Super-servicing reinforced concrete poles (RCP) which come from a road section in a power grid , including six pole shafts and six specimens with a mid-span steel joint ,were selected as samples to conduct a flexural strength test ,in which three shafts and three poles with steel joint in the middle span were strengthened by CFRP in the longitudinal direction .The mechanical behavior and failure mechanism under different CFRP layers pasted were comparatively studied .Based on the measured test data ,the calculation methods of strength and stiffness were investigated , and the mathematical expression of stiffness degradation mechanism was proposed .The result shows that the final failure mode of CFRP strengthened poles is the local bond failure between CFRP material and the external concrete ,and the longitudinal CFRP is snapped .The process of damage is rapid and brittleness .The mean strain of cross-section is in accord with the assumption of plane cross-section . The strength degradation of shaft specimens without strengthened is throughly serious .As for the strengthened poles ,the bearing capacity and stiffness under each forcing stage are improved with different levels . The damage of strengthened specimens develops faster and more intensive than that of none-strengthened ones . When multi-aspects are synthetically considered ,there is a suggestion that double layers of CFRP should be pasted along the longitudinal in the joint of the site within a certain distance ,and the single layer of CFRP should be adopted in the shaft .%以某电网某路段超过服役期的钢筋混凝土电杆为研究对象，选取电杆杆身与跨中带钢圈接头的杆身试件各6根，其中各取3根试件采用碳纤维布（CFRP ）沿杆件纵向进行加固，并对其进行抗弯承载力试验，对比研究在不同的碳纤维布黏贴层数下加固电杆的受力性能和破坏机理。基于试验实测数据，对强度及刚度计算方法进行了研究，并提出了刚度退化的数学表达式。研究结果表明：采用碳纤维布加固电杆后，其破坏表现为混凝土与碳纤维布的表面粘脱失效所致，纵向碳纤维布被拉断作为最终破坏形态，破坏过程迅速，脆性明显；试件的截面应变分布符合平截面假定。加固前杆身试件的承载力退化严重，加固后混凝土电杆的承载能力和刚度均有显著提高，但加固电杆的损伤发展较加固前提早，且快而集中，综合多方面考虑，建议在混凝土电杆接头附近的一定距离内采取双层、杆身其余部位采用单层的碳纤维布加固方法。
展开▼
