利用虚功原理计算T构悬臂端日照温差位移的方法

Calculating of the Relative Displacement of the T-Shape Rigid Frame Bracket End Caused by the Superficial Temperature Difference Using the Principle of Virtual Work

通过对某特大连续刚构桥施工监控过程中某些墩位(两边墩)T构两悬臂端在临近合拢时挠度出现反常现象的原因分析,推测日照温差是引起标高误差的主要因素;利用虚功原理推导出了一个简便的公式,用以计算变截面箱梁刚构桥T构悬臂端因桥梁表面温差引起的相对位移量;将计算结果与实测结果进行对比,验证在夏季热期施工中日照温差对悬臂挠度的影响是引起合拢高差难以控制的主要原因之一;结合现场监控,提出消除或缩小因温度位移而引起的合拢标高误差的建议,取得了明显效果。

Through analyzing abnormal deflections detected during the construction process of closing two bracket ends of T constructs on certain pillar positions（two side pillars） in one very-large-size continual rigid frame bridge,we found that the temperature difference due to sunshine is the primary factor that causes the elevation error.A parsimonious formula based on the principle of virtue work is developed to calculate the relative temperature-induced displacement of T construction cantilevers of a variable-cross-section rigid frame bridge.The computed results and the actual ones are compared to show that the sunshine temperature difference is one of main causes of the difficulty encountered in controlling the T cantilever deflection during the closing up process under highly variable temperatures.By combining the field monitoring techniques,we propose methods to eliminate such temperature-induced elevation.These methods have been successfully applied in the construction and have brought significant improvement to the current construction practice.