Local Stability Of Web Of Castellated Beams Under Uniform Moment

Compared with solid web steel beams, there are more advantages of castellated beams such as economical,handsome,higher resistance and so on. So castellated beams have been widely used in the world. However , analysis and researches of local stability of castellated beams are not development enough. Finite-element analysis using ANSYS, taking into account inelastic action, was used in this paper for the study of web stability of castellated beams with hexagon holes under uniform moment.Web of castellated beams is treated as simply supported plate with hexagon holes. The stability of plate with holes is studied under uniform moment. Buckling modes of plate with holes are described. The resistance capacity of plate with holes is little influenced by the number of half waves brought by plate buckling. In analysis, the stability of short plate with only one half wave is studied when the short plate is buckling. When plate length,height,thickness and the number of holes keep constant, the influence of holes scale on resistance capacity of plate with holes is taken into account. A conclusion is got that the width of holes has little influence on resistance capacity of plate and the height of holes has large influence on resistance capacity of plate. The limit ratio of plate height to thickness is obtained based on inelastic analysis. The elastic buckling moment of plate with holes is compared with that of plate without holes. The stability of plate with holes is analyzed according to the comparison results. By regression analysis, a formula for calculating elastic buckling moment of plate with holes is obtained. The effect of flanges restraint on the web in castellated beams under uniform moment is analyzed. The buckling modes of web of castellated beams are discussed. The differences of buckling modes between web of castellated beams and uniform plate with holes are described. The influences of different numbers of holes and holes scales on resistance capacity of castellated beams are analyzed. The limit ratio of web height to thickness is calculated by the effect of flanges restraint on the web buckling, compared with the limit ratio of plate with holes. The effect of flanges restraint on the web is obtained.