Prestress Loss Identification Method Based on Influence Matrix in Truss Structure
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摘要: 为计算出每束预应力钢束实时的预应力损失,依据预应力桁架结构观测变形,基于位移影响矩阵原理提出一种预应力损失识别方法. 通过有限元分析,建立预应力损失值与桁架结构观测点位移值之间的关系方程,并依据极小值优化原理,获得预应力损失值. 研究表明:当单位预应力损失取30%~50%时,得到的位移影响矩阵计算预应力损失时误差最小,约为1%~2%;三角形桁架1/4跨度和3/4跨度处位移观测点对预应力损失的敏感性最高. 最后,以黔渝线上某高铁站房的大跨钢筋预应力桁架结构为例,验证了该方法的正确性.Abstract: In order to calculate the real-time prestress loss of prestressed strands according to the observed deformation of prestressed truss structure, a prestress loss identification method based on displacement influence matrix is proposed. By finite element analysis, the relationship between the prestress loss and displacement of the observation point on the truss structure is formulated. Moreover, according to the minimum principle, the prestress loss is obtained. The results show that when the unit prestress loss ranges between 30% and 50%, there is minimum error around 1%–2% in calculating prestress loss with displacement influence matrix; the displacement observation point is most sensitive to prestress loss, when it is located at the 1/4 span and 3/4 span of the truss. Finally, by taking an example of the long-span prestressed truss structure near a high-speed railway station on the Qian-Yu line, the accuracy of the method is verified.
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表 1 精确度验算1(单位预应力损失取10%)
Table 1. Checking calculation of accuracy with unit prestress loss of 10%
假设预应力
损失反算预应力
损失相对
误差假设预应力
损失反算预应力
损失相对
误差假设预应力
损失反算预应力
损失相对
误差6.00 5.65 5.91 15.00 13.90 7.35 30.00 27.64 7.86 7.00 6.85 2.20 20.00 19.52 2.39 50.00 48.92 2.16 8.00 7.35 8.15 30.00 28.19 6.04 40.00 36.57 8.57 9.00 8.92 0.92 20.00 19.75 1.27 30.00 29.49 1.71 10.00 9.84 1.62 15.00 14.40 3.98 20.00 18.63 6.85 表 2 精确度验算2(单位预应力损失取30%)
Table 2. Checking calculation of accuracy with unit prestress loss of 30%
假设预应力
损失反算预应力
损失相对
误差假设预应力
损失反算预应力
损失相对
误差假设预应力
损失反算预应力
损失相对
误差6.00 5.96 0.62 15.00 14.81 1.25 30.00 29.65 1.15 7.00 6.98 0.21 20.00 19.93 0.37 50.00 49.85 0.31 8.00 8.09 1.18 30.00 29.81 0.64 40.00 39.67 0.83 9.00 8.98 0.28 20.00 19.93 0.36 30.00 29.90 0.34 10.00 10.04 0.40 15.00 14.97 0.21 20.00 19.75 1.24 表 3 精确度验算3(单位预应力损失取50%)
Table 3. Checking calculation of accuracy with unit prestress loss of 50%
假设预应力
损失反算预应力
损失相对
误差假设预应力
损失计算预应力
损失相对
误差假设预应力
损失反算预应力
损失相对
误差6.00 5.95 0.85 15.00 14.85 1.00 30.00 29.71 0.96 7.00 6.97 0.37 20.00 19.94 0.32 50.00 49.86 0.28 8.00 8.01 0.11 30.00 29.76 0.79 40.00 39.48 1.30 9.00 8.99 0.14 20.00 19.97 0.17 30.00 29.96 0.13 10.00 10.06 0.64 15.00 15.05 0.34 20.00 19.87 0.64 表 4 精确度验算4(单位预应力损失取100%)
Table 4. Checking calculation of accuracy with unit prestress loss of 100%
假设预应力
损失反算预应力
损失相对
误差假设预应力
损失反算预应力
损失相对
误差假设预应力
损失反算预应力
损失相对
误差6.00 6.14 2.34 15.00 15.36 2.42 30.00 30.67 2.23 7.00 6.89 1.54 20.00 19.71 1.43 50.00 49.22 1.57 8.00 8.06 0.81 30.00 29.92 0.28 40.00 39.67 0.83 9.00 8.87 1.49 20.00 19.70 1.51 30.00 29.54 1.53 10.00 10.12 1.20 15.00 15.16 1.06 20.00 20.01 0.03 表 5 观测点位移数据计算值
Table 5. Calculation results of observation point displacement
观测点 各组预应力
无损失时钢束组1预
应力损失钢束组2预
应力损失钢束组3预
应力损失钢束组4预
应力损失钢束组5预
应力损失1 7.009 6.775 7.475 6.878 6.993 7.000 2 11.980 11.664 12.252 12.044 11.932 11.949 3 12.331 12.030 12.443 12.364 13.012 12.270 4 3.521 3.341 4.055 3.456 3.508 3.516 5 9.930 9.619 10.332 10.024 9.911 9.908 6 11.010 10.695 11.207 11.062 12.068 10.967 7 10.100 9.868 10.177 10.123 10.556 10.308 表 6 预应力损失识别系数计算
Table 6. Identification coefficients of prestress loss
项目 σ% 10% 20% 25% 20% 30% 理论值 0.333 3 0.666 6 0.833 3 0.660 0 1.000 0 计算值 0.334 6 0.667 0 0.837 0 0.666 4 0.998 3 -
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