Publication
Nowadays, strengthening of existing steel structures using advanced carbon fiber reinforced polymer (CFRP) composites is becoming a common technique due to the unique advantages of the material such as light weight, high strength and fatigue endurance, as well as their relatively easy installation. Recently, the tendency to strengthen steel structures with prestressed CFRP plates is growing, especially in case of fatigue strengthening, where a reduction in acting stresses on the structures would be possible using prestressed reinforcements. However, the efficiency of using prestressed bonded CFRP reinforcements is severely affected by the undesirable premature debonding of CFRP from the steel substrate, before reaching the ultimate tensile capacity of the strengthening material. Consequently, it is of great importance to investigate the anchorage resistance and bond behavior of prestressed CFRP plates bonded to steel substrate. In the current study, a set of single lap-shear and prestress release tests was performed on CFRP-to-steel joints. All the tests were monitored using a 3D digital image correlation (DIC) system to understand the bond behavior of CFRP plates during lap-shear and prestress release tests. Moreover, the effect of accelerated curing on bond anchorage of the prestressed CFRP plates was investigated. Prestress release test results of the current study showed that the governing phenomenon in CFRP-to-steel joints is completely different than that in CFRP-to-concrete joints. The reason is that, despite in concrete, no tensile failure can occur in steel; consequently, relatively high prestressing forces can be transferred to the steel substrate before reaching debonding.
Aurelio Muttoni, Marko Pejatovic