Flexural behaviour of glulam timber beams reinforced with FRP cords

Fossetti, Marinella; Minafò, Giovanni; Papia, Maurizio

doi:10.1016/j.conbuildmat.2015.07.116

Cited by 70 publications

(21 citation statements)

References 9 publications

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“…Previous attempts to apply internal reinforcement to wood structures included the introduction of reinforcement inserts into the tensile zone or into the tensile and compression zone-a more effective method [3,4]. Both metallic, as well as fiber-reinforced polymer, reinforcement in the form of rods [5][6][7][8], laminates or mats were used [9][10][11]. The use of carbon fiber-reinforced polymer (CFRP) laminates bonded inside the cross-section perimeter has been presented [12] as an implementable solution for strengthening and reproducing the carrying capacity of solid timber beams in historical structures.…”

Section: Introductionmentioning

confidence: 99%

Strengthening of Bent LVL Beams with Near-Surface Mounted (NSM) FRP Reinforcement

2020

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The topic of the article is the analysis of the static work of unreinforced and reinforced with composite material timber beams under bending tests. The results of the experimental tests and a brief outline of the characteristics of the internal reinforcement of wood structures are presented. Experimental tests were performed on full-scale beams made of laminated veneer lumber (LVL) with nominal dimensions of 45 × 200 × 3400 mm. Two strips of carbon fiber-reinforced polymer (CFRP) reinforcement were glued into rectangular grooves in the component bottom with two-component epoxy resin (0.62% reinforcement percentage). The reinforcement mainly affected the enhancement of the maximum bending moment values evaluated at the points of application as having concentrated forces of 32% and 24% in comparison to the unreinforced elements. Increases of 11% and 7% in the global modulus of elasticity in the bending and stiffness coefficients were achieved, respectively. The failure of the reference beams was caused by exceeding the tensile strength of the LVL. The reinforced elements were characterized by a greater variation in failure mode, resulting from tension, compression or lateral torsional buckling. The strain profile reading showed a higher utilization of the compression characteristic of veneer in specimens reinforced with carbon laminates.

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Section: Introductionmentioning

confidence: 99%

Strengthening of Bent LVL Beams with Near-Surface Mounted (NSM) FRP Reinforcement

2020

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“…Analysis of studies conducted over the past decade [11][12][13][14][15][16][17][18], the most common material is carbon fiber or carbon plastics, having a number of advantages: high specific strength, corrosion resistance, low heat and electrical conductivity, as well as environmentally friendly material -non-toxic. Strengthening of wooden structures is carried out either by gluing the rods at different angles to the structure, or by layers, between the glued layers of planks, or by external reinforcement.…”

Section: Introductionmentioning

confidence: 99%

A research of stress/strain condition of reinforced timber structures with natural weakenings

Shchelokova

2018

MATEC Web Conf.

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In recent decades building structures are faced with more serious demands in a broad sense of this term, but in this case the lumber quality is gradually lowered due to large volumes of consummation along with sufficient time, needed to reproduce a stock lumber. As a result, there is a need for a more detailed and in-depth study of the influence of low-grade wood defects on the work of wooden structures. One of the methods to improve characteristics of structures, made with low-grade lumber is a reinforcement of these. The objective of the research below is to determine a degree of influence of a cross-sectional natural weakenings (such as knots) to a stress/strain condition of reinforced timber beams. The main research methods are as follows: mathematical calculations, computer modeling in the software “Cosmos/M” and an experiment. The methodic of an experiment planning is based on the “Latin Squares” principle [1]. The square is designed for three primary factors, each of which consists of three variants. The results of the research work are shown in form of graphs and tables. The main conclusions made after the research: the deformation of the reinforced beams is from 15 to 20% lower, as compared with non-reinforced; crushing of reinforced beams with weakened cross-section takes place without a sharp state of a former because of a supporting influence of reinforcement in tensioned zone and reliable connection of reinforcement with wood, which is ensured by a glued joint until the crushing of the timber. The safety factor of reinforced timber structures varies from 3 to 5.07.

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“…Shear or local reinforcements using FRP sheets have been studied by Triantafillou [19] and Schober et al [20]. Glued laminated timber (glulam), made of multiple layers of dimensioned lumber bonded together with durable, moisture-resistant structural adhesives, has been also reinforced with FRPs (sheets, plates or bars) and high increases in bending capacity have been measured [21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Uncertainty analysis of FRP reinforced timber beams

Corradi

Borri

Righetti

et al. 2017

Composites Part B: Engineering

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22Timber has been a popular building material for centuries and offers significant sustainable 23 credentials, high mechanical and durability properties. Availability, ease to use, convenience 24 2 and economy have made timber the most used construction material in history but, as it is a 25 natural material, uncertainty in its mechanical characteristics is considerably higher than 26 man-made structural materials. National codes and engineers usually employ high factor of 27 safety to incorporate timber strength uncertainty in design of new structures and 28 reinforcement of existing ones. This paper presents the results of 221 bending tests carried 29 out on unreinforced and reinforced soft-and hardwood beams (fir and oakwood) and 30 illustrates the reinforcement effect on timber capacity and strength uncertainty. 31Both firwood and oakwood beams have been tested in flexure before and after the application 32 of a composite reinforcement made of FRP (Fiber Reinforced Polymer) unidirectional sheet. 33The uncertainty in the strength of reinforced timber is also quantified and modelled. finding new uses for redundant historic constructions without affecting their significance. 56As a natural material, the strength of timber is appreciably reduced by the presence of defects 57 like knots, especially when located on the tension side, and distortion of the grain. For this 58 reason uncertainty in the strength of timber is considerably higher compared to an artificial 59 construction material (steel, concrete, bricks, etc.), which is produced through quality- UNREINFORCED TIMBER 111The bending strength of timber is governed by the modes of failure. Since the behavior of 112 timber in compression is different from that in tension, the failure modes could be highly 113 affected by this. Figure 1 show different characteristic failures of beams in bending. Simple 114 tension failure (Fig. 1a) due to a tensile stress parallel to the grain. This is common in 115 straight-grained beams made of high quality timber, particularly when the wood is well 116 seasoned and there is no diagonal cross grain. 117The most common failure mode is the cross-grained tension, in which the fracture is caused easy to see why a cross-grained timber would fail in this manner. 124As stated, an interesting effect of the analysis of the failure modes is that these usually occurs 125for different levels of bending loads. Failure mode in Figure 1b is usually activated for low 126 bending loads. This is also typical of low-grade timber where the high number of defects 127 facilitates the cross-grained tension failure. 128Failure on compression side is shown in Fig. 1c. This failure mode do not usually lead to the 129 collapse of the structure as the behavior of timber in compression is plastic (Fig. 3). Failure 130 modes in Figure 1a is usually activated for high bending loads as this occurs for straight- 131grained beams and tensile strength of timber is very high. In order to reduce the local crushing of the wood, the load was a...

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Flexural behaviour of glulam timber beams reinforced with FRP cords

Cited by 70 publications

References 9 publications

Strengthening of Bent LVL Beams with Near-Surface Mounted (NSM) FRP Reinforcement

Strengthening of Bent LVL Beams with Near-Surface Mounted (NSM) FRP Reinforcement

A research of stress/strain condition of reinforced timber structures with natural weakenings

Uncertainty analysis of FRP reinforced timber beams

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