000019942 001__ 19942
000019942 005__ 20170118182347.0
000019942 04107 $$aeng
000019942 046__ $$k2017-01-09
000019942 100__ $$aMazza, Mirko
000019942 24500 $$aNonlinear Seismic Response of Irregularly Masonry-Infilled R.C. Framed Buildings Retrofitted With Hysteretic Damped Braces

000019942 24630 $$n16.$$pProceedings of the 16th World Conference on Earthquake Engineering
000019942 260__ $$b
000019942 506__ $$arestricted
000019942 520__ $$2eng$$aAn irregular in-elevation distribution of the infill walls in a reinforced concrete (r.c.) framed building can produce significant variations in stiffness, strength and mass distribution leading to severe seismic damage. To mitigate these effects and retrofit the structure, hysteretic damped braces (HYDBs) can be suitably inserted in the framed structure. The retrofitting criteria are aimed to obtain a damped braced structure globally regular with regard to stiffness and strength. In detail, the stiffness distribution of HYDBs is evaluated consistently with a constant value of the drift ratio of the damped braced frame along the building height; moreover, the strength distribution of the HYDBs is assumed so that their activation tends to occur at every storey simultaneously, before reaching the shear resistance of the infilled framed structure. For proportioning the HYDBs, a Displacement-Based Design (DBD) procedure, in which the design starts from a target deformation of an equivalent elastic linear system, is adopted in the present work. To check the effectiveness and reliability of the DBD procedure, a numerical investigation is carried out with reference to a six-storey r.c. framed building, which, originally designed according to an old Italian seismic code (1996) for a medium-risk zone, has to be retrofitted by inserting of HYDBs to attain performance levels imposed by the current Italian code (NTC 2008) in a high-risk zone. It is supposed that the irregularity is consequent to a change in use of the first two floors, from residential to office, substituting the masonry infills of the first three storeys with glass windows. Nonlinear dynamic analyses of the unbraced, irregularly infilled and damped braced infilled frames are carried out by a step-by-step procedure, considering sets of artificially generated and real ground motions, whose response spectra match those adopted by NTC 2008 for different performance levels. To this end, r.c. frame members are idealized by a two-component model, assuming a bilinear moment-curvature law and considering the effect of the axial load on the ultimate bending moment of the columns. The response of an HYDB is idealized by a bilinear law, preventing buckling. Finally, masonry infills are represented as equivalent diagonal struts reacting only in compression according to an elastic-brittle law. Even though more refined analytical models can be used to simulate the hysteretic response of r.c. members and infill walls, the design procedure prove to be effective in the mitigation of the effects of the in-elevation irregular distribution of the infill walls.

000019942 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000019942 653__ $$aIrregularly infilled r.c. framed buildings; Seismic retrofitting; Hysteretic damped braces; Displacement-Based Design; Nonlinear dynamic analysis.

000019942 7112_ $$a16th World Conference on Earthquake Engineering$$cSantiago (CL)$$d2017-01-09 / 2017-01-13$$gWCEE16
000019942 720__ $$aMazza, Mirko$$iVulcano, Alfonso$$iMazza, Fabio
000019942 8560_ $$ffischerc@itam.cas.cz
000019942 8564_ $$s734116$$uhttps://invenio.itam.cas.cz/record/19942/files/476.pdf$$yOriginal version of the author's contribution as presented on USB, paper 476.
000019942 962__ $$r16048
000019942 980__ $$aPAPER