Critical regions of RC primary elements detailed in according to provisions rules for curvature ductility: comparisons and numerical analyses

In moment resisting frames beams and columns are designed for flexural, axial, and shear actions due to vertical and horizontal loads. Special proportioning and detailing requirements are applied in these elements for making them capable of resisting against severe earthquakes without significant loss of strength beyond the flexural elastic limit, and avoiding brittle failure (shear mechanisms). As known, the required flexural inelastic excursions (expressed by the local ductility demand) depend on the dissipative capacity of the structure. The flexural ductility significantly increases with the transverse reinforcement amount provided to confine section core and to prevent buckling of compressed longitudinal bars. In this paper detailing provisions adopted by some seismic codes are compared. At first, the codes provisions to be applied within critical regions of RC primary frames sections are discussed and compared as a function of the curvature ductility demand. Then, non-linear monotonic moment-curvature analyses are performed on fiber sections of columns and beams, and by taking into account the confinement effects on concrete core as well. The numerical investigations are carried out for comparing the available curvature ductility with the expected one applying the provisions mentioned by the seismic codes

Comparisons of Codal Detailing Rules for Curvature Ductility and Numerical Investigations

In moment resisting frame structures special detailing rules are applied to critical regions of primary columns and beams to ensure adequate curvature ductility. This is necessary for dissipating earthquake energy through hysteretical behavior of critical regions where inelastic flexural excursions occur. In this paper codal detailing rules for designing longitudinal and transverse reinforcement of primary elements as function of curvature ductility are assessed. Four seismic codes are considered: Italian code, New Zealand code, Eurocode 8 and American code. Non-linear monotonic moment-curvature analyses are performed on some sections of columns and beams detailed in according to the considered codal provisions. In the analyses the confinement effects within the concrete core have been taken into account as well. The paper concludes comparing the measured curvature ductility of the studied sections with the expected one by the codal pro- visions within the critical regions

Analytical cyclic constitutive model for confined concrete implementation in OpenSees: ConfinedConcrete02

This paper presents the new material developed inside the OpenSees by considering constitute modelfor the concrete subjected to revere cycling and monotonic loading. The new material intended toprovide the ability of model the cyclic behaviour of concrete subjected to compression in thecomputational programme. The analytical formulation proposed by the Braga, Gigliotti and Laterza(BGL model, 2006) is used for the envelope and reverse (loading and reloading) action of the materialgovern by the Yassin (1994) approach, which is given bilinear curve for unloading and loading. The lateral confinement of concrete enhances the strength and durability of the reinforcement concretesignificantly. Introducing this uniaxial material inside the OpenSees is capable to model the influenceof transverse hoops, ties and/or FRP, external wrapping with the section considered. Many numbers ofgreat researches have been conducted to understand the real compressive and tension behaviour of thereinforced concrete based on the experimental programme and analytical formulations. Research oncycling response of concrete is becoming a challenge of the earthquake engineering for modelling andcapable prediction of hysteretic characters of the reinforced concrete. This research work is devoted todevelop the computational methods to model and analyse the reinforced concrete structures subjectedto revere cycling specially by applying the confinement influence to section (Beam, column or jointpanel