BEHAVIOUR OF RC BOX GIRDER BRIDGES

Abstract

In today's fast modern world the ever increasing demand for the expansion of highway network, to cater for the increased traffic, has thrown challenges on researcher and designers to provide best innovative and safe bridge structures. The objective of the present work is to study the behavior of RC box girder bridge based on their reinforcement requirement. Box girder bridges are torsionally efficient structure. It provides efficient support to eccentric loading then the open system. In this thesis single cell two lane RC box girder bridge of different length are modeled to analysis and design. Continuous and simply supported both structural system of bridge are considered and compared. This help in taking quick decisions about the structural system to be preferred in the real world. The significance and evaluation of the secondary reinforcement in continuous bridge is also shown in the study. Model of the bridges are prepared in the software SAP2000 version 14.0.0. Non linear analysis for the calculation of the creep and shrinkage is done by the use of special literature BS5400 part-4- and the design is conducted by the use of IRC 21-2000. The loads and load combinations are taken with respect to IRC 6-2000. The creep and shrinkage is validated by calculating it manually. The discrepancy in results is quite small (4.6%). In the case of continuous bridges it is found that the secondary reinforcement has special consideration in the designing of bridges. Calculation of such forces and reinforcement are thoroughly considered in the design of continuous RC box grider bridges. The reinforcement due to secondary forces are compared with the total reinforcement of the continuous box girder bridges. It is found that the secondary reinforcement varies from 0.45% to 0.58% of cross section despite of change in number of span and length of the bridge. SAP2000 v14.0.0 is a sophisticated special purpose analysis and design program developed specifically for bridges. The use of software with steps and screen shot is thoroughly explained.