SOUTHWELL PLOT ESTIMATION OF LOCAL CRITICAL STRESSES IN THIN-WALLED COLUMNS

摘要

In spite of the phenomenal advances experienced in the field of numerical structural analysis, there is still (and will be for a longtime) an increasing need to perform experimental studies. In fact, it is rather difficult to gain a deep insight on the overall behavior of a given structure or structural element without carefully testing it. Moreover, experimental investigations remain an indispensable tool to gather data intended to calibrate and check the validity of design rules. In order to evaluate the structural efficiency of thin-walled columns, it is essential to study their buckling behavior, which is often affected by interaction phenomena between local (cross-section) and global modes. Therefore, one must assess the column local buckling behavior, i.e., identify the relevant modes and calculate the corresponding bifurcation stresses. The buckling behavior of most compressed thin-walled cross-sections (i.e., stub-columns) is conditioned by two types of buckling modes, designated as "local plate" (LPM) and "distortional" (DM). These buckling modes are illustrated in figure 1 and either of them may be critical for currently used cross-section shapes and dimensions.