Hot spot SCF computation method of concrete-filled and PBL-stiffened rectangular hollow section joint subjected to axial tensions
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摘要: 考虑了PBL加劲型矩形钢管混凝土支管受拉节点支主管宽度比与厚度比和主管宽厚比, 建立了热点应力集中系数有限元模型, 计算了支主管节点热点应力集中系数; 基于最小二乘法对计算结果进行拟合, 给出不同几何参数下节点热点应力集中系数计算公式, 对比了矩形钢管节点和PBL加劲型矩形钢管混凝土节点应力集中系数和荷载幅。计算结果表明: 采用有限元模型计算的热点应力集中系数曲线与静力试验曲线基本一致, 支主管交汇处各位置热点应力集中系数有限元计算结果与CIDECT规范公式计算结果平均比值分别为1.006、1.007、1.013、1.015和0.987, 两者差值小于15%, 因此, 有限元模型可靠; PBL加劲型矩形钢管混凝土支管受拉节点热点应力集中系数变化规律基本一致, 随支主管宽度比呈抛物线变化, 在0.60.8之间达到最大值, 随主管宽厚比和支主管厚度比增大而增大, 与CIDECT规范中矩形钢管节点计算结果一致; 拟合得到的PBL加劲型矩形钢管混凝土节点热点应力集中系数公式计算结果与有限元计算结果的平均比值为1.011, 均方差为0.222, 变异系数为0.219, 说明了拟合公式准确; 采用应力集中系数计算公式, 将PBL加劲型矩形钢管混凝土节点与矩形钢管节点进行对比, PBL加劲型矩形钢管混凝土节点支管热点应力集中系数下降了68%以上, 主管热点应力集中系数下降了61%以上, 在2.0×106循环次数作用下, 容许荷载幅提高到3倍以上。
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关键词:
- 桥梁工程 /
- PBL加劲型矩形钢管混凝土节点 /
- 热点应力集中系数 /
- 有限元分析 /
- 容许荷载幅
Abstract: The width ratio and thickness ratio of brace to chord and the width-to-thickness ratio of chord for concrete-filled and PBL-stiffened rectangular hollow section joint subjected to axial tensions were considered, and the finite element model of hot spot stress concentration factor (SCF) was established.The computation result of hot spot SCF was fitted by the least square method, the SCF computation formulas under different geometric parameters were proposed, andthe hot spot SCFs and load ranges of rectangular hollow section joint and concrete-filled rectangular hollow section joint stiffened with PBLs were compared by using the proposed formulas.Computation result shows that the SCF curve calculated by using the finite element model is almost consistent with the experiment curve obtained by the static test, and the average ratios of finite element calculation results to CIDECT calculation results are 1.006, 1.007, 1.013, 1.015 and 0.987 at the hot spots at the joint of brace and chord, respectively, and the differences are less than 15%, which verifies the reliability of finite element model.The SCFs of concrete-filled and PBL-stiffened rectangular hollow section joint subjected to axial tensions have the similar variation trend and change in parabola shape with the width ratio of brace to chord.The maximum value of SCF appears when the width of brace to chord is between 0.6 and 0.8, and increases when the width-to-thickness ratio of chord and the thickness ratio of brace to chord increase, which is same with the SCF of rectangular hollow section joint calculated by CIDECT.The computation formulas and finite element model of hot spot SCF of concrete-filled and PBLstiffened rectangular hollow section joint subjected to axial tensions are compared, the SCF average ratio is 1.011, the mean variance is 0.222, and the variation coefficient is 0.219, which proves that the fitting formulas are accurate and reliable.Concrete-filled and PBL-stiffened rectangular hollow section joint is compared with rectangular hollow section joint, the SCFs of brace and chord computed by using the proposed formulas decrease by more than 68% and 61%, respectively, and the allowable load ranges increase to more than three times under the action of 2.0×106 cycle times. -
表 1 设计参数
Table 1. Design parameters
表 2 试件参数
Table 2. Specimen parameters
表 3 热点应力集中系数计算结果
Table 3. Calculated results of hot spot stress concentration factors
表 4 荷载幅计算结果
Table 4. Calculated results of load range
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