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Dynamic Performance of Timber and Timber-Concrete Composite Flooring Systems

https://research.thinkwood.com/en/permalink/catalogue229
Year of Publication
2013
Topic
Connections
Serviceability
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Author
Rijal, Rajendra
Organization
University of Technology Sydney
Year of Publication
2013
Format
Thesis
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Topic
Connections
Serviceability
Keywords
Connections
Costs
Fasteners
Finite Element Model
Long Span
Multi-Storey
Sustainability
Vibrations
Small Scale
Static Load Tests
Damage Index (DI) Method
Loss of Composite Action Index (LCAI)
Research Status
Complete
Summary
In recent years, there has been an increasing trend in Australia and New Zealand towards the use of long-span timber and timber-concrete composite (TCC) flooring systems for the construction of multi-storey timber buildings. The popularity of these flooring systems is because of their low cost, easy construction and the use of environmentally sustainable materials. Due to their light-weight, such long-span floors are however highly susceptible to vibrations induced by service loads. Although longspan timber and TCC flooring systems can easily be designed to resist the static loads using currently available design guidelines, it is crucial to also investigate the dynamic behaviour of these floors as the occupant discomfort due to excessive vibration may govern the design. Moreover, many structural failures are caused by dynamic interactions due to resonances, which highlight the importance of investigating the dynamic behaviour of flooring systems. To date, there are very limited design guidelines to address the vibration in long-span floors, especially composite floors, due to a lack of sufficient investigation. In 2009, a research consortium named Structural Timber Innovation Company (STIC) was founded, with the aim to address various issues encountered with structural timber buildings including timber and TCC flooring systems. STIC is conducting Research and Development (R & D) work in a number of key areas to provide a new competitive edge for commercial and industrial structural timber buildings. The R & D work is undertaken with three parallel objectives at three universities, namely, the University of Technology Sydney (UTS), the University of Canterbury (UC) and the University of Auckland (UA). The focus of UTS is the assessment of various performance issues of long-span timber only and TCC flooring systems for multi-storey timber buildings. The work presented in this thesis deals with the investigation of the dynamic performance of timber only and TCC flooring systems, which is one of the sub-objectives of the research focus at UTS. In particular, the presented research assesses the dynamic performance of long-span timber and TCC flooring systems using different experimental und numerical test structures. For the experimental investigations, experimental modal testing and analysis is executed to determine the modal parameters (natural frequencies, damping ratios and mode shapes) of various flooring systems. For the numerical investigations, finite element models are calibrated against experimental results, and are utilised for parametric studies for flooring systems of different sizes. Span tables are generated for both timber and TCC flooring systems that can be used in the design of long-span flooring systems to satisfy the serviceability fundamental frequency requirement of 8 Hz or above. For floors where vibration is deemed to be critical, the dynamic assessment using the 8 Hz frequency requirement alone may not be sufficient and additional dynamic criteria such as response factor, peak acceleration and unit load deflection need to be satisfied. To predict the fundamental frequency of various TCC beams and timber floor modules (beams), five different analytical models are utilised and investigated. To predict the cross-sectional characteristics of TCC systems and to identify the effective flexural stiffness of partially composite beams, the “Gamma method” is utilised. Essential input parameters for the “Gamma method” are the shear connection properties (strength, serviceability stiffness and ultimate stiffness) that must be identified. Therefore, a number of experimental tests are carried out using small scale specimens to identify strength and serviceability characteristics of four different types of shear connection systems and three of them were adopted in the TCC beams. The connections included two types of mechanical fasteners (normal wood screw and SFS screw) and two types of notched connectors (bird-mouth and trapezoidal shape) with coach screw. Traditionally, the composite action of a system is determined from static load testing using deflection measurements. However, static load testing is expensive, time consuming and difficult to perform on existing flooring systems. Therefore, two novel methods are developed in this thesis that determines the degree of composite action of timber composite flooring systems using only measurements from non-destructive dynamic testing. The core of both methods is the use of an existing mode-shape-based damage detection technique, namely, the Damage Index (DI) method to derive the loss of composite action indices (LCAIs) named as LCAI1 and LCAI2. The DI method utilises modal strain energies derived from mode shape measurements of a flooring system before and after failure of shear connectors. The proposed methods are tested and validated on a numerical and experimental timber composite beam structure consisting of two LVL components (flange and web). To create different degrees of composite action, the beam is tested with different numbers of shear connectors to simulate the failure of connection screws. The results acquired from the proposed dynamic-based method are calibrated to make them comparable to traditional static-based composite action results. It is shown that the two proposed methods can successfully be used for timber composite structures to determine the composite action using only mode shapes measurements from dynamic testing.
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Evaluation of Retrofit Procedures for Nail-Laminated and Stringer Bridges

