Time-dependent and residual behavior of pultruded GFRP beams subjected to sustained intensities and cold temperature

This paper presents the time-dependent response and residual behavior of pultruded glass fiber reinforced polymer (GFRP) beams. A total of nine beams are tested in four-point bending. One beam is served as control and eight beams are loaded to failure after exposing to three levels of sustained intensities (20%, 40%, and 60% of the static capacity) at room (25 degrees C) and cold (similar to 30 degrees C) temperatures for 2000 h. Time-dependent material parameters are obtained from the test. Analytical approaches are used to predict the behavior of test beams, based on mechanics-based failure criteria and Findley's creep theory. Three-dimensional finite element models are also developed, based on the experimentally obtained material parameters. The GFRP beams demonstrate time-dependent material degradation due to the sustained load. Cold temperature alters the load-carrying capacity and creep response of the beams. Brittleness of the GFRP is accelerated when the beams are exposed to sustained intensities and cold temperature. The contribution of shear deformation to the deflection of the beams increases with sustained load. Although the proposed modeling approaches agree with the experiment, further development is recommended to account for micro-level material deterioration characteristics. (C) 2012 Elsevier B.V. All rights reserved.