橋梁專業(yè)外文翻譯--歐洲橋梁研究(完整版)
【正文】 entral hollow trapezoidal concrete box section m high and 4 m wide. The majority of the south and central spans are constructed using m long precast concrete trapezoidal box units, posttensioned together. This box section supports the in site concrete transverse cantilever slabs at bottom flange level, which carry the rail tracks and ballast. The center and south span sections are of posttensioned construction. These posttensioned sections have five types of prestressing: 1. Longitudinal tendons in grouted ducts within the top and bottom flanges. 2. Longitudinal internal draped tendons located alongside the webs. These are deflected at internal diaphragm positions and are encased in in site concrete. 3. Longitudinal macalloy bars in the transverse cantilever slabs in the central span . 4. Vertical macalloy bars in the 229 mm wide webs to enhance shear capacity. 5. Transverse macalloy bars through the bottom flange to support the transverse cantilever slabs. Segmental construction The precast segmental system of construction used for the south and center span sections was an alternative method proposed by the contractor. Current thinking suggests that such a form of construction can lead to ‘brittle’ failure of the entire structure without warning due to corrosion of tendons across a construction joint， The original design concept had been for in site concrete construction. Inspection and assessment Inspection Inspection work was undertaken in a number of phases and was linked with the testing required for the structure. The initial inspections recorded a number of visible problems including: Defective waterproofing on the exposed surface of the top flange. Water trapped in the internal space of the hollow box with depths up to 300 mm. Various drainage problems at joints and abutments. Longitudinal cracking of the exposed soffit of the central span. Longitudinal cracking on sides of the top flange
公司管理相關(guān)推薦
鄂ICP備17016276號-1