【作者】 陈亚亮；

【导师】 郑建岚；

【作者基本信息】 福州大学 ， 结构工程， 2005， 博士

【摘要】 为了获得良好的抗震性能,扁梁节点的构造复杂,最近的研究把钢纤维应用于扁梁节点以降低对密集箍筋的要求。目前对于扁梁结构的研究还局限于扁梁构件和节点,对扁梁框架抗震性能的研究还未见报道。本文首次对钢纤维预应力扁梁框架进行拟静力、拟动力试验和非线性分析,主要进行了以下几个方面的工作: 1、对不同掺量的钢纤维无粘结预应力混凝土扁梁框架进行水平低周反复荷载下的拟静力试验,研究钢纤维对无粘结预应力扁梁框架破坏形态、滞回特性、延性、耗能以及强度和刚度退化等的影响。试验结果表明,钢纤维不仅可以提高无粘结预应力混凝土扁梁框架的开裂荷载、屈服荷载和极限荷载,改善其破坏形态,还可以有效提高其刚度、延性和耗能,从而提高结构的抗震性能。 2、对不同掺量的钢纤维预应力混凝土扁梁框架结构进行拟动力试验,研究结构在动力荷载作用下的地震反应,分析钢纤维对其动力性能的影响。试验结果表明,钢纤维扁梁框架结构屈服后,其最大位移反应和阻尼比均比普通混凝土扁梁框架要大,钢纤维可以降低预应力混凝土扁梁框架在剧烈地震运动作用下的结构损伤。在极限荷载前,钢纤维对无粘结预应力扁梁框架的刚度、自振频率和动力放大系数的变化影响不大。对地震损伤后扁梁框架的拟静力试验研究表明,地震损伤钢纤维预应力扁梁框架的破坏和滞回性能与无损伤构件相似,地震损伤会降低钢纤维对其抗震性能的有利作用。 3、采用ABAQUS软件对69个无粘结预应力混凝土扁梁框架试件进行非线性分析,研究钢纤维掺量、轴压比和预应力度对其受力性能的影响。计算结果表明,较大的轴压比可以提高结构极限承载力,但降低结构延性和耗能;较大的预应力度对极限承载力没有大的影响,但降低扁梁框架的延性和耗能。钢纤维可以提高预应力扁梁框架的极限承载力、延性和耗能,从而提高其抗震性能,钢纤维对构件的有利作用随轴压比地增大而降低。本章还讨论了钢筋应力、钢筋的粘结滑移和不平衡弯矩对横梁的影响,并结合有关文献的研究成果,对钢纤维无粘结预应力混凝土扁梁结构抗震设计计算和构造提出建议。 4、在上述研究的基础上,分析了无损伤和地震损伤的钢纤维预应力扁梁框架滞回曲线的主要特征,进而分别提出了适合于无损伤和地震损伤的钢纤维无粘结预应力扁梁框架结构的恢复力模型。恢复力模型的骨架曲线均为带软化阶段的三线性折线模型,卸载—再加载曲线分别采用三折线模型和双折线模型。本文还给出了该恢复力模型的数学表达式,可供结构非线性分析参考。更多还原

【Abstract】 A considerable amount of special reinforcement details for wide-beam joints are necessary to provide sufficient seismic resistance, recent investigations have identified fiber-reinforced concrete as a possible alternative to reduce the requirement of closely spaced ties. The emphasis of previous research focused on the seismic behavior of wide-beam joints. No research work on seismic behavior of wide-beam frames was found. This paper describes the investigation on the seismic performance of fiber-reinforced wide-beam frames the first time by using of quasi-static testing, pseudo-dynamic testing and nonlinear finite element analysis as following:(1) Experimental study on seismic behavior under low reversed cyclic loading of three unbonded-prestressed wide-beam frames designed with different volume fraction of steel fibers was carried out, the effects of steel fibers to the failure pattern, hysteretic behavior, energy dissipation, displacement ductility and rigidity degeneration etc. have been studied. The results show that the presence of steel fibers has significant effects not only on improving the cracking load, yielding load and ultimate load, changing the failure pattern, but also enhancing substantially the ductility and energy dissipation, contributing to reducing the rigidity degeneration, thus improving the seismic behavior of prestressed wide-beam frames.(2) Seismic evaluation of fiber-reinforced prestressed concrete wide-beam frame was performed by pseudo-dynamic testing. Dynamic response corresponding to input excitation and the influence of steel fibers to dynamic behavior of prestressed wide-beam frame are discussed. The results show that fibered reinforced wide-beam frames exhibit large displacement and large damping ratio after yielding of structure. Steel fibers contributed to causing less damage during high-level ground motion. Otherwise, steel fibers could not change the internal dynamic response such as stiffness, natural frequency and dynamic magnification factor of prestressed wide-beam frame. Quasi-static testing to damaged wide-beam frames shows that, the failure pattern and hysteretic behavior were same as that of undamaged frames, contribution of steel fibers to seismic behavior of damaged wide-beam frames were less than that of undamaged frames.(3) Nonlinear finite element analysis to 69 fiber-reinforced prestressed wide-beam frames was performed using the ABAQUS FEA program. Influence of steel fibers, axial compression ratio and PPR on mechanics behavior was discussed. The results showed that large axial compression ratio resulted in high ultimate loading capacity, but low ductility and energy dissipation. Large PPR caused a slight improvement on ultimate loading capacity, but low ductility and energy dissipation too. Steel fibers could effectively improve the ultimate loading capacity, ductility and energy dissipation, thus contributed to improving the mechanics behavior ofwide-beam frames, contribution of steel fibers to mechanics behavior decreased as the axial compressing ratio raise. The effect of torsion moment to lateral beam, stress of reinforcement and interaction between bar and concrete were discussed, some advice for seismic design were presented according to the study in this paper and previous research work.(4) Based on the experimental study, the hysteretic behavior of fiber-reinforced prestressed wide-beam frames was discussed. Two hysteretic models suitable for damaged and undamaged fiber-reinforced prestressed wide-beam frames were proposed sequentially. The hysteretic models consisted of a skeleton curves which based on the concept of three stage polygonal line with soften region and some hysteretic rules. The unload-reloading curves of the hysteretic models also based on a three stage polygonal line and a two stage polygonal line. Some numerical equations of the hysteretic models were presented for nonlinear analysis at the end of this paper.更多还原