Load and Deformation Analysis in Experimental and Numerical Studies of Full-Size Wooden Beams Reinforced with Prestressed FRP and Steel Bars

Abstract

The use of composite precast or steel bars as reinforcements for timber beams is an important technique that can improve effectiveness or allow cross sections to be reduced. This paper presents experimental, theoretical, and numerical studies of full-size timber beams measuring 82 × 162 × 3650 mm3 using prestressed steel bars and 10 mm diameter basalt and glass bars with a prestress of 10 MPa. In addition, parametric studies were carried out using FEM numerical simulations. In the experimental tests, an increase in load-bearing capacity and stiffness of up to 58% and 10.7% for steel bars, 32% and 10.1% for basalt bars, and 27% and 7.8% for glass bars, respectively, was obtained compared to unreinforced beams. The different levels of improvement in reinforcement efficiency was also related to the different elastic modulus of the reinforcement itself. Unreinforced beams showed a linear elastic range. In contrast, on beams reinforced with steel bars, the curve had a slightly steeper line than the control beam, and the slope of the curve then decreased when a certain load was reached. All beams failed when the lower wood fibers reached maximum tensile strain. The allowable compressive strain then decreased by 36.6% for basalt bars, 32.9% for glass bars, and 30.4% for steel bars. The use of prestressing further exploited the strength of the reinforcement beyond the yield point. All unreinforced beams primarily failed in the tension zone due to fracture of the timber fibers. Prestressed and reinforced beams were already failing due to bending and shear. The experimental and numerical analysis was also compared, and the results showed a good agreement and a maximum difference of approximately 5.7%.

Application of Composite Bars in Wooden, Full-Scale, Innovative Engineering Products—Experimental and Numerical Study

“…Then, it is very important to perform full-scale research. Therefore, as already written in published works [16,[41][42][43], the next stage of these experimental, theoretical and numerical studies will be the study of the fire resistance of small-sized wooden elements (solid wood, laminated timber, cross-laminated timber, glued laminated timber beams, solid timber joined with glued joints, I-beams, laminated veneer lumber) reinforced with steel and FRP materials in various forms and structures, including different artificial fibers, natural fibers, etc. (FRP composite materials will be the external reinforcement; additionally, they will also constitute the internal reinforcement of the cross-section, so the same chopped fibers will be used and placed inside the crosssection as well as outside the cross-section); fire resistance of full-size wooden elements, including in the form of beams (solid wood, laminated wood, cross-laminated timber, solid wood joined with glued joints, glued laminated timber beams, I-beams, laminated veneer lumber) reinforced with steel and FRP materials in various forms and structures, including different artificial fibers and natural fibers (FRP composite materials will be the external reinforcement; additionally, they will also constitute the internal reinforcement of the crosssection, so the same chopped fibers will be used and placed inside the cross-section as well as outside the cross-section); and the impact of elevated temperatures on physical and mechanical properties-the behavior in the event of fire, as well as the physical and mechanical properties after fire of small-and full-size wooden elements will be examined, including in the form of beams (solid wood, laminated wood, glued laminated timber beams, cross-laminated timber, solid wood joined with glued joints, I-beams, laminated veneer lumber) reinforced with steel and FRP materials in various forms and structures, including different artificial fibers and natural fibers (FRP composite materials will be the external reinforcement; additionally, they will also constitute the internal reinforcement of the cross-section, so the same chopped fibers will be used and placed inside the crosssection as well as outside the cross-section).…”

Impact of basalt fiber reinforced concrete in protected buildings: a review

“…Similarly, the reinforced timber beam is made up of several sorts of bars, such as steel, basalt, and glass. Their results showed that steel bars increased maximum loading by 57%, basalt bars by 32%, and glass bars by 27% (Wdowiak-Postulak et al, 2023). When basalt rebar was used to determine a beam's maximum loading capacity, it was discovered that the capacity was increased by ribbed, fiber-free basalt rebar (Li et al, 2024).…”