大型斜拉桥下横梁支架设计与施工

Design and Construction of Lower Support Beams under Large Cable-stayed Bridge

介绍忠县长江大桥主塔的下横梁支架设计和施工。大型斜拉桥的主塔下横梁一般较大且离承台顶面较高,本桥悬空高度69.5 m,国内施工通常采用钢管桩或万能杆件支撑等落地式支架,本桥采用了悬空支架,利用塔柱预埋件焊接钢管桩斜撑作为支架,较通常落地式支架受力更明确、使用材料更少、工序更少、施工工期更短、成本大大降低,证明大型悬空支架的可行性,总结出相应的计算和施工方法。

The design and construction of the main tower＇s lower beams＇ strut of Zhongxian County Yangtze River Bridge are described. The main tower lower beams of large cable-stayed bridge are generally large and usually far above the top of the platform. The bridge＇s head room is 69.5 m. In China, ground struts such as steel pipe pile or universal members are usually adopted in construction under this kind of situation. But in this project, suspension struts, are utilized, i.e. using pre-embedded members welded with steel pipe piled diagonal bracing as the strut, which has the advantageous of more clear and definite stress, less material, less working procedure, and shorter construction period comparing with those of common ground struts. Moreover, the cost is also cut down greatly by the ＂suspened strut＂ method. All the above prove the feasibility of the large suspended strut. Relevant computation and construction methods are also summarized.