BEHAVIOR OF STEEL FRAMES WITH ECCENTRIC BRACING SUBJECTED TO SEISMIC SEQUENCES.

Abstract

ABSTRACT

In areas of high seismicity, the structures in addition to resisting major seismic events, may be subjected to aftershocks and subsequent events; for this reason, it is important to analyze the behavior of structures subjected to seismic sequences. In this paper presents the results of static and dynamic nonlinear analyses of different steel frames with eccentric bracing two-dimensional modeling; were analysed porticoes of two to five regular levels in elevation with mezzanines slabs deck. The different analyses were carried out with spectra and scaled earthquakes considering the regulations in force in Ecuador with return periods of 475 years in soils characteristic of Portoviejo city type D and E, the spectrum of local seismic microzoning was also considered. The simulation of seismic aftershocks or sequences in static nonlinear pushover analysis consisted of the addition of displacements and in nonlinear dynamic time-history analysis, the aftershock separates several seconds after the main quake. The behavior in the elastic range of the structural members of the frames was determined, but the links presented variations in the inelastic range in the face of seismic aftershocks; varying the provisions of the steel construction regulations in force in the United States (ANSI/AISC 341); in terms of the functioning of this type of structural system.