1. Experimental investigation of the shear force capacity of prismatic cross laminated timber beamsHenrik Danielsson, Tomaž Pazlar, Erik Serrano, Boris Azinović, 2024, izvirni znanstveni članek Povzetek: Experimental tests of Cross Laminated Timber (CLT) under in-plane beam loading conditions are presented. The influence of the element layup, the individual lamination width, and the beam overhang at the supports on the shear force capacity was investigated. All the CLT beams had the same gross cross section, and a 4-point-bending test setup was used. The experimentally determined load-bearing capacities are compared with the load-bearing capacities resulting from analytical methods proposed for structural design, focusing on shear failure in the crossing areas of flatwise bonded laminations (shear failure mode III). The test results indicate no or very small influence of the element layup and the lamination width on the shear force capacity. These results partly contradict the predictions of the proposed design methods. Of the three studied beam geometry parameters, the beam overhang at the support had the greatest influence on the load-bearing capacity.
Ključne besede: cross laminated timber, CLT, beam, shear testing, shear capacity, design methods
Objavljeno v DiRROS: 15.04.2024; Ogledov: 146; Prenosov: 75
 Celotno besedilo (3,32 MB)
Gradivo ima več datotek! Več... |
2. Preiskave lesenih okvirnih stenskih panelov s cementno-ivernimi obložnimi ploščamiMeta Kržan, Tomaž Pazlar, Ivan Grašič, Boštjan Ber, 2020, izvirni znanstveni članek Povzetek: V članku so predstavljeni rezultati eksperimentalnih preiskav študije obnašanja lesenih okvirnih stenskih panelov s cementno-ivernimi obložnimi ploščami pri horizontalnih obremenitvah. Posebnost predstavljene preiskave je uporaba cementno-ivernih plošč pri proizvodnji okvirnih stenskih panelov, saj njihovo obnašanje še ni dobro raziskano. Preiskave so bile izvedene v dveh fazah. Ker je za strižno obnašanje panela bistveno pritrjevanje obložnih plošč na leseni okvir, so se na manjših vzorcih najprej določile nosilnosti zvez s kovinskimi paličastimi sponkami ter analiziral vpliv debelin plošč in razmika med sponkami. Nadalje so bile zasnovane in izvedene monotone in ciklične strižne preiskave različnih izvedb stenskih panelov. Preskušani so bili trije osnovni tipi panelov, med drugim tudi panel z različnima debelinama obložnih plošč. Rezultati preiskave kažejo ugoden duktilen odziv sten pri strižnih obremenitvah ter potrjujejo, da nosilnost sten zaradi različnih debelin obložnih plošč ni dodatno zmanjšana, kot to pri izračunu nosilnosti predvideva SIST EN 1995-1-1. Ključne besede: leseni okvirni stenski paneli, cementno-iverna plošča, strižni preskus, nosilnost sponke v eni strižni ravnini.
Ključne besede: leseni okvirni stenski paneli, cementno-iverna plošča, ciklični strižni preskus, nosilnost sponke v eni strižni ravnini
Objavljeno v DiRROS: 04.12.2023; Ogledov: 244; Prenosov: 94
Celotno besedilo (1,84 MB)
Gradivo ima več datotek! Več... |
3. Experimental investigation of the axial strength of glued-in rods in cross laminated timberBoris Azinović, Erik Serrano, Miha Kramar, Tomaž Pazlar, 2018, izvirni znanstveni članek Povzetek: This paper presents results from an experimental assessment of glued-in rods in cross laminated timber (CLT). For the purposes of the study more than 60 pull-pull tests were performed, where the specimens varied in terms of bonded-in length (from 80 to 400 mm), rod diameter (16-24 mm) and rod-to-grain angle (parallel and perpendicular). Several different failure modes that are not common for other applications of glued-in rods (e.g., a failure between CLT layers) were obtained for the analysed CLT specimens. It was found that these failure mechanisms can substantially influence the obtained ultimate tension loads. At the end, the experimental results were compared with empirical and semi-empirical equations for estimating the pull-out strength of glued-in rods in structural timber and glulam. The comparison showed that most of the existing equations overestimate the ultimate tension loads for specimens with the rod parallel to the grain and underestimate the ultimate tension load for specimens with the rod perpendicular to the grain. The results vary because the possible CLT failure modes were not included in previous studies. Further studies are proposed to improve the equations for glued-in rods in CLT.
