主桥预应力箱梁施工方案

本桥主桥采用变截面三向预应力连续现浇箱梁结构，顶板设2％横坡，腹板倾斜，通过左右侧腹板不同高度来调整横坡。主跨为55m，边跨32.95m，桥面为双幅6车道。综合考虑工期、造价等因素，采用支架现浇。由于主跨跨过海虞北路，在架设支架时，需预留海虞北路的行车道及人行道。
一、施工准备工作
（一）材料及材料试验
箱梁混凝土设计为50号，属高标号预应力混凝土，混凝土所使用的有关原材料严格按照技术规范的要求提前取样进行认真试验与检测，各项质量指标必须达到规范规定的标准，并经监理工程师和指挥部复检抽检合格后，方可按计划进行分批采购入场，在采购进场的过程中，指定专门材料试验人员，按规定的频率进行抽检，发现有不合格的材料，拒绝验收并坚决清退出场。50号砼所用水泥及箱梁所用I、II级钢筋，均按照规范要求进行产品质量控制，合格后方可采购。
以上均为箱梁主体结构用材，严把材料质量标准关，是确保工程质量最重要的也是最关键的工作，应以高度负责的精神，严肃认真一丝不苟的工作态度做好这项工作。
（二）混凝土配合比设计与强度试配工作
前面关于施工准备工作第1条已经提到，现浇钢筋砼连续箱梁砼设计标号为50号，是高标号砼。因此，在设计50号混凝土时，我公司将严格按照交通部2000年颁布的技术规范（范本）及公路工程水泥混凝土试验规程的各项规定认真进行混凝土配合比设计，做混凝土配合比设计除按照技术规范的有关规定外，还必须考虑施工现场的实际情况，进行必要的修改与补充，特别是掺加砼添加剂以后对砼强度的影响。
接着，根据砼配合比设计的计算成果，在工地试验室
Program of the main bridge prestressed box beams

The main bridge of the bridge to prestressed continuous variable cross-section three-place box girder structure, 2% cross slope roof design, web inclined, through the left and right flanks plates of different heights to adjust the cross slope. Main span of 55m, side span 32.95m, deck for the double width 6 Drive. Considering the duration, cost and other factors, using support cast. As the main span across the Haiyu North Road, in the erection of scaffolds, to be reserved for Haiyu North Road carriageway and pavement.
1, construction preparation work
(A) materials and material testing
Concrete box girder design for the 50, is a high-grade prestressed concrete, concrete materials used in strict accordance with the specifications of the request early sampling and testing for serious testing, quality indicators must meet the specifications of the standards required by the supervising engineer recheck sampling and command-requisite for admission according to plan purchases in batches, in the course of the procurement approach, appoint a special material testing personnel, the required frequency of sampling, found substandard materials, refuse acceptance and firm and return appearance. 50 used in cement and concrete used in Box I, II grade steel, all in accordance with the specifications for product quality control, qualified only after purchase.
Box above the main structure of all timber, strict quality standards related materials, ensure the engineering quality the most important and most critical work should be highly responsible manner, serious and meticulous approach to their work Renzhen do this work.
(B) of the concrete mix design and strength test with work
In front of the preparatory work on the construction of the first one has already been mentioned, place reinforced concrete box girder concrete design numbered 50, is a high-grade concrete. Therefore, in the design of concrete 50, the company will be strictly in accordance with the Ministry of Transportation specifications issued in 2000 (model) and highway test procedures of Concrete provisions carefully to concrete mix design, concrete mix design to do except in accordance with the technical specifications of the relevant provisions, it must consider the actual situation on site, make the necessary changes and added, especially after the mixing of concrete additives to the concrete strength.
Then, according to the calculation of concrete mix design results, the site laboratory