Stability of castellated beam webs

A study on the web-buckling behavior of castellated beams is described in this thesis. Both elastic and plastic methods of analysis are utilized to predict the failure modes of these beams.Interaction diagrams predicting formation of plastic mechanisms, yielding of the horizontal weld length and elastic buckling analysis using the finite element method are correlated with a number of experimental test results from previous studies given in the literature.Test-to-predicted ratios for a total of 42 test beams ranging from 45° to 60° openings are computed with the plastic and elastic methods of analysis, and a mean of 1.086 and coefficient of variation of 0.195 are obtained. A parameter study covering a wide range of 60° castellated beam geometries is performed to derive elastic buckling coefficients under pure shear and bending forces. An elastic buckling interaction diagram is then defined, which along with the diagrams utilized in the plastic analysis, can be used to predict the elastic buckling and plastic failure loads under any given moment-to-shear ratio.To incorporate the effect of plasticity associated with buckling, expressions are derived to improve the previous theoretical models used, by combining both elastic and plastic results. This results in an improvement in the coefficient of variation of the test-to-predicted ratios or the 60° beams considered from 0.170 to 0.137