无粘结预应力CFRP筋钢纤维轻骨料混凝土梁受弯性能试验研究  

FLEXURAL BEHAVIOR OF STEEL FIBER-REINFORCED LIGHTWEIGHT AGGREGATE CONCRETE BEAMS PRESTRESSED WITH CARBON FIBER-REINFORCED POLYMER BARS

作　　者：孙艺嘉 吴涛[2] 刘喜[2] SUN Yi-jia;WU Tao;LIU Xi(State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,Qinhuangdao,Hebei 066004,China;School of Civil Engineering,Chang’an University,Xi’an,Shaanxi 710061,China)

机构地区：[1]燕山大学亚稳材料制备技术与科学国家重点实验室,河北秦皇岛066004 [2]长安大学建筑工程学院,陕西西安710061

出　　处：《工程力学》2022年第3期64-74,共11页Engineering Mechanics

基　　金：国家自然科学基金项目(51878054,52078042);陕西省重点研发计划项目(2018ZDCXL-SF-03-03-02)。

摘　　要：建立无粘结预应力FRP筋张拉锚固体系,对8根以CFRP筋为非预应力筋的无粘结预应力CFRP筋轻骨料混凝土梁与1根普通混凝土对比试件进行两点对称加载,观察其破坏过程与破坏形态,分析了混凝土种类、预应力度和净跨长度对开裂弯矩、弯矩-跨中挠度曲线、裂缝宽度等受弯性能的影响。从等效轴向刚度思想出发,修正了现有的以钢筋为非预应力筋的无粘结预应力FRP筋梁的挠度与裂缝宽度计算模型,并基于试验结果对修正模型的适用性进行了评估。结果表明:无粘结预应力CFRP筋试件正常使用极限状态主要由裂缝宽度控制,最大裂缝宽度达到限值0.5 mm时,试件所受弯矩处于极限弯矩的41%~52%;总配筋量相同的前提下,提高预应力度有利于延缓构件开裂;增大非预应力与无粘结预应力CFRP筋配筋量均可起到改善刚度、抑制裂缝开展的作用;修正的程东辉模型与修正的孟履祥模型能够准确预测配置非预应力CFRP筋的无粘结预应力CFRP筋轻骨料混凝土受弯构件正常使用阶段的挠度。An unbonded prestressing anchorage system for carbon fiber-reinforced polymer(CFRP)tendons was introduced.Eight lightweight aggregate concrete(LWC)beams prestressed with unbonded CFRP tendons which used CFRP auxiliary reinforcements and one fabricated using normal weight concrete(NWC)were tested under a four-point bending condition.The influences of concrete type,of prestressed degree and,of clear span length on the cracking moment,on the moment-deflection response and,on the crack width were analyzed.The existing deflection and crack width models for unbonded FRP prestressed beams with steel auxiliary reinforcements were modified from the view of equivalent axial stiffness.The applicability of the modified models was evaluated based on the test results.It is shown that the serviceability limit state of the beams is mainly governed by the crack width limit.The ratios between the moment at crack width of 0.5 mm and the ultimate moment range from 41%to 52%.With the same total reinforcement amount,the increase in the prestressed degree helps delay the cracking of the specimens.Increasing the amount of the auxiliary reinforcement and of the unbonded prestressed tendons both improve the beam stiffness and restrain the propagation of the cracks.The modified Cheng’s and modified Meng’s deflection models provide accurate deflection predictions for LWC beams with unbonded prestressed and auxiliary CFRP reinforcements.

关 键 词：轻骨料混凝土梁 碳纤维增强筋 无粘结预应力 受弯性能 等效刚度法 

分 类 号：TU377.1[建筑科学—结构工程]