Study of Behaviour of Cellular Steel Beams Under Lateral Torsional Buckling

Abstract

newline ABSTRACT newlineSteel I section beams with circular web openings are called cellular beams. The most newlinecommon method of fabrication of cellular beams is longitudinal thermal cutting of the web newlineof a hot-rolled I section in a specific pattern, and the welding of the two halves together newlineto obtain a member having a deeper web as well as web openings. Often, such beams newlineare fabricated by creating perforations in the webs of hot rolled steel beams to avoid newlinethe irregularities in beam behaviour due to the presence of unwanted residual stresses, newlinecaused by the cutting and welding process. A major advantage of cellular beams is their newlineeconomic material behaviour in strong axis bending, however, they can also be used for newlineaesthetic considerations because of their appearance. Another advantage of the same is newlineto accommodate building services and utilities such as air ducts or pipelines through the newlineopenings, thus reducing the floor-to-floor height and increasing the headroom. newlineModes of failure of a beam are affected due to the presence of openings in the web. The newlineregion between the two openings is known as web post and this region tends to buckle newlineout of plane when the openings are closely spaced or when there are high shear loads. newlineApart from web post buckling, due to the yielding of material around the openings, the newlineVierendeel mechanism comes into existence. In addition to these new failure modes, the newlineexisting failure modes of plain web beams are also seen in cellular beams, only with newlinecertain modifications. Often existing failure modes such as lateral buckling are seen in newlinea combination with web post buckling or web distortional buckling. Special attention is newlinerequired while designing cellular beams because of the probable simultaneous occurrence newlineof more than one failure mode. AISC and Eurocode are the only standards to have newlineproposed certain guidelines for design of cellular beams, wherein, lateral torsional buckling newlineof cellular beams is covered in the AISC specifications. However, guidelines relating to newlinesteel beams with web