MODELING AND DESIGN OPTIONS FOR REINFORCED CONCRETE DUAL WALL-FRAME BUILDINGS

This study assesses the influence of two issues that are relevant to the seismic design and analysis of reinforced concrete dual wall-frame buildings. The first issue is the inclusion of special boundary elements (SBEs) in shear walls. In Chile, SBEs became mandatory in some cases after the 2010 earthquake, but to the best of the authors’ knowledge, the actual contribution of the SBEs to the seismic performance of dual wall-frame buildings is still largely unknown. SBEs intend to provide more ductility, but whether such objective is achieved or not remains unclear. The second issue is the explicit incorporation of the slabs in full 3D nonlinear models of dual wall-frame buildings. Since slab spans are typically large in dual wall-frame buildings, they are sometimes not included in analytical models to alleviate the computational burden. However, detailed studies on whether inclusion of the slabs is actually necessary or not seem to be absent in the literature, particularly on dual wall-frame buildings. These issues are assessed by evaluating different analytical models of a representative dual wall-frame building (16 stories plus 3 underground levels). The models were developed in Perform3D. The models account for different number of stories with SBEs (from 0 to 5) and different values of the effective flexural stiffness of the slabs (from 0% to 100% of the gross cross-section stiffness). The models were subjected to a set of subduction ground motions recorded in Chile, carefully selected, and scaled based on a detailed probabilistic seismic hazard analysis at the building site. The seismic behaviour of the models is evaluated in terms of collapse fragility curves and collapse probabilities in 50 years. Other response parameters, such as the location and extension of inelastic deformations in the shear walls, are also evaluated.