Performance of torsionally eccentric RC wall frame buildings designed to DDBD under bi-directional seismic excitation

The seismic performance of a class of reinforced concrete eccentric wall frame buildings under bi-directional ground motion excitation is investigated. For this purpose, four and eight-storey RC buildings comprising structural walls, flat-plates and gravity columns, having different strength and stiffness eccentricity and torsional restrain, are designed in accordance with the Direct Displacement Based Design (DDBD) method for damage control. The structures are analysed under static and dynamic inelastic response, considering ten ground motion record pairs, three intensity levels and different angles of incidence. Several global and local engineering demand parameters, namely, inter-storey drift, slab rotation, member plastic rotations and wall internal forces are evaluated and compared with the DDBD limits. It is shown that ground motion directionality effects are small, and the average drift and wall moment profiles are within DDBD predictions and, often, considerably lower than DDBD demanded. However, wall shear force and local inelastic demands are underpredicted by both DDBD and static inelastic analyses and, more significantly so, for the torsionally flexible structures.