World Conference on Timber Engineering
www.WCTE2012.com
Final Papers
Edited by Pierre Quenneville
Poster Papers
Dear WCTE 2012 delegates,
On behalf of the steering committee of the World Conference on Timber Engineering 2012, we are very pleased to introduce the Book of Abstracts. This reference document summarises the full papers that cover the state-of-the-art across the breadth of timber engineering, materials, connections, architecture and manufactured products.
This conference is hosted by the New Zealand Timber Design Society and our Australian colleagues. It is the first time that WCTE has returned to its roots which started with the Pacific Timber Engineering Conference in 1984.
To those who are present at WCTE 2012 in Auckland, the beautiful “City of Sails”, we welcome you and invite you to peruse the wide range of abstracts for the 240 oral presentations that you will have opportunity to hear, or over 100 posters to see and discuss.
Following the Christchurch earthquakes of last year and the Tohoku earthquake in Japan, the resilience and post disaster performance offered by timber structures has become increasingly of interest and is emphasised in the sessions devoted to seismic engineering and case studies.
Typical of last conferences, there are numerous presentations on connections, materials, lateral load resisting systems and CLT. Architecture is specially emphasized in the Wednesday sessions.
There is one book of abstracts for each day and the abstracts for the posters are included in the last book.
Finally, we wish to thank the sponsors and the various contributions from the support organisations. We especially wish to thank those who gave their time reviewing the very large number of abstracts.
Hugh Morris Pierre Quenneville
WCTE 2012 Chair WCTE2012 Technical Chair
construction.
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Timber Engineering Challenges and Solutions Till Vallée, Thomas Tannert, Quentin Gadais
INFLUENCE OF STRESS REDUCTION METHODS ON THE CAPACITY OF ADHESIVELY BONDED
TIMBER JOINTS 17
Jose R. Aira, Francisco Arriaga, Guillermo Íñiguez-González, Manuel Guaita, Miguel Esteban
ANALYSIS OF THE STRESS STATE OF A HALVED AND TABLED TRADITIONAL TIMBER SCARF
JOINT WITH THE FINITE ELEMENT METHOD 22
Mengting Tsai, Mikio Koshihara
THE RESEARCH OF PLAN MIXED HYBRID TIMBER STRUCTURE AND PARAMETRIC
EQUIVALENT BRACE STUDY OF FLOOR SLAB 27
Bo-Han Xu, Abdelhamid Bouchaïr, Mustapha Taazount
FINITE ELEMENT SIMULATION OF STEEL-TO-TIMBER JOINT IN TENSION WITH ANGLE
TO GRAIN 33
Kei Sawata, Masahiko Toda, Satoru Kanetaka, Takashi Harada, Yoshihisa Sasaki, Takuro Hirai
BENDING RESISTANCE OF REPAIRED COLUMNS AND STUDS OF WOODEN WALL 37 Hideyuki Honda
VIBRATION SERVICEABILITY OF BONGOSSI WOOD PEDESTRIAN BRIDGE 43 Yoshihiro Yamazaki, Kazuhiko Kasai, Hiroyasu Sakata
REDUCED EXPRESSION FOR TIMBER STRUCTURE WITH FLEXIBLE HORIZONTAL
DIAPHRAGM AND SEISMIC RESPONSE EVALUATION METHOD 49 Arch. Kobayashi Yoshihiro, Kamachi Ken, Inayama Masahiro
MOMENT RESISTING PERFORMANCE OF WEDGED AND HALVED SCARFED JOINTS,
OKKAKE-TSUGI IN PLASTIC REGION METHOD 55
Hidemaru Shimizu, Tatsuru Suda, Masatoshi Ogasawara, Seiyu Hashimoto, Tatsuo Okuda, Yoshiyuki Suzuki SEISIMIC PERFORMANCE OF TRADITIONAL WOODEN HOUSES DAMEDED IN THE 2011
PACIFIC COAST TOHOKU EARTHQUAKE 65
Wolfgang Winter, Werner Hochhauser, Alireza Fadai
TIMBER-GLASS COMPOSITE TRUSSES AND PLATES 69
Leandro Dussarrat Brito, Carlito Calil Junior
TOPICS ABOUT MANUAL OF DESIGN AND CONSTRUCTION OF STRUCTURES WITH ROUNDWOOD
FROM REFORESTATION IN BRAZIL 75
LONG –TERM EXPERIMENTAL TEST ON TIMBERCONCRETE COMPOSITE BEAMS 80 Liu Yan, She Chengang, Zou Xiaojing
TEST RESEARCH ON THE MECHANICAL PROPERTIES OF WOOD FRAME SHEAR WALLS UNDER
LATERAL LOAD 86
Weidong Lu, Erwei Song, Min He, Kong Yue, Weiqing Liu
