Experimental Study on Deformation Behavior of Polypropylene Fiber Reinforced Concrete Beams
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摘要: 为探究PP-ECC梁与RC梁变形发展规律的区别,通过逐级加载和循环加载两种加载制度对4根PP-ECC梁和4根RC梁进行抗弯试验;同时,基于有效惯性矩法推导出适用于短期荷载作用下PP-ECC梁的最大变形计算公式. 研究结果表明:逐级加载下,PP-ECC梁呈现出更为明显的塑性变形阶段,与RC梁相比,PP-ECC梁经过5次循环加载后的循环荷载变形曲线与原曲线拟合度较好;循环加载过程中,PP-ECC梁在基准荷载下的加载变形增长率和卸载变形增长率均小于相同配筋率的RC梁,呈现出更好的抗损伤变形能力和变形恢复能力;基于有效惯性矩法推导出的变形修正模型计算结果与试验结果拟合度较好,可应用于实际工程对PP-ECC梁在短期荷载作用下最大变形的计算.Abstract: In order to explore the difference in deformation behaviors of polypropylene engineered cementitious composite (PP-ECC) beam and reinforced concrete (RC) beam, bending resistance tests were performed on four PP-ECC beams and four RC beams using two loading systems, i.e., step loading and cyclic loading. Meanwhile, based on the effective moment of inertia method, the maximum deformation calculation formula applicable to the PP-ECC beams under short-term loads was derived. The results show that the PP-ECC beam undergoes a more obvious plastic deformation stage under successive loading. Compared with the RC beam, the deformation curve of the PP-ECC beam after 5 cycles of cyclic loading fits better with the original curve. During cyclic loading, the growth rates of the loading and unloading deformation of PP-ECC beams under the reference load are both lower than those of RC beams with the same reinforcement ratio, showing better damage resistance and deformation recovery ability. In general, the calculated results of deformation correction model based on the effective moment of inertia method fit well with the test results, and the proposed method can be applied to the calculation of maximum deformation of PP-ECC beams under short-term load in practical engineering.
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表 1 试件参数
Table 1. Sample parameters
编号 加载
方式材料 纵筋直
径/mm纵筋
型号箍筋直
径/mm箍筋
型号LRA-1 LRA C30 8 HRB400 6 Q235 LRA-2 C30 10 HRB400 6 Q235 LRA-3 PP-ECC 8 HRB400 6 Q235 LRA-4 PP-ECC 10 HRB400 6 Q235 LRB-1 LRB C30 8 HRB400 6 Q235 LRB-2 C30 10 HRB400 6 Q235 LRB-3 PP-ECC 8 HRB400 6 Q235 LRB-4 PP-ECC 10 HRB400 6 Q235 表 2 PP纤维性能指标
Table 2. PP fiber performance indexes
参数 长度/
mm密度/
(kg•m−3)直径/
μm抗拉强
度/MPa弹性模
量/GPa伸长
率/%取值 12 0.91 × 103 20 480 5.00 15 表 3 PP-ECC性能指标
Table 3. PP-ECC performance indexes
参数 开裂抗拉强度/
MPa开裂抗拉应变/
%极限抗拉强度/
MPa极限抗拉应变/
%极限抗压强度/
MPa极限抗压应变/
%弹性
模量E/GPa取值 0.84 0.09 2.32 3.8 32.09 0.41 13.35 表 4 C30混凝土性能指标
Table 4. C30 concrete performance indexes
参数 抗压强度/MPa 抗压应变/% 弹性模量/GPa 取值 33.47 0.09 24.80 表 5 HRB400钢筋性能指标
Table 5. HRB400 steel performance indexes
参数 直径/
mm截面面
积/mm2屈服强
度/MPa极限强
度/MPa弹性模
量/GPa取值 8 50.24 406 576 197.00 10 78.50 411 535 203.00 表 6 卸载变形增长
Table 6. Unloading deformation growth
编号 平均卸载变形增长率/% 卸载变形增长方差/mm 0 2.5 kN 0 2.5 kN LRB-1 195.59 106.13 5.530 1.090 LRB-2 164.71 68.05 1.620 0.230 LRB-3 59.58 34.78 0.086 0.012 LRB-4 22.61 14.99 0.041 0.014 -
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