Assessment of glued laminated timber beams reinforced with steel bars under bending at high temperatures

Abstract

The greater the distance between the reinforcement and the edges of the glulam beam, the less effective it becomes, although it offers increased protection against the loss of the steel’s mechanical properties at high temperatures. As edge degradation increases, the section’s load-bearing capacity decreases, whereas the reinforcement’s effectiveness is enhanced. The effectiveness of positioning the steel reinforcement away from the tensioned edge to improve the load-bearing capacity of glulam beams under fire conditions remains unclear. This study evaluates the mechanical behavior of reinforced glulam beams under bending in fire. Numerical simulations were conducted using Abaqus, with variations in span lengths and reinforcement, while the remaining effective wood cross section—where mechanical properties are not affected by temperature—was determined analytically. The novelty of this work lies in the investigation of reinforcement effectiveness when placed in a protected location, considering fire exposure for up to 60 min due to sacrificial layers for carbonization. Different combinations of span length, bar diameter, and fire exposure time were analyzed. The results show that reinforcement is more effective at high temperatures and has less influence on load-bearing capacity at ambient temperature than the variation in span length.