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• The effects of UV, moisture and elevated temperature on mechanical properties of GFRP pultruded profiles have been studied. • Different cross-sections were used to study the effect of profile type. • Effect of conditioning on different failure modes were investigated. • Regression models have been developed to predict the mechanical properties retentions. The present research examines the effects of UV radiation, moisture and elevated temperature on the mechanical properties of GFRP pultruded profiles. Flexural, compressive and tensile properties of different GFRP sections were studied after they were exposed for 1000, 1500, 2000 and 3000 h to UV radiation and water vapour condensation cycles. Mechanical tests, including three-point bending, compression and tension tests, SEM analyses, and statistical studies were conducted to gather comprehensive results. The results showed that the mechanical properties of various GFRP sections generally decreased with the duration of conditioning: however, the rate of the decrease that was only slight up to 1000 h, increased rapidly during 1000–2000 h, and again it was slow during 2000–3000 h. The maximum reductions were 34%, 28% and 23% after exposure to 3000 h cycles for bending, tensile and compression tests, respectively. In the bending tests, where inter-laminar shear failure controls ultimate strength, the degradation was greater compared to the situation where fibres fracture controls the failure. Further, regarding the cross-section parameter, it was concluded that the thickness and perimeter are the effective factors; the thinner the sample and the larger the perimeter, the greater is the reduction. However, the maximum effect of the cross section in terms of thickness and perimeter did not exceed 13% among all sections. [ABSTRACT FROM AUTHOR]

This study investigates the effect of Thermal cycles on the mechanical properties of GFRP pultruded profiles with different geometries. Bending specimens consisted of I-shaped and U-channel profiles that were tested in three-point bending along their both principal weak and strong axes, whereas box profiles and laminates were used in compression and tension tests, respectively. Each specimen was exposed to a range of thermal cycles, between −20 °C and 20 °C. The failure modes of the profiles were closely investigated at both major and minor scales. Results were analyzed using ANOVA to determine the influence of each factor and a model was developed to predict the strength retention of profiles after exposure to thermal cycles. The results showed that the thermal cycles have a significant effect on the strength of the resin and a minor effect on the strength of the fibers. Bending specimens experienced a lower strength loss along their principal weak axis than that along their strong axis after conditioning. Tension specimens performed better in comparison to compression specimens in terms of strength retention after thermal exposure. These results are expected to contribute significantly toward the understanding of the influence of thermal cycles on the behavior of GFRP profiles. [ABSTRACT FROM AUTHOR]

• Mechanical properties of various GFRP pultruded profiles under SWSSC is investigated. • Effect of initial exposure to UV radiation and moisture before subjecting to SWSSC is studied. • Samples initially exposed to UV and moisture show higher reductions after exposure to SWSSC. • Profiles with interlaminar shear failure are more vulnerable than profiles with bending failure. In this research, the mechanical properties of various glass fibre reinforced polymer (GFRP) pultruded profiles exposed to seawater sea sand concrete (SWSSC) and its combination with UV radiation and water vapour condensation were studied. The effect of different conditions, duration of conditioning, and the profile cross-section configuration on the mechanical properties were investigated. Three-point bending, tension, and compression tests were carried out to obtain the mechanical properties, including flexural, tensile and compressive strengths and tensile elastic modulus. Furthermore, in order to scrutiny the mechanisms and extent of damage, scanning electron microscopy (SEM) was carried out on the test samples before and after the exposures. Finally, regression models were derived according to the experimental data to describe the mechanical properties of profiles after exposure to the aggressive environments used in this study. The maximum reductions of about 30%, 33% and 46% were observed in three-point bending, tensile and compressive tests, respectively amongst all samples when exposed for 90 days to simulated SWSSC. These reductions increased for the same sections to 52%, 47%, and 50% when the GFRP profiles were pre-exposed for 3000 h to UV radiation and moisture before exposing for 90 days to simulated SWSSC. [ABSTRACT FROM AUTHOR]