TY - THES
AU - Lara, Otton
PY - 2011
TI - The flexural seismic resistant design of reinforced concrete bridge columns
KW - Thesis/Dissertation
LA - eng
M3 - Text
AB - Experimental studies about the cyclic response of reinforced concrete bridge columns designed
to avoid shear failure and subjected to cyclic, reversible, and increasing displacements have been
performed in several laboratories around the world. As a consequence there are several force-displacement relationships, called resultant models, that allow to predict the response of those
columns. However, the use of the resultant models for earthquake response requires extensive
calibration of several parameters.
In this investigation a Finite Fiber Element Model, FFEM, is obtained after calibrating first, the
response of 30 circular reinforced concrete bridge columns tested under cyclic, reversible, and
increasing displacements. Then a re-calibration is carried out in order to simulate the response of
two additional columns shake table tested under two earthquake ground motions. After obtaining
satisfactory results the FFEM was used to simulate the seismic response of three bridge columns
designed according to the prescriptions of the new seismic design bridge code.
The FFEM is able to predict directly four flexural failure mechanisms: cracking and crushing of
the unconfined and confined concrete, fracture of the longitudinal steel bars due to tension, P-Δ
effects, and fatigue of the longitudinal steel bars. Indirectly, the FFEM is able to predict the
possible buckling of the longitudinal bars by capturing the confined concrete strain time-history.
In order to capture the low-cyclic fatigue, the FFEM through inelastic dynamic analysis is able to
calculate the number of cycles and the amplitude of the cyclic plastic strains so these quantities
are introduced into the fatigue equation. The fracture of the bars due to low-cyclic fatigue is a
failure mechanism that depends on the accumulation of damage along the severe ground motion.
The way to estimate the loss of fatigue life in a steel bar is considering the effect of the duration
in the calculations since the materials stress-strain relationships are independent of the duration
of the ground motion.
In order to determine the accumulation of damage in the bridge column a Cyclic Damage Index
is proposed here. The Index is based on the energy dissipated by the column at the end of the
ground motion.
N2 - Experimental studies about the cyclic response of reinforced concrete bridge columns designed
to avoid shear failure and subjected to cyclic, reversible, and increasing displacements have been
performed in several laboratories around the world. As a consequence there are several force-displacement relationships, called resultant models, that allow to predict the response of those
columns. However, the use of the resultant models for earthquake response requires extensive
calibration of several parameters.
In this investigation a Finite Fiber Element Model, FFEM, is obtained after calibrating first, the
response of 30 circular reinforced concrete bridge columns tested under cyclic, reversible, and
increasing displacements. Then a re-calibration is carried out in order to simulate the response of
two additional columns shake table tested under two earthquake ground motions. After obtaining
satisfactory results the FFEM was used to simulate the seismic response of three bridge columns
designed according to the prescriptions of the new seismic design bridge code.
The FFEM is able to predict directly four flexural failure mechanisms: cracking and crushing of
the unconfined and confined concrete, fracture of the longitudinal steel bars due to tension, P-Δ
effects, and fatigue of the longitudinal steel bars. Indirectly, the FFEM is able to predict the
possible buckling of the longitudinal bars by capturing the confined concrete strain time-history.
In order to capture the low-cyclic fatigue, the FFEM through inelastic dynamic analysis is able to
calculate the number of cycles and the amplitude of the cyclic plastic strains so these quantities
are introduced into the fatigue equation. The fracture of the bars due to low-cyclic fatigue is a
failure mechanism that depends on the accumulation of damage along the severe ground motion.
The way to estimate the loss of fatigue life in a steel bar is considering the effect of the duration
in the calculations since the materials stress-strain relationships are independent of the duration
of the ground motion.
In order to determine the accumulation of damage in the bridge column a Cyclic Damage Index
is proposed here. The Index is based on the energy dissipated by the column at the end of the
ground motion.
UR - https://open.library.ubc.ca/collections/24/items/1.0050739
ER - End of Reference