Abstract

HERNANDEZ GARCIA, Daniel Alberto  and  TENA COLUNGA, Arturo. Parametric study of representative models of structures prone to develop soft or weak stories subjected to ground motions typical of soft soils. Ing. sísm [online]. 2016, n.95, pp.53-80. ISSN 0185-092X.

A parametric study where two-degree of freedom (2DOF) simplified models are used to represent structures likely to develop soft or weak stories is presented. Different stiffness and strength balances were considered to define a realistic range of structures with the potential to develop soft story mechanisms according to recommendations of current seismic building codes. Therefore, 338 models were studied for all the considered stiffness and strength combinations which represent typical buildings structures with soft or weak stories currently built in the lakebed zone of Mexico City. Step by step nonlinear dynamic analyses were conducted using 10 artificial acceleration records generated to be compatible with the design spectrum for zone III-a of 2004 Mexico´s Federal District Code, corresponding to soft soil conditions in Mexico City. Peak ductility demands and story drifts were obtained, which were compared with some reference value currently proposed in building codes. The results obtained from this parametric study mostly confirm that a soft story mechanism is triggered or prevented with a right combination of strength and stiffness balances for the structural system, which are close to what it is currently proposed in Mexican seismic building codes.

Keywords : soft story; weak story; stiffness and strength balances; ductility demands; story drifts; nonlinear dynamic analyses; soft soil acceleration records.

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