EXPERIMENTAL STUDY ON BENDING CREEP BEHAVIOUR OF REINFORCED GLULAM BEAM 91 Takumi Ito, Wataru Kambe, Saki Kondo
AN EXPERIMENTAL STUDY ON RESISTANT MECHANISM OF PLYWOOD PANEL -STEEL
COMPOSITE MEMBER 97
Vanessa Baño, Julio Vivas, Soledad Rodríguez, Keith Crews
NUMERICAL AND EXPERIMENTAL ANALYSIS OF THE VERTICAL VIBRATIONS ON SEVERAL
DESIGNS OF TIMBER FOOTBRIDGES 101
Haruhiko Ogawa, Hisamitsu Kajikawa, Hiroyuki Noguchi
A STUDY ON HORIZONTAL RESISTANCE MECHANISM OF WOODEN FLOOR WITH OPENING 106 Wolfgang Gard, Nadine Montaruli, Jan-Willem van de Kuilen
END-OF-LIFE WOOD QUALITY OF MOORING POLES 112
Shiro Aratake, Atushi Shiiba, Hideki Morita
MECHANICAL PROPERTIES OF REAL-SIZE BEAMS SAWN UP FROM SUGI (CRYPTOMERIA
JAPONICA D.DON) CURVED LOGS 116
Koji Murata, Yuji Kurenuma, Takato Nakano
EFFECT OF THERMAL TREATMENT BASED ON HIGH-TEMPERATURE SETTING METHOD ON FRACTURE ENERGY OF WEDGE SPLITTING SPECIMEN MODELED 121 Wilfried Beikircher, Christian Lux
MICROWAVE PRETREATMENT OF NORWAY SPRUCE (PICEA ABIES) FOR PRESERVATIVE
TREATMENT 126
Jan Niederwestberg, Ying Hei Chui
CHARACTERIZING INFLUENCE OF LAMINATE CHARACTERISTICS ON ELASTIC PROPERTIES
OF SINGLE LAYER IN CROSS LAMINATED 130
Henry Meleki, Ian Smith, Andi Asiz
MOISTURE INDUCED DEFORMATIONS IN GLULAM MEMBERS – EXPERIMENTS AND
3-D FINITE ELEMENT MODEL 136
Atsushi Shiiba, Shiro Aratake, Hideki Morita
BENDING PERFORMANCE OF SUGI (CRYPTOMERIA JAPONICA) LUMBER SAWN PARALLEL TO
THE EDGE OF LARGE DIAMETER LOGS 144
Dr Geoffrey Boughton
A NEW ERA OF COMMERCIAL STRESS GRADING 152
Takashi Takeda, Yoshihiro Hosoo, Takahisa Yoshida
CHANGES OF MECHANICAL PROPERTIES OF JAPANESE LARCH SQUARE TIMBER KILN-DRIED BY THE HIGH-TEMPERATURE SETTING METHOD DURING VARIOUS STORAGES 157 Tomaž Pazlar, Jelena Srpčič, Mitja Plos, Goran Turk
STRENGTH GRADING OF SLOVENIAN STRUCTURAL TIMBER 163 Wilson Fabiano Ribeiro, Maiko Cristian Sedoski, Jorge Luís Nunes de Góes
ANALYSIS OF DIFFERENT WEB-TO-FLANGE JOINTS OF WOOD I-JOISTS COMPOSITE 169 Tomohiro Chida, Humihiko Gotou, Hidefumi Yamauchi, Takanobu Sasaki, Yasuo Okazaki, Yasuo Kawai, Yasuo Iijima THE FUNDAMENTAL STUDY OF THE PROPOSAL OF SHEAR FAILURE TEST METHOD AND
ESTIMATION OF PURE SHEAR STRENGTH OF JAPANESE CEDAR 173 Cecilia Alonso, Abdy Kermani
PERFORMANCE OF A MECHANICALLY LAMINATED TIMBER ARCHED SUSPENSION BRIDGE 179 Carlos Eduardo de Jesus Martins, Alfredo Manuel Pereira Geraldes Dias
SELECTION AND GRADING METHODS FOR MARITIME PINE UTILITY POLES 183 Njungab Emmanuel, Ntede N. Hippolyte, Regis Pommier, Ndikontar M. Kor, Ayina. O, Noah N. Joseph, Rene oum lissouk, Mpon Richard
‘GREEN; GLUING OF TWO TROPICAL TIMBERS 187
Meng Gong, Stephen Delahunty, Shuzhao Rao, Y. H. Chui
DEVELOPMENT OF A MATERIALS-EFFICIENT FINGERJOINT PROFILE FOR STRUCTURAL
FINGER-JOINED LUMBER 191
Geert Ravenshorst, Wolfgang Gard, Jan-Willem van de Kuilen
CLASSIFICATION AND SAMPLING OF TROPICAL WOOD SPECIES FOR STRENGTH AND
DURABILITY ASSIGNMENTS LUMBER 195
Yoshinori Ohashi, Susumu Kawamura, Takuro Hirai
MECHANICAL PROPERTIES OFWOODEN I-JOISTS WITH DIAGONAL PLYWOODWEBS 200 Harri Metsälä
THE POTENTIAL OF ASPEN TIMBER IN NORDIC WOODEN BUILDINGS 204 Lenka Melzerová, Petr Kuklík, Michal Šejnoha
SPECIFICATION OF FEM MODELS OF GLUED LAMINATED TIMBER WITH VARIABLE
LOCAL MODULUS OF ELASTICITY 208
MODE I FRACTURE TOUGHNESS FOR CRACK INITIATION BY CT TESTS AND THREE-POINTED-
BENDING TESTS WITH STRUCTURAL GLULAM 214
Eudir A. Affonso, Inácio M. Dal Fabbro, Mauro A. Demarzo
OPTICAL EXTENSOMETRY BY GEOMETRIC MOIRÉ DIGITAL ANALYSIS OF STRESS
IN THE PLANE – AN APPLICATION IN TIMBER 218
Steffen Franke, Pierre Quenneville
THE EMBEDDING BEHAVIOUR OF DOUGLAS FIR 224
Bettina Franke, Pierre Quenneville
INVESTIGATION OF THE SPLITTING BEHAVIOUR OF RADIATE PINE AND LVL UNDER
TENSION AND SHEAR 230
Andreas Rais, Jan-Willem G. van de Kuilen
