Seismic design of structures based on plastic energy balance


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Merter O., Ucar T.

PAMUKKALE UNIVERSITY JOURNAL OF ENGINEERING SCIENCES-PAMUKKALE UNIVERSITESI MUHENDISLIK BILIMLERI DERGISI, vol.24, no.3, pp.350-361, 2018 (ESCI) identifier

Abstract

Energy-based approaches are developed as an alternative to displacement-based methods in nonlinear analysis and design of structures. The structural design methodology based on energy concepts incorporates the displacement concept simultaneously and it may be mentioned more rational by comparison with the other existing methods. Earthquake is considered as an energy input to the structure within the study and then the general energy-balance equation is written for the structure system. Ideal collapse mechanism, where plastic hinges are assumed to be located on beam ends and column bases, is considered. An admissible interstory drift ratio is targeted for the design and base shear force expression is derived by equating the plastic energy from general energy-balance with the external work done by the design lateral forces. The new energy-based base shear force is distributed to story levels of 3- and 5-story steel structures as equivalent static lateral forces and then plastic design of structural system, which is predesigned that comply with a seismic code at the beginning of the methodology, is implemented. The structural design method involves an iterative technique and it is continued until the same sections of the former iteration are obtained. The interstory drift ratios obtained from pushover analysis using the inverted triangular distribution of energy-based base shear force are compared with the target drift of the design. The accepted ideal collapse mechanism is checked whether it occurs or not. The results are interpreted and compared to the results of nonlinear time history analyses performed by using the time histories of real earthquakes scaled in time domain.