The inelastic seismic responses of plan asymmetric multi-storey reinforced concrete moment-resisting frames stiffened with ductile reinforced concrete structural walls have been investigated under bi-directional far-field and near-field ground motions. Asymmetric models were created by adding shear walls in two orthogonal directions of some symmetric frames developed using the generic structures algorithm. A realistic modelling of the non-linear ductile behaviour of reinforced concrete elements was utilised in combination with both mass and stiffness eccentricities in dynamic torsional response of asymmetric buildings. The torsional responses of models including the ductility demands for both stiff and flexible edge elements including shear walls and columns were normalised to the corresponding values of the symmetric models. The distribution of normalised ductility demands along the height of structures was used to assess the torsional effects in multi-storey structures. It was also shown that for dual lateral load-resistant systems, columns at the corners of flexible sides demand more ductility compared with similar frame systems.

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This study aims to evaluate the torsional effects and soil-structure interaction simultaneously under near-fault pulse-like earthquakes in a probabilistic framework. Incremental dynamic analysis and fragility curves are employed for this goal. An eight-story R/C dual lateral load-resistant building consisting of shear walls and moment resisting frames is used. The median incremental dynamic analysis curves reported the maximum capacity for the symmetric structure in each foundation conditions. In addition, the capacity of structure will be increased when more shear wave velocity is assumed. Therefore, from this view, neglecting the soil-structure interaction will not be in the safe side. Fragility curves (using intensity measure directly) show that for different cases (except for very low shear wave velocity), more value of eccentricity leads to more probability of collapse. Moreover, the fragility curves show that (for each eccentricity), soil-structure interaction effect is significant only for the flexible base structure with the very low shear wave velocity (100 m/s) and more eccentricity value leads to less soil-structure interaction effects. Results show that the significant eccentricity value may lead to reduce the soil-structure interaction effect in the shear-wall structures under the near-fault events.

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