scholarly journals Glulam beams: Performance of PVA and PUR adhesives on bending strengths of locally selected Nigerian timber species

2021 ◽  
Vol 40 (3) ◽  
pp. 363-370
Author(s):  
C. Arum ◽  
I.O. Olofintuyi ◽  
O.O. Ekundayo
Keyword(s):  
Flexural Strength ◽  
Timber Species ◽  
Structural Members ◽  
Gmelina Arborea ◽  
Structural Applications ◽  
Different Types ◽  
Loading System ◽  
Failure Loads ◽  
Bending Loads ◽  
Continuous Use

The applicability of structural timber to construction is due to its desirable qualities such as lightweight, aesthetics and eco-friendliness. However, continuous use of timber for structural purposes comes with the challenge posed by the anisotropic nature of various timber species. Advanced societies have developed and modified their sawn timber species in form of glue-laminated structural members such as beams, columns, joist etc. Nigeria timber species are yet to be fully explored along glued-laminated beams production. This paper assesses the suitability of three selected Nigerian timber species namely; Gmelina Arborea (ML), Terminalia superba (AF) and Pycnanthus angolensis (AK) for production of glued-laminated (glulam) beams. They are locally known respectively as Melina (ML), Afara (AF) and Akomu (AK). The applicability and glue-ability of the glues and their ultimate effect on the flexural strength were investigated through the use of two different types of glue components namely; polyvinyl acetate (PVA) and polyurethane (PUR) glue. The physical properties of the timber species such as moisture content (MC) and densities were determined using BS EN 408. The beams produced which are 1680mm by 150mm by 120mm in dimension were subjected to two points loading system to determine their flexural strengths and failure loads in accordance with ASTM D-198. The flexural strengths results indicated that Pycnanthus angolensis offered most resistance to bending loads with an average flexural strength value of 16.04N/mm2 when PUR glue was used and 13.04N/mm2 when PVA glue was used. The ANOVA result showed that glue types have significant effect on the flexural strength at confidence level of 95%. It was concluded that Pycnanthus angolensis is most suitable for structural applications. PUR is considered the better glue in terms of strength and glue-ability while PVA glue is considered better in terms of workability and applicability based on almost perfect glue line integrity achieved.

scholarly journals A Study on the Effect of Hollow Tubular Flange Sections on the Behavior of Cold-Formed Steel Built-Up Beams

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Balaji Shanmugam ◽  
Manikandan Palanisamy ◽  
Paul O. Awoyera ◽  
Senthilnathan Chinnasamy ◽  
Mahalakshmi Subramaniam
Keyword(s):  
Flexural Strength ◽  
Failure Modes ◽  
Flexural Behavior ◽  
Test Results ◽  
Structural Members ◽  
Iron And Steel ◽  
Loading System ◽  
Failure Loads ◽  
Cold Formed Steel ◽  
The Web

This paper deals with a study conducted on flexural behavior of cold-formed steel built-up I-beams with hollow tubular flange sections. There were two types of test sections, namely, built-up sections that were assembled with either stiffened or unstiffened channels coupling back-to-back at the web and a hollow tubular rectangular flange at the top and bottom of the web to form built-up I-beam. The flexural behavior along with the strength and failure modes of the built-up sections was examined using the four-point loading system. Nonlinear finite element (FE) models were formulated and validated with the experimental test results. It was observed that the developed FE models had precisely predicted the behavior of built-up I-beams. Further, the verified FE models were used to conduct a detailed parametric study on cold-formed steel built-up beam sections with respect to thickness, depth, and yield stress of the material. The flexural strength of the beams was designed using the direct strength method as specified in American Iron and Steel Institute (AISI) for the design of cold-formed steel structural members and was compared with the experimental results and the failure loads predicted from FE models. Since the results were not conservative, a new customized design equation had been mooted and delineated in the study for determining the flexural strength of cold-formed steel built-up beams with hollow tubular flange sections.

scholarly journals Biaxial flexural strength of different types of monolithic zirconia

2019 ◽  
Vol 22 (1) ◽  
pp. Process
Author(s):  
Shereen Ahmed Nossair ◽  
Tarek Salah ◽  
Kamal Khaled Ebeid
Keyword(s):  
Flexural Strength ◽  
Zirconia Ceramic ◽  
Group 4 ◽  
Dental Esthetics ◽  
Biaxial Flexural Strength ◽  
Different Types ◽  
Monolithic Zirconia ◽  
Group 5 ◽  
Group 2 ◽  
Post Hoc

