Effect of compressive creep in load transfer components on relaxation behavior of FRP cable extrusion anchorages

This study investigates 1000-hour and million-hour creep behaviors in load transfer components (LTCs) and evaluates the impact of LTC’s compression creep on fiber-reinforced polymer (FRP) cable extrusion-anchorage relaxation. The static compression properties and 1000-hour creep resistance of LTCs were tested under varying volume fractions, stress levels, and hybrid ratios. The effects of material modifications (e.g., glass microfibers, quartz sand) and vacuum processing were further examined. In this study, the 1000-hour and million-hour creep coefficients were predicted using the Findley model (FM) and logarithmic model (LM). Finite element analysis was used to examine the effect of LTC compression creep on extrusion anchorage relaxation by changing the thickness and conical angle of LTCs. The results showed that a lower height-to-diameter ratio (1.2) improved compressive performance. Vacuuming increased compressive strength by 18.0% to 113.3% and elastic modulus by 22.5% to 48.0%. Glass microfibers outperformed quartz sand in modification, with longer fibers providing optimal enhancement. Higher compressive stresses induced notch damage in both the upper and lower zones of the cylinder specimens. Fibers reduced the 1000-hour creep coefficient more effectively than sand. Excessive stresses and volume fractions decreased strength retention after creep. Both FM and the LM accurately predicted the 1000-hour creep. Stress levels should be limited to 0.5 f u ( f u = ultimate strength) for plain resin, 0.8 f u for single glass microfiber-modified resin, and 0.5 f u for single quartz sand-modified resin. The finite element model accurately described experimental strain-time curves. Compressive stress within the cylinder specimens varied, with higher stress in the middle and lower stress at the ends. Increasing the conical angle and loading-end LTC thickness resulted in greater stress losses in extrusion anchorages.