A comparative study on Balanced Cantilever and Simply Supported Bridge

Abstract

Bridges are essential infrastructure elements that link towns and allow for effective transportation systems. In civil engineering, choosing the right bridge is essential, considering things like structural performance, construction techniques, material needs, economic effectiveness, and environmental effects. This study presents a comparison of two widely utilized bridge types—balanced cantilever (BCB) and simply supported bridges (SSB). This study compares and contrasts the functionality of BCB and SSB from various civil engineering point of view. This work includes a thorough survey of the literature followed by detailed analysis and design of both bridges, which focuses on the structural behavior of BCB and SSB, including their capability for carrying loads, deflection characteristics, bending moment and shear forces, and structural stability evaluation. The balanced cantilever of a span of 30 m two-lane bridge is compared with the same span and lane of a simply supported bridge. Half of the span of the balanced cantilever bridge is used to analyze and design of the bridge, and the calculated values of bending moments, shear forces, and deflection are used to compare with simply supported RCC bridges. The analysis and design of the BCB carried out manually in MS excel, and analyzed by subjecting the structure under standard loading conditions as suggested by IRC - 6. Courbon’s Method is used for the analysis of deck slab and longitudinal girders. The maximum bending moment in BCB obtained at supports subjected under dead and live loads. Maximum bending moments and shear forces is obtained by plotting the governing influence lines at various points along the span of the girder. The maximum bending moment is acting on the outer girder of the bridge, whereas the maximum shear force is acting in the inner girders. In order to estimate the material requirements for the BCB and SSB, the quantities of concrete, steel, and other building materials needed for each bridge type were taken into consideration. The amount of steel required in the BCB is lower compared to the simply supported bridge. Similarly, the quantity of concrete needed for the BCB is also lower. Thus, from a quantity and aesthetic perspective, the BCB proved to be more efficient. However, constructing the parabolic profile girder in the BCB is complex as compared to simply supported bridges, as skilled manpower is required to construct the BCB with a parabolic profile girder.