Research Of The Overall Stability Of Castellated Beams With Different Hole Condition

Castellated beams are steel I-beams or Hot-rolled H-beams with a certain line on the web by cutting, assembling and welding,which have holes on the web. Castellated beams have the advantages of light weight,high bearing capacity, economy, beauty and so on, because they are with the original height of cross section of 1.3 to 1.6 times the beam, greatly improved the steel beams bending strength and stiffness. They can save more than steel solid web beam of 25% to 50%, save the paint and installation of transpotation costs 15% to 34.6%. Holes in the castellated beam web is beautiful and easy to install pipes and wires,therefore,practical applications in engineering castellated beam has great practical value, castellated beams are being more widely used.The stability of steel beams to determine their carrying capacity is an important factor. The stability of steel beams including the In-plane bending buckling and Outside the plane bending buckling, if it can not provide enough lateral support, often occurs the plane bending buckling. With the web openings, castellated beam is weakened by such a high degree of relative lateral stiffness of solid web beam. Under the loading, castellated beams more likely occur the case of overall instability or local instability.In this paper, based on energy method, and theoretical analysis will be complemented, comparative the castellated beams with the same opening hole high by hexagon and circle. Analysis the castellated beams with various moments of critical load about flexural-torsional buckling. And by the principle of equal size and moment of inertia castellated beams are derived contortion equivalent stiffness of the relevant. In this paper, the finite element analysis software ANSYS will be used to check the precision of the formula,and analyze the reason of error. Based on the regressive computation of the results of the finite element analysis, the paper offers the design formula about the equivalent conversion coefficient of the circle hole castellated beam changing into the hexagon hole castellated beam. The study of this paper can serve as some reference for the setup of the formula in codes for design of steel structures to accurately calculate the overall stability of castellated beams and for the engineering practice.