel. This synergy is essential as concrete, while excellent at resisting compression, is weak under tension. Steel bars, or rebars, are embedded in the concrete to handle these tensile forces. The choice of steel is strategic; it shares a similar coefficient of thermal expansion with concrete, which ensures uniformity in response to...
70
01:12Bonding and Strength of Aggregate
139
The bond between aggregate particles and the cement matrix is significantly influenced by the shape and surface texture of the aggregates. High-strength concretes benefit from a rougher texture, which leads to stronger bonding due to greater adhesion. Angular aggregates with larger surface areas also enhance this bond. The bonding quality, however, is complex to assess as no universally accepted test exists. Good bonding is indicated when a crushed concrete specimen shows some aggregate...
139
01:23Design of Prismatic Beams for Bending
210
The design of prismatic beams, structural elements with a uniform cross-section, focuses on ensuring safety and structural integrity under load. The design process begins by determining the allowable stress, either from material properties tables, or by dividing the material's ultimate strength by a safety factor. This safety factor is essential for accommodating uncertainties, and varies depending on the material—timber, steel, or concrete—with each having unique strength and...
210
01:25Effects of Creep
89
Creep in concrete, the gradual deformation under prolonged stress, significantly impacts the integrity of structures. For reinforced concrete beams, it can be a vital design consideration, as it increases deflection, sometimes necessitating additional design measures. In columns, especially slender ones under eccentric loads, creep can cause buckling, compromising their stability. However, creep can be beneficial in indeterminate structures by mitigating stresses that arise from shrinkage,...
89
01:16Tensile Strength Considerations of Concrete
112
Considering the tensile strength of concrete involves recognizing that the theoretical strength of cement paste can be up to a thousand times higher than what is observed in practical applications. This significant discrepancy is largely attributed to the presence of microscopic cracks within the concrete. These cracks tend to amplify stress at their tips when a load is applied, a phenomenon explained by Griffith's theory of brittle fracture.
The dimensions and shape of a concrete specimen...
The dimensions and shape of a concrete specimen...
112