Test Setup Design and Cyclic Evaluation of Rocking CLT Wall and Floor Restoring Force Lateral System PDF Download

Author:
Publisher:
ISBN:
Category : Building, Wooden
Languages : en
Pages : 0

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Book Description
The introduction of the demand for mass timber buildings in areas with seismic hazards has called for new lateral systems. Lateral systems in mass timber building typically utilize a rocking shear wall with post-tensioned rods to provide system re-centering. These post-tensioned rods add axial load to the shear wall and potentially endure long term creep affects. Mass Timber buildings consist of cross laminated (clt) shear walls and floor slabs along with glulam beams. The flexural capacity of the CLT floor slabs along with dead load can provide an alternative source for the restoring force. This project developed a test setup to accommodate a full scale cyclic testing of this restoring force. Cyclic testing included determining the influence of dead load on the system and the influence of ductile hold-downs. Hold-downs properties can be varied to alter shape of the hysteric curve and to allow re-centering. The hold-downs will serve as sacrificial fuses with the goal all yielding occurs to them while mass timber members remain elastic.

Author: Md Kobir Hossain
Publisher:
ISBN:
Category :
Languages : en
Pages : 454

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Book Description
There is a recognized need for tall building (8-20 story) construction in the United States due to growing population in the urban areas. In addition, there is a significant emphasis placed by the communities on sustainability. Wood is a sustainable construction material with a negative carbon footprint in comparison to steel and concrete, which are the traditional building materials used predominantly in tall buildings. Traditional Light Wood Frame Shear Wall system used in residential building construction in the U.S. cannot be used to construction tall building as it fails to provide necessary strength and stiffness. Mass timber panel such as Cross-Laminated Timber has been recognized as a promising building construction material in recent times and has been used in hundreds of building mostly in low seismic regions. However, to realize an all wood tall building in high seismic areas, lateral load resisting system (LLRS) using CLT needs to be developed and characterized before its implementation into building construction. This research focusses on addressing some of the issues in developing a robust LLRS using unbonded post-tensioned rocking CLT wall system for high seismic application. The parameters that affect the behavior of this system such as the compression, moisture diffusion and creep behavior of CLT material were studied by conducting laboratory testing. The performance of CLT rocking wall system was investigated through laboratory testing of four full scale specimens using different wall dimensions and detailing to gain a thorough understanding of this system behavior under reverse cyclic loading. The results show that this system can provide full recentering up to 3% drift with limited sustained damage at the rocking toes and limited energy dissipation capability. The rocking wall system can be designed as a robust LLRS but can be further improved by incorporating external energy dissipating elements into the system. To improve the system performance by including damping in the rocking wall system, o-connector and LiFS are used to connect two rocking walls. The coupled walls still provide the recentering while reduces the seismic displacement demand resulting from higher damping. Tests and finite element analysis of o-connectors were carried to understand its force-displacement behavior and energy dissipating capacity under reverse cyclic load. Design equations based on the test and FEA results are proposed. Laboratory tests were conducted on two CLT-LiFS hybrid walls in addition to component level tests on LiFS and CLT-LiFS connection. A load transfer mechanism in CLT-LiFS hybrid wall is proposed and used with a simplified calculation procedure to predict the force-displacement behavior of hybrid wall. The study shows that the analysis procedure predicts force capacity within 20% of the test results and can be conservatively used for practice. The test results show that the hybrid wall system has improved energy dissipation capacity while providing almost full recentering at 4% drift. The CLT building performance can be improved and the cost associated with LLRS may be reduced by taking into account the beneficial effect of non-rectangular shear walls (such as T-wall, I-wall). Non-rectangular walls can be achieved by connecting them at web-to-flange interface with high stiffness connections. Also, a high stiffness wall-to-foundation connection which can transfer the high base shear to foundation needs to be developed. Two connections, one for web-to-flange interface and another for wall-to-foundation interface, is developed by using grouted shear key incorporating ultra-high performance concrete and self-tapping screw. Laboratory tests on these two connection show that the connections have very high stiffness (4 times) compared to traditional bracket type ones and they have high strength as high as 3 to 4 times.

