冻融环境下混凝土力学行为及结构抗震性能研究

发布时间：2018-05-11 06:07

本文选题：冻融循环 + 力学性能　；参考：《西安建筑科技大学》2017年博士论文

【摘要】：地处寒冷地区的水工、海工、桥梁等混凝土结构常常发生冻融损伤,造成既有混凝土结构材料、构件、结构动力行为和地震灾变机理发生改变。本文采用试验研究、理论分析及其相结合的研究手段,围绕冻融损伤后混凝土材料动力本构、混凝土与钢筋粘结行为、钢筋混凝土构件抗震性能等问题进行试验研究和理论分析。具体研究工作如下:1.通过四批次共108个100mm×100mm×300mm试件的冻融循环试验及其单调与重复荷载试验,研究了单调与重复荷载作用下冻融损伤混凝土应力-应变关系曲线的变化规律,探讨了冻融循环次数、混凝土强度变化、引气与否对相应力学指标的影响规律。在试验的基础上,建立混凝土基于Weibull统计分布理论的冻融损伤随机本构模型。2.通过三批次共108个钢筋与混凝土短埋试件的冻融循环试验和中心拔出试验,测试了单调与反复荷载作用下不同混凝土强度等级、不同冻融循环次数的钢筋与混凝土试件的粘结-滑移曲线,探讨了冻融循环次数、混凝土强度等级、钢筋外形对钢筋与混凝土粘结-滑移曲线的影响。在试验研究的基础上,建立了钢筋与混凝土单调和反复荷载作用下的粘结-滑移本构关系,并给出模型相关参数的确定方法。3.通过四批次8根200mm×200mm×1180mm钢筋混凝土柱的冻融循环试验和低周反复荷载试验,研究了冻融循环次数对不同轴压比钢筋混凝土柱抗震性能的影响,探讨了冻融循环次数与钢筋混凝土柱滞回性能之间的关系,揭示了低周反复荷载作用下冻融循环次数与钢筋混凝土柱骨架曲线参数、延性、耗能能力、刚度退化之间的关系。4.以冻融前后的相对抗压强度“c d cff”作为基本变量,通过对本文试验数据和已有研究成果数据的回归分析,给出了混凝土受压、受拉本构模型相关参数的确定方法,运用有限元分析软件ABAQUS对冻融损伤后的钢筋混凝土构件柱进行数值模拟分析工作。5.在低周反复荷载试验的基础上,提出了冻融损伤钢筋混凝土柱“指向定点”的刚度退化三线型恢复力模型,并给出模型骨架曲线特征点的确定方法,提出卸载及其再加载的计算公式。比较试验结果和计算结果发现,所提恢复力模型能较好地反映冻融损伤钢筋混凝土柱在低周反复荷载下的恢复力特性,可为冻融环境下钢筋混凝土结构地震反应分析提供参考。
[Abstract]:The concrete structures, such as water workers, sea workers, bridges and other concrete structures which are located in the cold regions often occur freezing and thawing damage, resulting in the change of concrete structure material, component, structure dynamic behavior and earthquake catastrophe mechanism. The experimental research and theoretical analysis of the behavior of the cohesive soil with the reinforcement and the seismic performance of the reinforced concrete members are carried out. The specific research work is as follows: 1. the freezing thawing cycle tests of 108 100mm x 100mm x 300mm specimens with four batches and the monotonic and repeated load tests have been carried out to study the freezing and thawing damage concrete under the action of single and repeated loads. The law of the variation of force strain relation curve, the influence law of freezing thawing cycle times, concrete strength change, air entraining or not on the corresponding mechanical index is discussed. On the basis of the experiment, the freeze-thaw damage stochastic constitutive model of concrete based on the Weibull statistical distribution theory.2. has been established through three batches of 108 steel and concrete short buried specimens. The freeze-thaw cycle test and the center pull out test are used to test the bond slip curves of the reinforced concrete specimens with different concrete strength grades and different cycles of freezing and thawing cycles under the action of monotonous and repeated loads. The effects of the number of freezing and thawing cycles, the strength grade of concrete and the shape of the reinforced bar on the bond slip curve of the reinforced concrete and concrete are discussed. On the basis of the study, the bond slip constitutive relation of steel and concrete under monotonic and repeated loads is established, and the method for determining the related parameters of the model.3. is given by the freezing thawing cycle test and low cycle loading test of 8 200mm x 200mm x 1180mm reinforced concrete columns with four batches, and the different cycles of freezing and thawing cycles are studied. The relationship between the number of freeze-thaw cycles and the hysteretic behavior of reinforced concrete columns is discussed. The relationship between the number of freeze-thaw cycles and the skeleton curve parameters, ductility, energy dissipation capacity and stiffness degradation of reinforced concrete columns under low cycle cyclic loading is revealed by the relative compressive strength of.4. before and after freezing and thawing. The degree "C D CFF" is used as the basic variable. Through the regression analysis of the experimental data and the data of the existing research results, the method of determining the concrete compression and the related parameters of the drawing model is given. The finite element analysis software ABAQUS is applied to the numerical simulation analysis of the reinforced concrete column after the freezing and thawing damage..5. is in the low cycle. On the basis of the complex load test, the stiffness degradation three linear restoring force model of the frozen and thawing damaged reinforced concrete column "pointing point" is put forward. The method of determining the characteristic points of the model skeleton curve is given and the calculation formula of the unloading and reloading is put forward. The comparison test results and the calculation results show that the proposed restoring force model can be well reflected. The restoring force characteristics of RC columns damaged by freeze-thaw damage under low cyclic loading can provide reference for seismic response analysis of reinforced concrete structures under freeze-thaw environment.

【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU37;TU352.11

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