【作者】 高鹏；

【导师】 魏松； 朱大勇；

【作者基本信息】 合肥工业大学 ， 水工结构工程， 2021， 硕士

【摘要】 钢筋混凝土柱作为混凝土结构中的主要承重部件,经常会因为环境腐蚀和自然损伤等原因需要进行维修加固以确保安全。纤维增强复合材料(Fiber Reinforced Polymer,FRP)以其轻质高强和耐腐蚀等优点已成为混凝土结构的常用加固材料,其中碳纤维增强复合材料(CFRP)的研究和应用最为广泛。近些年来,玄武岩纤维增强复合材料(BFRP)因其较好的力学性能和较低的价格开始受到关注,但是关于BFRP加固钢筋混凝土结构的研究数量还较少,相关理论计算模型多基于CFRP试验数据得到,应用于BFRP时精确度较低。因此,对比研究BFRP与CFRP加固钢筋混凝土柱的力学性能,具有较大的理论与现实意义。本文通过试验研究、数值模拟和理论分析相结合的方式,对BFRP和CFRP加固钢筋混凝土柱的轴压性能及其应力-应变关系模型进行了较为系统的研究。主要研究内容如下:首先,进行了6根BFRP和CFRP加固足尺钢筋混凝土柱的轴压性能试验,研究了FRP布种类和混凝土强度两种参数对柱轴压性能的影响,重点对比了等侧向约束强度下BFRP和CFRP加固柱的极限承载力和极限应变。试验结果表明:加固后柱的破坏模式显著改变;CFRP和BFRP加固C25级混凝土配筋柱的极限承载力较未加固柱分别提高了66%和61%,C50级混凝土加固柱则分别提高了51%和34%,说明CFRP的承载力提高能力较BFRP更强;CFRP和BFRP加固C25级混凝土配筋柱的横向极限应变较未加固柱分别提高了682%和1683%,轴向极限应变分别提高了562%和882%,说明BFRP的极限应变提升效果较CFRP更好,但其对高强混凝土加固柱的极限应变提升有限。然后,采用ABAQUS有限元软件建立了BFRP和CFRP加固钢筋混凝土柱的三维有限元模型,重点分析了试件的轴向应力-应变曲线以及达到极限荷载时FRP布的环向应变、钢筋的Mises应力和混凝土的轴向应力的分布规律。模拟结果表明:模拟轴向应力-应变曲线总体与试验曲线接近,各试件的峰值应力模拟值与试验值相对误差在5.09%～14.28%之间,模拟结果与试验结果吻合较好;纵向钢筋和环向箍筋均达到屈服状态,钢筋骨架充分发挥作用;FRP布的有效约束率在54.53%～70.67%之间,有效地发挥了其约束作用。最后,深入分析了FRP加固钢筋混凝土柱的约束机理,选取了与本试验相吻合的三个考虑强弱约束作用的FRP加固混凝土柱应力-应变关系模型和三个FRP加固钢筋混凝土柱应力-应变关系模型进行计算。基于试验和模拟结果,从FRP加固柱的应力-应变曲线、抗压强度与极限应变等方面评估了六个模型,建议了可同时适用BFRP和CFRP加固钢筋混凝土柱的应力-应变关系模型。更多还原

【Abstract】 As the main load-bearing component in the concrete structures,the reinforced concrete columns are always repaired and reinforced to ensure safety caused by the environmental corrosion and natural damage.Fiber Reinforced Polymer(FRP)has become a common reinforcement material for concrete structures due to its advantages of light weight,high strength and corrosion resistance.Among them,Carbon Fiber Reinforced Polymer(CFRP)has been studied and applied widely.In recent years,Basalt Fiber Reinforced Polymer(BFRP)has attracted attention because of its better mechanical properties and lower price.However,there are few studies on the reinforced concrete structures confined by BFRP.The majority of relevant theoretical calculation models are based on CFRP test data,and the accuracy is relatively low when applied to BFRP.Therefore,it is of great theoretical and practical significance to compare the mechanical properties of reinforced concrete structures strengthened by BFRP and CFRP.In this paper,the axial compressive behavior and stress-strain model calculation of reinforced concrete columns strengthened by BFRP and CFRP are systematically studied by experimental,numerical simulated and theoretical analysis.The main research contents are as follows.Firstly,six full-scale reinforced concrete columns confined with BFRP and CFRP were tested under axial compression.The effects of the FRP distribution and concrete strength on the axial compression performance of the columns were studied.The ultimate bearing capacity and strain of the confined columns under the same lateral confinement strength were compared emphatically.The test results show that the failure mode of the confined column changed significantly.The ultimate bearing capacities of C25 grade concrete columns reinforced with CFRP and BFRP were 66% and 61%higher than those of unreinforced columns.The ultimate bearing capacities of C50 grade concrete columns were 51% and 34% higher than those of unreinforced columns,indicating that the capacities of CFRP-confined columns were larger than those of BFRP-confined columns.The transverse ultimate strains of C25 grade concrete columns reinforced by CFRP and BFRP were increased by 682% and 1683% compared with those of unreinforced columns.The axial ultimate strains of C25 grade concrete columns reinforced by CFRP and BFRP were increased by 562% and 882%,respectively.The data indicated that the increasing effect of ultimate strain in BFRP was better than that in CFRP,but the increasing effect of ultimate strain on high-strength concrete reinforced columns was limited.Then,the three-dimensional finite element models of reinforced concrete columns confined by BFRP and CFRP were established by using the software ABAQUS.The axial stress-strain curves of the specimens,the circular strain distributions of FRP,Mises stresses of reinforcements and axial stresses of concrete at the ultimate load were analyzed,respectively.The results show that the simulated axial stress-strain curves were generally close to the experimental curves.The relative errors of peak stresses of the columns between the simulated and the experimental values were between 5.09%and 14.28%,which indicated the simulated results were in good agreement with the experimental results.The longitudinal reinforcement and the circumferential stirrups both reach the yield state,and the reinforcement skeleton take maximum advantage.The effective confinement rates of FRP cloth were 54.53%～70.67%,which shows FRP confined effectively.Finally,the confinement mechanism of FRP reinforced concrete columns is analyzed deeply.Three stress-strain relationship models of FRP confined concrete columns considering strong and weak constraints and of FRP reinforced concrete columns are selected for calculation.Based on the test and simulation results,six models were evaluated in terms of stress-strain curves,compressive strength and ultimate strain of FRP confined columns,and a stress-strain relationship model for both reinforced concrete columns confined by BFRP and CFRP was proposed.更多还原