Abstract
In trusses, deck type and through type truss systems are generally provided with various member arrangements. To utilize the materials used in the trusses more efficiently, RCC decks are nowadays made composite with the truss members. In this paper, analysis of 72.0 m deck type and through type, non-composite and composite bridges is presented. The bridges are modelled using STAAD. Pro v8i software with truss members as beam element and deck slab modelled as four noded plate element. The loading on the bridge is done as per the provisions of IRC-6 and IRC-24. The composite deck effectively reduces the horizontal deflections due to lateral seismic and wind loads in both the truss systems. Decrement in vertical deflection of the truss system was also observed making the structure mode stiffer. Stresses in the members made composite with the deck slab were also reduced and hence resulted in material saving and decreased steel offtake. In the case of composite deck type bridges due to load sharing by the deck slab, the stresses in the top chord are reduced significantly hence eliminating the chances of buckling. Advantages of composite deck are better utilized in deck type bridge system compared to through type bridge system.
Highlights
The most common type of steel bridges are through-type and deck-type bridges
In the through-type bridge system the carriage way is located at the bottom level of the load carrying structure (fig 1(a)), where as in the deck-type system the carriage way is located on the top of load carrying system (fig 1(b))
Whereas in composite steel truss bridges, the deck is made composite with the truss members so that the deck starts participating in load sharing
Summary
The most common type of steel bridges are through-type and deck-type bridges. In the through-type bridge system the carriage way is located at the bottom level of the load carrying structure (fig 1(a)), where as in the deck-type system the carriage way is located on the top of load carrying system (fig 1(b)). Concrete can carry compression more economically, and can be used in composite action with the top chord in deck type truss system. Continuous span steel truss bridges can be constructed with the advantage of approximately 1/3rd mid span sagging moment, and 2/3rd support hogging moment, of the total supported span moment This type of construction was adopted in case of Chauras and Garudchatti bridges [8], [9]. In the continuous composite truss bridge, due to tensile shrinkage strain, and tensile flexural strain under live load condition, cracking of the deck slab at the support sections is unavoidable. Supported medium span (30m to 100m) deck type composite truss bridges are most suitable, especially for deep valley condition in mountainous regions. In Indian code IRC: 22-2015 [15] for steel concrete composite construction, no separate provisions are made for the design of composite truss bridges
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
