盐-碱环境下GFRP管力学性能演化规律

Evolution of Mechanical Properties of GFRP Tubes in Saline-alkali Environment

纤维增强复合材料(FRP)管-混凝土组合柱因其能充分发挥FRP管和混凝土材料的性能优势,具有广泛的应用前景,然而,当结构处于极其恶劣腐蚀环境下时,其耐久性仍是值得关注的问题,在我国北方盐-碱地区,建筑桥墩易受到盐-碱侵蚀。为研究盐-碱环境下GFRP管的力学性能演化规律,制备了GFRP管和环,两种试样内径均为100 mm,厚均为3 mm,高分别为100 mm、10 mm,浸泡在盐(NaCl)-碱(NaOH)溶液中,以温度、周期为变量,通过试件浸泡前后干质量变化以及轴压和环拉试验测试,获得相应的力学性能,并基于Arrhenius公式开展了GFRP管环向拉伸强度寿命预测。结果表明:温度对GFRP管强度影响显著,随着浸泡周期的增加,GFRP管轴压强度和环拉强度呈现下降趋势;温度越高,强度下降速率越快;40℃和60℃温度条件下,在浸泡30 d后环拉强度退化速率减缓。轴压弹性模量受温度和浸泡周期影响较小,环拉弹性模量随温度升高而显著降低,浸泡周期对其影响较小;通过寿命预测,7.5℃全表面积浸泡半年时,环拉强度保留率低于40%,盐-碱环境对GFRP管材的腐蚀作用显著,环氧树脂GFRP管并不适用于盐-碱环境下的长期使用。

Friber reinforced composite(FRP)tube-concrete combination columns had a wide application prospect because they could give full play to the performance advantages of FRP tubes and concrete materials.However,their durability was still a concern when the structure was in an extremely harsh corrosive environment.In the salt-alkaline region of northern China,construction bridge piers were susceptible to salt-alkaline erosion.In order to study the evolution of mechanical properties of GFRP tubes under salt-alkali environment,GFRP tubes and rings were prepared,both specimens with an inner diameter of 100 mm,a thickness of 3 mm and a height of 100 mm and 10 mm,respectively,immersed in salt(NaCl)-alkali(NaOH)solution.Taking temperature and period as variables,the specimens were tested by dry mass changes before and after immersion of the specimens as well as axial compression and annular tensile tests to obtain the mechanical properties.The prediction of the annular tensile strength life of GFRP tubes were carried out based on the Arrhenius formula.The results show that temperature has a significant effect on the strength of GFRP tubes,with the increase of soaking cycle,the axial compressive strength and ring tensile strength of GFRP tubes show a decreasing trend.And the higher the temperature,the faster the rate of strength could decrease.The degradation rate of ring tensile strength slows down after 30 d of soaking at 40℃and 60℃.The axial compressive modulus of elasticity is less affected by temperature and soaking period,while the ring tensile modulus of elasticity decreases significantly with increasing temperature,and the soaking period has less influence on it.At half a year,the retention of ring tensile strength is less than 40%.The corrosive effect of salt-alkali environment on GFRP tubes is significant and epoxy resin GFRP tubes are not suitable for long-term use in salt-alkali environment.