Long-term behavior of CFRP plates under sustained loads

This paper studies the long-term behavior of carbon fiber–reinforced polymer (CFRP) plates under sustained loads. Two typical loading conditions, CFRP plate loading controlled by displacement constraints and force constraints, are studied. The first section investigates the prestress loss of the CFRP plate when it is loaded via displacement constraints, which serves as a prestressed system applied for prestressed structures. Short- and long-term measurements show that the prestress loss of CFRP is caused by material creep, temperature change, and CFRP and anchorage slippage. When the CFRP prestress level is 5.0%–12.3%, the average prestress loss after 42 days is 5.1%. The second section investigates the permanent deformation of the CFRP plate with curved anchorages caused by creep under a certain sustained load (i.e., controlled by force constraints), which serves as a suspension bar or cable applied for determinate structures. The creep strain-to-time relationship, creep rate, and residual strength were obtained. The creep strain-to-time relationship strongly depends on the stress level applied; the creep coefficient is less than 10.94% and the residual strength is greater than 80% of the initial tensile strength after 1000 h. The findings show the effectiveness and reliability of these two typical cases of CFRP plates under long-term sustained loads.