The influence of the concrete cyclic laws on the dynamic response of slender RC walls

The cyclic laws for dynamic analyses of reinforced concrete (RC) structures usually neglect the concrete traction strength and the re-loading branch from traction to compression. These assumptions may lead to unreal results in cyclic or dynamics analyses. For example, flag-shaped moment-curvature diagrams of slender RC walls are presented. For this reason, the behaviour of concrete in cyclic tension, determined by Reinhardt et al. (1986,1989) and modified by Ferracuti and Savoia (2005), is added to an existing cyclic stress-strain law. Making use of the finite element (FE) software OpenSees, the resulting concrete law is firstly validated by simulating experimental tests on RC cantilever beams cyclically loaded. Then, slender RC walls in multi-storey buildings are considered and dynamic analyses are done. Moment-curvature curves at base sections are obtained, together with force and displacement envelopes. The results obtained with the implemented law are compared against the ones obtained with a common law. Results show that concrete reloading behaviour from tension to compression affects significantly the walls designed for a larger response in the inelastic field.