曾家沟大桥主拱圈施工阶段挠度计算和分析

拱桥施工中，确保拱轴线的线形非常重要。当采用钢拱架砌筑混凝土预制块拱圈时，钢拱架的下挠直接影响着拱桥的拱轴线形。利用有限元软件Midas进行数值分析，分别考虑了砌筑拱圈刚度和不考虑砌筑拱圈刚度2种情况下的挠度变化，然后与施工中实测情况进行对比。分析结果表明，在设计中考虑拱圈刚度与否，相同工况下拱架的下挠值变化很大，实测挠度值表明施工中拱圈的实际刚度比计算中的理想化刚度要小，故在施工时可以通过提高砌筑拱圈的实际刚度来控制主拱圈挠度，从而保证拱轴线线形。

Deflection Calculation and Analysis in Construction Stage of Main Arch Ring of Zengjiagou Bridge

During the construction of arch bridges, it is very important to ensure the shape of axis line of the arch. When steel arch is used to make prefabricated concrete block arch tings by ways of brickwork, the lower deflection of the steel arch has direct influence on the shape of axis line of the arch bridges. Finite element software Midas is used to make numerical analysis. Changes of deflection in two cases, which rigidity of masonry arch tings is taken into consideration in one case and is not in the other case, are compared with field measurements in engineering. The results of analysis show that value of the lower deflection of the arch varies greatly under the same working condition, no matter the rigidity of arch rings is considered or not, and the measured deflection value indicates that the actual rigidity of the arch tings in construction is less than the ideal one obtained from calculation. Therefore, the deflection of the main arch ring can be controlled by increasing the actual rigidity of the masonry arch tings in engineering so as to guarantee the shape of axis line of the arch.