The design of coupled frame-wall structures for seismic actions

A methodology for the design of reinforced concrete frame-wall structures for seismic resistance is presented. By using capacity design principles, plasticity is restricted to well detailed beam and wall base hinge zones where energy is expected to be dissipated primarily via the flexural yielding. Numerous inelastic time history analyses, simulating earthquake attacks, were performed for simplified 6 and 12 storey buildings. Major variables examined included relative frame:wall stiffness, wall base fixity and wall: frame height. Response to the NS El Centro 1940 accelerogram indicated the likelihood of very satisfactory seismic response for prototype structures. Member actions were able to be estimated with good accuracy although the dynamic magnification of wall base shear forces is viewed with concern. Complementary to the analytical study, four approximately 1/3 scale model cantilever structural wall units were tested under a regime of cyclic lateral loading. The units exhibited very good hysteretic behaviour prior to failure via out of plane buckling or material compression failure accelerated by the former mode of response. Features of behaviour of wall sections with large concrete compression strains and lateral instability were the major targets of study in these experiments. Recommendations are made regarding confining hoop reinforcement and dimensional limitations for the plastic hinge zones of structural walls.