摘要
用CFRP(Carbon Fiber Reinforced Polymer)筋替代高强钢筋作预应力筋,用普通钢筋作非预应力筋,可避免因预应力筋锈蚀而引起的结构物承载力下降和耐久性降低。为解决CFRP筋锚固问题,在XM夹片锚具与CFRP筋间设置2个一定长度的半圆钢管,通过填充于2个半圆钢管与CFRP筋间的环氧树脂,将张拉及锚固时锚具的夹持力较均匀地分布给夹持区的CFRP筋。根据综合配筋指标的不同,设计和完成了4根以CFRP筋作无粘结预应力筋、普通Ⅱ级钢筋作非预应力筋的无粘结部分预应力混凝土简支梁试验。试验表明:试验梁的平均裂缝间距仅与非预应力筋直径、有效配筋率及混凝土保护层厚度有关,与无粘结CFRP筋的配置无关。使用阶段按应力增量类比,将无粘结CFRP筋等效为有粘结非预应力筋的换算系数,取为0.35;裂缝分布不均匀系数为1.31;给出计算结果与试验结果吻合良好的裂缝宽度及刚度计算公式;获得了这类梁中无粘结CFRP筋极限应力增量随综合配筋指标增大而线性减小的变化规律,进而基于力的平衡提出了这类梁正截面承载力计算公式。
The bearing capacity and durability decline in structure caused by the corrosion of prestressed tendon could be effectively avoided with CFRP （Carbon Fiber Reinforced Polymer） tendon as prestressing tendon instead of high strength steel bar and with ordinary reinforcement as non-prestressing tendon. To solve the problem of CFRP tendon anchorage, two semicircle steel tubes with definite length were placed between CFRP tendon and XM clip anchorage. The gap between tube and CFRP tendon were filled with epoxy resin, so the grip force were evenly distributed in relatively long zone. According to different integrated tendon index, four unbonded partially prestressed simply supported concrete beams, with CFRP tendon as the unbonded prestressing tendon and the ordinary reinforcement as non-prestressing tendon, were designed and tested. Tests show that the average distance of the tested beam cracks is only related with the diameter of non-prestressing tendon, effective tendon ratio and the thickness of concrete protection layer. It is irrelated with unbonded prestressing CFRP tendon. The conversion coefficient is adopted as 0.35 according to drawing stress increment in CFRP tendon analogy with non-prestressing tendon, and uneven coefficient of cracks distribution is 1.31. The formula for calculating crack width and stiffness was put forward, and the calculation results agree well with test results. The change rule is obtained, in which the increment of the ultimate stress in unbonded CFRP tendon decreases linearly with the increase of integrated tendon index. And then, the formula is presented based on force equilibrium for calculating the bearing capacity of the normal section for this kind of beam.
出处
《中国铁道科学》
EI
CAS
CSCD
北大核心
2008年第2期59-66,共8页
China Railway Science
基金
黑龙江省自然科学基金资助项目(E200732)
哈尔滨市重点科技攻关项目(2005AACG009)
教育部新世纪优秀人才支持计划资助项目(教育司[2005]290号)
