Shear resistance of RC circular members with FRP discrete hoops versus spirals

Nowadays, design guidelines and codes contain valuable shear provisions for the design of concrete bridge members reinforced with fiber-reinforced-polymer (FRP) bars. Limited researches seem to have assessed the shear strength of circular concrete members reinforced with FRP reinforcement. Therefore, these standards do not provide specific formulae for circular RC members designed with FRP bars, hoops and spirals under shear loads. This paper reports experimental data about the shear strength of circular concrete specimens reinforced with FRP bars, discrete hoops and continuous spirals. Full-scale circular concrete specimens with a total length of 3,000 mm and 508 mm in diameter were constructed and tested up to failure. The test parameters included the type of reinforcement (glass FRP and carbon FRP versus steel) and configuration of the shear reinforcement (discrete hoops versus continuous spirals). The investigation revealed that the specimen reinforced with FRP hoops exhibited high load-carrying capacity comparable to the counterpart reinforced with FRP spirals. The experimental shear strengths of the FRP-reinforced concrete specimens were compared to theoretical predictions provided by current codes, design guidelines. The results of this study can be used as a fundamental step toward code provisions for using CFRP or CFRP spirals and hoops as internal shear reinforcement.

如今，设计指南和规范包含了对纤维增强聚合物（FRP）筋混凝土桥梁构件设计有价值的抗剪规定。似乎很少有研究对FRP筋增强的圆形混凝土构件的抗剪强度进行评估。因此，这些标准没有为在剪力荷载作用下采用FRP筋、箍筋和螺旋筋设计的圆形钢筋混凝土构件提供具体公式。本文报道了有关FRP筋、离散箍筋和连续螺旋筋增强的圆形混凝土试件抗剪强度的试验数据。制作了总长度为3000毫米、直径为508毫米的足尺圆形混凝土试件，并进行试验直至破坏。试验参数包括钢筋类型（玻璃纤维增强聚合物和碳纤维增强聚合物与钢材对比）以及抗剪钢筋的配置（离散箍筋与连续螺旋筋对比）。研究表明，FRP箍筋增强的试件表现出与FRP螺旋筋增强的对应试件相当的高承载能力。将FRP增强混凝土试件的试验抗剪强度与现行规范、设计指南提供的理论预测值进行了比较。本研究结果可作为朝着制定使用碳纤维增强聚合物或碳纤维增强聚合物螺旋筋和箍筋作为内部抗剪钢筋的规范条文迈出的基础性一步。