PRE-GRADING OF DOUGLAS-FIR LOGS FOR GLULAM LAMELLA PRODUCTION 236 Alexandre Monteiro de Carvalho, Vitor Cesar Magnan Teixeira, Gustavo Cantarino Barata, Ananias Francisco Dias Junior, Rodrigo Braga de Almeida, Elaine Ferreira Avelino
EVALUATION OF PHYSICAL PROPERTIES AND MACHINING OF AFRICAN MAHOGANY
(KHAYA IVORENSIS A. CHEV.) WOOD 241
Xiaobin Song, Yunfan Zhang , Xianglin Gu, Weiping Zhang, Rui Jiang , Leo Ravel
NON-DESTRUCTIVE TESTING OF WOOD MEMBERS FROM EXISTING TIMBER BUILDINGS
BY USE OF ULTRASONIC METHOD 245
Eduard Correal-Mòdol, Marcel Vilches Casals
PROPERTIES OF CLEAR WOOD AND STRUCTURAL TIMBER OF PINUS HALEPENSIS FROM
NORTH-EASTERN SPAIN 251
Cláudio H. S. Del Menezzi
ASSESSING PROPERTIES OF TROPICAL HARDWOODS TO MANUFACTURE ENGINEERED
WOOD PRODUCTS 255
Jieying Wang, Chun Ni
REVIEW AND SURVEY OF DIFFERENTIAL MOVEMENT IN WOODFRAME CONSTRUCTION 261 Hui-Feng Yang, Wei-Qing Liu, Wei-Dong Lu, Ju Tang
EXPERIMENTAL STUDY ON THE BOND AND ANCHORAGE BEHAVIORS OF GLUED-IN
ROD JOINTS IN GLULAM 266
Emanuella S. R. Silva, Cláudio H. S. Del Menezzi, Mário R. Souza
EFFECT OF THE PRESSURE ON THE GLUE-LINE SHEAR STRENGTH OF TWO TROPICAL HARDWOODS
271 Hideyuki Hirasawa, Tomoya Yoshida, Jun Tonuma, Tetsuya Sato, Hiroshi Watanabe
TIMBER TRUSS BRIDGE FOR CASCADE USE 275
Mikio Koshihara
THE SECULAR CHANGE OF THE TIMBER BRIDGE “KINTAI-KYO” 284 Cinthia Dias Rocha, Elias Taylor Durgante Severo, Fred Willians Calonego, Cláudio Angeli Sansígolo
CHEMICAL PROPERTIES AND DECAY RESISTANCE OF EUCALYPTUS GRANDIS WOOD
FROM STEAMED LOGS 289
Mizuho Yasukawa, Asami Suzuki, Noboru Yasui, Yuji Hasemi, Naohisa Kameyama, Koji Toyoda, Naoya Kadooka, Daisuke Kamikawa, Mikio Koshihara, Tetsuro Ono
MECHANICAL PERFORMANCE OF HARDWOOD(ZELKOVA SERRATA) FRAME
ASSEMBLIES IN FIRE 293
Daniel P. Hindman, Lance D. Shields, Joseph R. Loferski
INVESTIGATION OF THE TENSILE STRENGTH OF KEYED MORTISE AND TENON JOINTS IN
TIMBER FRAME STRUCTURE 297
Sung-Jun Pang, Jung-Kwon Oh, Chun-Young Park, Se-Jong Kim, Jun-Jae Lee
EFFECTS OF SIZE RATIOS ON DOVETAIL JOINTS IN KOREAN TRADITIONAL
WOODEN BUILDING 304
H. Tran, C. Delisée, P. Doumalin, J. C. Dupre, J. Malvestio, A. Germaneau
COMPRESSIVE BEHAVIOUR OF WOOD-BASED FIBREBOARDS 308 Nataša Zavrtanik, Goran Turk
THE USE OF ARTIFICIAL NEURAL NETWORKS IN TIMBER GRADING 312 Tomaž Hozjan, Goran Turk, Stanislav Srpcic, Staffan Svensson
THE EFFECT OF CHANGING AMBIENT HUMIDITY ON MOISTURE CONDITION IN TIMBER ELEMENTS
316 Tomaž Hozjan, Tomaž Pazlar, Stane Srpcic
EPERIMENTAL AND NUMERICAL ANALYSIS OF GLULAM BEAMS IN NATURAL CLIMATIC
CONDITIONS 311
René Oum Lissouck, Régis Pommier, Patrick Castéra, Louis Max Ayina Ohandja
TIMBER ENGINEERING AS A TOOL FOR SPECIES CONSERVATION IN TROPICAL RAIN FORESTS:
THE CASE OF THE CONGO BASIN FOREST 327
Srecko Vratuša, Manja Kitek Kuzman, Vojko Kilar
PARAMETRICAL COMPARISON OF GLUED LAMINATED BEAMS WITH VARIABLE HEIGHT 333 Akito Kikuchi, Hisamitsu Kajikawa
THE TIMBER HUT THAT PEOPLE CAN ASSEMBLE BY THEIRESELVES THE PROJECT OF THE
RECOVERY OF THE GREAT EAST JAPAN EARTHQUAKE 339
TIMBER STRUCTURE SEISMIC DESIGN ASSISTED BY MICRO-TREMOR MEASUREMENT 343 José Amorim Faria
MECHANICAL BEHAVIOUR OF ANCIENT TIMBER STRUCTURAL ELEMENTS AFTER FIRE 347 José Amorim Faria
GRADING PORTUGUESE OAK. A SIMPLIFIED METHOD 353
Beatrice Faggiano, Maria Rosaria Grippa
MECHANICAL CHARACTERIZATION OF OLD CHESTNUT CLEAR WOOD BY
NON-DESTRUCTIVE AND DESTRUCTIVE TESTS 358
Pouyan Zarnani, Pierre Quenneville
WOOD EFFECTIVE THICKNESS IN BRITTLE AND MIXED FAILURE MODES OF RIVETED
CONNECTIONS 365
Sulistyono, Naresworo Nugroho, Surjono Surjokusumo, Osly Rahman
MONOTONIC TEST OF SHEAR WALL PANEL MADE FROM MANGIUM WOOD 369
Strength and Serviceability – Extreme Events
Massimo Fragiacomo, Claudio Amadio, Giovanni Rinaldin, Ljuba Sancin
NON-LINEAR MODELLING OF WOODEN LIGHT-FRAME AND X-LAM STRUCTURES 371 Adlin Roseley, Martin P. Ansell, Dave Smedley, Shane Porter