Objective: This study was designed to evaluate the biaxial flexural strength (BFS) of different types of unshaded and shaded monolithic zirconia. Material and Methods: 120 monolithic zirconia ceramic discs were fabricated. They were divided into twelve groups (n=10), Group 1; Bruxzir unshaded, Group 2; Bruxzir shaded A2, Group 3; Bruxzir anterior white, Group 4; Bruxzir anterior shade A2, Group 5; Prettau unshaded, Group 6; Prettau shaded with A2 coloring liquid, Group 7; Prettau anterior white, Group 8; Prettau anterior shaded with A2 coloring liquid, Group 9; Katana HT white, Group 10; Katana HT shade A2, Group 11; Katana ST white, Group 12; Katana ST shade A2. All discs were milled using a dental milling machine, and had final dimensions after sintering of 15 mm diameter and 1 mm thickness. BFS was tested using piston on three ball technique. Results:  One-way ANOVA revealed significant differences among the 12 groups. Tukey post-hoc tests revealed no significant differences between the groups 3, 4, ,7 ,8 11, and 12. However, they all had BFS values that are significantly lower than all other groups. Group 2 showed statistically significant higher BFS values when compared to group 3,4, 7, 8, 11, and 12 while it showed statistically significant lower values when compared to groups 1, 5, 6, 9, and 10. Conclusion: Increase in the yttria content in zirconia led to a decrease in its BFS. Shading of zirconia did not have a significant effect on the final strength of zirconia. KeywordsDental ceramics; Dental esthetics; Flexural strength; Shaded zirconia. 

scholarly journals ANALYSIS OF PROPERTIES OF CONCRETE USING STEEL FIBERS AS FIBER REINFORCEMENT ADMIXTURE

2017 ◽  
Vol 5 (4RASM) ◽  
pp. 59-62
Author(s):  
Vishal Gadgihalli ◽  
Meena ◽  
Sindu ◽  
Raghavendra Prasad Dinakar
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Steel Fibre ◽  
Fiber Reinforcement ◽  
Paper Analysis ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Different Types ◽  
Discrete Uniform

Fiber reinforced concrete is composite material consisting of mixtures of cement, mortar or concrete, discontinuous discrete uniform dispersed suitable fibers. Fiber reinforced concrete are of different types and properties. In this paper analysis of properties of concrete using steel fibre as fiber reinforcement admixture is studied and verified the strength of concrete to normal plane concrete with absence of admixtures. Using steel fibers as fiber reinforcement admixture increases bond strength by enhancing surface tension as steel is better in taking flexural strength this gives better results, hence we can use this steel fiber reinforcement to concrete where the compressive and flexural strength place a crucial role in construction and maintenance.

scholarly journals Selección de Árboles Semilleros en Plantaciones Forestales de la Península de Santa Elena. Ecuador.

2017 ◽  
Vol 4 (2) ◽  
Author(s):  
Juan Valladolid Ontaneda ◽  
Ángel León Mejía ◽  
Daniel Paredes Flores
Keyword(s):  
Morphological Characteristics ◽  
Timber Species ◽  
Cedrela Odorata ◽  
Gmelina Arborea ◽  
Forest Species ◽  
Swietenia Macrophylla ◽  
Cordia Alliodora ◽  
Santa Elena ◽  
Number Of Seeds ◽  
Selection Of

El estudio de selección de árboles semilleros se realizó en las comunas Olón, Dos Mangas y Salanguillo del cantón Santa Elena, provincia de Santa Elena, Ecuador. El objetivo del estudio fue, identificar, caracterizar y seleccionar árboles semilleros de especies maderables con buenas características morfológicas, y que permitan disponer de semillas para trabajos de propagación de especies forestales en viveros con fines de reforestación. El estudio se inicia con la identificación y ubicación de plantaciones forestales de varias especies forestales establecidas entre los años 2000 a 2005, en las plantaciones se evaluaron las características dasométricas y morfológicas, las que permitieron seleccionar 11 árboles con características morfológicas deseables correspondientes a cinco especies forestales laurel blanco(Cordia alliodora), laurel negro(Cordia megalantha), caoba (Swietenia macrophylla), cedro (Cedrela odorata) y melina (Gmelina arbórea); cada árbol fue georreferenciado utilizando coordenadas UTM Datum WGS 1984 Zona 17M. La cantidad de semillas que pueden producir dichas especies forestales es proyectada por año la cual servirá como referencia para establecer programas de reforestación con materiales propios y adaptados a las condiciones ambientales en la provincia de Santa Elena Abstract  The study of selection of seed trees was carried out in the Olón, Dos Mangas and Salanguillo communes of the canton Santa Elena, Santa Elena province, Ecuador. The objective of the study was to identify, characterize and select seedlings of timber species with good morphological characteristics, and to allow seeds to be used for the propagation of forest species in nurseries for reforestation purposes. The study began with the identification and location of forest plantations of several forest species established between 2000 and 2005, on the plantations, the dasometric and morphological characteristics were evaluated, allowing the selection of 11 trees with desirable morphological characteristics corresponding to five forest species White laurel (Cordia alliodora), black laurel (Cordia megalantha), mahogany (Swietenia macrophylla), cedar (Cedrela odorata) and melina (Gmelina arborea); Each tree was georeferenced using coordinates UTM Datum WGS 1984 Zone 17M. The number of seeds that can produce these forest species is projected per year which will serve as a reference to establish reforestation programs with their own materials and adapted to the environmental conditions in the province of Santa Elena.

