Fig 2 - available via license: CC BY
Content may be subject to copyright.
Source publication
This paper aims to describe the performance of mix-glue laminated timber beams that are given a nylon strapping as external reinforcement with the three-point bending test to three groups of beams based on the span-to-depth ratio, i.e.: G11, G8, and G5 groups. Each group consists of three types of lamination compositions, namely: Type I, whole lami...
Context in source publication
Similar publications
This paper was intended to describe the performance of mix-glue laminated timber beams (mix-glulam) compose of coconut wood (Cocos nucifera) and sengon wood (Albizia falcatara) in the outer zone and core zone, respectively. Mix-glulam system is an alternative to utilizing a low-grade timber as structural member of building. Through the analysis of...
Citations
... Also, with slender diaphragm in the middle to endure shear stresses and maintain separation between the flanges, as the materials in the beam centre experiences lower stress levels (Kretschmann & Hernandez, 2006). A study carried out on glulam with 33 % Coconut (Cocos nucifera) timber as the outermost lamination and 67 % Sengon (Albizia falcatara) timber as core lamination indicated an improved shear strength, flexural strength and elastic modulus by 34 %, 13 % and 28 % respectively using urea-formaldehyde resin powder (UF) adhesive (Kusnindar et al, 2018). Theoretical concepts and experimental evaluations have been developed in several literatures permitting the combination of various timber species into glulam of various sizes, shapes and configurations due to the processes of manufacturing which addresses the extent of variation in the mechanical characteristics of timber and reduces lapses like knots and cracks due to an increase in number of laminations (Ezeagu et al, 2015;Alayande et al, 2019). ...
Quality timber species are declining due to over-exploitation in Nigeria. This has propelled the utilisation of low-grade timbers species that are considered for low-end constructions in the past which called for concern. This study establishes the viability of a typical beam made from locally sourced non-durable Obeche (Triplochiton scleroxylon) with highly durable Opepe (Nauclea diderrichii) timber specie in a combined glulam form, using polyvinyl acetate (PVA) adhesive which serves the impact of environmental sustainability and reduced cost of engineering construction. Seasoned timber samples and PVA adhesive were all obtained locally in Nigeria. Beam specimens were tested in the Department of Civil Engineering, Ahmadu Bello University, Zaria according to EN 338 (2009). Based on tests, it is evident that solid Opepe and Obeche timber specimens exhibited more durable characteristics than their homogenous glulam when fabricated with PVA adhesive. The combined Opepe/Obeche (GLc OP/OB) glulam beam specimen was proposed into GL18c strength class according to EN 338 based on minimum constraints which it satisfies, reflecting a 41 % greater Modulus of Elasticity (MoE) in comparison with EN 338 experimental value. This study recommends the enhancement of the bending strength, density and modulus of elasticity of a typical non-durable solid Obeche timber beam by 38 %, 47 % and 35 % respectively with 40 % durable Opepe timber in a combined glulam form using PVA adhesive for engineering construction purposes.
... Thus, the commercial production of coconut wood lumber can be found just in smallscale businesses [6]. Recently, coconut wood has gained attention as alternative raw material for producing mass timber products such as glued laminated timber [7] and cross-laminated timber [8,9], increasing its value and utilization volume while reducing waste as a plantation crop. Although some experimental studies were conducted on coconut wood's physical and mechanical properties [10][11][12][13][14][15], comprehensive research on the engineering properties, such as embedment properties, is required to adopt this material in building construction. ...
... As expressed in Eq. (7), the bearing area is projected from the dowel making the bearing width equal to the dowel diameter. However, Hong and Barrett [37] reported that the stress distribution around the dowel bearing area disperses perpendicular to the loading direction more as the dowel diameter increases, indicating that the effective bearing area is greater than the area defined in Eq. (7). Moreover, this stress distribution trend becomes more severe when the dowel is loaded perpendicular to the grain, as shown in Figs. 14 and 15. ...
Different from most species of monocot clade, palm trees (Arecaceae) have woody materials which could be used for construction. However, the engineering embedment properties of coconut wood are not available in modern building codes. In this study, half-hole dowel embedment experiments, according to ASTM D5764-97a, were conducted on coconut wood with three dowel diameters in directions parallel and perpendicular to the grain for the full range of densities. The results showed that the empirical equations for common structural wood in an internationally acknowledged wood design standard overestimate the embedment strength of coconut wood by 32.9% on average.
... Another factor that strongly influences the bending properties of glulam is the combination of wood species. Kusnindar et al. [42] tested combined glulam, whereby using a denser wood species in the outer lamellae resulted in a 28 % increase in modulus of elasticity. This finding is consistent with our results, as the use of alder in the central lamellae and beech in the outer lamellae resulted in a 46.24 % increase in modulus of elasticity. ...
This study investigates the effect of cyclic temperature variation on the bending properties of glued laminated timber made from combinations of wood species. One hundred sixty timber beams were created from three species, Norway spruce (Picea abies (L.) H. Karst.), Black alder (Alnus glutinosa (L.) Gaertn.), and European beech (Fagus sylvatica L.), which were chosen to represent hardwood and softwood species. Beams were glued together using one-component polyurethane (1C PUR) adhesive according to a combination key, with the verification series consisting of beams glued together from a single species. The beams were split into four groups, with three of them undergoing temperature cycling (-25 °C and + 60 °C) and the fourth serving as a reference. The bending characteristics, namely modulus (MOE) of elasticity and bending strength (MOR), were investigated. As a result, the cycling of our chosen temperatures does not affect the density change in the beams. The modulus of elasticity (MOE) was significantly negatively affected for the single species beams, while it was not affected for the combinations of wood species. Bending strength (MOR) was also negatively affected by temperature, especially for the hardwood species; generally, there was an increase in bending strength for the combined GLT. Density in combined beams showed an increase compared to alder and spruce and a decrease compared to beech. The mechanical properties were affected by a significant increase compared to the softwood species.
The fire performance of glulam beams of high-quality structural materials was examined in this study. Beam specimens of different wood species were subjected to different fire durations and their tension-zone (bottom) fire performance and residual bearing capacity were measured. The charring rate of the Chinese fir glulam beam mixed Douglas fir and larch wood in the tension-zone was lower and its residual bearing capacity higher than a pure Chinese fir glulam beam. A set of residual section calculation results was compared with the test values to determine their feasibility in evaluating the fire performance of mixed species glulam beams. The error between the test and calculated values was less than 10%. This research could achieve effective use of low-quality fast-growing wood (Chinese fir) and save costs. In addition, the residual bearing capacity of these beams was increased by 69.1–245.4% compared with Chinese fir glulam beams.
