Abstract The axial compressive stress-strain behavior of CFRP-confined lightweight aggregate concrete (LWAC) with short carbon fiber and/or polypropylene fiber was investigated. Thirty cylinders with different concrete types (normal weight concrete and LWAC), fiber types (carbon fiber, polypropylene fiber, and mixture of these two fibers), volume faction of fibers (from 0% to 0.4% for each fiber type in single and hybrid form), and spacing between CFPR straps (0 mm, 30 mm, and 50 mm) were experimentally studied. The compressive strengths of CFRP-confined LWAC were improved to 1.01–1.51 times the unconfined strength, and LWAC showed less enhancement in compressive strength provided by confining pressure compared with normal weight concrete. The increase in spacing between CFRP straps declined the confining effect. Addition of carbon fiber in both single and hybrid form positively affected the toughness of CFRP-confined LWAC, while the polypropylene fiber showed few influences on properties of LWAC. Models for the peak stress and corresponding strain were established by collected and present test data. Then theoretical stress-strain model was developed by combining iterative calculation of ascending portion and close-form formula of descending branch. The proposed model showed good match to the test results.

中文翻译：

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混合纤维增强CFRP约束轻骨料混凝土的压缩应力应变行为

摘要 研究了碳纤维短纤维和/或聚丙烯纤维的CFRP约束轻骨料混凝土(LWAC)的轴向压应力-应变行为。三十个不同混凝土类型（普通混凝土和 LWAC）、纤维类型（碳纤维、聚丙烯纤维和这两种纤维的混合物）、纤维体积分数（单纤维和混合纤维中每种纤维类型从 0% 到 0.4%）的圆柱体形式）和 CFPR 带之间的间距（0 毫米、30 毫米和 50 毫米）进行了实验研究。CFRP 有约束的 LWAC 的抗压强度提高到无侧限强度的 1.01-1.51 倍，与正常重量混凝土相比，LWAC 的围压提供的抗压强度增强较少。CFRP 带之间间距的增加降低了限制效应。添加单一和混合形式的碳纤维对 CFRP 约束的 LWAC 的韧性有积极影响，而聚丙烯纤维对 LWAC 的性能几乎没有影响。通过收集和提供的测试数据建立峰值应力和相应应变的模型。然后结合上升部分的迭代计算和下降分支的闭式公式，建立了理论应力应变模型。所提出的模型显示出与测试结果的良好匹配。然后结合上升部分的迭代计算和下降分支的闭式公式，建立了理论应力应变模型。所提出的模型显示出与测试结果的良好匹配。然后结合上升部分的迭代计算和下降分支的闭式公式，建立了理论应力应变模型。所提出的模型显示出与测试结果的良好匹配。