Ključne besede: glued-in rods, cross laminated timber (CLT), pull-pull experiment, glued-in length, rod-to-grain angle, failure mechanisms in CLT
Objavljeno v DiRROS: 29.11.2023; Ogledov: 225; Prenosov: 179
Celotno besedilo (4,13 MB)
Gradivo ima več datotek! Več... |
4. Improving the flame retardancy of wood using an eco-friendly mineralisation processAndreja Pondelak, Andrijana Sever Škapin, Nataša Knez, Friderik Knez, Tomaž Pazlar, 2021, izvirni znanstveni članek Povzetek: A novel environmentally friendly method for in situ formation of CaCO3 deep inside a wood’s structure is presented. The method is based on vacuum-pressure impregnation using a one-component treatment medium – a water solution of calcium acetoacetate - and a single stage process to significantly improve the fire retardancy of the treated material.
Ključne besede: mineralisation, flame retardancy, calcium acetoacetate, calcium carbonate, wood
Objavljeno v DiRROS: 31.07.2023; Ogledov: 318; Prenosov: 218
Celotno besedilo (2,69 MB)
Gradivo ima več datotek! Več... |
5. The influence of flexible sound insulation layers on the seismic performance of cross laminated timber wallsBoris Azinović, Tomaž Pazlar, Meta Kržan, 2021, izvirni znanstveni članek Povzetek: This paper presents the results of an experimental campaign investigating the seismic behaviour of full-size cross laminated timber (CLT) wall systems with sound-insulated shear-tension angle brackets. The main aim of the study was to investigate the influence of more and less flexible soundproofing bedding under the CLT wall. The paper shows a comparison of lateral load-bearing capacity, displacement capacity, ductility and stiffness obtained from racking tests on uninsulated specimens and specimens with various types of bedding insulation and levels of vertical load. Moreover, an analytical procedure to estimate the lateral load-displacement response of CLT walls with bedding insulation is proposed. This model is verified by direct comparison to the experimentally determined lateral load-displacement backbone curves. The results show that the elastomeric bedding does not have a significant effect on the bearing capacity of the wall system tested, but it reduces the stiffness and increases the displacement capacity. Due to the large decrease in stiffness, the insulation causes an overall reduction in ductility. The analytical estimation proposed was able to capture the reduction in lateral stiffness and adequately predict the load-bearing capacity.
Ključne besede: CLT wall system, insulated angle bracket, elastomer sound insulation, racking tests, lateral load-bearing capacity, stiffness, open access
Objavljeno v DiRROS: 26.06.2023; Ogledov: 302; Prenosov: 237
Celotno besedilo (9,10 MB)
Gradivo ima več datotek! Več... |
6. Improved seismic response of light-frame-timber panels with cement-particle-board sheathing of various thicknesses and different configurations of fastenersMeta Kržan, Tomaž Pazlar, Boštjan Ber, 2022, izvirni znanstveni članek Povzetek: Due to their comparable fire characteristics and surface preparation, light-frame timber panels using cement-particle boards (CPB) as a sheathing material present a potential alternative to gypsum-fibre boards. An experimental campaign was conducted to evaluate the behaviour of CPB light-frame-timber panels under in-plane lateral loading. Monotonic and cyclic in-plane shear tests were conducted on full-size panels, following preceding tests on the stapled sheathing-to-timber connections used in the panels. The influence of the boards’ thickness and staple geometry on the response of connections and panels was studied, also on panels with an asymmetrical CPB layout, which proved not to have a negative influence on the panels’ lateral load-bearing capacity. Furthermore, in order to improve the seismic response, panels, which had almost twice the number of staples compared to the basic panel, were tested; one variation with two rows of staples, and the other with the staples spaced closer together, such that the spacing distance was halved. The tests revealed a significant, though not proportional, increase in lateral resistance in the strengthened panels. Fastening the CPB with two rows of staples proved the better option, since subsequent failure of the CPB along the connections, as opposed to ductile failure of the staples in the basic panels, proved not to reduce the panels’ deformation capacity. The paper also compares the test results of the connections and panels to analytical results according to Eurocode 5 (EC5), the European code provision for the design of timber structures.
