Cumulative Seismic Damage of Circular Bridge Columns: Benchmark and Low-Cycle Fatigue Tests.
Cumulative Seismic Damage of Circular Bridge Columns:
Benchmark and Low-Cycle Fatigue Tests.
El-Bahy, A.; Kunnath, S. K.; Stone, W. C.; Taylor, A. W.
ACI Structural Journal, Vol. 96, No. 4, 633-641,
bridges (structures); damage; reinforced concretes;
piers; earthquakes; fatigue (materials); structures;
cyclic loads; ductility; material properties
An experimental study was undertaken to investigate
cumulative damage in reinforced concrete circular bridge
piers subjected to a series of earthquake excitations.
Twelve identical quarter-scale bridge columns, designed
in accordance with current AASHTO specifications, were
fabricated and tested to failure. This paper summarizes
the results of Phase 1 testing that consisted of
benchmark tests to establish the monotonic
force-deformation envelope and the energy capacity under
standard cyclic loads, and constant amplitude tests to
determine the low-cycle fatigue characteristics of
typical flexural bridge columns. A companion paper will
present the results of variable amplitude testing that
focused on the effects of load path on cumulative
damage. Test observations indicate two potential
failure modes: low cycle fatigue of the longitudinal
reinforcing bars; and confinement failure due to rupture
of the confining spirals. The former failure mode is
associated with relatively large displacements
amplitudes in excess of 4 percent lateral drift, while
the latter is associated with a larger number of smaller
amplitude cycles. A fatigue life expression is
developed that can be used in damage-based seismic
design of circular, flexural bridge columns.