Experimental Comparison of Different Carbon Fiber Composites in Reinforcement Layouts for Wooden Beams of Historical Buildings

TLDR

The study quantitatively compares the mechanical performance of three CFRP reinforcement layouts—pultruded laminate on the tension side (LR), U‑shaped wrapping (UR), and a combined UR‑P configuration—applied to historic timber beams compromised by defects and biological decay. Unidirectional and bidirectional CFRP fabrics were tested on timber elements sourced from the roof of the University of Granada’s Faculty of Law building, a recently rehabilitated historical structure. Bending tests show all reinforcement layouts increase capacity and stiffness relative to unreinforced beams, though the extent of ductility improvement varies markedly among the layouts.

Abstract

This paper offers a detailed, quantitative and exhaustive experimental comparison in terms of mechanical properties of three different layouts of carbon composite materials (CFRP) used to strengthen existing old timber beams highly affected by diverse natural defects and biological attacks, testing the use of pultruded laminate attached on the tension side of the element (LR), CFRP fabrics totally U-shape wrapping the timber element (UR), and the combined use of both reinforcement solutions (UR-P). Moreover, unidirectional and bidirectional fabrics were considered and compared. Timber elements used for the experimental program were extracted from a recent rehabilitation of the roof of the current Faculty of Law building, University of Granada (Spain), catalogued as a historical edifice. Experimental results from bending tests show that in all cases reinforcement provides a clear improvement in terms of bending capacity and stiffness as compared with the control specimens (without reinforcement). However, improvements in terms of ductility differ considerably depending on the kind of layout.