Deformation and energy absorption capacity of steel structures in the inelastic range

This report summarizes the status of knowledge on the inelastic deformability of steel members and frames. It demonstrates that the inelastic response of planar beams, beamcolumns, connections and frames is well understood and can be adequately, though conservatively, predicted by theory provided the loading is static, proportional and monotonic, and adequate provisions are made to inhibit premature local and lateral-torsional instability. The report reviews the available theoretical work, and examines the experimental evidence. It shows that the inelastic rotation capacity, which defines also the ductility factor and the inelastic energy absorption capacity, is both predictable and large enough to meet the requirements of plastically designed frames. The report demonstrates that the knowledge of the behavior of members and frames subjected to non-proportional or reversible loading, which may be the result of dynamic phenomena, is not complete. Methods of frame analysis are available, but information needs to be generated on the inelastic behavior of individual structural components under reversed loading. This information is vital for the performance of a proper dynamic analysis. A similar need exists in the area of biaxially loaded structures. The report considers separately the available research on beams, beam-columns, connections and frames. Particular emphasis is placed on the inelastic deformability. Each section of the report contains specific suggestions for further research and study. Selected references appear at the end of the report. The large amount of research performed for the development of plastic design has relevance for the study of the behavior of structures subjected to earthquake motion or blast, because it provides information on basic behavior, and it defines methods of analysis and experimentation. This research does not, however, give all the answers, and some additional areas need to be investigated