CREEP OF THIXOTROPIC ADHESIVES IN BONDED-IN TIMBER CONNECTIONS AS A FUNCTION
OF TEMPERATURE AND HUMIDITY 377
Takuro Mori, Kotaro Kawano, Kei Tanaka, Yoshiyuki Yanase, Hiroshi Kurisaki, Mitsunori Mori, Yasunobu Noda, Masafumi Inoue, Yasuhiro Hayashi, Kohei Komatsu
PROPOSE OF DECAY-ACCELERATION METHOD FOR REAL SIZE COLUMN-SILL JOINT AND
EVALUATION OF STRENGTH PROPERTIES 379
Xiaojun Yang, Youfu Sun, Zheng Wang
STUDY ON ENDURING PERFORMANCE OF SELF-TAPPING SCREW CONNECTION IN WOOD
STRUCTURE MEMBERS 384
Pouyan Zarnani, Pierre Quenneville
CONSISTENT YIELD MODEL FOR STRENGTH PREDICTION OF TIMBER RIVET CONNECTION
UNDER DUCTILE FAILURE 388
Haibei Xiong, Jiahua Kang, Xilin Lu
RESEARCH ON COMPOSITE ACTION BETWEEN SHEATHING AND JOIST IN TIMBER FLOOR:
TEST, FORMULATION, AND FINITE ELEMENT MODEL ANALYSIS 393 Carlito Calil Junior
HEALTH ASSESSMENT OF HAUFF TIMBER STRUCTURES IN BRAZIL 398
Naoki Utsunomiya, Mitsuhiro Miyamoto, Minoru Yamanaka, Manabu Matsushima
MECHANICAL MODEL OF MUD WALL BASED ON SOIL MECHANICS 407 Chun Ni, Mohammad Mohammad, Abdullah Al Mamun, Ghasan Doudak
PERFORMANCE OF WOOD PORTAL FRAME SYSTEMS AS ALTERNATIVE BRACING SYSTEMS IN
LIGHT WOODFRAME BUILDINGS 412
Abdullah Al Mamun, Ghasan Doudak, Chun Ni, Mohammad Mohammad
PORTAL FRAME BRACING SYSTEMS USING FIBER REINFORCED POLYMER (FRP) IN
LIGHT-WOOD FRAME BUILDINGS 418
Zhong Ma, Minjuan He
EXPERIMENTAL ANALYSIS OF TIMBER DIAPHRAGM’S CAPACITY ON TRANSFERRING
HORIZONTAL LOADS IN TIMBER-STEEL HYBRID STRUCTURE 424 Tomoki Furuta, Masato Nakao
EVALUATION OF EARTHQUAKE RESPONSE OF WOOD FRAME WITH DIAGONAL
BRACE FASTENED BY NEW BRACE FASTENER 430
Koji Yamada, Yoshiyuki Suzuki, Masami Goto, Hiroyuki Nakaji
NUMERICAL ANALYSIS ESTIMATION OF HORIZONTAL RESISTANT FORCES OF VARIOUS
MUD PLASTERED WALLS IN JAPANESE TRADITIONAL WOODEN STRUCTURES 436 Tomiya Takatani
LOAD-DISPLACEMENT RELATIONSHIP OF ACM WOODEN-HOUSE RETROFITTING BRACE 440 Tamura Yui, Furukawa Tadatoshi, Fujimori Shigeru, Yoshida Takuya
STUDY ON IMPROVEMENT OF PERFORMANCE OF LATTICE SHEAR WALL USING DOMESTIC TIMBER - EXPERIMENT ON ROTATIONAL STIFFNESS OF HALF-LAP JOINT INSERTED DOWEL 444 Seyed Ali Moayed Alaee, Timothy Sullivan, Colin A. Rogers, Roberto Nascimbene
SEMI-EMPIRICAL METHOD TO PREDICT THE DISPLACEMENT CAPACITY AND RESISTANCE OF COLDFORMED STEEL FRAME WOOD-PANEL SHEAR WALLS 450 Hiroyuki Nakaji, Teruo Kamada, Masami Gotou, Koji Yamada, Yoshiyuki Suzuki
SEISMIC PERFORMANCE OF MUD-WALLS WITH SILL BASED ON FULL-SCALE CYCLIC
LOADING TESTS 456
Wen-Shao Chang, Takehiro Wakita, Akihisa Kitamori, Kohei Komatsu, Tasuo Kataoka, Min-Fu Hsu DYNAMIC PROPERTIES OF A TRADITIONAL COMPLEX BRACKET SETS IN AN
ORIENTAL TEMPLE 460
Ji-young Park, Toshihiro Kuwano, Kei Tanaka, Masafumi Inoue
SEISMIC RETROFIT METHOD FOR EXISTING WOODEN HOUSES WITH LATTICE BEARING
WALL USING THICK PLYWOOD 464
A STUDY ON TECHNICAL DEVELOPMENT OF HORIZONTAL DIAPHRAGM WITH GRID BEAMS OF STAIRWELL
470 Tatsuru Suda, Yoshiyuki Suzuki, Yasuhiko Tashiro, Kyosuke Mukaibou
SEISMIC REINFORCEMENT FOR TRADITIONAL WOODEN FRAME BY IMPROVING RESTORING
FORCE DUE TO COLUMN ROCKING 474
Bo Källsner, Ulf Arne Girhammar, Johan Vessby
EVALUATION OF TWO ANALYTICAL PLASTIC DESIGN MODELS FOR LIGHT-FRAME
SHEAR WALLS 479
Takafumi Nakagawa, Mikio Koshihara, Naohito Kawai, Yukio Saito, Yoshiyuki Suzuki
DEVELOPMENT OF NUMERICAL ANALYSIS METHOD FOR JAPANESE TRADITIONAL WOOD
HOUSES CONSIDERING THE SLIDING BEHAVIOR OF COLUMN ENDS 489 Taishi Hatakeyama, Kento Suzuki, Kenji Miyazawa, Naohito Kawai
SEISMIC BEHAVIOR AND SEISMIC PERFORMANCE IMPROVEMENT ON THE COMPLICATEDLY
PLANE SHAPE OF WOODEN HOUSE 493
Daniele Casagrande, Simone Rossi, Tiziano Sartori, Roberto Tomasi
ANALYTICAL AND NUMERICAL ANALYSIS OF TIMBER FRAMED SHEAR WALLS 497 Yasuhiro Hayashi, Noriko Takiyama, Shinichi Hirosue, Takuya Matsumoto, Atsushi Nakagawa