https://research.thinkwood.com/en/permalink/catalogue1434
Year of Publication
2002
Topic
Mechanical Properties
Material
NLT (Nail-Laminated Timber)
Application
Bridges and Spans
Author
Larson, Timothy
Seavey, Robert
Organization
University of Minnesota
Year of Publication
2002
Format
Report
Material
NLT (Nail-Laminated Timber)
Application
Bridges and Spans
Topic
Mechanical Properties
Keywords
Retrofit
Static Load Tests
Dynamic Load Tests
Deflection
Research Status
Complete
Summary
Many of the 1,400 timber bridges in Minnesota do not meet present day standards. Some of these bridges can be improved rather than replaced. When the desired service level can be attained by widening a bridge six feet or less, the bridge can be retrofitted by placing a second, wider, transverse deck onto the existing deck and substructure. Bridge components must be carefully inspected prior to a retrofit project. The retrofit of Bridge #6641 in Sibley County is a good example. First, the bituminous surface was removed. A longitudinal beam supported the extended deck. Grout was poured and leveled and then nail-laminated panels were laid transversely. A bituminous surface was laid over the full width of the new deck. The cost of the project was $51,632. (Replacing the bridge was estimated to take 2-3 years and cost $215,000.) The county quantified the strength change and load distribution characteristics by performing static and dynamic load tests before and after the retrofit. Adding a second deck effectively decreased the static deflections and improved the transverse load distribution. Nail-laminated timber bridge #2642, also in Sibley County, was retrofitted in 1992 and load-tested again in 1995. All dynamic deflections were lower than those of the post-retrofit tests in 1992. This improvement can be explained in part by the drying of the moisture that was introduced into the bridge deck during grouting. A retrofitted timber bridge is expected to last an additional 20-40 years.
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Study on Seismic Performance of Building Construction with Cross Laminated Timber: Part 14: Deformation of Joints and Fracture Behavior on Three Story Full-Scale Static Load Test

https://research.thinkwood.com/en/permalink/catalogue981
Year of Publication
2013
Topic
Seismic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Nasu, Hideyuki
Yahaura, Sota
Gosei, Murakami
Goto, Hiroshi
Hamamoto, Takashi
Miyake, Tatsuya
Yasumura, Motoi
Organization
Architectural Institute of Japan
Year of Publication
2013
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Connections
Keywords
Static Load Tests
Mid-Rise
Fracture Behavior
Full Scale
Seismic Performance
Research Status
Complete
Summary
This paper gives a bibliographical review of the finite element methods (FEMs) applied in the analysis of wood. The added bibliography at the end of this article contains 300 references to papers and conference proceedings on the subject that were published between 1995 and 2004. The following topics are included: Wood as a construction material—material and mechanical properties; wood joining and fastening; fracture mechanics problems; drying process, thermal properties; other topics. Wood products and structures—lumber; glulam, panels, wood composites; trusses and frames; floors, roofs; bridges; other products/structures.
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Study on Seismic Performance of Building Construction with Cross Laminated Timber: Part 16: Ex Post Fact Analysis for the Static Test of the Full Scale 3-Story Model

https://research.thinkwood.com/en/permalink/catalogue979
Year of Publication
2013
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Matsumoto, Kazuyuki
Miyake, Tatsuya
Hamamoto, Takashi
Goto, Hiroshi
Kaiko, Naoto
Yasumura, Motoi
Organization
Architectural Institute of Japan
Year of Publication
2013
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Keywords
Static Loading Tests
Displacement
Full Scale
Research Status
Complete
Summary
Performance-Based Earthquake Engineering (PBEE) has been developed mainly for the region of high seismicity for the last three decades. Though abundant information on PBEE is available throughout the world, the application of this PBEE to the moderate-seismicity regions such as their maximum considered earthquake being less than magnitude 6.5 is not always straightforward because some portion of the PBEE may not be appropriate in these regions due to the environment different from the high-seismicity regions. This paper reviews the state-of-art in PBEE briefly. Then, the seismic hazard in moderate-seismicity regions including Korean Peninsula is introduced with its unique characteristics. With this seismic hazard, representative lowrise RC MRF structures and high-rise RC residential wall structures are evaluated by using PBEE approach. Also, the range of forces and deformations of the representative building structures in Korea is given. Based on these reviews, some ideas for the use of PBEE to improve the state-of-practice in moderate-seismicity regions are proposed.
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Study on Seismic Performance of Building Structure with Cross Laminated Timber: Part 13: Relative Story Displacement of Full Scale 3-Story Model -Comparisons with Shaking Table Test

https://research.thinkwood.com/en/permalink/catalogue982
Year of Publication
2013
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Yahaura, Sota
Goto, Hiroshi
Hamamoto, Takashi
Gosei, Murakami
Miyake, Tatsuya
Matsumoto, Kazuyuki
Kaiko, Naoto
Organization
Architectural Institute of Japan
Year of Publication
2013
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Keywords
Static Load Tests
Shaking Table Test
Shear Force
Seismic Performance
Research Status
Complete
Summary
The material presented in this paper refers to a part of the investigation on cross-laminated (XLam) wall panel systems subjected to seismic excitation, carried out within the bilateral project realized by the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) and the Faculty of Civil and Geodetic Engineering at the University of Ljubljana (UL FCGE). The full program of the research consista of basic tests of small XLam wooden blocks and quasi-static tests of anchors, then quasi-static tests of full-scale wall panels with given anchors, shaking-table tests of two types of XLam systems including ambient-vibration tests, and finally analytical research for the definition of the computational model for the analysis of these structural systems. In this paper, the full-scale shaking-table tests for one XLam system type (i.e. specimen 1 consisting of two single-unit massive wooden XLam panels) that have been performed in the IZIIS laboratory are discussed. The principal objectives of the shaking-table tests have been to get an insight into the behavior of the investigated XLam panel systems under seismic excitations, develop a physical and practical computational model for simutalion of the dynamic response based on the tests, and finally correlate the results with those from the previously performed quasi-static tests on the same wooden panel types. The obtained experimental results have been verified using a proposed computational model that included new contitutive relationships for anchors and contact zones between panels and foundations. Because a reasonable agreement between the numerical and experimental results has been achieved, the proposed computational model is expected to provide a solid basis for future research on the practical design of these relatively new materials and systems.
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