橋梁工程本科畢業(yè)設(shè)計(jì)外文翻譯---混凝土橋梁的結(jié)構(gòu)形式-橋梁設(shè)計(jì)-wenkub
2023-05-18 13:38:36 本頁(yè)面
【正文】 1 The Structure of Concrete Bridge Prestressed concrete has proved to be technically advantageous, economically petitive, and esthetically superior bridges, from very short span structures using standard ponents to cablestayed girders and continuous box girders with clear spans of nearly 100aft .Nearly all concrete bridges, even those of relatively short span, are now prestressed. Precasting, castinplace construction, or a bination of the two methods may be used .Both pretensioning and post tensioning are employed, often on the same project. In the United States, highway bridges generally mustmeet loading ,design ,and construction requirements of the AASHTO Specification .Design requirements for pedestrian crossings and bridges serving other purposes may be established by local or regional codes and specifications .ACI Code provisions are often incorporated by reference . Bridges spans to about 100ft often consist of precast integraldeck units ,which offer low initial cost ,minimum ,maintenance ,and fast easy construction ,with minimum traffic interruption .Such girders are generally pretensioned .The units are placed side by side ,and are often posttensioned laterally at intermediate diaphragm locations ,after which shear keys between adjacent units are filled with nonshrinking mortar .For highway spans ,an asphalt wearing surface may be applied directly to the top of the precast concrete .In some cases ,a castinplace slab is placed to provide posite action . The voided slabs are monly available in depths from 15 to 21 in .and widths of 3 to 4 ft .For a standard highway HS20 loading, they are suitable for spans to about 50 ft, Standard channel sectio
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