【作者】 余文华；

【导师】 王苏岩；

【作者基本信息】 大连理工大学 ， 结构工程， 2010， 硕士

【摘要】 随着结构向大跨、重载、高层、超高层体系的发展,高强混凝土在土木工程中的应用也越来越多。然而,随着混凝土强度等级的提高,混凝土的脆性越来越显著,构件的延性也越来越差,对结构抗震十分不利。外包FRP加固法由于其具有轻质高强、抗腐蚀、耐疲劳、温度稳定性好、施工便捷且不改变结构刚度等优点,受到了土木工程界普遍关注。对于FRP加固高强混凝土性能方面虽然做了不少研究,但专门针对FRP改善高强混凝土柱延性方面的研究却不多,或考虑因素相对较少,或不够系统,基于延性系数加固指标的设计方法也还未建立。基于此,本文结合国家自然科学基金项目(50878035)专门进行了CFRP增强高强混凝土柱在低周反复荷载作用下的延性性能试验,主要从横向包裹CFRP和锚固措施两个方面来研究了CFRP对高强混凝土柱延性性能的改善情况,完成了以下几个方面的研究工作：(1)通过低周反复试验对CFRP增强高强混凝土方柱抗震性能进行研究,探讨了轴压比、剪跨比、加固量对高强混凝土柱延性与耗能能力的影响。试验结果表明,轴压比越大或剪跨比越小,试件延性越差,耗能越少,强度退化越快,但经横向包裹CFRP加固后,轴压比大的或剪跨比小的其效果更为显著；随着加固量的增加,试件延性和耗能能力都增大,但增加幅度在逐渐降低。(2)通过低周反复试验,对仅横向包裹CFRP和同时加锚固措施方式的高强混凝土柱进行了研究。研究结果表明,组合加固方式相对仅横向包裹FRP加固方式而言,不仅对角部混凝土产生了约束,而且对边中部混凝土也提供了一定的约束,进而增大了有效约束区的面积,对柱的延性提高程度更大。(3)利用不同锚固方式(植螺栓法和夹板法)对高强混凝土方柱非约束区进行锚固约束,研究了两种方式对CFRP增强高强混凝土柱抗震性能的影响。由于夹板组合加固方式相对植筋组合方式而言是一种主动的约束方式,有效约束区面积提高程度更大,所以其延性要好于植筋组合加固方式这种被动约束方式。(4)根据试验所采集的应变数据结果,综合分析有效约束系数影响因素,提出了碳纤维布有效约束系数的计算方法。(5)根据CFRP加固高强混凝土柱研究结果,综合考虑剪跨比、轴压比、箍筋体积配箍特征值、碳纤维体积配箍特征值、箍筋形式、纤维有效约束性能及锚固措施等因素影响,提出了位移延性系数的计算公式。更多还原

【Abstract】 In recent years, with the development of structures toward long-span, heavy load, high-rise and super high-rise, high-strength concrete is frequently used in civil engineering However, as concrete strength increases, its brittleness becomes notable and its ductility reduces remarkably, which is harmful for anti-seismic. The strengthening method of being externally wrapped fiber-reinforced polymers (FRP) can significantly improve the seismic performance of concrete structures. Because of its low density, high-strength, anticorrosion, fatigue resistance, good temperature stability, convenient construction and no changes in structure rigidity, the method has attracted popular attention in civil engineering. It is proved that research on FRP improving the behavior of the high-strength concrete has been examined in many literatures, but researcher rarely consider FRP about improving the ductility of the high-strength RC columns specifically, or a relatively small consideration, or not systematic. Besides, the calculation method of strengthening index based on ductility coefficient has not been established. Therefore, a cyclic horizontal loading test was conducted combining with the research programs of National Natural Science Foundation of China (50878035) in order to study the ductility performance of CFRP strengthening high-strength RC columns mainly from being wrapped externally CFRP in transverse and anchoring measures. The main contents are following:(1) Through a cyclic horizontal loading test, CFRP improving the seismic behavior of the high-strength RC columns was researched and the influence of axial load ratio, aspect ratio and strengthening volume on the ductility and energy absorption capacity of the high-strength RC columns was discussed. Experimental results showed that the ductility, energy absorption capacity and strength can be significantly reduced as the increase of axial load ratio and the decrease of aspect ratio. However, the seismic behavior of columns with high axial load ratio or low shear span ratio was improved obviously after being wrapped CFRP in transverse. And the ductility, energy absorption capacity increased with the increase of strengthening volume, but the improvement extent reduced gradually.(2) Through a cyclic horizontal loading test, the high-strength RC columns with only being wrapped CFRP and being wrapped CFRP plus anchoring measures were studied. Experimental results showed that hybridized retrofit method not only supplied the corner concrete with confinement, but also supplied confinement for the core concrete, which increased the effective confinement areas and improved the ductility of the columns more than the strengthening technique of only being wrapped CFRP.(3) Using two different anchoring techniques (embedding bolt bar and clamping plates), to confine the non-confinement areas of the high-strength RC square columns, the effect of the two techniques on CFRP improving the seismic behavior of the high-strength RC columns was studied. Because the hybridized retrofit technique of combining clamping plates and wrapping CFRP sheets was an active confinement method compared with the one of combining embedding bolt bars and wrapping CFRP that a passive confinement method, the effective confinement areas were increased and the ductility was enhanced.(4) Based on the test results of CFRP strain, comprehensively analyzing the influence factors about effective constraint coefficient, the calculation method of CFRP effective constraint coefficient was proposed.(5) According to the research results of the high-strength RC columns strengthened by CFRP, the calculation formula of displacement ductility coefficient, comprehensively consider shear span ratio, axial load ratio, volumetric ratio eigenvalue of transverse reinforcement, volumetric ratio eigenvalue of CFRP, tie configuration, effective confinement of CFRP and anchoring measures, was presented.更多还原