Author: Farhan A. Chowdhury
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :

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Book Description
Cross Laminated Timber (CLT) is emerging as a sustainable alternative to traditional building construction materials for tall buildings in high seismic regions. However, before they can be incorporated into the building codes, different categories of CLT shear wall systems need to be fully characterized and novel solutions must be implemented to overcome the limitations of existing timber systems. This dissertation addresses analytical modelling of unbonded post-tensioned (PT) CLT rocking wall (CLTRW) system for its use in both rectangular and nonrectangular configurations. A set of laboratory experimental tests and nonlinear finite element analysis (FEA) were compared to investigate and characterize the flexural and lateral behavior of CLTRW system. The flexural performance was studied using a full-scale, 5-layer rectangular CLT panel testing in three-point loading configuration. A three-dimensional (3D) finite element (FE) model with nonlinear geometry and contact properties was developed in ABAQUS using measured material properties. The FE model was validated using the experimental data from the CLT panel bending test. Based on the validated FE model, additional FE models of previously tested post-tensioned CLTRW panels with different wall aspect ratios and tendon configurations were also developed. A close agreement between the measured and FEA models was found in the stiffness behavior, which suggested that the proposed nonlinear FE modelling approach can be employed to predict the performance of other CLTRW systems. This research further analytically investigates shear behavior of high stiffness web-to-flange connections for nonrectangular CLTRW system. The proposed shear connections use spatially arranged self-tapping screws (STS) together with ultra-high-performance concrete (UHPC) shear-keys. 3-D nonlinear FE models for connections with and without UHPC were validated using the available experimental data, which showed that the inclusion of UHPC would significantly improve the stiffness of the connections. The FEM technique for connections was subsequently used to evaluate the lateral load performance of a 36-ft tall, T-shape CLTRW wall with multiple connections. The results from this model were compared to a T-wall without shear-key connections. It was found that the wall with high-stiffness shear-key connections showed better lateral load performance compared to traditional connection wall.

Author: Sven Thelandersson
Publisher: John Wiley & Sons
ISBN: 9780470844694
Category : Technology & Engineering
Languages : en
Pages : 460

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Book Description
Timber construction is one of the most prevalent methods of constructing buildings in North America and an increasingly significant method of construction in Europe and the rest of the world. Timber Engineering deals not only with the structural aspects of timber construction, structural components, joints and systems based on solid timber and engineered wood products, but also material behaviour and properties on a wood element level. Produced by internationally renowned experts in the field, this book represents the state of the art in research on the understanding of the material behaviour of solid wood and engineered wood products. There is no comparable compendium currently available on the topic - the subjects represented include the most recent phenomena of timber engineering and the newest development of practice-related research. Grouped into three different sections, 'Basic properties of wood-based structural elements', 'Design aspects on timber structures' and 'Joints and structural assemblies', this book focuses on key issues in the understanding of: timber as a modern engineered construction material with controlled and documented properties the background for design of structural systems based on timber and engineered wood products the background for structural design of joints in structural timber systems Furthermore, this invaluable book contains advanced teaching material for all technical schools and universities involved in timber engineering. It also provides an essential resource for timber engineering students and researchers, as well as practicing structural and civil engineers.

Author: Gustavo Alejandro Acuna Alegria
Publisher:
ISBN:
Category : Earthquake engineering
Languages : en
Pages : 0

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Book Description
The continuous search for new construction techniques and materials has led to an increased interest in Cross-Laminated Timber (CLT) in the United States. Particularly, Post Tensioned (PT) CLT rocking wall structures paired with yielding dissipator devices have been trending in recent years; they represent a potential alternative as primarily lateral resistance system in high seismic regions because of both structural and environmental benefits.Past investigations have shown that PT CLT rocking walls can withstand major earthquake events, presenting a satisfactory displacement response and concentrating the damage only in the energy dissipator devices and at the base of the walls, maintaining most of the CLT panel in its elastic range. However, research has indicated that the dynamic response of mid-rise rocking systems and CLT wall structures is influenced by higher modes, which amplifies the acceleration response and increases the seismic forces into de structure, risking the integrity of the lateral system.This investigation focused on studying the influence of geometric, damping, and boundary parameters on the dynamic response of low- and mid-rise PT CLT rocking wall systems. It was analyzed the influence of additional rocking joints, position of the PT rods, wall aspect ratio, and type and location of the dissipator devices. In total, 36 structures were subjected to nonlinear time-history analyses, using 44 far-field acceleration traces. There were assessed acceleration, displacement, inter-story drift ratio, shear, and moment profiles; average volume of damaged CLT; and the Fourier amplitude spectrum of the roof acceleration response.The analysis results showed that the presence of multiple rocking joints, lower wall aspect ratios, and inclusion of viscous dampers improved the seismic performance and decreased the influence of higher modes in CLT wall structures: additional rocking interfaces had more impact in taller structures and with reduced initial PT force, the aspect ratio had more effect in shorter structures, and viscous dampers were more effective when uniformly distributed. In contrast, the repositioning of the PT rods only reduced the expected damage in the CLT walls, maintaining the global responses essentially unchanged, regardless of the wall height.