scholarly journals Comparison of Parallel Dowel-Bearing Strength of Mengkulang, Kempas and Pine Glulam between ASTM D 5764-97a and BS EN 383: 2007

2018 ◽  
Vol 7 (3.11) ◽  
pp. 206
Author(s):  
Nor Jihan A. Malek ◽  
Rohana Hassan ◽  
Azmi Ibrahim ◽  
Hussein M. H. Almanea ◽  
Tee H. Hean
Keyword(s):  
Moisture Content ◽  
Strength Test ◽  
Wood Moisture Content ◽  
Timber Species ◽  
Wood Moisture ◽  
Bearing Strength ◽  
Significant Parameter ◽  
Different Types ◽  
Wood Grain ◽  
Bolt Diameter

Dowel-bearing strength is a significant parameter for designing wood connection. The strength of timber connection can be influenced by the bolt diameter, wood grain direction either parallel or perpendicular, thickness of wood, moisture content and other parameters. The dowel-bearing strength test was conducted with a 12 mm bolt diameter dowel, for three different types of timber species, which were mengkulang (Heritiera sp.), kempas (Koompassia malaccensis) and pine (Pinus sp.) glulam. The dowel was placed parallel to the timber grain direction with a glue line at the center of the half-hole test. The 5% diameter offset load (F5%) for dowel-bearing strength (Fy) was determined by using the ASTM D 5764-97a whereas the dowel-bearing strength (Fh) was determined based on BS EN 383: 2007. The results of the three different types of wood showed that the Malaysian timber kempas and mengkulang were 51.740% and 32.966%, respectively, which were higher than the European timber pine. The results of the dowel-bearing strengths (Fh), which were based on the BS EN 383: 2007 gave higher values compared to ASTM D 5764-97a.  

scholarly journals A Pilot Study on the Flexural Properties of Vinyl Ester Composites Filled with Glass Powder

2010 ◽  
Vol 123-125 ◽  
pp. 3-6
Author(s):  
Harry Ku ◽  
Mohan Trada ◽  
Rezwanul Huq
Keyword(s):  
Flexural Strength ◽  
Vinyl Ester ◽  
Glass Powder ◽  
Filler Content ◽  
Flexural Modulus ◽  
Research Centre ◽  
Flexural Properties ◽  
Structural Applications ◽  
Flexural Tests ◽  
Sufficient Strength

Vinyl ester resin was filled with of glass powder with a view to increasing the flexural strength of the composites for civil and structural applications by a research Centre on composites, University of Southern Queensland (USQ). In order to reduce costs, the Centre wishes to fill as much glass powder as possible to the resin subject to maintaining sufficient strength of the composites in civil and structural applications. This project varies the percentage by weight of the glass powder in the composites, which are then subjected to flexural tests. The flexural strength and strain of the glass powder filled vinyl ester composites decreased with increasing filler content but the flexural modulus was highest at 20 w/t % of glass powder. Scanning Electron Microscope (SEM) was used to analyze the fractured samples and it was found that the fractured surfaces examined were correlated with the flexural properties.

scholarly journals The Effect of Fire on the Strength of Concrete Material

2021 ◽  
Vol 12 (1) ◽  
pp. 63-68
Author(s):  
HM Iqbal Mahmud ◽  
Md Kawser Babu Raju ◽  
Md Lokman Hosen
Keyword(s):  
Experimental Investigation ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Engineering Science ◽  
Structural Members ◽  
Concrete Material ◽  
Two Systems ◽  
Forced Cooling ◽  
In Fire

Structural members exposed to fire may damage considerably, lose their durability, and even collapse due to the failure of the members. This work presents the results of an experimental investigation of the effect of fire on the strength of concrete. Cylindrical and beam specimens were prepared and burnt in the fire for one hour. In both cases, two systems were followed for cooling the samples, (i) natural cooling in the air (ii) forced cooling in the water. Afterwards, the compressive and flexural strength of the specimens were determined. The result shows that the strength of concrete was considerably reduced due to burning in fire. The compressive strength of cylindrical specimens was decreased by 44% and 60%, respectively, for the natural and forced cooling of the specimens. In the case of beam samples, the flexural strength was decreased60% and 69%, respectively, for the natural and forced cooled specimens. This research also reveals that the specimen cooled in air showed better performance compared to that cooled in water. Journal of Engineering Science 12(1), 2021, 63-68

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