Engineering Model for Forecast of Stress Rupture Strength of Stressed Aramid Fiber Reinforced Polymer Bars Embedded in Concrete
F. S. Rostasy and M. Scheibe
Appears on pages(s):
alkaline solution; aramid fibers; durability; environment;
AFRP tensile elements (bars, strands etc.) can be successfully applied for the pre-tensioning of precast concrete members, for post-tensioning tendons, ground anchors etc. In such applications, the AFRP may come into permanent contact with the alkaline pore solution of concrete or cementitious grout. Many tests prove that such aggressive environment may seriously damage the stressed AFRP and significantly abbreviate its lifetime due to premature stress rupture. The stress rupture strength of FRP is the relevant durability property to ensure the serviceability and safety of a structural concrete member during its service life. The stress rupture behaviour is usually studied on stressed AFRP bars placed in aggressive solutions etc.. It is though evident that such severe environment does not realistically reflect the true environment of AFRP in dense concrete and grout. It is was therefore the aim of the authors to develop - on basis of experiments in several stages and by theoretical studies - an engineering model for the prediction of the stress rupture strength of stressed AFRP in concrete or grout. This model was verified by tests. Provided the stress rupture strength of AFRP in dry air or in alkaline solution etc. was experimentally established afore-hand, the parameters of the mean stress rupture relationship can be sharpened. Additional deliberations are however necessary to transfer the model into the real environment of concrete or grout around the FRP element. Suitable procedures are presented.