A Study On Cable Suspension Footbridge

Dr. S.V. Itti, and Amar R. Chougule, Professor, M-Tech. Student, Dept. of Civil Engg., KLESCET, Belgaum

The Government of Karnataka has taken to restore one of the famous Gangambika Temple which is submerging over eight months in a year under back water of Malaprabha dam. The temple is situated in the central part of Malaprabha river basin near MK Hubli of Belgaum district. To overcome the difficulty for Devi darshan during its submergence a footbridge is recommended on either side of the temple. There are many systems for footbridges construction using such as Rcc, steel, cable stayed cable suspensions, etc. Looking at the site conditions and economy, it has been recommended to provide a cable suspension footbridge. This also enhances the beauty of surrounding area. As per the survey details, the cable suspension footbridge having dimension of 4m width and 90 m overall span at left and 75 m overall span at right has been proposed for accessibility. In the present work the analysis of a left side cable suspension footbridge has been carried out by STAAD.Pro 2006 and the various components of bridges are designed using the programs written in excel spreadsheets. The parametric study has been carried out for different spacing of suspenders and sags of the cable. The study shows that the design is economical and safe for 1.25m spacing of suspenders and ratio span/10 as sag.

Introduction

Cable suspension bridges are supported by two main steel cables. The deck is hung from suspender cables or steel rods. The cables are anchored into the stream banks and are supported by intermediate towers Figure 1. Longer span cable suspension bridges are usually designed with a stiffening truss. The stiffening truss supports and stiffens the deck. Cables are then added to carry live loads. To reduce the bending moment in the towers anchor cables are provided. The cables will be having either guided pulley support or roller support like as shown in Figure 2.