Skip header and navigation

17 records – page 2 of 2.

Lateral Behaviour of Cross Laminated Timber Shear Walls under Reversed Cyclic Loads

https://research.thinkwood.com/en/permalink/catalogue198
Year of Publication
2015
Topic
Seismic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Li, Minghao
Lam, Frank
Year of Publication
2015
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Connections
Keywords
Finite Element Model
Conference
Pacific Conference on Earthquake Engineering
Research Status
Complete
Notes
November 6-8, 2015, Sydney, Australia
Summary
Cross laminated timber (CLT) shear walls typically consist of solid engineered timber panels connected by metal hardware such as hold-downs, angle-brackets and others. Under seismic loads, the panel elements deform mainly in a rocking mode coupled with a sliding mode and small amount of in-plane bending/shear deformations. The connection system normally governs the lateral behaviour of CLT shear walls. This paper presents a finite element wall model CLTWALL2D to study CLT shear wall behaviour. The model consists of elastic orthotropic plate elements for the panels and nonlinear spring elements for the connections. Contact elements are also used for the panel-to-panel interactions. The nonlinear spring properties are represented by a subroutine called HYST that is able to model the strength and stiffness degradation and the pinching effect commonly observed in timber connections. The HYST parameters are calibrated by experimental data of CLT connections and embedded to the CLTWALL2D model. The wall model is validated against experimental data of a CLT shear wall test database. Parametric studies are then carried out to study the influence of gravity loads and vertical connection densities on the wall behaviour in terms of strength, stiffness, ductility, and energy dissipation.
Online Access
Free
Resource Link
Less detail

Long-term Dynamic Characteristics of Pres-Lam Structures

https://research.thinkwood.com/en/permalink/catalogue1647
Year of Publication
2016
Topic
Design and Systems
Seismic
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Author
Smith, Tobias
Sarti, Francesco
Granello, Gabriele
Marshall, Jack
Buckton-Wishart, Victoria
Li, Minghao
Palermo, Alessandro
Pampanin, Stefano
Year of Publication
2016
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Topic
Design and Systems
Seismic
Keywords
Pres-Lam
Long-term
Dynamic Behaviour
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3462-3470
Summary
Pres-Lam timber structures are being adopted throughout New Zealand and around the world. This innovative method of timber construction combines the use of large engineered timber members with posttensioning cables/bars. The hybrid version of the Pres-Lam system improves seismic performance through the addition of external or internal steel reinforcing. While the post-tensioning provides re-centering properties, the steel increases energy dissipation from the system as well as increasing moment resistance. The design of these structures is performed to withstand high levels of seismic loading without damage to the structural system. Over time, the post-tensioning force being applied to the structural timber members causes them to reduce in length that has a subsequent impact on the quantity of force being applied. This paper looks at the dynamic characteristics of fundamental period and elastic damping of three recently constructed Pres-Lam buildings, investigating the influence of these losses on the dynamic characteristics. Following this a study of the performance under strong motion is performed. The paper concludes that although the losses in post-tensioning are clear they do not impact on the dynamic characteristics and have only a minor impact on strong motion response.
Online Access
Free
Resource Link
Less detail

Mode Cross-Over and Ductility of Dowelled LVL and CLT Connections under Monotonic and Cyclic Loading

https://research.thinkwood.com/en/permalink/catalogue1228
Year of Publication
2018
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Ottenhaus, Lisa-Mareike
Li, Minghao
Smith, Tobias
Quenneville, Pierre
Publisher
American Society of Civil Engineers
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Mechanical Properties
Connections
Keywords
Steel Dowels
Steel Plates
Ductility
Brittle
Monotonic Loading
Cyclic Loading
Research Status
Complete
Series
Journal of Structural Engineering
Summary
This paper presents an experimental study on dowelled connections in Cross Laminated Timber (CLT) and Laminated Veneer Lumber (LVL) using 20 mm mild steel dowels and internal steel plates. Connections designed to fail in brittle row shear and group tear-out were tested under monotonic loading to assess the validity of analytical models from literature and code provisions. Connections designed to provide non-linearity before failure and thus produce ductility were tested under both monotonic and cyclic loading to study the influence of cyclic loading on ductility and the possibility of mode cross-over. It was found that cross layers in CLT improve ductility. Furthermore, mode cross-over from ductile response to brittle failure was observed in both CLT and LVL connections. Nevertheless, a good amount of ductility was achieved in all layouts (except the LVL connections designed for group tear-out failure) before cross-over to brittle failure occurred.
Online Access
Free
Resource Link
Less detail

Modeling the Coupling Effect of CLT Connections Under Bi-Axial Loading

https://research.thinkwood.com/en/permalink/catalogue2366
Year of Publication
2019
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Liu, Jingjing
Lam, Frank
Foschi, Ricardo
Li, Minghao
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Connections
Keywords
Coupling Effect
Biaxial loading
Degradation
Modeling
Research Status
Complete
Series
Journal of Structural Engineering
Summary
This paper presents the modeling of coupling effect of tension and shear loading on Cross Laminated Timber (CLT) connections using a finite element based algorithm called HYST. The model idealizes the connections as a “Pseudo Nail” - elastoplastic beam elements (the nail) surrounded by compression-only spring elements (steel sheath and wood embedment). A gap size factor and an unloading stiffness degradation index of the spring elements under cyclic loading were integrated into the optimized HYST algorithm to consider the coupling effect. The model was calibrated to compare with 32 configurations of CLT angle bracket and hold-down connections tests: in tension with co-existent constant shear force, and in shear with co-existent tension force. The results showed that the proposed model can fully capture the coupling effect of typical CLT connections, considering strength degradation, unloading and reloading stiffness degradation, and pinching effect. The model provided a useful tool for nailbased timber connections and a mechanism-based explanation to understand the hysteretic behaviour of CLT connections under bi-axial loading.
Online Access
Free
Resource Link
Less detail

