Drift Capacity of Reinforced Concrete Columns with Light Transverse Reinforcement

Abstract

Existing reinforced concrete columns with light transverse reinforcement are vulnerable to shear failure during seismic response. Shear strength models, modeling the degradation of shear strength with increasing displacement ductility demand, have been widely used to evaluate the interstory drift capacity of such columns. The application of a shear strength model to determine the drift capacities for a database of 50 shear-critical columns demonstrates significant inaccuracies with such a method. An empirical drift capacity model based on the shear-critical column database provides a better estimate of the interstory drift at shear failure. The new drift capacity model identifies the most critical parameters affecting the drift capacity of shear-critical columns, namely, transverse reinforcement ratio, shear stress demand, and axial load ratio.

Criterio columna fuerte viga débil en edificios de baja altura

“…El modelo de Elwood y Moehle [9] que se muestra en la Ec. (3) controla en ambos casos el criterio de máxima deformación.…”

“…▪ Modelo de Elwood y Moehle [9], para estimar la deriva para la que se inicia la degradación por cortante en columnas de hormigón armado: donde D es la deformación de entre piso, L la longitud libre de la columna, tm es la relación de refuerzo transversal, v es el esfuerzo de corte, f c m es la resistencia a compresión del hormigón, P es la carga axial que soporta la columna, Ag es el área gruesa de la sección de la columna, i es el ángulo de la fisura crítica, s es la separación entre estribos, Ast es el área de los estribos, fyt es la resistencia a la fluencia del acero del estribo y dc es la profundidad del núcleo confinado. Con estos criterios de colapso, se supone que la falla de una columna implica el colapso de la estructura completa, suposición que resulta conservadora pues se han observado fallas de columnas en edificios de pórticos de hormigón que no generan un colapso global de la estructura [12,13].…”

The influence of coupled horizontal–vertical ground excitations on the collapse margins of modern RC-MRFs

“…8). In case the columns are vulnerable to shear failure after flexural yielding, then the drift capacity model proposed by Elwood and Moehle (2005) can be utilized to define the accurate limit curve. Other shear failure criterion such as plastic rotation at the two ends of the column is also proposed by LeBorgne (2012).…”

An Empirical-Based Approach for Modeling and Assessment of Rc Columns With Plain Bars

“…These drift limits were used to model the shear-controlled response of RC elements (subjected to flexure-shear failure mode) in [14], by means of a modeling approach based on the use of the "limit state" material in OpenSees [15]. Aslani and Miranda [16] re-evaluated and simplified the formulations by Elwood and Moehle [12] [13]. Zhu et al [17] proposed a procedure for failure mode classification and, accordingly, empirical formulations for the prediction of drift capacity (at 20% strength drop) for columns failing in flexure or in shear/flexure-shear, and for the prediction of the drift capacity at axial failure of shear-controlled columns.…”

“…In the last years, several studies by Elwood and co-workers are focusing on the deformation capacity of existing non-ductile RC elements. Elwood and Moehle [12] [13] proposed empirical formulations providing the drift at "collapse" (20% strength drop) and at "axial failure" (loss of vertical load-carrying capacity) of RC columns failing in shear following flexural yielding. These drift limits were used to model the shear-controlled response of RC elements (subjected to flexure-shear failure mode) in [14], by means of a modeling approach based on the use of the "limit state" material in OpenSees [15].…”