Study on mechanical properties of poplar timber bending members of ancient buildings strengthened with CFRP sheets embedded

The reduction of the section area of timber beams in ancient buildings leads to the decline of their flexural mechanical properties. In order to study the effect of the reinforcement method with near-surface mounted CFRP sheets, three groups of 14 scaled poplar timber beam specimens were designed for static loading tests, and the strengthening effects of the new members replacing the damaged members and the concealed CFRP sheets strengthening the damaged members were compared. The results show that the ultimate flexural capacity and flexural stiffness of the strengthened timber beams are significantly improved compared with the simulated damaged beams; the bending performance of the optimum strengthened timber beam is equivalent to that of the undamaged beam. The distribution of the section strain of the strengthened timber beam along the height of the beam section basically conforms to the plane section assumption. A formula for calculating the ultimate flexural capacity of poplar timber beams strengthened with CFRP sheets is proposed. The calculated results are in good agreement with the experimental results.