Direct Strength Method (DSM) Design of Short-to-Intermediate Angle Columns

Recently, Dinis et al. (2011) unveiled the different mechanical behaviours offixed and pinned short-to-intermediate equal-leg angle columns. Theirfindings led Silvestre et al. (2012) to propose different design approaches forthose columns, both based on the Direct Strength Method (DSM) andcombining (i) the experimentally-based global design curve of Young (2004)with (ii) either the current DSM local design curve (fixed columns) or anempirical lower local design curve (pinned columns). Although thesedesign approaches predict the available failure load data quite efficiently,they are not based on a rational structural model − the dependence of thecolumn behaviour and failure on the interaction between minor-axis flexuraland major-axis flexural-torsional buckling is not incorporated. Very recently,Dinis et al. (2013, 2014) contributed to overcome the above limitation byproposing more rational DSM-based design approaches for fixed and pinnedequal-leg angle columns − the key contribution was showing the lengthdependenceof the column post-buckling behaviour and effective centroidshift effects (the latter only in pinned columns). Moreover, they also showedthat this dependence can be linked to column buckling mode characteristics,namely the amount of major-axis flexure.This work uses the above findings to propose and assess the merits of a novelDSM-based approach to predict failure loads of fixed and pinned short-tointermediateequal-leg angle columns. Following a careful calibrationprocedure, the selection of the appropriate flexural-torsional strength curve(post-buckling behaviour) and erosion coefficient (effective centroid shifteffects) is based solely on the column torsional and flexural-torsional criticalbuckling loads.

کلیدواژه ها:

Cold-formed steel equal-leg angles ، Ultimate strength ، Direct Strength Method (DSM) design ، Fixed-ended columns ، Pin-ended columns