Steel built-up I sections, composed of plates with high width-to-thickness ratios (slender sections), are commonly used in pre-engineered buildings under the premise that the design is governed by wind. However, in the event of a severe earthquake, the sections are susceptible to local buckling and may exhibit a non-ductile behavior. Therefore it is imperative to check the performance of such structures under the maximum credible earthquake (MCE). As a first step towards this objective, it is necessary to evaluate the post-buckling strength and ductility of such sections. In this study, a Finite element model is developed to analyze the inelastic post-buckling response of semi-compact and slender plates. The information can be used to predict the moment-rotation curves for I-sections with slender webs. A parametric study was carried out on a total of 54 pinned-base PEB frames of varying spans and heights. The elastic seismic demand under severe earthquake was estimated and compared with the design lateral capacity of PEB frames. From the results, it is concluded that even for higher seismic zones, low ductility sections (1.5 to 2) are adequate to survive MCE. Alternatively, if the design is verified for a response reduction factor of 2, then non- ductile sections can also be used.
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