Overstrength of Dowelled CLT Connections Under Monotonic and Cyclic Loading

https://research.thinkwood.com/en/permalink/catalogue1385
Year of Publication
2018
Topic
Connections
Mechanical Properties
Seismic
Material
CLT (Cross-Laminated Timber)
Author
Ottenhaus, Lisa-Mareike
Li, Minghao
Smith, Tobias
Quenneville, Pierre
Publisher
Springer Netherlands
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Seismic
Keywords
Overstrength
Ductility
Three Point Bending Test
Fasteners
Yield Moment
Monotonic Loading
Cyclic Loading
Steel Dowels
Steel Plates
Research Status
Complete
Series
Bulletin of Earthquake Engineering
Summary
This paper presents an evaluation of overstrength based on an experimental study on dowelled connections in cross-laminated timber (CLT). Connection overstrength needs to be well understood in order to ensure that ductile system behaviour and energy dissipation can be achieved under seismic loading. Overstrength is defined as the difference between the code-based strength, using characteristic material strengths, and the 95th 4 percentile of the true strength distribution. Many aspects contribute to total connection overstrength, which makes its definition challenging. In this study, half-hole embedment tests were performed on CLT to establish embedment strength properties and three point bending tests were performed to determine the fastener yield moment. Different connection layouts, making use of mild steel dowels and an internal steel plate, were tested under monotonic and cyclic loading to evaluate theoretically determined overstrength values and study the influence of cyclic loading on overstrength. Experimental results were compared with strength predictions from code provisions and analytical models for ductile response under monotonic loading. It was found that cyclic loading does not significantly influence overstrength for connections that respond in a mixed-mode ductile way indicating that in future more expedient monotonic test campaigns could be used. This work also provides further experimental data and theoretical considerations necessary for the estimation of a generally applicable overstrength factor for dowelled CLT connections.
Online Access
Free
Resource Link
Less detail

Seismic Performance Assessment of Steel Frame Infilled with Prefabricated Wood Shear Walls

https://research.thinkwood.com/en/permalink/catalogue1313
Year of Publication
2018
Topic
Seismic
Material
Light Frame (Lumber+Panels)
Application
Shear Walls
Hybrid Building Systems
Author
Li, Zheng
He, Minjuan
Wang, Xijun
Li, Minghao
Publisher
ScienceDirect
Year of Publication
2018
Format
Journal Article
Material
Light Frame (Lumber+Panels)
Application
Shear Walls
Hybrid Building Systems
Topic
Seismic
Keywords
Timber-Steel Hybrid
Seismic Performance
Multi-Story
Numerical Model
Damage
Stiffness
Nonlinear Time History Analysis
Research Status
Complete
Series
Journal of Constructional Steel Research
Summary
Steel-timber hybrid structural systems offer a modern solution for building multi-story structures with more environmentally-friendly features. This paper presents a comprehensive seismic performance assessment for a kind of multi-story steel-timber hybrid structure. In such a hybrid structure, steel moment resisting frames are infilled with prefabricated light wood frame shear walls to serve as the lateral load resisting system (LLRS). In this paper, drift-based performance objectives under various seismic hazard levels were proposed based on experimental observations. Then, a numerical model of the hybrid structure considering damage accumulation and stiffness degradation was developed and verified by experimental results, and nonlinear time-history analyses were conducted to establish a database of seismic responses. The numerical results further serve as a technical basis for estimating the structure's fundamental period and evaluating post-yielding behavior and failure probabilities of the hybrid structure under various seismic hazard levels. A load sharing parameter was defined to describe the wall-frame lateral force distribution, and a formula was proposed and calibrated by the time-history analytical results to estimate the load sharing parameter. Moreover, earthquake-induced non-structural damage and residual deformation were also evaluated, showing that if designed properly, desirable seismic performance with acceptable repair effort can be obtained for the proposed steel-timber hybrid structural system.
Online Access
Free
Resource Link
Less detail

Torque Loading Tests on the Rolling Shear Strength of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1416
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Lam, Frank
Li, Yuan
Li, Minghao
Publisher
Springer Japan
Year of Publication
2016
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Rolling Shear Strength
Polyurethane
Mountain Pine Beetle
Torque Loading Tests
Failure Modes
Monte Carlo
Finite Element Model
Brittle Failure
Research Status
Complete
Series
Journal of Wood Science
Summary
In this study , torque loading tests on small shear blocks were performed to evaluate the rolling shear strength of cross-laminated timber (CLT). The CLT plates in the tests were manufactured with Mountain Pine Beetle-afflicted lumber boards and glued with polyurethane adhesive; two types of layups (five-layer and three-layer) with a clamping pressure 0.4 MPa were studied. The small block specimens were sampled from full-size CLT plates and the cross layers were processed to have an annular cross section. These specimens were tested under torque loading until brittle shear failure occurred in the middle cross layers. Based on the test results, the brittle shear failure in the specimens was evaluated by detailed finite element models to confirm the observed failure mode was rolling shear. Furthermore, a Monte Carlo simulation procedure was performed to investigate the occurrence probability of different shear failure modes in the tests considering the randomness of the rolling shear strength and longitudinal shear strength properties in the wood material. The result also suggested the probability of rolling shear failure is very high, which gives more confident proof that the specimens failed dominantly in rolling shear. It was also found that the torque loading test method yielded different rolling shear strength values compared to the previous research from short-span beam bending tests; such a difference may mainly be due to the different stressed volumes of material under different testing methods, which can be further investigated using the size effect theory in the future.
Online Access
Free
Resource Link
Less detail

17 records – page 2 of 2.