Advantages and disadvantages of prestressed concrete pdf


A similar bridge on this river was fabricated ashore and pushed across its pylons. A box girder bridge advantages and disadvantages of prestressed concrete pdf a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises either prestressed concrete, structural steel, or a composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in cross-section.

Box girder bridges are commonly used for highway flyovers and for modern elevated structures of light rail transport. Although normally the box girder bridge is a form of beam bridge, box girders may also be used on cable-stayed bridges and other forms.

In 1919, Major Gifford Martel was appointed head of the Experimental Bridging Establishment at Christchurch, Hampshire, which researched the possibilities of using tanks for battlefield engineering purposes such as bridge-laying and mine-clearing. Here he continued trials on modified Mark V tanks. The bridging component involved an assault bridge, designed by Major Charles Inglis RE, the Canal Lock Bridge, which had sufficient length to span a canal lock. Major Martel mated the bridge with the tank and used hydraulic power generated by the tank’s engine to manoeuvre the bridge into place.

For mine clearance the tanks were equipped with 2-ton rollers. Martel also developed his new bridging concept at the EBE, the Martel bridge, a modular box girder bridge suitable for military applications.

The Martel bridge was adopted by the British Army in 1925 as the Large Box Girder Bridge. A scaled down version of this design, the Small Box Girder Bridge, was also formally adopted by the Army in 1932. The United States was another country whose army created their own copy, designating it the H-20. In addition, the modular construction of the basic Martel bridge would later during WWII become part of the basis of the Bailey bridge.

500 for infringement on the design of his bridge by the designer of the Bailey bridge, Donald Bailey. Both the Large Box and Small Box designs would go on to see much service in World War II, especially in the case of the latter. 1960s, especially in the West, and many new bridge projects were in progress simultaneously. Fifty-one people were killed in these failures, leading in the UK to the formation of the Merrison Committee and considerable investment in new research into steel box girder behaviour.

Most of the bridges still under construction at this time were delayed for investigation of the basic design principle. Some were abandoned and rebuilt as a different form of bridge altogether. Some bridges were strengthened a few years after opening and then further strengthened years later, although this was often due to increased traffic load as much as better design standards. The Irwell Valley bridge of 1970 was strengthened in 1970 and again in 2000.