纤维网-超高韧性水泥基复合材料加固钢筋混凝土柱抗震性能研究

Seismic behavior of reinforced concrete columns strengthened by textile-UHTCC

外包纤维网-超高韧性水泥基复合材料(UHTCC)作为一种高性能复合加固方式,具有高强、高耐久性的优势。针对纤维网-UHTCC加固钢筋混凝土(RC)柱,开展5个加固RC柱和1个未加固柱的水平低周反复加载试验,研究纤维网层数、加固高度和轴压比等参数对加固柱抗震性能的影响。试验结果表明:采用纤维网-UHTCC加固RC柱可有效约束核心混凝土变形,抑制柱身裂缝扩展,延缓屈服后柱的刚度退化,显著提高柱的变形、延性和耗能能力;随着纤维网层数的增加,柱的变形能力和延性显著提升,而承载能力提高较小;从变形和破坏形态角度分析,三层纤维网加固的综合效益较优;当轴压比从0.15增大至0.30时,加固柱的承载力提升明显,且延性和耗能能力仍保持较高水平;当加固区高度为1.2~2倍截面高度时,抗震能力基本相当,建议加固高度为1.2倍截面高度。提出了纤维网-UHTCC加固RC柱的荷载-变形骨架曲线理论计算方法,计算结果与试验曲线吻合较好。

Textile-ultra high toughness cementitious composite(UHTCC), a high-performance composite strengthening method with UHTCC as the matrix and textile as the reinforcing material, has the advantages of high strength and high durability. In this paper, cyclic lateral loading tests were carried out on five textile-UHTCC strengthened reinforced concrete(RC) columns and one unstrengthened column to investigate the effects of the number of textile layers, axial compression ratio and strengthening height on the seismic behavior of the strengthened columns. The experimental results indicate that the textile-UHTCC jacket effectively confines the deformation of core concrete in columns, restrains the development of cracks, delays the stiffness degradation at the late loading stage, and significantly improves the displacement, ductility and energy dissipation capacity. With an increase of the number of textile layers, the ductility and deformation capacity are enhanced greatly while the load bearing capacity are enhanced slightly. In view of the deformation capability and failure mode, three layers of textile have been demonstrated to be a good scheme. When the axial compression ratio increases from 0.15 to 0.30, the load bearing capacity of strengthened columns is increased, and the ductility and energy dissipation capacity remain high. The seismic capacity is similar for the columns with the strengthening height in the range of 1.2-2 times the section height of the columns, so the strengthening height is suggested to be 1.2 times the section height. A theoretical calculation model for the load-deformation skeleton curves is proposed for textile-UHTCC strengthened RC columns, and a good agreement between the calculated and tested curves is obtained.