混杂纤维活性粉末混凝土梁抗剪性能试验研究

发布时间：2018-06-04 00:23

本文选题：混杂纤维 + 活性粉末混凝土　；参考：《土木工程学报》2015年05期

【摘要】：为了研究高强钢筋混杂纤维增强活性粉末混凝土(Hybrid Fiber Reinforced Reactive Powder Concrete,HFRPC)抗剪性能,进行12根HFRPC梁抗剪试验,变化参数包括:剪跨比、配箍率、箍筋强度、箍筋放置角度和纤维掺量等。试验结果表明:混杂纤维显著改善了RPC梁的抗剪变形能力,使梁由脆性剪切破坏变为延性破坏,粗聚烯烃纤维有效阻止了临界斜裂缝的扩展,峰值荷载后承载力下降缓慢,梁斜裂缝条数增多、宽度减小;剪跨比为3.5时,发生了以斜拉破坏为主的剪切破坏;剪跨比增加,承载力下降;高强箍筋屈服,配箍率由0.42%提高到0.64%时,剪跨比为1.5、2.5和3.5,抗剪承载力分别提高22.1%、7.1%和8.1%,再增加配箍率对抗剪承载力的增强作用不大;钢纤维体积率由1%提高到2%,抗剪承载力约提高17.0%。采用现有规范计算梁的抗剪承载力会导致过于保守;法国规范是针对RPC建立的公式,但离散系数大,斜拉破坏时计算值偏不安全。首次提出了剪切韧性指数的概念,以表征混杂纤维增强RPC梁的剪切变形能力和韧性;基于塑性理论,在抗剪承载力公式中首次引入塑性剪切系数,以考虑混杂纤维阻裂、桥联作用和剪跨比对剪切承载力和变形的影响,理论计算值与试验值吻合良好。
[Abstract]:In order to study the shear resistance of hybrid Fiber Reinforced Reactive Powder reinforced reactive powder concrete (HPC) reinforced with high strength reinforced hybrid fiber, the shear tests of 12 HFRPC beams were carried out. The variation parameters include: shear span ratio, hoop ratio, stirrups strength, stirrups placement angle and fiber content. The test results show that the hybrid fiber improves the shear deformation ability of RPC beams significantly, and makes the beams change from brittle shear failure to ductile failure, the coarse polyolefin fiber effectively prevents the critical diagonal crack from spreading, and the bearing capacity decreases slowly after the peak load. When the shear span ratio is 3.5, the shear failure is mainly caused by cable-stayed failure; the shear span ratio increases and the bearing capacity decreases; the high-strength stirrups yield, and the hoop ratio is increased from 0.42% to 0.64%. When the shear / span ratio is 1.5% and 3.5%, the shear bearing capacity increases by 22.1% and 8.1%, respectively, and the increase of hoop ratio has little effect on the strengthening of shear bearing capacity, while the volume ratio of steel fiber increases from 1% to 2%, and the shear bearing capacity increases about 17.0%. Using the existing codes to calculate the shear capacity of beams will lead to too conservative. The French code is a formula established for RPC, but the discrete coefficient is large, and the calculation value is not safe in the case of cable-stayed failure. The concept of shear toughness index is proposed for the first time to characterize the shear deformation ability and toughness of hybrid fiber reinforced RPC beams, and based on the plastic theory, the plastic shear coefficient is first introduced into the shear bearing capacity formula to consider the crack resistance of hybrid fibers. The effects of bridge action and shear span ratio on shear capacity and deformation are in good agreement with the experimental values.
【作者单位】：北京工业大学工程抗震与结构诊治北京市重点实验室;河北钢铁股份有限公司唐山分公司;
【基金】：国家自然科学基金(51378032) 教育部博士点基金(20131103110017) 北京市自然科学基金(8142005)
【分类号】：TU528.572

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