Effect of reinforcement of the galvanized steel, Aluminum sheet and Glass fiber reinforcement polymer wrapped on flexural behavior of screwed glued laminated timber (glulam) made with poplar

The aim of this study was to investigate flexural strengthening of screwed Glulam made with poplar (Populus alba). Polyurethane adhesive and screw were used for joining layers and applying pressure for manufacturing of three-layer glulam. The variables of this study were types of reinforcing (galvanized steel, aluminum sheet and glass fiber reinforcement polymer) and arrangements of reinforcing: No. 1 (bonded on the bottom (tension) side); No. 2 (bonded on the bottom and top (Tension and compression) side); No. 3 (bonded on the bottom, top and between two bottom layers); No. 4 (bonded on the bottom, top and among layers). Bending test was conducted by Instron according to ASTM D7341. The highest MOR (82.96 MPa) and MOE (1066.33 MPa) were both observed in Glulams reinforced by galvanized steel sheet with arrangement of No. 2 and the lowest MOR (57.82 MPa) and MOE (4397.33 MPa) were both related to Glulams reinforced by GFRP wrapped with arrangement of No. 1. MOR and MOE of control Glulams were 48.1 and 4330 MPa. The increasing percentage of MOR due to reinforcing by galvanized steel, aluminum sheet and GFRP Wrapped were 72.5, 57.8 and 42.6, respectively. The increasing percentages for MOE were 134.2, 57.6 and 28.4, respectively. Failure modes of Glulams changed from brittle to ductile by reinforcing resulted in improving of flexural behavior. The independent effect of types and arrangements of reinforcing on MOR and MOE and also the interaction of types and arrangements of reinforcing on MOE were statistically significant.