Strengthening of old timber floor joists with cross-laminated timber panels and tempered glass strips

This article deals with the procedure for strengthening existing timber floor joists with CLT panels and additional tempered glass strips. The proposed strengthening procedure was investigated on eight old timber floor joists from the historical Zgornja Polskava manor from Slovenia. The glass strips were adhesively bonded or screwed to the joists, while the CLT panels were screwed to the joists with self-tapping screws. The proposed procedure was evaluated based on four-point bending tests of the joists. The efficiency was determined by comparing the bending test results of the strengthened and unstrengthened joists. The bonded glass strip variant always resulted in a higher load-bearing capacity and a higher effective bending stiffness, while the screwed glass strip also always resulted in a higher effective bending stiffness, but only in some instances increased the load-bearing capacity. The experimental results were compared with analytical and numerical calculation results. The results showed good agreement, despite the joists being visually severely damaged, which was also demonstrated by performing acoustic tomography on a timber joist sample. (c) 2021 Elsevier Ltd. All rights reserved.