Maharashtra state board of Technical education (M.S.B.T.E, Mumbai) introduces Design of steel structure by limit state method SUBJECT in 5th semester in the curriculum from 2013-14 for civil engineering branch. The study of IS-800 -2007 is done at Pimpri Chinchwad Polytechnic,Which is one of best polytechnic in Pune.
Overview of IS-800-2007
Since last two decades Limit State concept of Design (LSD) of steel structure has been adopted by the structural engineers worldwide. In India it is still a new concept for the practicing structural engineers as the formal publication of IS 800-2007 was made in Dec, 2007, only seven years back. As a result Indian engineers are to face a real challenge to cover-up the gap in between. Publication of ISO: 2943 in 90‟s is a mile stone of global acceptance of LSD. Revision of IS 800-1984 to IS: 800: 2007 is made for a complete change of concept of design hitherto followed. Implementation of LSD was a problem in all most all the countries in the world. India is also facing the same due to delayed introduction of LSD codes when the level of knowledge on limit state developed very fast internationally. Today it becomes an urgent task for the Indian structural engineers to study and review more and more the basic philosophy and concept in contrast to the traditional method of Working Stress Design (WSD) in a documented manner so that this can help everyone in this field for effective application of LSD in practical design. This paper will address this issue as why it becomes a real historical challenge for engineers in India. Here it will also be attempted to highlight the basic philosophical understanding required for successful transformation from the traditional concept to this new concept of LSD. Some comparative design review of both the codes will also be presented for practical understanding of the conceptual changes.
Concept of limit state method
The object of limit state design can be paraphrased as achievement of an acceptable probability that a part or whole of structure will not become unfit for its intended use during its life time owing to collapse, excessive deflection etc, under the actions of all loads and load effects. The acceptable limits of safety and serviceability requirements before failure occurs are called as limit state. For achieving the design objectives, the design shall be based on characteristic values for material strengths and applied loads (actions), which take into account the probability of variations in the material strengths and in the loads to be supported. The characteristic values shall be based on statistical data, if available. Where such data is not available, these shall be based on experience. The design values are derived from the characteristic values through the use of partial safety factors, both for material strengths and for loads. In the absence of special considerations, these factors shall have the values given in this section according to the material, the type of load and the limit state being considered. The reliability of design is ensured by satisfying the requirement:
Design action ≤ Design strength
Lecturer Civil Engineering
Pimpri Chinchwad Polytechnic