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Analytical investigations of seismic responses for reinforced concrete bridge columns subjected to strong near-fault ground motionChin-Kuo Su (ËÕ½ø¹ú);Yu-Chi Sung (ËÎÔ£ì÷); Shuenn-Yih Chang (ÕÅ˳Òæ) and Chao-Hsun Huang (»ÆÕÑÑ«) Dept. of Civil Engineering, Taipei University of Technology, Chinese Taipei Abstract:
Strong near-fault ground motion, usually caused by the fault-rupture and
characterized by a pulse-like velocity-wave form, often causes dramatic
instantaneous seismic energy (Jadhav and Jangid 2006). Some reinforced concrete
(RC) bridge columns, even those built according to ductile design principles,
were damaged in the 1999 Chi-Chi earthquake. Thus, it is very important to
evaluate the seismic response of a RC bridge column to improve its seismic
design and prevent future damage. Nonlinear time history analysis using
step-by-step integration is capable of tracing the dynamic response of a
structure during the entire vibration period and is able to accommodate the
pulsing wave form. However, the accuracy of the numerical results is very
sensitive to the modeling of the nonlinear load-deformation relationship of the
structural member. FEMA 273 and ATC-40 provide the modeling parameters for
structural nonlinear analyses of RC beams and RC columns. They use three
parameters to define the plastic rotation angles and a residual strength ratio
to describe the nonlinear load-deformation relationship of an RC member.
Structural nonlinear analyses are performed based on these parameters. This
method provides a convenient way to obtain the nonlinear seismic responses of RC
structures. However, the accuracy of the numerical solutions might be further
improved. For this purpose, results from a previous study on modeling of the
static pushover analyses for RC bridge columns (Sung et al. 2005) is adopted for
the nonlinear time history analysis presented herein to evaluate the structural
responses excited by a near-fault ground motion. To ensure the reliability of
this approach, the numerical results were compared to experimental results. The
results confirm that the proposed approach is valid.
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