FULL SCALE STATIC LOADING TESTS FOR TWO STORIED PLANE FRAME OF TRADITIONAL
TOWN HOUSE IN KYOTO, JAPAN 504
Asif Iqbal, Stefano Pampanin, Massimo Fragiacomo, Alessandro Palermo, Andrew Buchanan
SEISMIC RESPONSE OF POST-TENSIONED LVL WALLS COUPLED WITH PLYWOOD SHEETS 510 Chikako Tabata, Yoshimitsu Ohashi
STUDY ON SEISMIC DIAGNOSIS FOR WOODEN STRUCTURES PART 2:
RELATIONSHIP BETWEEN EVALUATION OF SEISMIC DIAGNOSIS AND DAMAGE LEVEL 516 Iuko Tsuwa, Mikio Koshihara
A STUDY ON THE VIBRATION CHARACTERISTICS OF TRADITIONAL TIMBER FRAMES
INCLUDING BRACKET COMPLEXES 520
Hyung-Kun Kim, Chun-Young Park, Sung-Jun Pang, Kwon-Hwan Hwang, Jun-Jae Lee
EFFECT OF LINTEL ON SEISMIC PERFORMANCE IN POST-BEAM STRUCTURE 525 Kenji Aoki, Tatsuya Shibusawa
EVALUATING IN-PLANE SHEAR MODULUS OF WOODBASED STRUCTURAL PANELS BY
RACKING TEST OF SMALL NAILED WALL 529
Mislav Stepinac, Vlatka Rajčić, Boris Androić, Dean Čizmar
RELIABILTY OF GLULAM BEAMS EXPOSED TO FIRE 534
Alar Just, Joachim Schmid, Birgit Östman
FIRE PROTECTION ABILITIES PROVIDED BY GYPSUM PLASTERBOARDS 540
Dean Čizmar, Vlatka Rajčić, Mislav Stepinac
ROBUSTNESS ANALYSIS OF STRUCTURAL TIMBER TRUSS SYSTEMS 551
Architecture and Engineering Case Studies
In-hwan Yeo, Kyung-suk Cho, Bum-yean Cho, Byung-yeol Min, Myung-o Yoon
AN EXPERIMENTAL STUDY ON MEASUREMENT OF SOUND INSULATION OF LIGHT WEIGHT WALL WITH LOESS BOARD USED IN KOREAN TRADITIONAL HOUSE(HAN-OK) 556 Hisamitsu Kajikawa, Yoko Miyamoto, Hiroyuki Noguchi
POSSIBIRITY OF MID-RISE TIMBER STRUCTURE APPROCH BY 1/6 SCALE MODEL EXPERIENCE 561 Chee Siang Tan, Kaori Fujita
CONSTRUCTION METHODS AND EARTHQUAKE ENCOUNTER RECORDS OF JAPANESE
TRADITIONAL TIMBER THREE STOREY PAGODAS 567
Hei-Soo Baek, Hideki Morita, Atsushi Shiiba, Yutaka Iimura, Fujio Imai
INFLUENCE OF SHAPE FACTORS OF WOOD SCREW ON WITHDRAWAL PERFORMANCE −
DEVELOPMENT OF WOOD SCREW USED FOR SOFT AND LIGHT WOOD 546 Makoto Nakatani, Takuro Mori, Kohei Komatsu
DEVELOPMENT OF CROSS EMBEDDED JOINT USING LAGSCREWBOLT 579 Sana Munir, Abdy Kermani, Ian Harrison
A HYBRID SYSTEM FOR ENHANCING RACKING PERFORMANCE OF TIMBER PANELS 583 Roberto Lecomte de Mello, Catharina Macedo, Ana Carolina Salustiano
TIMBER STRUCTURES IN THE NEW FACILITIES OF ÁGUAS EMENDADAS ECOLOGICAL
STATION IN BRASÍLIA – BRAZIL 587
Roberto Lecomte de Mello, Renato Sette
GLULAM STRUCTURES IN THE NEW LPF’S WOOD DRYING AND WOOD TREATMENT
LABORATORIES – BRAZIL 591
Katsuhiko Kohara, Masaya Kishita, Masaru Tabata, Yasushi Komatsuzaki, Masato Ohchi
A STUDY ON THE EDUCATIONAL EFFECTIVENESS OF THE TIMBER STRUCTURAL DESIGN
WORKSHOP 595
Sejong Kim, Hyun Bae Kim, Joo Saeng Park, Moon Jae Park, Jun Jae Lee
AIR INFILTRATION IN TIMBER FRAME HOUSE WITH WOOD STUD INFILL WALL 599 Kazuhiro Matsuda, Kazuhiko Kasai, Hiroyasu Sakata
EARTHQUAKE RESPONSE ANALYSIS OF 2-STORY TIMBER FRAMES WITH PASSIVE CONTROL
SCHEME BY DETAILED FRAME MODEL 603
WOOD PRODUCTS FOR THE ITALIAN CONSTRUCTION INDUSTRY – AN LCA-BASED
SUSTAINABILITY EVALUATION 609
Katsuhiko Kohara, Masaya Kishita, Masaru Tabata, Yasushi Komatsuzaki, Masato Ohchi
AN EFFECTIVENESS OF SEISMIC PERFORMANCES ASSESSMENT FOR SUSTAINABLE TIMBER
HOUSES ON MICROTREMORS MEASUREMENT 614
Rostand Moutou Pitti, Frédéric Dubois, Nicolas Sauvat, Eric Fournely
STRAIN ANALYSIS IN DRIED GREEN WOOD: EXPERIMENTATION AND MODELING
APPROACHES 618
Finn Larsen, Sigurdur Ormarsson
A NUMERICAL AND EXPERIMENTAL STUDY OF STRESS AND CRACK DEVELOPMENT IN
KILN-DRIED WOOD 624
Pablo Guindos, Manuel Guaita
THE PHENOMENOLOGICAL FRACTURE CRITERIA AND THE STRESS INTEGRATION
VOLUMES IN HETEROGENEOUS MODELS OF WOOD 629
In-hwan Yeo, Bum-yean Cho, Byung-yeol Min, Kyung-suk Cho, Myung-o Yoon5
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INFLUENCE OF STRESS REDUCTION METHODS ON THE CAPACITY OF ADHESIVELY BONDED TIMBER JOINTS
Till Vallée
1, Thomas Tannert
2, Quentin Gadais
