@conference {686, title = {RC members in cyclic loading: strength, deformation capacity, failure modes}, booktitle = {8th International Conference on Analytical Models and New Concepts in Concrete and Masonry Structures AMCM 2014}, year = {2014}, address = {Wroc{\l}aw, Poland}, abstract = {

A portfolio of simple, practical models is presented for a) the resistance of a RC member in flexure or shear under cyclic loading; b) its deformation at flexural yielding and its secant-to-yield-point stiffness; and c) the member ultimate deformation in flexure or shear under cyclic loading. They are based on a databank of several thousand tests of RC members - the largest in the world. They cover beams, rectangular columns or walls, members with circular, T-, H-, U- or hollow rectangular section, with or without detailing for earthquake resistance, with bars ribbed or smooth, continuous or lap-spliced in the plastic hinge. Most of the models, or earlier versions based on a smaller data-bank, were adopted in Eurocode 8-Part 3 and/or fib MC2010, for performance- and displacement-based seismic design, assessment or retrofitting. So, the paper serves as a background document for the models adopted in these codes, improving and extending them, or presenting new ones.

}, author = {Fardis, MN and Biskinis, D and Grammatikou, S} } @article {687, title = {Residual displacements of RC structures as SDOF systems}, journal = {Earthquake Engineering and Structural Dynamics}, volume = {44}, year = {2014}, pages = {713-734}, abstract = {

Residual displacements are sensitive to ground motion details, hence more random than peak inelastic displacements. Among the factors with systematic impact on residual displacements, the post-yield-stiffness-ratio has been studied thoroughly; its effects are not investigated further. Concerning another important factor, the hysteresis law, past studies have focused on the bilinear model, which does not represent concrete structures. Residual displacements from nonlinear response-history analyses of bilinear systems are compared to those from models tuned to concrete structures, conforming to modern codes, deficient or intermediate. Deficient-type structures, with their narrow, almost self-centering hysteresis loops, develop markedly smaller residual displacements than those with stable energy-dissipating behavior. A velocity pulse in the motion increases peak inelastic and residual displacements by about the same proportion. As a fraction of the peak inelastic or spectral displacement, residual displacements are on average almost independent of the period and increase when the lateral strength ratio increases, reaching a limit at a lateral strength ratio of 2 to 5. Peak inelastic displacements are a better basis for estimation of residual displacements than spectral ones: the ratio of the two is almost independent of the period, the lateral strength ratio (beyond values of 2 to 3) and velocity pulses. The spectrum of the ratio of residual displacement to peak inelastic or spectral displacement is considered as a random process of period; its mean and variance functions, marginal probability distributions and autocorrelation functions are given in terms of the lateral strength ratio, the hysteresis model and the presence of a velocity pulse.

}, keywords = {concrete structures, hysteresis models, permanent seismic displacements, pulse-type ground motion, residual seismic displacements, seismic response spectra}, doi = {DOI: 10.1002/eqe.2483}, url = {http://onlinelibrary.wiley.com/doi/10.1002/eqe.2483/abstract}, author = {Liossatou, Ε and Fardis, MN} }