Performance of Polyolefin Fiber ReinforcedConcrete Under Cyclic Loading

Abstract

In structures, such as bridges, bridge-deck overlays, pavements, offshore structures, parts of high-rise buildings and crane-girders in the industrial buildings, which are subject to cyclic loading and dynamic loading, the flexural fatigue strength and endurance limit of concrete are important design parameters. Most modern building codes concentrate on providing sufficient ductility in a structure to prevent its collapse during a major seismic event. Structures may be deformed beyond the elastic limit in order to absorb all of the energy imparted to them. In such cases ductility, the ability of the structure to undergo increasing deformations beyond yield stresses while still sustaining gravity and other loads, is therefore necessary in order to prevent catastrophic collapse. Non-metallic fiber reinforced concrete represents a potential solution. The behavior of non-metallic fiber reinforced concrete under cyclic loading needs to be studied. This paper presents the results of an experimental and analytical investigation to determine the flexural fatigue strength and endurance limit of non-metallic (polyolefin) fiber reinforced concrete. Six different polyolefin FRC mixes with varying compressive strengths were investigated. The FRC beams were subjected to flexural fatigue with third point loading at a frequency of 25 load cycles per second. It was found that polyolefin fiber reinforced concrete reaches an endurance limit at about two million cycles. The fatigue life model (S-N curve) was more accurate when presented on a log-log scale than on a log-normal scale. Statistical and probabilistic concepts are introduced to predict the flexural fatigue model and the fatigue life expectancy of the composite.