Application of Composite Structures in Bridge Engineering. Problems of Construction Process and Strength Analysis

Steel-concrete composite structures have been used in bridge engineering from decades. This is due to rational utilisation of the strength properties of the two materials. At the same time, the reinforced concrete (or prestressed) deck slab is more favourable than the orthotropic steel plate used in steel bridges (higher mass, better vibration damping, longer life). The most commonly found in practice are composite girder bridges, particularly in highway bridges of small and medium spans, but the spans may reach over 200 m. In larger spans steel truss girders are applied. Bridge composite structures are also employed in cable-stayed bridge decks of the main girder spans of the order of 600, 800 m. The aim of the article is to present the cionstruction process and strength analysis problems concerning of this type of structures. Much attention is paid to the design and calculation of the shear connectors characteristic for the discussed objects. The authors focused mainly on the issues of single composite structures. The effect of assembly states on the stresses and strains in composite members are highlighted. A separate part of problems is devoted to the influence of rheological factors, i.e. concrete shrinkage and creep, as well as thermal factors on the stresses and strains and redistribution of internal forces.

Mission Bridge—Design and Construction of the Steel Box Girder

The main span of the four-lane highway Mission Bridge is 440 ft (134.1 m) long with 290 ft (88.4 m) flanking spans, and consists of a steel box girder with an orthotropic steel plate deck. A box girder was adopted due to the structural efficiency of the box section and advantages in using thin plate material. The design is based on CSA Standard S6-1966 and the AISC Design Manual for Orthotropic Steel Plate Deck Bridges as far as applicable and with some deviations. The design was reviewed subsequent to the failure of steel box girder bridges abroad. The strength of the bottom plate in compression and the transverse bolted joints in compression received special attention. The joints of the deck plate made in the field are welded.In the fabrication and erection of the bridge, advantage was taken of the marine location of the fabrication yard. Special erection equipment was developed for the job. A key element in the scheme was ease with which the erection crane scow could be positioned.The application of the hot asphaltic concrete paving caused considerable thermal expansion of the steel structure.The cost of the steel superstructure was about the same as was estimated for a concrete superstructure. However, site conditions were such that the weight of the concrete structure would have increased the foundation costs.