Ductility and Stiffness of Laminated Veneer Lumber Beams Strengthened with Fibrous Composites

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Optimization of structural elements via composition of different components is a significant scientific and practical point-of-view problem aimed at obtaining more economical and environmentally friendly solutions. This paper presents the results of a static work analysis of small-size laminated veneer lumber (LVL) beams reinforced by a Carbon Fiber Reinforced Polymer (CFRP) sheet. The nominal dimensions of LVL beams were 45 × 45 × 850 mm, and 0.333- and 0.666-mm thick reinforcement layers were used. The reinforcement was applied on opposite sides of the cross section obtaining a sandwich-type structure. An epoxy resin was used as a bonding layer. The bending tests were conducted in the so-called four-point bending static scheme in edgewise and flatwise conditions. The results of experimental tests confirmed the validity of this combination of materials. The highest load-bearing capacity was obtained for configuration, where CFRP sheets with a thickness of 0.666 mm were placed on the sides of the core, parallel to the direction of loading and the veneer’s grain in the core. The increase in this case was up to a maximum of 57% compared to the core alone. The highest bending stiffness increase, 182% compared to the core alone, involves placing two layers of sheets perpendicular to the direction of loading, i.e., on the upper and lower surfaces. The presented novel sandwich structure can be competitive against traditional steel and reinforced concrete elements in civil engineering and can be utilized as beams or slabs.

“…Bending stiffness coefficient k was evaluated according to the formula [ 35 ]: k = F/u, where F is the loading force and u is the deflection at the midspan.…”

Section: Results and Analysesmentioning

confidence: 99%

Numerical, Theoretical, and Experimental Analysis of LVL-CFRP Sandwich Structure

Bakalarz,

Kossakowski

2023

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“…This may be due to the binding of timber defects by covering the side surface. A greater increase in bending strength and stiffness was observed in the full-sized beams than in those tested on a laboratory scale [ 39 , 40 ]. As the volume of the LVL beams increased, their bending strength decreased.…”

Section: Discussionmentioning

confidence: 99%

Strengthening of Full-Scale Laminated Veneer Lumber Beams with CFRP Sheets

Bakalarz

Kossakowski

2022

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This paper presents the results of experimental research on full-size laminated veneer lumber (LVL) beams unreinforced and reinforced with CFRP sheets. The nominal dimensions of the tested beams were 45 mm × 200 mm × 3400 mm. The beams were reinforced using the so-called U-type reinforcement in three configurations, differing from each other in the thickness of the reinforcement and the side surface coverage. An epoxy resin adhesive was used to bond all the components together. A four-point static bending test was performed according to the guidelines in the relevant European standards. The effectiveness of the reinforcement increased with the level of coverage of the side surface and the level of reinforcement. The average increases of bending resistance were 42%, 51% and 58% for configurations B, C and D, respectively. The average value of bending stiffness increased for the beams of series B, C and D by 15%, 31% and 43%, respectively. Their failure mode changed from brittle fracture initiated in the tensile zone for unreinforced beams to more ductile fracture, initiated in the compression zone. The influence of the coverage of the side surface by the CFRP sheet and reinforcement ratio on the mechanism of failure and effectiveness of strengthening was studied in the article.

“…The ductility and stiffness analysis of the LVL beams on a laboratory scale and strengthened with aramid, glass, and carbon sheets with high strength and ultra-high modulus of elasticity were described in [ 26 ].…”

Section: Discussionmentioning

confidence: 99%

“…The studies described above were focused on the analysis of solid and glue laminated timber beams strengthened with composite and steel materials. A limited number of works were devoted to the strengthening of laminated veneer lumber beams with composite materials [ 6 , 23 , 24 , 25 , 26 , 27 ]. Therefore, the main aim of this article is to create a comprehensive study that includes analysis of the strain, stiffness and ductility of full-scale laminated veneer lumber LVL beams strengthened with CFRP.…”

Section: Introductionmentioning

confidence: 99%

Application of Digital Image Correlation to Evaluate Strain, Stiffness and Ductility of Full-Scale LVL Beams Strengthened by CFRP

Bakalarz

Tworzewski

2023

Self Cite

Due to limitations of traditional measuring methods, a necessity of verification of applicability of optical measuring systems in different fields of science is required. The paper presents the application of a non-contact, non-destructive ARAMIS optical system in the analysis of static work of unstrengthened and strengthened laminated veneer lumber beams (LVL) with composite materials, subjected to a four-point bending test. The beams were strengthened with Carbon Fiber Reinforced Polymer (CFRP) sheets and laminates. The sheets were bonded to the external surfaces in three configurations differing in the number of layers applied and the degree of coverage of the side surface. The CFRP laminates were glued into predrilled grooves and applied to the underside of the beams. An adhesive based on epoxy resin was used. The scope of the work includes analysis of the strain distribution, stiffness and ductility. The analysis was performed on the basis of measurements made with an optical measurement system. The strain analysis indicated a change of the distribution of the strain in the compressive zone from linear for the unstrengthened to bilinear for the strengthened beams. The stiffness increase was equal from 14% up to 45% for the application of the CFRP laminates in the grooves and CFRP sheets bonded externally, respectively. Similar improvement was obtained for the ductility.