3ABSTRACT: Adhesively bonded joints are characterized by stress peaks towards the ends of the overlaps, which trigger failure. A repeatedly reported method to increase the joint capacity is to reduce the stress peaks by either acting on the geometry or on the adhesive. In the presented research, the effectiveness of three stress reduction methods: i) adhesive grading, ii) chamfering, and iii) reverse chamfering, was experimentally and numerically investigated. The experiments on full-scale double lap joints showed that none of the applied methods significantly affected joint capacity. A probabilistic method considering a statistical formulation of size-effects was applied to predict the joint capacity and delivered accurate values for the experimental series. The presented work allows for a better insight into the relation between stress-state and capacity of adhesively bonded timber joints.
KEYWORDS: Adhesive bonding, timber joints, joint capacity, stress reduction methods, finite element analysis
1 INTRODUCTION
123Adhesively bonded joints, due to their complexity, are almost inaccessible to simple analytical analyses. To quantify the influence of parameters that deviate from the usual idealizations made on the stress-strain state, e.g. [1-3], only numerical methods such as Finite Elements Analysis (FEA) can be used. The range of parameters that justifies the use of FEA is wide: among them adherend or adhesive roundings; adherend shaping, adhesive gaps and adhesive grading.
Adhesively bonded joints are characterized by stress peaks towards the ends of the overlaps, which trigger failure. A repeatedly reported, and at first sight intuitive method to increase the joint capacity is to reduce the stress peaks by either acting on the geometry (e.g.
chamfering the adherends) or on the adhesive (e.g.
grading them with ductile adhesives).
The idea to grade the adhesive layer, i.e. using adhesives of different stiffnesses is to associate strain peaks at the
1 Till Vallée, College of Architecture and Engineering, University of Applied Sciences Fribourg, Bd de Pérolles 80, Fribourg, Switzerland. Email: till.vallee@fibreworks.org
2 Thomas Tannert, Department of Wood Science, The University of British Columbia, 2424 Main Mall, Vancouver, Canada. Email: thomas.tannert@ubc.ca
3 Quentin Gadais, University and Technological Institute of Saint-Nazaire, Nantes University, F 44606 Saint Nazaire, France. Email: qgadais@yahoo.com
end of the overlap to a more ductile adhesive, while the less stressed inner part is associated to a stiffer adhesive.
The goal is to achieve a more even stress distribution and higher joint strengths. The concept can be traced back to the 1970’s [4-5] and is still pursued today, e.g. [6-7].
Chamfering the adherend ends to reduce the stresses in adhesive joints has also been investigated. Adams et al.
[8] have shown that tapering the metallic outer adherends greatly reduced the stresses; the resulting experimentally gathered joint strengths increased more than twofold. Similar numerical results were obtained by Hildebrand [9] on single lap joints composed of composite and metallic adherends. The effect of chamfering on the reduction of stresses at the end of the overlaps of bonded joints was subsequently confirmed, often only numerically, e.g. [10-11].
When reviewing these works, two caveats have to be made: 1) numerical investigations usually point out the stress reduction effects and conclude that there ought to be a benefit for strength; (2) experimental validation has been, in most cases, performed on adherends which do not exhibit brittleness. The situation for bonded joints involving brittle adherends has not yet received much attention. This is, for a great part, due to the fact that capacity prediction methods for joints involving brittle adherends were just recently formulated [12-13].
