scholarly journals EXPERIMENTAL INVESTIGATION OF LOAD-BEARING CAPACITY AND DEFLECTIONS OF FULL-SCALE GLUED LAMINATED TIMBER BEAMS

2020 ◽  
Vol 2 (61) ◽  
pp. 5-11
Author(s):  
S. Shekhorkina ◽  
◽  
К. Shliakhov ◽  
А. Sopilniak ◽  
◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Strength Class ◽  
Failure Load ◽  
Timber Structures ◽  
Load Bearing Capacity ◽  
Concentrated Load ◽  
Load Bearing ◽  
Glued Laminated Timber ◽  
Deformation Properties ◽  
Timber Beams

With the transition to the design of timber structures in accordance with European standards, problems arise in assessment of the load-bearing capacity of glued timber structures that are caused by insufficient amount of data about the physical, mechanical and deformation properties of glued timber, which is produced in Ukraine. The aim of the work was to determine the load bearing capacity in bending and deflection of a glued timber beam under the action of a concentrated load in the middle of the span. Two glued laminated timber beams were used in the experiment. Both beams were made using lumber from pine wood and a moisture-curing onecomponent polyurethane adhesive Kleiberit PUR 510 FiberBond. The beams have the dimensions of the cross-section: width of 120 mm and height of 180 mm. The length of the beams was 9880 mm. Each beam consisted of 9 layers of 20 mm thick lamellas glued together. Considering the absence of the data on the strength class of the beam material, the theoretical load bearing capacity and deflection were determined according to the characteristics of the GL24h class (minimum strength class), and amounted to 722 kgf and 19.1 cm, respectively. As a result of the tests, the failure load and the deflection of the beams were determined, and the dependences of the deflection on the load were obtained. The actual deflection of the beams determined was 251 mm and 275 mm, which is 1.31 and 1.44 times higher than the predicted deflection. Accordingly, the failure load determined experimentally is 1.96 and 2.03 times higher than the theoretical value. During the tests, the features of the deformation and the nature of the destruction of the beams were investigated. Wherein, the determining factor was the presence of defects in timber and lamellas joints along the length in the most stressed layers. Based on the data obtained, recommendations on manufacturing aimed at the increasing the bending strength of glued laminated timber beams are given. The results obtained will be further used in the development of structural solutions for hybrid timber-concrete floors.

Experiments on Wall Panels with One-Sided Board Sheathing for Timber Structures

2017 ◽  
Vol 1144 ◽  
pp. 3-8
Author(s):  
Jiří Celler ◽  
Jakub Dolejs ◽  
Vera Hlavata
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Timber Structures ◽  
Bearing Material ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Glued Laminated Timber ◽  
Wall Panels ◽  
The Stability ◽  
Shaped Cross Section

Timber elements with an I-shaped cross-section are used as supporting elements in wall, ceiling and roof panels of light timber frames. The reinforcement of the panel (I-stud) is provided by means of glued timber composite I-shaped element consisting of a web made of a wood-based desk embedded into flanges of solid or glued laminated timber. The stability of the wall panels is usually ensured by sided board sheathing, which prevents buckling of studs in the plane of the wall or their twist. Walls with one-side board sheathing are used for some types of modern timber structures and their load bearing capacity is determined for situation when one-side sheathing burns down during fire or sheathing is not made of a load-bearing material.

Deflection behavior and load-bearing period of structural glued laminated timber beams in fire including cooling phase

2018 ◽  
Vol 9 (4) ◽  
pp. 287-299
Author(s):  
Hitoshi Kinjo ◽  
Yusuke Katakura ◽  
Takeo Hirashima ◽  
Shuitsu Yusa ◽  
Kiyoshi Saito
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Shear Failure ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Content Type ◽  
Glued Laminated Timber ◽  
Cooling Phase ◽  
Timber Beams

Purpose This paper aims to discuss the fire performance of glulam timber beams based on their deflection behavior and load-bearing period, which were obtained from load-bearing fire tests under constant load conditions. Design/methodology/approach In this report, the fire performance, primarily deflection behavior and load-bearing period of glued laminated (glulam) timber beams will be discussed from the standpoint of load-bearing fire tests conducted during the cooling phase under constant load conditions. Then, based on the charring depth and the per section temperature transformation obtained from loading test results, the load-bearing capacity of the glulam timber beams will be discussed using the effective section method and the strength reduction factor, which will be calculated in accordance with the European standards for the design of timber structures (Eurocode 5). Findings In the cooling phase, the charring rate is decreases. However, as the temperature in the cross section rises, the deflection is increases. The failure mode was bending failure because of tensile failure of the lamina at the bottom of the beam. Moreover, a gap caused by shear failure in a growth ring in the beam cross-section in the vicinity of the centroid axis was observed. Shear failure was observed up until 1 to 3 h before end of heating. The calculated shear strength far exceeded the test results. Shear strength for elevated temperature of glued laminated timber is likely to decrease than the shear strength in Eurocode 5. Originality/value Unlike other elements, a characteristic problem of timber elements is that their load-bearing capacity decreases as they are consumed in a fire, and their bearing capacities may continue to degrade even after the fuel in the room has been exhausted. Therefore, the structural fire performance of timber elements should be clarified during not only the heating phase but also the subsequent cooling phase. However, there are few reports on the load-bearing capacity of timber elements that take the cooling phase after a fire into consideration.

