SIMPLIFIED ANALYSIS OF CABLE-STAYED/ EXTRADOSED BRIDGES

Abstract

Bridges play a key role in all transportation networks. In the current scenario, with the increase in traffic, their significance is increasing day by day. Cable-stayed/ extradosed bridges have emerged as a better solution whenever medium spans need to be covered. Among the various types of bridges Cable-stayed and Extradosed are such types of bridges where a bridge deck is supported by inclined stay cables. visual appeal, cost-effectiveness, and ease of construction make the cable-stayed and extradosed bridge the most suitable form for medium-span bridges with spans ranging from 200m to 800m. These are relatively new structural forms and lack proper design standards for their analysis and design. Further, a greater number of design variables are involved so analysis and design become tedious, and intuition does not work. Hence design automation based on a simplified analysis approach, which can be used iteratively to get quick, approximate but rational results that can guide initial design decisions is very much useful. In the present work, an attempt is made to develop a unified simplified analysis approach for cable-stayed and extradosed bridges utilizing continuous beams supported on springs. The stiffness method is used to analyse the beam incorporating the contribution of pylon and cable stiffness and subsequently cable tension evaluation is done keeping the desired bridge profile as a target. The tool initially focused on determining the optimal initial cable tension. It was then extended to include analysis of the construction stage, allowing for a more thorough evaluation of the bridge’s behaviour. The analysis was verified using the cases reported in the literature as well as using the results of numerical analysis carried out using MIDAS.