The research presented herein studied the influence of adhesive roundings and adherend chamfering on the strength of adhesively bonded timber joints.
World Conference on Timber Engineering 15 - 19 July 2012
2 EXPERIMENTAL INVESTIGATION
2.1 SPECIMEN DESCRIPTION
In order to investigate the effect of stress reduction methods, symmetrical double-lap joints with rectangular sections were fabricated. The joints consisted of two outer (to = 38 mm) and two inner adherends (ti = 19 mm) connected by a layer of adhesive. Specimens were b = 50 mm wide, with an overlap of L = 100 mm and an adhesive layer thicknesses of ta = 1 mm. Figure 1 details the nomenclature. The timber surface was mechanically planed and subsequently residual dust was removed. The adhesive layer thickness was enforced using PVC washers put at a distance of 25 mm from the overlaps. In all cases, the adhesive cured at laboratory temperature (22±2°C) for at least a week.
Figure 1: Nomenclature used for the bonded joints 2.2 STRESS REDUCTION METHODS
Three stress reduction methods were investigated: (i) adhesive grading; (ii) chamfering, and (iii) inverse chamfering. Grading was investigated on Series S1 by using two different adhesive types for the bonded splice:
a stiff adhesive in the centre part, and a softer adhesive towards the ends of the overlap. The adhesive grading level was defined as the ratio of the stiffer adhesive related to the full overlap.
In the frame of the investigations of chamfers, in series S2 (Figure 2), the chamfer level was varied in four steps:
0%, 33%, 66% and 100%. In series S3 (Figure 3) the inverse chamfer level was varied in four steps: 0%, 33%, 66% and 100%.
Figure 2: Specimens series S2 chamfering levels
Figure 3: Specimens series S3 inverse chamfering levels 2.3 MATERIALS
Two different cold-curing 2C adhesives were used: (i) a stiff and brittle epoxy, SikaDur330, not exhibiting any plastic behaviour; and a very soft acrylic adhesive exhibiting major plasticity, SikaFast5221. The adhesives were experimentally characterized in tension according to EN ISO 527-2 [14]; the results are listed in table 1.
The timber species used was Spruce (Picea abies) cut from high quality defect-free boards and conditioned to 12% moisture content prior to specimen manufacturing and then stored in constant climate until testing. The longitudinal modulus of elasticity E1, and the transverse modulus of elasticity E2 were determined on small clear specimens from the same boards.
The strength of the timber was characterized based upon the Norris failure criterion [15], which has, in a 2D stress state, the form given by Eq. (1):
1 1
1 2
2 2 12
2 122
2 22
2 2 2 1
1
2
f f
f f f f f
Z X
XZ Z Z X
X
(1)
To determine the strength parameters, f1, f2, and f12, tests were performed on dog-bone specimens exhibiting different orientations, α, relatively to the grain. All samples were tested according to ISO 527 at room temperature using an Instron universal testing machine.
Four series were performed: 0°; 10°; 45°; and 90°.
Table 1: Material properties Material E1 E2
[GPa] 13 [–] 23
[–] f1* f2 = f3* f12* [MPa]
Timber 18 1.1 0.4 0.04 98.2 4.5 16.5 SikaDur 4.56 0.37 39.0 (εf ≈0.85%) SikaFast 0.14 0.40 11.8 c (εf ≈50%)
2.4 PROCEDURE AND RESULTS
All tests were carried out on Zwick universal testing machines with a capacity of 250 kN. Quasi-static axial tensile tests were performed under a displacement- controlled rate of 5 mm/s, in all cases up to failure load.
Because of their low through-thickness stiffness and strength, the timber specimen had to be cut in dog-bones shapes, to allow for the tensile force to be introduced.
All individual tests were repeated three times.
All investigated adhesively bonded joints failed in a brittle manner, independently on the fact if they involved brittle or ductile adhesives. The joints almost always failed by splitting just below the end of the overlap, as illustrated by Figure 4. The experimentally gathered strengths for each series are displayed in Figures 5-7.
Figure 4: Typical failure of specimens
3 NUMERICAL MODELLING
All configurations were numerically modelled using the FEA software package Ansys. Two-dimensional 8-node orthotropic elements were used to build up a model that exploited the two symmetry axis. The timber was modelled as linear-elastic orthotropic; SikaDur330 was modelled linear-elastic isotropic, while SikaFast5221 were idealized as exhibiting bi-linear von Mises plasticity. In all cases, the mesh size was refined at the loci of stress peaks; mesh sizes were approx. 0.1mm.
Figure 5: Experimental and predicted results series S1
Figure 6: Experimental and predicted results series S2
Figure 7: Experimental and predicted results series S3 For the sake of brevity, only the stress profiles of Series S2, both shear and through-thickness, are presented in Figures 8-9. The stresses do concentrate at the ends of the overlaps, and as far as adhesive grading is concerned, at the limit of the two adhesives in the bond-line.
Figure 8: Shear stress profile for S2 (graded joints)
World Conference on Timber Engineering 15 - 19 July 2012
Figure 9: Tension perpendicular stress profile for S2
4 PROBABILISTIC PREDICTION
As stress-based approaches, due to the huge stress peaks generated at the ends of the overlaps, are deemed to fail regarding the strength prediction of adhesively bonded joints, a probabilistic method has been pursued herein.
