Experimental and Computational Modeling of Low Cycle Fatigue Damage of CFRP Strengthened Reinforced Concrete Beams

Improvement in the short-term behavior of deficient reinforced concrete beams is very well known through extensive testing of reinforced concrete beams strengthened by externally bonded carbon fiber reinforced polymer strips. However, long-term performance of such beams needs to be assessed before the method can gain full acceptance. Prominent modes of failure in strengthened reinforced concrete beams reported in literature are concrete crushing in compression, carbon fiber reinforced polymer plate rupturing in tension and peeling of the carbon fiber reinforced polymer plate due to high interfacial shear and peeling stresses at the plate cut-off point. Modeling of the overall system of strengthened reinforced concrete beams requires modeling of the individual components that ultimately leads to failure i.e., concrete, carbon fiber reinforced polymer and concrete - carbon fiber reinforced polymer. Component elasto-damage constitutive models are developed for concrete crushing, carbon fiber reinforced polymer rupture and concrete-carbon fiber reinforced polymer interface failure, calibrated by data from both suitably designed experiments and from experiments reported in literature, and are utilized to investigate the low cycle fatigue behavior of reinforced concrete beams strengthened by carbon fiber reinforced polymer strips. The predictive ability of the model is tested by comparison to data from two different beam strengthening schemes i.e., with end anchorage and without end anchorage.