CFRP strengthening of timber beams recovered from a 32Â year old quonset: Element and system level tests

This paper presents an experimental program for examining the behavior of Douglas Fir timber beams recovered from a 32 year old quonset. Selected beams are intentionally damaged by creating a notch at midspan and strengthened with carbon fiber reinforced polymer (CFRP) composites. Two types of CFRPs are used with different types of epoxy adhesives. The test program consists of two phases incorporating 27 beams: the element-level test with six individual beams and the system-level test with seven beam-assemblies consisting of three beams per system representing an actual service condition. Such a unique experimental approach enables to study the load-sharing mechanism of CFRP-strengthened beam-floor modules. Test beams are simply supported and monotonically loaded until failure occurs. The beams strengthened with the CFRP exhibit a significant improvement in load-carrying capacity of up to 184% and in deflection ductility of up to 165% when compared to the unretrofitted control. Stress concentrations at the notch (simulated damage) are an important factor that influences the failure characteristics and ultimate capacity of the beams. CFRP-strengthening results in improved load-distribution among the constituent beams in the assembly despite the localized damage.