The principles of this method were published previously [12-13], so that it is only summarized herein. The prediction method takes into consideration the scale sensitivity of the material strength, considering not only the magnitude of the stress fields, but also the volume over which they act. For a general overview on size effects and its relations to strength, the reader is kindly redirected to Bažant [16]. The following is reminded: (i) probabilistic strength prediction methods assume that the investigated material exhibits brittle failure; (ii) the material strength is then usually statistically described as being Weibull-distributed. For the implementation of any strength prediction method, including the ones based on probabilistic concepts, a failure criterion for the material in needed, herein the Norris criterion was used.
Idealizing the joints under consideration as being constituted by n elements that could potentially fail, its survival depends on the simultaneous non-failure of all elements i ≤ n. As a result, for a given applied load, F, the probability of survival of the joint can be calculated by Eq. (2):
, 1
( ) ( )
nS S i
i
P F P F (2)
The function PS stands for the probability of survival of the constituent element i corresponding to a load level F.
Herein a two-parameter Weibull distribution has been considered to express PS, formulated using Eq. (3).
exp
k s V
P dV
m (3)
In Eq. (4), is the stress acting over a volume V, m is the characteristic stress or scale parameter and k is the shape parameter that gives a measure of strength variability.
Although initially established for main stresses, Weibull theory has been extended for any stress operator that defines failure [12-13]. The failure criterion from Eq. (1) can be interpreted as being stress operators governing the failure of the respective materials. In the following, failure functions labelled F are defined by reformulation Eq. (1) which leads to Eq. (4):
2 2 2 2 2
F 2 2 2 2 2
1 2
1 2 12 1 2
2 min ; ;
x x z z xz x z
f f
f f f f f (4)
Consequently, if each constituent element i, with a volume Vi is subjected to a constant value of the failure function F,i, the probability of survival of the whole member is given by Eq. (5):
, ,
1
1 0 0
exp exp
n i F i k n i F i kS i i
V V
P V m V m (5)
Eq. (5) can be implemented in a post-processing routine for FEA results and the strength of joints can then be easily predicted. Failure load has been defined as being the point of equal probability of survival i.e. for PS = 0.5, which in a first approach designates the value Fpred for which half of specimen would survive.
The above detailed procedure was applied for all configurations tested within the experimental series.
FEA had to be performed iteratively until PS = 0.5 was achieved. The computed joint strengths are displayed in Figures 5-7, where they are compared to the corresponding experimental results.
5 DISCUSSION
The influence of adhesive grading on the stress distribution is displayed in Figures 8 and 9. The two extreme grading levels, i.e. 0% and 100%, which correspond to a splice completely made up of the stiff or ductile adhesive, respectively, are representative for the influence of the adhesive stiffness. It can be seen that the stiff adhesive leads to higher stress peaks, compared to the soft adhesive, with maximal stress magnitudes lower by around one third. Despite this lowering in the stress magnitude, which in a stress-based context would yield in a strength increase. The experimental evidence, however, shows that strength is almost independent from the grading level. The probabilistic method on the other hand delivers predictions that are reasonably consistent with the experimental data.
Figures 8 and 9 also indicate that the corresponding stress profiles exhibit their maximum at the boundary between the two adhesives, and that these peaks are almost identical in shape and magnitude. Thus, even without consideration of probabilistic concepts, it is to expect that the corresponding joints strengths should be comparable, which is confirmed by the experimental results shown in Figure 5.
Similarly to the adhesive grading, adherend chamfering does significantly reduce the magnitude of the stress peaks. The corresponding experimentally determined
joint strengths were not affected by this particular stress reduction method. Here again, taking into account the fact that the joint strength is not only driven by the magnitude of stresses, but also by their distribution, applying a probabilistic approach, sheds light onto this apparent inconsistency by predicting joint strengths that are in good agreement with the experimental values.
The results on the inverse chamfering indicate that failure is no longer governed by the failure criterion;
instead cohesive failure was the dominant mode. Results show that increasing the level of inverse or internal chamfering leads to a reduction of joint strength, instead of the expected increase.
6 CONCLUSIONS
Adhesively bonded joints are characterized by extreme stress peaks towards the ends of the overlaps, which trigger failure, and thus define capacity. A repeatedly reported, and at first sight intuitive method to increase the strength these structural elements is to reduce the stress peaks by grading the adhesives or chamfering the adherends. The research presented herein allowed for the following observations:
1. All adhesively bonded joints failed in a brittle manner, so did the materials they were constituted of.
2. Adhesive grading and adherend chamfering, according to FEA, lead to stress reductions. These reductions are typically associated to changes in the stress field, i.e. the reduced stresses act on larger volumes of the adherends.
3. Within the frame of the study presented herein, there is no direct correlation between stress magnitude and failure, even considering a verified failure criterion.
4. Since direct stress based approaches to predict the strength of adhesively bonded joints composed of brittle adherends are inapt, a probabilistic capacity prediction method was computationally implemented.
5. The probabilistic method delivered accurate joint strengths; it also offered a mechanically coherent for the apparent contradictions between stress reduction and lack of corresponding joint strength increase.
It should be pointed out that these conclusions were only experimentally validated on the static strength of the joints, the authors explicitly discourage drawing any similar conclusions regarding the fatigue behaviour of bonded joints, for which the aforementioned stress reduction method might well have a positive effect.
ACKNOWLEDGEMENT
The research was funded by the Bern University of Applied Sciences (BFH) and supported by the technical staff at BFH and Sika Schweiz AG.
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[14] EN ISO 527-2 Plastics - Determination of tensile properties - Part 2: Test conditions for moulding and extrusion plastics, 1993.
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World Conference on Timber Engineering 15 - 19 July 2012
Figure. 1: Halved and tabled scarf joint
Figure 2: Different arrangements of the halved and tabled scarf joint
