Investigation of Shear Fatigue Behavior of Reinforced Concrete Beams Under Moving Load
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Date
2020-01-16
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Addis Ababa University
Abstract
Reinforced concrete beams subjected to moving cyclic loads has a reduced fatigue
life as compared to that of fixed-point pulsating loading. Moving loads has more
damaging effect to the concrete, this might cause brittle shear failure.
In this study experimental and analytical investigation was conducted on six
reinforced concrete beams without web reinforcements, to study the behavior of
shear fatigue in reinforced concrete beams subjected to moving loads. One beam
was made to fail monotonically to determine the static shear capacity. Three beams
were subjected by a step wise moving load to 85%, 75% and 68% of the static shear
capacity. The other two beams were subjected to a fixed-point pulsating load to
75% of the static shear capacity, but in different loading location (at midspan and
at a location where the shear force to capacity ratio is maximum). Step wise moving
load caused faster shear strength degradation compared to fixed pulsating load.
Rate of increase in residual deflections with number of load cycles in step wise
moving loads is higher compared to stationary cyclic loading which shows higher
damage accumulation more than that of fixed pulsating load. Crack formation and
propagation was monitored throughout the experimental programs by manually
marking when new cracks formed. In fatigue loading the major diagonal cracks in
beams are more horizontal than that of monotonic loading conditions. Depending
on the amplitude of loading it is difficult for diagonal cracks to propagate into the
compression zone in case of fatigue loading.
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Keywords
Step-wise moving load, fixed-point pulsating load, shear fatigue, RC beam