Experimental and analytical study of the mechanical behavior of heterogeneous glulam–UHPFRC beams assembled by bonding: Short- and long-term investigations

• Experimental research on the short- and long-term (creep) behavior of glulam–UHPFRC beams in a bending test is presented.
• The long-term experimental tests were conducted in indoor and outdoor environments.
• An analytical model was developed to predict the response of the short- and long-term behaviors of heterogeneous beam multi-materials based on an iterative procedure.

In wood-based structural design, in addition to the criteria of strengthening and stiffness, the criterion of deformability due to the creep of wood, especially in horizontal members, is a factor that often limits the design. New developments have further improved the structural performance, such as the strengthening of timber (glulam) beams by bonding composite material combined with an ultra-high performance fiber reinforced concrete (UHPFRC) that is internally reinforced with or without carbon fiber reinforced polymer (CFRP) bars. Glulam, UHPFRC and CFRP may be an interesting composite mix for responding to the problem of the creep behavior of composite structures made of different materials with different rheological properties. This paper describes an experimental and analytical investigation on the short-term and long-term (creep) performances of glulam–UHPFRC–CFRP beams. The experimental investigations of creep behavior were conducted in indoor and outdoor environments under constant loading for approximately 1 year. The measured results are compared to the results from an analytical model. This model was developed to predict the creep response of the glulam–UHPFRC–CFRP beams based on the creep characteristics of the individual components. The results indicate that heterogeneous glulam–UHPFRC beams improve both strength and stiffness and can also effectively reduce the creep deflection of wooden beams.