Enhancement of the flexural performance of retrofitted wood beams using CFRP composite sheets

The main objective of this study was to investigate the flexural performance of wood beams retrofitted by using carbon fiber reinforced plastic (CFRP) composite sheets. First, a theoretical analysis of wood beams retrofitted with CFRP composite sheets was derived. The four-point bending test was then used to determine the load–displacement relationships of wood beams. The performance of the CFRP sheets adhered to the tensile side of two different species of wood beams was investigated. Observations of the experimental load–displacement relationships show that flexural strength increased and middle vertical displacement decreased for wood beams retrofitted with CFRP composite sheets, compared to those without CFRP sheet. The increased percentages of flexural strength for the retrofitted Cunninghamia lanceolata with 1, 2 and 3 layers of CFRP composite sheets were 39%, 44% and 61%, respectively. The increased percentages of flexural strength for the retrofitted Tsuga chinensis with 1, 2 and 3 layers of CFRP composite sheets were 44%, 55% and 58%, respectively. Comparisons of the theoretical and experimental ultimate loads show the absolute errors of the ultimate load for C. lanceolata and T. chinensis to be 5.05% and 8.65%, respectively.