【作者】 唐亮；

【导师】 许斌；

【作者基本信息】 湖南大学 ， 结构工程， 2010， 硕士

【摘要】 正确把握钢筋混凝土柱在动力作用下(例如强震、强风等)的力学性能和动力行为对结构抗震和抗风设计至关重要。然而我国现行的抗震设计规范并没有充分考虑应变率对材料本构关系、结构构件的承载能力、变形、耗能能力以及破坏模式的影响。虽然少数研究者已经开展了高应变率下钢筋混凝土构件的动力试验研究,但目前为止还没有获得到足够的试验数据充分理解混凝土结构和构件的动力性能。因此,本文对钢筋混凝土柱在快速加载下的动力性能和数值计算方法进行了深入研究,具体工作如下：(1)进行了三个不同配筋率的钢筋混凝土柱构件快速加载试验,研究了混凝土柱在不同加载速率下的滞回性能、骨架曲线、延性指标、耗能性能以及破坏模态,为钢筋混凝土柱非线性纤维模型分析提供了试验数据。(2)通过在混凝土本构关系中考虑应变率效应的方法,采用纤维模型实现了钢筋混凝土柱在不同加载速率的单调荷载下的动力行为的数值模拟。模型考虑了二阶效应、塑性铰区域和剪切变形的影响。通过比较已有研究和本文中混凝土柱子试件的试验结果和数值模拟结果,验证了考虑应变率效应的动力纤维单元模型的有效性,结果显示了动力纤维单元模型能够准确地预测混凝土柱的动力性能,特别是在模型中考虑了剪切变形的模拟得到的变形能力与试验更为接近。(3)采用考虑剪切变形影响的模型,研究了混凝土柱的在不同纵向配筋率和体积配箍率下的动力性能。结果显示随着加载速率的增加,柱极限承载力和构件刚度在各个体积配箍率和纵向配筋率下均有不同程度的提高；而低体积配箍率试件的动力极限承载力相对增长率比高体积配箍率试件的要小,高纵向配筋率试件的动力极限承载力相对增长率比低配筋率试件的要小。模拟发现考虑剪切变形与不考虑剪切变形的得到的极限承载力差别很小。(4)运用一种基于压电陶瓷的智能骨料健康监测技术,实现了快速加载试验中的钢筋混凝土柱的损伤状况的监测。根据压电陶瓷的测量信号,采用基于小波包分析的损伤指标,评估了混凝土柱在不同加载水平下的损伤发展情况。通过比较试验观测结果,证明了基于压电陶瓷智能骨料的健康监测技术的可行性。更多还原

【Abstract】 The precise prediction of mechanical properties and behavior of reinforced concrete (RC) columns under dynamic loadings such as severe earthquakes or strong winds is crucial to aseismic design of civil engineering structures. In traditional aseismic design code,the effect of strain rate on materials strength, load carrying capacity, deformation, energy dissipation capacity and failure mode of structural members are not considered properly. Even though tests on dynamic behavior of reinforced concrete members under high strain rate have recently been carried out, there is a far way to accumulate enough test results to understand the dynamic performance of RC structures and members.This paper describes the seismic behaviors and numerical method of reinforced concrete columns under fast loading. The main achievements can be summarized as follows:(1) Experiments of three reinforced concrete columns with various reinforcement ratios under constant axial loads and fast cyclic lateral reversed loads are presented in this paper. Meanwhile, the characters of hysteretic loops, skeleton curves, displacement ductility coefficient, energy dissipation capacity and the failure mode at different loading rate are studied, and the experiment results can be provided for the nonlinear analysis of the reinforced concrete columns.(2) Numerical simulations on the dynamic behavior of a typical RC column specimen under monotone dynamic loading were performed. A recently developed constitutive model of concrete considering the strain rate effect was introduced into a dynamic fiber model to characterize the nonlinear strain rate dependent behavior of concrete. The effects of second order, plastic hinge zone and shear deformation are considered in the fiber model. Then the developed dynamic fiber element model is validated by comparing the simulated results of RC column specimens with the test results reported in related literatures and the fast loading test results in this paper. Results show that the developed fiber element model can predict the behavior of RC columns with acceptable accuracy. Especially in the model considered shear deformation, the simulated deformation capacity is much closer to the experimental results.(3) The dynamic properties of the RC column considered the influence of reinforcement ratio were simulated. Utilizing the developed model, the ultimate bearing capacity of columns with various longitudinal reinforcement ratios and volumetric stirrup ratios were investigated. As the loading rate increases, the ultimate carrying capacity and stiffness of columns, with various hoop or longitudinal reinforcement ratio, also increase; the ultimate bearing capacity growth factors relative to static loading of the specimens with lower volumetric stirrup ratios are smaller than the ones with higher ratios; the ultimate carrying capacity growth factors relative to static loading of the specimens with higher longitudinal reinforcement ratios are smaller than the ones with lower ratios. It is found the differences of simulated ultimate carrying capacity between the model considering the shear deformation and the model not considering are minute.(4) Utilizing an innovative smart aggregate approach based on piezoceramic, damage status of one column in the fast loading experiment was monitored. According to the measured signal, wavelet-packet-based damage index evaluates the damage development in concrete columns under fast loading. The experimental results show that the developed smart aggregate-based approach can effectively evaluate the health status of concrete columns during the loading procedure.更多还原