Tapia-Hernández, Edgar

Behavior of Eccentrically Braced Steel Frames of Regular Buildings in Soft Soils

Abstract eng:
Results of nonlinear analyses of 6- and 9-stories regular buildings structured with moment-resisting eccentrically braced steel frames are discussed in this paper. Models were designed following the capacity design principle for a seismic modification factor Q= 4.0, the maximum allowed for these structures, according to the Mexico City Building Code. Nonlinear pushover and dynamic analyses were performed in 3D in OpenSees and were supposed located in soft soil site condition (Mexico City’s lake-bed zone). Dynamic analyses were performed under ten historical records related to the considered design spectra. For this purposes, a detailed model in OpenSees with material and geometrical non-linearities was developed. Nonlinear beam-column elements, with plasticity spread along the element length, were considered for the link beam elements, beam segments outside of the shear links, braces and columns; and a detailed model of the connection at the ends of link elements with springs was considered. A quadratic perturbation shape was used to define the initial camber in the bracing system and an out-of-plumbness of columns was also considered as imperfections in the locations of points of intersection of elements. Through 1,756 certified laboratory coupons test of steel samples a better reference of the actual yielding steel stress was included in order to evaluate the material overstrength capacity at the local market. According to the results, the overall response of the structure was governed by the maximum link rotations by interstory. Top stories reported practically an elastic behavior, whereas peak story drifts were developed at the middle stories, driving potential weak stories under static and dynamic inelastic analyses. Median link rotations went beyond the code limit (0.08 rad). A magnitude of the rotation link capacity is proposed in order to better predict the seismic response, which is based on a statistical study of results of experimental tests with respect to the beam link cross-section. A slight relationship among ductility and building height was noticed.

Contributors:

García-Carrera, Salvador

Conference Title:

Proceedings of the 16th World Conference on Earthquake Engineering

Conference Title:

16th World Conference on Earthquake Engineering

Conference Venue:

Santiago (CL)

Conference Dates:

2017-01-09 / 2017-01-13

Rights:

Text je chráněný podle autorského zákona č. 121/2000 Sb.