scholarly journals The Influence of CFRP Sheets on the Load-Bearing Capacity of the Glued Laminated Timber Beams under Bending Test

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4019
Author(s):  
Klaudia Śliwa-Wieczorek ◽  
Krzysztof Adam Ostrowski ◽  
Justyna Jaskowska-Lemańska ◽  
Anna Karolak
Keyword(s):  
Bearing Capacity ◽  
Standard Procedure ◽  
Bending Test ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Existing Structures ◽  
Reinforced Beams ◽  
Glued Laminated Timber ◽  
Before And After ◽  
Timber Beams

Composite materials are increasingly used to strengthen existing structures or new load-bearing elements, also made of timber. In this paper, the effect of the number of layers of Carbon Fiber Reinforced Polymer (CFRP) on the load-bearing capacity and stiffness of Glued Laminated Timber beams was determined. Experimental research was performed on 32 elements—a series of eight unreinforced beams, and three series of eight reinforced beams: with one, three and five layers of laminate each. The beams with a cross-section of 38 mm × 80 mm and a length of 750 mm were subjected to the four-point bending test according to standard procedure. For each series, destructive force, deflection, mode of failure, and equivalent stiffness were determined. In addition, for the selected samples, X-ray computed tomography was performed before and after their destruction to define the quality of the interface between wood and composite. The results of the conducted tests and analyses showed that there was no clear relationship between the number of reinforcement layers and the load-bearing capacity of the beams and their stiffness. Unreinforced beams failed due to tension, while reinforced CFRP beams failed due to shear. Despite this, a higher energy of failure of composite-reinforced elements was demonstrated in relation to the reference beams.

scholarly journals An Analysis of the Load-Bearing Capacity of Timber-Concrete Composite Beams with Profiled Sheeting

2017 ◽  
Vol 27 (4) ◽  
pp. 143-156 ◽  
Author(s):  
Maciej Szumigała ◽  
Ewa Szumigała ◽  
Łukasz Polus
Keyword(s):  
Numerical Analysis ◽  
Bearing Capacity ◽  
Concrete Slab ◽  
Composite Beams ◽  
Concrete Slabs ◽  
Timber Beam ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Shear Connectors ◽  
Timber Beams

Abstract This paper presents an analysis of timber-concrete composite beams. Said composite beams consist of rectangular timber beams and concrete slabs poured into the steel sheeting. The concrete slab is connected with the timber beam using special shear connectors. The authors of this article are trying to patent these connectors. The article contains results from a numerical analysis. It is demonstrated that the type of steel sheeting used as a lost formwork has an influence on the load-bearing capacity and stiffness of the timber-concrete composite beams.

Estimation of Load-Bearing Capacity and Stiffness of Timber Beams with Through-Thickness Cracks

2013 ◽  
Vol 778 ◽  
pp. 361-368
Author(s):  
Anatoly Yakovlevich Naychuk
Keyword(s):  
Crack Length ◽  
Bearing Capacity ◽  
Cross Section ◽  
Span Length ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Crack Location ◽  
Crack Tips ◽  
Beam Height ◽  
Timber Beams

The results of experimental and theoretical study of the load-bearing capacity and stiffness of wooden beams with through-thickness cracks depending on their length and location throughout the height of cross-section are given. The analysis of the regularity of change of stress-strain state, stress intensity factors (SIF) and at crack tips, deflections and timber beams load-bearing capacity depending on beam span length versus cross-section height, crack length versus span length, crack location throughout beam height was made. It has been established that load-bearing capacity and stiffness of timber beams with through-thickness cracks depends not only on the crack length, but its location throughout cross-section height as well. Procedure of assessing load-bearing capacity and stiffness of timber beams with through-thickness cracks based on fracture mechanics methods is given.

Experimental Study on Deformation Properties of Lining Structure of Hydraulic Tunnel

2011 ◽  
Vol 105-107 ◽  
pp. 1320-1325
Author(s):  
Shi Lang Xu ◽  
Wei Shen
Keyword(s):  
Bearing Capacity ◽  
Water Pressure ◽  
Interaction Force ◽  
Surrounding Rock ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Water Seepage ◽  
Deformation Properties ◽  
Lining Structure ◽  
Stress And Deformation

A large-scale indoor model test with water pressure is conducted in order to investigate the stress and deformation properties of reinforced concrete lining structures with circular cross-sections. After lining structure cracks, the stress and deformation of reinforcement in lining structures tend to decrease. Although the interaction force between lining structure and surrounding rock increases with the increase of water pressure, but the ratio of interaction force and water pressure decreases, which reveals that the load-bearing capacity of lining structures decreases, and surrounding rock gradually performs as the primary load-bearing body. The internal water pressure carried by lining structure is about 20%~40% of water pressure before cracking and less than 30% after cracking. Test results illustrate that surrounding rock and inner water seepage significantly influence the stress and deformation properties of lining structure, and inner water seepage is the main reason for the reduction of load-bearing capacity of lining structures.

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