Section nonlinear analysis of salt-freezing reinforced concrete pure bending component based on damage theory
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摘要: 在试验基础上, 引入损伤力学中的Loland模型进行盐冻混凝土的单轴抗压分析, 并将模型下降段修正为非线性关系表达式。依据试验数据, 对《混凝土结构设计规范》(GB50010—2002)建议的混凝土应力-应变表达式中的参数进行回归, 结合修正Loland模型, 得到与冻融循环次数和水灰比相关的混凝土盐冻损伤本构模型。编制Fortran程序, 应用所提出的本构模型对盐蚀、持续荷载和冻融循环共同作用下的钢筋混凝土梁进行截面非线性全过程分析。研究结果表明: 多因素复合作用下, 随冻融循环次数与水灰比的增加, 混凝土初始损伤不断增大, 峰值应力降低, 对应应变加大, 但延性无明显变化; 盐冻条件下, 随着持续荷载增大, 梁的极限承载力降低。
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关键词:
- 钢筋混凝土梁 /
- 混凝土盐冻损伤本构模型 /
- 修正Loland模型 /
- 持续荷载 /
- 截面非线性分析
Abstract: Based on the experiments, the Loland model used in damage mechanics was introduced into concrete uniaxial compression analysis and the descending portion of the model was modified into nonlinear expression.The parameters of the stress-strain relationship for concrete suggested by code for design of concrete structures(GB 50010—2002)were processed by data regression fitting.Combined with the modified Loland model, the concrete salt-freezing damage constitutive model related to freezing-thawing cycle time and water-cement ratio was derived.With the compiling programs by Fortran language, the section nonlinear analysis of RC beam under salt attack, sustaining load and 400 times freezing-thawing cycles was done.The result indicates that under the action of multi-factors, with the increase of the cycle times and the ratio, the initial damage of concrete is growing, the peak stress reduces and its corresponding strain increases, but the ductility is not significant change.With the increase of continuous load, the ultimate bearing capacity of the beam decreases. -
图 5 拟合应力-应变曲线与试验值(w/c=0.44)
Figure 5. Stress-strain fitting curves and experiment data(w/c=0.44)
图 6 拟合应力-应变曲线与试验值(w/c=0.50)
Figure 6. Stress-strain fitting curves and experiment data(w/c=0.50)
图 7 拟合应力-应变曲线与试验值(w/c=0.55)
Figure 7. Stress-strain fitting curves and experiment data(w/c=0.55)
图 8 预测应力-应变曲线与试验值(w/c=0.44)
Figure 8. Prediction stress-strain curves and experiment data(w/c=0.44)
表 1 混凝土初始损伤值
Table 1. Initial damage values of concrete
w/c N 0 50 100 150 200 0.44 0.000 0.181 0.385 0.530 0.674 0.50 0.000 0.295 0.618 0.750 0.898 0.55 0.000 0.445 0.733 0.821 0.939 
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表 2 计算参数
Table 2. Computational parameters
N a b σcN εcN 300 2.236 2.172 18.32 0.004 28 400 2.008 2.764 16.86 0.005 08
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表 3 RC梁截面极限弯矩计算值与试验值
Table 3. Limit bending moment's calculation results and experiment data of RC beam's cross section
Mu/(kN·m) 参考梁 0 30%Pu 50%Pu 70%Pu 计算值 4.828 4.579 4.415 4.289 4.074 试验值 5.548 5.320 4.568 4.401 4.235 误差/% 12.98 13.93 9.67 2.54 3.80
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