Limit State Design of R.C. Bridge Superstructure

Abstract

Revolutionary changes have taken place in the practices and philosophies in bridge design during the last century. Yet many important factors were lost sight of the design because of inadequate knowledge and experience. This has adversely affected the durability and serviceability of the bridge and has resulted in their premature de- terioration and other problems. The bridge designers are now becoming increasingly aware of many new factors and dimensions in the designing of modern bridges. This is going to be great help in designing more beautiful and durable bridges which will be constructed with ease, efficiency and economy and which will remain in service for a very much longer period. There are many factors which affects bridge durability, which is both environmental conditions and design philosophy. In present study, comparison of limit state design and load and resistance factored design is done. By taking an bridge superstructure data, which is analysed and de- signed by both methods. And are compared to obtain economical design. The main emphasis is given on limit state method design as per IS 456-2000 and and partial safety factors from IRC-6 amendments no.8, which covers limit state of collapse , limit state of cracking ,limit state of serviceability and partial safety factors. And load and resistance design is done using ASSTHO specifications. By taking different depth for different span the economical L/D ratio is obtained. Quantity and rate analysis is done to obtain the total economic cost of bridge super- structure. The bridge superstructure is designed by both the methods and compared with working stress design method to find most efficient design philosophy.