Design of Flexural Members (IS 800:2007) And Comparison with Other Codes and Design Aids

Abstract

Limit state design method has been developed in the early 1970. Till then steel structure design has been carried out by the Working Stress Method (WSM).This new design approach adopted by many countries has been proved to be technologically sound and resulted in significant economy in the completed structures. In India because of globalization in engineering practice, practicing engineers required to adopt new method of design. Realizing the advantages of Limit State Method (LSM), the Bureau of Indian Standards, IIT Madras and Institute for Steel Design and Growth (INSDAG) Kolkata, together have introduced a draft of IS:800 (LSM Version). Limit State Method is a totally new method in India. Mainly designers are familiar with the philosophy of LSM as it is being used in the design of concrete structures but LSM in the design of steel structures considers completely different design considerations. Therefore attempt is made to illustrate some problems using LSM, which helps to understand the new method of design and design aids is prepared which will be proved helpful to structural engineers and will lead to quick implementation of the IS 800:2007. Few problems of simply supported laterally restrained and unrestrained beam have been illustrated by preparing a design table of load carrying capacity for different span. In design of gantry girder, spread sheets and design table are prepared for different load capacity with varying span for single crane and double crane. Plate girders are built-up beams comprising of plate sections for web and flanges when welded connections are used. Present study includes theory behind pre buckling and post buckling behaviour of slender web when it is transversely stiffened and use of different types of stiffeners. Example of plate girder is illustrated. Comparison of IS 800:2007 with other codes like AISC 360-05, BS-5950, and Eurocode-3 is also included.