Collapse of a nonductile concrete frame: Shaking table tests

Abstract

Post-earthquake reconnaissance has reported the vulnerability of older reinforced concrete (RC) columns lacking details for ductile response. Research was undertaken to investigate the full-range structural hysteretic behavior of older RC columns. A two-dimensional specimen frame, composed of nonductile and ductile columns to allow for load redistribution, was subjected to a unidirectional base motion on a shaking table until global collapse was observed. The test demonstrates two types of column failure, including flexure-shear and pure flexural failure. Test data are compared with various simplified assessment models commonly used by practicing engineers and researchers to identify older buildings that are at high risk of structural collapse during severe earthquake events. Comparison suggests that ASCE/SEI 41-06 produces very conservative estimates on load-deformation relations of flexure-shear columns, while the recently proposed ASCE/SEI 41-06 update imposes significant modifications on the predictive curve, so that improved accuracy has been achieved.

Collapse of a nonductile concrete frame: Evaluation of analytical models

“…For the analysis described herein, the median drift capacity models developed by Zhu et al [11] were used to determine the point of shear or axial failure. (The median drift capacity models by Zhu et al [11] were presented in the companion paper [2].) Figure 2 illustrates how the shear spring influences the total lateral behavior of the nonductile column.…”

“…Elwood and Moehle [1] conducted planar shaking table tests on a three-column frame to investigate the failure of existing concrete columns and the redistribution of gravity loads during collapse. With similar goals, a shaking table test on a three-bay single story frame with two ductile and two nonductile columns was undertaken at the National Centre for Research on Earthquake Engineering (NCREE) in Taiwan in 2005 [2]. Kabeyasawa et al [3] and Shirai et al [4] have investigated the seismic response up to the stage of collapse for full-scale reinforced concrete buildings on the E-Defense shaking table in Japan.…”

“…The purpose of this study is to evaluate the ability of selected nonlinear models to adequately simulate the behavior of the reinforced concrete frame tested at NCREE [2]. Evaluation of analytical models using results from dynamic tests is more beneficial, and yet more challenging, compared with static tests.…”

“…The test was designed to observe the process of shear and axial-load failure in reinforced concrete columns and the subsequent load redistribution when subjected to ground shaking. The specifications of the specimen and test observations were described in a companion paper by Wu et al [2]. In the current study, empirical drift capacity models are used to predict the hysteretic response of the nonductile reinforced concrete columns subjected to gravity and seismic loading.…”

Seismic damage assessment and FRP retrofit of reinforced concrete structures

“…Many studies have been undertaken to improve the behaviour and response of these structures. Numerous experiments have been performed on columns [41,[123][124][125] and structural frames [126][127][128][129][130][131]. More recent studies focused on developing a better understanding of structural behaviour so that strengthening strategies can be devised as needed.…”