Nonlinear modeling of a RC beam-column connection subjected to cyclic loading

Norberto Dominguez,Jesús Pérez-Mota 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.3

When reinforced concrete structures are subjected to strong seismic forces, their beam-column connections are very susceptible to be damaged during the earthquake event. Consequently, structural designers try to fit an important quantity of steel reinforcement inside the connection, complicating its construction without a clear justification for this. The aim of this work is to evaluate –and demonstrate- numerically how the quantity and the array of the internal steel reinforcement influences on the nonlinear response of the RC beam-column connection. For this, two specimens (extracted from an experimental test of 12 RC beam-column connections reported in literature) were modeled in the Finite Element code FEAP considering different stirrup’s arrays. The nonlinear response of the RC beam-column connection is evaluated taking into account the nonlinear thermodynamic behavior of each component: a damage model is used for concrete; a classical plasticity model is adopted for steel reinforcement; the steel-concrete bonding is considered perfect without degradation. At the end, the experimental responses obtained in the tests are compared to the numerical results, as well as the distribution of shear stresses and damage inside the concrete core of the beam-column connection, which are analyzed for a low and high state of confinement.

Coupling of nonlinear models for steel-concrete interaction in structural RC joints

Dominguez, Norberto,Perez-Mota, Jesus Techno-Press 2014 Coupled systems mechanics Vol.3 No.2

When strong seismic forces act on reinforced concrete structures, their beam-column connections are very susceptible to damage during the earthquake event. The aim of this numerical work is to evaluate the influence of the internal steel reinforcement array on the nonlinear response of a RC beam-column connection when it is subjected to strong cyclic loading -as a seismic load. For this, two specimens (extracted from an experimental test of 12 RC beam-column connections reported in literature) were modeled in the Finite Element code FEAP considering different stirrup's arrays. In order to evaluate the nonlinear response of the RC beam-column connection, the 2D model takes into account the nonlinear thermodynamic behavior of each component: for concrete, a damage model is used; for steel reinforcement, it is adopted a classical plasticity model; in the case of the steel-concrete bonding, this one is considered perfect without degradation. At the end, we show a comparison between the experimental test's responses and the numerical results, which includes the distribution of shear stresses and damage inside the concrete core of the beam-column connection; in the other hand, the effects on the connection of a low and high state of confinement are analyzed for all cases.

Numerical formulation of a new solid-layer finite element to simulate reinforced concrete structures strengthened by over-coating

Suarez-Suarez, Arturo,Dominguez-Ramírez, Norberto,Susarrey-Huerta, Orlando Techno-Press 2022 Coupled systems mechanics Vol.11 No.5

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-Of-Freedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

Numerical formulation solid-layer finite element to simulate reinforced concrete structures strengthened by over-coating

Arturo Suarez-Suarez,Norberto Dominguez-Ramirez,Orlando Susarrey-Huerta Techno-Press 2023 Coupled systems mechanics Vol.12 No.6

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-OfFreedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

Viscoelastic behavior of concrete structures subject to earthquake

Mejia-Nava, Rosa Adela,Ibrahimbegovic, Adnan,Dominguez-Ramirez, Norberto,Flores-Mendez, Esteban Techno-Press 2021 Coupled systems mechanics Vol.10 No.3

This paper investigates an alternative way to the Raleigh formula to catch con- tributions of damping effects. Nowadays, thanks to the power of new software and effi- cient computational methods, there exist possibility to implement new analysis of damping through multiscale approach. The corresponding homogenization of a representative elemen-tal volume of concrete is used to calculate the effective properties of the composite, since energy dissipation properties such as viscoelasticity are not taken into account. At the end of this work, these methodologies are incorporated into a column of a building subject to seismic action. More precisely, with concrete as a composite material (aggregate+cement), we can use homogenization methods to calculate its effective properties by using the classical approach of a representative elemental volume. This can help to take into account properties of energy dissipation, such as produced by viscoelasticity. Finally, for illustration, the pro- posed methodology is applied to structural analysis of a column under the most unfavorable conditions in a building subject to earthquake action.