PARAMETRIC STUDIES OF TRUSS BRIDGES FOR ECONOMIC CONSIDERATIONS

Modification of forms and shapes of conventional truss bridges reduces the cost of structures with the increase of span and height of trusses. It is observed that the economy of truss bridges are based on different parameters such as span length, panel length, angle of truss and height of truss bridge. Paper deals with the comparison of weight of conventional truss bridges with the modified form of two truss bridges. The conventional warren truss bridge is selected as a reference bridge for the comparison of economy with modified camel back parker truss and segmental arch truss bridge. An analysis and design of the selected three bridges are carried out for railway broad gauge main line loading. In addition to this, following parameters are also taken in to consideration:- ? Span of truss bridge: 18 m & 24 m ? Height of truss: 3 m & 4 m ? Panel length: 3 m to 4 m Neglecting the seismic and wind effect with end supports as hinged and roller respectively, using working stress method, forces in all members of truss bridges are calculated. As per the magnitude and nature of forces of members of trusses, the steel sections are provided. All the results in terms of weight are shown in a tabular form for comparison. It is concluded that as the span of truss and height of truss increases, the modified trusses are economical with respect to conventional truss bridge.