Author: Kent A. Harries
Publisher: Woodhead Publishing
ISBN: 0081027052
Category : Technology & Engineering
Languages : en
Pages : 718

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Nonconventional and Vernacular Construction Materials: Characterisation, Properties and Applications, Second Edition covers the topic by taking into account sustainability, the conservation movement, and current interests in cultural identity and its preservation. This updated edition presents case studies, information on relevant codes and regulations, and how they apply (or do not apply) to nocmats. Leading international experts contribute chapters on current applications and the engineering of these construction materials. Sections review vernacular construction, provide future directions for nonconventional and vernacular materials research, focus on natural fibers, and cover the use of industrial byproducts and natural ashes in cement mortar and concrete. - Takes a scientifically rigorous approach to vernacular and non-conventional building materials and their applications - Includes a series of case studies and new material on codes and regulations, thus providing an invaluable compendium of practical knowhow - Presents the wider context of materials science and its applications in the sustainability agenda

Author: United States. Federal Emergency Management Agency
Publisher:
ISBN:
Category : Building laws
Languages : en
Pages : 468

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Author: Erol Karacabeyli
Publisher:
ISBN: 9780864885531
Category : Engineered wood construction
Languages : en
Pages :

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Author: Simon Aicher
Publisher: Springer Science & Business Media
ISBN: 9400778112
Category : Technology & Engineering
Languages : en
Pages : 815

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Book Description
This book contains the contributions from the RILEM International Symposium on Materials and Joints in Timber Structures that was held in Stuttgart, Germany from October 8 to 10, 2013. It covers recent developments in the materials and the joints used in modern timber structures. Regarding basic wooden materials, the contributions highlight the widened spectrum of products comprising cross-laminated timber, glulam and LVL from hardwoods and block glued elements. Timber concrete compounds, cement bonded wood composites and innovative light-weight constructions represent increasingly employed alternatives for floors, bridges and facades. With regard to jointing technologies, considerable advances in both mechanical connections and glued joints are presented. Self-tapping screws have created unprecedented options for reliable, strong as well as ductile joints and reinforcement technologies. Regarding adhesives, which constitute the basis of the jointing/laminating technology of modern timber products, extended options for tailor-made bonding solutions have to be stated. Apart from melamine-urea and phenolic-resorcinol adhesives, one-component-polyurethanes, emulsion isocyanate polymers and epoxies offer a wide range of possibilities. The contributions dealing with experimental and numerical investigations on static, cyclic and seismic behavior of structures clearly reveal the enhanced potential of modern timber construction for reliable and sustainable buildings and bridges of the new millennium. The book is structured in nine thematic areas, being I) Structures II) Mechanical Connections III) Glued Joints and Adhesives IV) Timber and Concrete/Cement/Polymer Composites V) Cyclic, Seismic Behavior VI) Hardwood, Modified Wood and Bamboo VII) Cross-Laminated Timber VIII) Properties and Testing of Wood IX) Glulam

Author: Andrew H. Buchanan
Publisher: John Wiley & Sons
ISBN: 0470972890
Category : Technology & Engineering
Languages : en
Pages : 437

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Book Description
Structural Design for Fire Safety, 2nd edition Andrew H. Buchanan, University of Canterbury, New Zealand Anthony K. Abu, University of Canterbury, New Zealand A practical and informative guide to structural fire engineering This book presents a comprehensive overview of structural fire engineering. An update on the first edition, the book describes new developments in the past ten years, including advanced calculation methods and computer programs. Further additions include: calculation methods for membrane action in floor slabs exposed to fires; a chapter on composite steel-concrete construction; and case studies of structural collapses. The book begins with an introduction to fire safety in buildings, from fire growth and development to the devastating effects of severe fires on large building structures. Methods of calculating fire severity and fire resistance are then described in detail, together with both simple and advanced methods for assessing and designing for structural fire safety in buildings constructed from structural steel, reinforced concrete, or structural timber. Structural Design for Fire Safety, 2nd edition bridges the information gap between fire safety engineers, structural engineers and building officials, and it will be useful for many others including architects, code writers, building designers, and firefighters. Key features: • Updated references to current research, as well as new end-of-chapter questions and worked examples. •Authors experienced in teaching, researching, and applying structural fire engineering in real buildings. • A focus on basic principles rather than specific building code requirements, for an international audience. An essential guide for structural engineers who wish to improve their understanding of buildings exposed to severe fires and an ideal textbook for introductory or advanced courses in structural fire engineering.