Shear Behavior of GFRP Composite Materials at Elevated Temperature

The use of fiber-reinforced polymer (FRP) materials is becoming commonplace in various civil engineering applications due to the several advantages they offer over traditional materials. However, the limited knowledge about some aspects of the behavior of these materials, particularly when subjected to elevated temperatures, is hampering their widespread use. This paper presents experimental and analytical investigations about the shear behavior of pultruded glass fiber-reinforced polymer (GFRP) profiles at elevated temperatures. The primary objectives were twofold: to quantify the changes in the in-plane shear modulus and strength caused by temperature increase, namely when glass transition temperature (Tg) of the material is exceeded; and to assess the accuracy of different analytical models in simulating those changes. The experimental campaign consisted of shear tests, performed in V-notched specimens obtained from a GFRP pultruded flat plate, from room temperature (Troom) up to 180°C. The results obtained show that (1) the in-plane shear strength presents significant reduction with temperature (88% at 180°C, compared to Troom); (2) such reduction is considerably higher compared to that obtained from 10° off-axis tests (in particular, for T<140°C); and (3) the shear modulus reduction with temperature is slightly lower than that experienced by the in-plane shear strength (78% at 180°C). All empirical formulations assessed in the present study were able to provide reliable estimates of the degradation with temperature of the shear strength and modulus.