Ključne besede: light-frame timber panels, cement-particle board sheathing, cyclic shear tests, sheathing-to-timber connection, asymmetrical panel, staple spacing distance, EN 1995–1-1, open access
Objavljeno v DiRROS: 31.05.2023; Ogledov: 422; Prenosov: 202
Celotno besedilo (15,48 MB)
Gradivo ima več datotek! Več... |
7. Brittle failure of laterally loaded self-tapping screw connections for cross-laminated timber structuresBoris Azinović, José Manuel Cabrero, Henrik Danielsson, Tomaž Pazlar, 2022, izvirni znanstveni članek Povzetek: The performance of structural timber connections is of utmost importance since they control the global response of the building. A ductile failure mechanism on the global scale is desirable, especially in the design of structures in seismic areas, where dissipative components in which ductile failure modes need to be ensured are considered. Therefore, the knowledge of possible brittle failure modes of connections is crucial. The paper investigates the brittle failures of laterally loaded dowel-type connections in cross-laminated timber subjected to tensile load in a lap joint configuration through experimental investigations and analytical estimations. A set of 13 different test series has been performed with fully threaded self-tapping screws of 8 mm diameter and different lengths (40 to 100 mm) in cross-laminated timber composed of 3 or 5 layers (layer thickness range from 20 to 40 mm), giving rise to the activation of different brittle failure modes at different depths. Plug shear was among the most typically observed failure modes. A previously proposed model for the brittle capacity was applied to the tested connections at the characteristic level. As shown by the performed statistical analysis, the existing model is not reliable and mainly unconservative. A very low performance is observed (CCC = 0.299), but with a good correlation (c = 0.750) for the tests in the parallel direction. Further research work is required to improve the current model predictions and to gain a better understanding of the underlying resisting mechanisms.
Ključne besede: cross-laminated timber, dowel type fasteners, connections, brittle failure, experimental investigations, self tapping screws, open access
Objavljeno v DiRROS: 31.05.2023; Ogledov: 296; Prenosov: 215
Celotno besedilo (7,84 MB)
Gradivo ima več datotek! Več... |
8. Composite beams made of waste wood-particle boards, fastened to solid timber frame by dowel-type fastenersMeta Kržan, Tomaž Pazlar, Boštjan Ber, 2023, izvirni znanstveni članek Povzetek: To increase the sustainability of prefabricated timber buildings and constructions, composite timber beams with “box” cross-sections were developed in collaboration with an industry partner. They were constructed from a solid timber frame and from webs made of residual waste wood- particle boards from prefabricated timber buildings production. The developed beams’ design concepts presented in this paper were governed by architectural features of prefabricated timber buildings, geometrical limitations, available production technology, and structural demand related to various possible applications. The paper presents the results of experimental bending tests of six variations of the developed composite timber beams constructed by mechanical fasteners only. The developed design concept of composite timber beams without adhesives is beneficial compared to glued beams in terms of design for deconstruction and lower VOC emissions. The tests were conducted to study the influence of the following parameters on the beams’ mechanical behavior: (i) web material (oriented strand boards (OSBs) vs. cement-particle boards); (ii) the influence of beam timber frame design (flanges and web stiffeners vs. flanges, web stiffeners, and compressive diagonals), and (iii) the influence of stiffener–flange joint design. Besides the beams’ load-bearing capacities, their linear and non-linear stiffness characteristics were the main research interest. While adding compressive timber diagonals did not prove to significantly increase the stiffness of the beams in the case of cement-particle board webs, it increased their load-bearing capacity by enabling the failure of flanges instead of prior webs and stiffener–flange joints failure. For beams with OSB webs, failure of the bottom flange was achieved already with the “basic” timber frame design, but timber diagonals proved beneficial to increase the stiffness characteristics. Finally, mechanical characteristics of the developed beams needed in structural design for their application are provided together with further development guidelines.
Ključne besede: composite timber beam, box beam, OSB, cement-particle boards, innovative engineered wood product, experimental tests, flexural performance, mechanical fasteners, open access
Objavljeno v DiRROS: 29.05.2023; Ogledov: 287; Prenosov: 164
Celotno besedilo (7,82 MB)
Gradivo ima več datotek! Več... |
