Uniaxial Confinement Model for Normal- and High-Strength Concrete Columns

Finite Element Analysis of the Behaviour of Reinforced Concrete Columns Confined by Overlapping Hoops Subjected to Rapid Concentric Loading

“…To consider the strain rate sensitivity of concrete, the dynamic compressive cylinder strength fcd of concrete can be estimated from Equations 1 and 2 provided by CEB-FIP Model Code 1990 [1]. where fcs is the quasi-static compressive strength of unconfined concrete; fcs=0.85fc considering a strength-reduction factor related to the column shape, size and the difference between the strength of in situ concrete and the strength determined from standard cylinder tests [22][23];  is the strain rate (s -1 ); fc0=10 Mpa; and cs  =30×10 -6 s -1 . fcd increases with increasing strain rate; the other parameters in the following uniaxial compressive stress-strain curve correspondingly change, and the dynamic uniaxial compressive stress-strain curve is formed.…”

“…fh was proposed by Le´geron and Paultre [23] as follows: where s and c (as shown in Figure 4, c=cx=cy) are the spacing of transverse reinforcement and diameter of the core measured centre-to-centre of the hoops, respectively; Ash is the total area of transverse bars in the x or y direction and is defined as 3.41 and 3.61 times the cross-section area of a single tie leg for the type-A and type-B configurations in Table 1, respectively [24]; Es and c are the modulus of elasticity of transverse reinforcement and the axial strain, which corresponds to the concrete cylinder strength, respectively; and ke is the geometrical effectiveness coefficient of confinement, which represents the ratio of the smallest effectively confined concrete area at midway between two layers of stirrups to the nominal concrete core area. ke was proposed by Mander et al [25] as follows: (11) where wi is the ith clear distance between adjacent longitudinal bars (as shown in Figure 4); s is the clear spacing of transverse reinforcement; c is the ratio of the area of longitudinal steel to the area of the core of the section; and cx and cy are the core dimensions to centrelines of the perimeter hoop in the x and y directions, respectively.…”

“…Based on the expression of cc50 proposed by Le´geron and Paultre [23], the modified expression of cc50 is [26] Article no. 42 Uniaxial compression stress-strain relations of cover concrete considering the strain rate effect…”

Estudio Experimental Y Numérico De La Capacidad De Deformación De Soportes Esbeltos De Hormigón Armado

“…En elementos sometidos a flexo-compresión, el efecto de la armadura transversal en la capacidad de deformación ha sido ampliamente estudiado, tanto teórica como experimentalmente (Priestley y Park (1987) [110], Légeron y Paultre (2003) [79],En realidad, el comportamiento dúctil de los soportes depende de la interacción de diferentes variables, como, por ejemplo, el nivel de carga axial, la esbeltez geométrica, la resistencia del hormigón y el confinamiento transversal, entre otros. En lo que respecta a la cuantía de armadura transversal, los estudios realizados por Mendis et al [91], [92], y Legeron y Paultre [78], [79] han destacado la necesidad de incluir el nivel de carga axial como parámetro indispensable en el cálculo de la cuantía de armadura transversal necesaria para garantizar un adecuado confinamiento del elemento y una apropiada ductilidad.…”

“…En lo que respecta a la cuantía de armadura transversal, los estudios realizados por Mendis et al [91], [92], y Legeron y Paultre [78], [79] han destacado la necesidad de incluir el nivel de carga axial como parámetro indispensable en el cálculo de la cuantía de armadura transversal necesaria para garantizar un adecuado confinamiento del elemento y una apropiada ductilidad. Dicho parámetro ya ha sido…”