000019719 001__ 19719
000019719 005__ 20170118182333.0
000019719 04107 $$aeng
000019719 046__ $$k2017-01-09
000019719 100__ $$aFavero, Francesco Del
000019719 24500 $$aNonlinear Dynamic Analysis of In-Plan Irregular R.C. Structures Retrofitted With Hysteretic Damped Braces

000019719 24630 $$n16.$$pProceedings of the 16th World Conference on Earthquake Engineering
000019719 260__ $$b
000019719 506__ $$arestricted
000019719 520__ $$2eng$$aThe seismic retrofitting of unsymmetric plan reinforced concrete (r.c.) framed buildings can be carried out by the insertion of damped braces (DBs), which are made of steel braces connecting two consecutive storeys and incorporating energy dissipating devices. Yet most of the proposals to mitigate the seismic response of asymmetric framed buildings by DBs rest on the hypothesis of elastic (linear) structural behaviour. The aim of the present work is to evaluate the effectiveness and reliability of a Displacement-Based Design procedure of hysteretic damped braces (HYDBs) based on the nonlinear behaviour of the frame members. An expression of the biaxial viscous damping equivalent to the hysteretic energy dissipated by the damped braced frame is assumed under bidirectional seismic loads, where corrective factors are adopted as a function of design parameters of the HYDBs. Moreover, the extended N2 method considered by Eurocode 8, which combines the nonlinear static analysis along the principal in-plan directions of the structure with elastic modal analysis, is adopted to evaluate the higher mode torsional effects. To this end, the Town Hall of Spilinga (Italy), a reinforced concrete framed structure with an L-shaped plan built at the beginning of the 1960s, is supposed to be retrofitted with HYDBs to attain performance levels imposed by the Italian seismic code (NTC08) in a high-risk zone. Ten structural solutions are compared by considering two alternative in-plan distributions of the HYDBs, to eliminate (elastic) torsional effects, and different design values of the frame ductility combined with a constant design value of the damper ductility. Reinforced concrete (r.c.) structures with asymmetric plan may require the assessment of the critical incident angle of bidirectional ground motions. To this end, a computer code for the nonlinear dynamic analysis of r.c. spatial framed structures is adopted. Frame members are simulated with a lumped plasticity model, including flat surface modelling of the axial load-biaxial bending moment elastic domain, at the end sections of r.c. beams and columns where inelastic deformations generally occur, while a bilinear law is used to idealize the behaviour of a HYDB. Vulnerability index domains of r.c. frame members and HYDBs are adopted to estimate the directions of least seismic capacity, considering artificial ground motions whose response spectra match those adopted by NTC08 at serviceability and ultimate limit states.

000019719 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000019719 653__ $$aUnsymmetric-plan framed structures; equivalent biaxial viscous damping; extended N2 method; hysteretic dampers; displacement-based design; nonlinear dynamic analysis.

000019719 7112_ $$a16th World Conference on Earthquake Engineering$$cSantiago (CL)$$d2017-01-09 / 2017-01-13$$gWCEE16
000019719 720__ $$aFavero, Francesco Del$$iPedace, Emilia$$iMazza, Fabio
000019719 8560_ $$ffischerc@itam.cas.cz
000019719 8564_ $$s1293552$$uhttps://invenio.itam.cas.cz/record/19719/files/424.pdf$$yOriginal version of the author's contribution as presented on USB, paper 424.
000019719 962__ $$r16048
000019719 980__ $$aPAPER