基于预应力损失识别的连续刚构桥内力计算方法

从连续刚构桥病害成因出发,以桥梁实测挠度为基础,采用位移影响矩阵建立非确定性预应力损失与主梁下挠的关系,通过求解非线性约束优化问题,识别非确定性损失大小及分布,可以得到由此产生的内力增量,进而计算桥梁实际受力状态。由于未考虑箱梁开裂及徐变模型误差等因素,预应力非确定性损失识别结果存在一定程度的夸大。通过不同约束条件的敏感性计算,分析了损失比取值范围对损失识别结果及内力计算结果的影响。将此方法应用于某桥的承载力分析中,计算结果与桥梁实际情况符合性较好,对同类桥梁的计算分析及加固设计有一定的参考意义。

Calculation Method of Internal Force of Continuous Rigid Frame Bridge Based on Prestress Losses Identification

The reasons of continuous rigid frame bridge faults were discussed at first.Based on the measured deflection,the displacement influence matrix was erected to connect uncertain prestress losses with the deflection in the main span.By solving the problem of nonlinear restriction optimization,the uncertain prestress losses value and distribution were identified,the increment of the internal forces and the real internal force of the bridge were then calculated.For the reason of box girder cracking and the uncertainty of creep model,the values of prestress losses were magnified to some extent.The results of the prestress losses identification and internal forces calculation that affected by prestress losses rate region were analyzed through the sensitivity analysis with different restrictions.Case study shows that the calculating results agree well with the test results.It could be a reference to the calculation and strengthening design for same kind of bridges.