DESIGN AND ECONOMICAL OF ROOF TRUSSES & PURLINS (COMPARISON OF LIMIT STATE AND WORKING STRESS METHOD)

A.Jayaraman, R Geethamani, N Sathyakumar

Abstract: For a structural design to be satisfactory, generally four major objectives – utility, safety, economical and elegance must be fulfilled. This paper presents a study on behaviour and economical of roof trusses and purlins by comparison of limit state and working stress method. Roof trusses and purlins are therefore an integral part of an industrial building and the like for supporting the roofing system. This paper presents a study on behaviour and economical of fink type roof trusses, channel section purlins by comparison of limit state and working stress method. This study involves in examination of theoretical investigations of specimens in series. Overall two methods were designed and comparison of all the internal force, economical, and hence, to evaluate the coexisting moments and shear forces at the critical cross-section with same configuration area by keeping all other parameters constant. The theoretical data are calculated using Indian Standard code IS 875-1975 (part III), IS 800 – 2007 using limit state method, IS 800- 1984 using working stress method and the section properties of the specimens are obtained using steel table. The specimens are designed under uniformly distributed loading with simply supported condition. The research project aims to provide which method is economical, high bending strength, more load carrying capacity and high flexural strength. The studies reveal that the theoretical investigations limit state method design is high bending strength, high load caring capacity, minimum deflection and minimum local buckling& distortional buckling compare to the working stress method. But working stress method is most economical compare to the limit state method design.

Keywords: bending strength, deflection, limit state method, purlins, roof trusses, working stress method.

DOI: https://doi.org/10.15623/ijret.2014.0310030