PVA纤维掺量对钢筋HPFRCC/混凝土复合梁受弯性能的影响

INFLUENCE OF PVA FIBER CONTENT ON FLEXURAL BEHAVIOR OF REINFORCED HPFRCC / CONCRETE COMPOSITE BEAMS

为改善普通钢筋混凝土梁易开裂的缺点,可将受拉区部分混凝土采用同体积的HPFRCC替代形成HPFRCC/混凝土复合梁。基于复合梁的正截面弯曲性能试验,主要研究PVA纤维体积掺量对复合梁受弯性能的影响,研究结果表明,受拉区HPFRCC层的存在,可有效分散裂缝且抑制裂缝的扩展,复合梁的裂缝呈"根系状"分布形态,且随着HPFRCC层内纤维掺量的增加,裂缝变得更加细密;开裂后,PVA纤维的桥接承拉作用使复合梁中受拉钢筋与压区混凝土的应变增长较为迟缓;与普通混凝土梁相比,复合梁的初裂荷载、屈服荷载与极限荷载均有不同程度的提高且开裂荷载的提高幅度最为明显。

In order to improve the shortcoming of easy-cracking of reinforced concrete beams,concrete of tension zone can be partly replaced by HPFRCC to make reinforced HPFRCC / concrete composite beam. Based on experiments on normal section flexural behavior of composite beams,the influence of PVA fiber content by volume on flexural performance of composite beams were studied. Experimental results indicate that the HPFRCC layer in tension zone can inhibit and disperse the extension of cracks effectively and the crack distribution of composite beams are similar to root system. With the increase of PVA fiber content by volume,cracks become more fine. After cracking,the strain increases of tension steel and compression concrete slow down owing to the bridging effect of PVA fiber. Compared with ordinary concrete beam,the cracking load,yielding load and ultimate load of composite beams are all increased and the increases of cracking load are more obvious.