Abstract The shear response of thirteen slender geopolymer concrete (GPC) beams reinforced with basalt fiber reinforced polymer (BFRP) bars as longitudinal reinforcements without stirrups was investigated. Different fiber combinations were used to enhance the shear capacity of the beams, including (1) single type of macro-steel fibers (SF) or (2) macro-synthetic polypropylene fibers (PF), (3) hybridization of SF and micro-polyvinyl alcohol fibers (PVF) or (4) PF and micro- carbon fibers (CF). The experimental results indicated that the presence of SF yielded the greatest improvement in the cracking behavior, post-cracked stiffness, and shear capacity of the beams. The addition of 0.5% SF to the GPC and OPC beams increased the normalized shear strength most by 56% and 14%, respectively. The higher contribution of SF to the shear strength of GPC can be attributed to the superior adhesive bonding strength of fiber and GPC matrix. Despite being less effective than SF, adding PF also improves significantly the normalized shear strength up to 33% with 0.5% fiber content. The hybridization of SF and PVF showed a good synergy in enhacing the shear capacity. Meanwhile, the combination of PF and CF did not improve the shear strength but enhanced considerably the ductility of the beams. In addition, three analytical models were proposed to estimate the shear capacity of the SF reinforced concrete beams. The comparison of prediction and experimental results demonstrated the model derived from the modified compression field theory (MCFT) achieved the best correlation.

中文翻译：

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混合纤维对无箍筋玄武岩纤维增强聚合物 (BFRP) 钢筋增强地聚合物混凝土梁剪切性能的影响

摘要 研究了用玄武岩纤维增强聚合物 (BFRP) 钢筋作为纵向无箍筋的 13 根细长地质聚合物混凝土 (GPC) 梁的剪切响应。不同的纤维组合用于增强梁的剪切能力，包括（1）单一类型的粗钢纤维（SF）或（2）粗合成聚丙烯纤维（PF），（3）SF和微纤维的混合聚乙烯醇纤维 (PVF) 或 (4) PF 和微碳纤维 (CF)。实验结果表明，SF 的存在对梁的开裂行为、开裂后刚度和抗剪承载力产生了最大的改善。在 GPC 和 OPC 梁中添加 0.5% SF 使归一化剪切强度分别增加了 56% 和 14%。SF 对 GPC 剪切强度的更高贡献可归因于纤维和 GPC 基质的优异粘合强度。尽管不如 SF 有效，但添加 PF 也可显着提高归一化剪切强度高达 33%，纤维含量为 0.5%。SF和PVF的杂交在提高剪切能力方面表现出良好的协同作用。同时，PF和CF的组合并没有提高剪切强度，但显着提高了梁的延性。此外，提出了三种分析模型来估计 SF 钢筋混凝土梁的抗剪承载力。预测和实验结果的比较表明，从修正压缩场理论（MCFT）导出的模型实现了最佳相关性。