ANALYSIS AND DESIGN OF TWO LANE CABLE-STAYED BRIDGE

Abstract

Cable stayed bridges are very popular in Western countries and some countries like China. Now a day's very large span cable-stayed bridges are being constructed all over the world, but in India this type of bridges are less popular. Only a few bridges are constructed in India like Bandra-Worli Sea Link in Mumbai, Vidysager-Setu in Calcutta, Akkar Bridge in Sikkim and few others. This may be due to lack of standard design procedure and techniques which are not readily available in standard text books and bridge codes. In my thesis work I tried to model a cable stayed bridge in STAAD Pro and obtained the forces and moments in all the components. After getting the forces and moments, emphasis was given to design the different components of the cable-stayed bridge. The structural design of a cable stayed bridge is perhaps not a major problem. The problems lie in construction. The bridge is launched stage-by-stage by the cantilever method. At the end of construction, typically a horizontal profile of the deck may be desired. This profile may be hard to attain, and owing to the weight of the bridge it may be difficult to adjust the length of the cable stays. Therefore, to calculate the required positions of the deck during the launched construction of the bridge is a computation task, which most designers are not familiar with. This task requires computer programs which can model stage-by-stage construction and/or stage-by-stage deconstruction. Effects like creep, shrinkage, relaxation, etc., also need to be modeled, otherwise the desired bridge profile shall not be attained at the end of the construction. Most designers do not know how to model these effects and computation software is also required for this task. Following are the works that got emphasis in my thesis work 1. A model is developed to find the design moments in longitudinal girders, cable forces, bending moments in tower and compressive force in STAAD Pro 2. To design the components of cable-stayed bridge 3. Achievement of horizontal profile 4. Comparison of forces with suspension bridge