Effects of Geometric, Damping, and Boundary Parameters on the Dynamic Response of Cross-Laminated Timber Rocking Wall Systems PDF Download
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Author: Gustavo Alejandro Acuna Alegria Publisher: ISBN: Category : Earthquake engineering Languages : en Pages : 0
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: Gustavo Alejandro Acuna Alegria Publisher: ISBN: Category : Earthquake engineering Languages : en Pages : 0
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: Jeroen Jose Julien Houbrechts Publisher: ISBN: Category : Languages : en Pages : 81
Book Description
Introduced as a system in earthquake engineering in 2004 [6], rocking walls are a fairly new system in earthquake engineering. Their performance has been proven, both in research as in practice. However, a few uncertainties about their behavior still remain. One of these uncertainties is the effect of radiation damping on the motion of the system. Existing estimations for the radiation damping use an equivalent damping ratio, which was actually derived for a rocking block that is not connected to any structure. The formula for this equivalent damping ratio also assumes both the block as the soil to be rigid. The validity of the latter can be questioned. This thesis will research the influence of the flexibility of the soil on the motion of a rocking wall. The influence of the shear wave velocity and the Poisson ratio will be considered. The flexible soil medium is modeled with the finite element method, using a 2D plain strain analysis. In order to be able to use a reasonably fine mesh, the dimensions of the soil island will be small. Viscous boundaries are therefore used to absorb incoming waves. The assumption of a rigid rocking wall is considered to be still valid. Therefore, the motion of the rocking wall is modeled by adding only three degrees of freedom to the finite element model of the soil, applying constraint equations and inserting bilinear springs in the interface between the rocking wall and the soil. The dynamic response will be simulated with an implicit, unconditionally stable time domain method. Results show that the motion of the rocking wall strongly depends on the shear wave velocity. The Poisson ratio has a clear but negligible effect. The simulation also shows that it is, as expected, not valid to estimate an equivalent damping ratio for the rocking wall and using this ratio for the system's response.
Author: Md Kobir Hossain Publisher: ISBN: Category : Languages : en Pages : 454
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: Jan Weckendorf Publisher: ISBN: Category : Languages : en Pages :
Book Description
The dynamic response of structural timber flooring systems can cause vibrational serviceability problems in terms of discomfort experienced by the occupants. A unified method to control timber floor vibrations has not been established to-date. The vibration problem is manifold. The complexity and the limited amount of research with respect to timber floor vibrations have shown an urgent need for further investigations. This thesis has focused on the effects of structural and non-structural modifications on the dynamic performance of timber flooring systems by using experimental data from sixty-seven full-scale flooring systems for analytical investigations so as to identify structural configurations and vibration parameters, which are promising to further the design against disturbing vibrations. The collected data have also been used to identify weaknesses of current design criteria and to build and validate a finite element (FE) model for eigenproblem analyses of timber I-joist floors. The experimental work has been carried out with support from industry, and part of the investigations with respect to the design criteria has been conducted as Visiting Scientist within a Short Term Scientific Mission of COST Action E55 at VTT - Technical Research Centre of Finland in Espoo, Finland. The significant effects of floor make-up and different configurations on their dynamic response are examined, with specific interest to stiffen dynamically sensitive locations targeted, and the most promising designs (configurations) are identified. The important effects of damping on the dynamic performance of flooring systems are addressed by determination of damping ratios from the full-scale experimental work. The results were then used to perform a series of statistical studies to identify and recommend more appropriate damping ratios for design of bare light-weight timber flooring structures based on a number of distinct structural properties. The computer-based finite element analysis has been successfully used to model a series of timber flooring systems incorporating timber I-joists for predicting modal parameters and their relative changes due to structural modifications. The analysis has demonstrated the significant influence of assigning spring stiffness at the supports and at the interface of deck and joists on the floor responses. Overall, this research has helped to achieve a much broader knowledge and greater understanding of dynamic response and vibrational characteristics of timber flooring systems, and has made a contribution to identifying improved structural design and furthering vibration prediction and assessment. Undertaking of any such measures and future work as suggested in this thesis could significantly contribute to the improvement of the structural design and the design to Eurocode 5 if results are incorporated in future revisions. This would lead to fewer nuisances for residential occupants and enhanced quality of life.
Author: Sven Thelandersson Publisher: John Wiley & Sons ISBN: 9780470844694 Category : Technology & Engineering Languages : en Pages : 460
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: Simon Aicher Publisher: Springer Science & Business Media ISBN: 9400778112 Category : Technology & Engineering Languages : en Pages : 815
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: Ahmed Elghazouli Publisher: CRC Press ISBN: 1498751601 Category : Technology & Engineering Languages : en Pages : 383
Book Description
This book focuses on the seismic design of building structures and their foundations to Eurocode 8. It covers the principles of seismic design in a clear but brief manner and then links these concepts to the provisions of Eurocode 8. It addresses the fundamental concepts related to seismic hazard, ground motion models, basic dynamics, seismic analysis, siting considerations, structural layout, and design philosophies, then leads to the specifics of Eurocode 8. Code procedures are applied with the aid of walk-through design examples which, where possible, deal with a common case study in most chapters. As well as an update throughout, this second edition incorporates three new and topical chapters dedicated to specific seismic design aspects of timber buildings and masonry structures, as well as base-isolation and supplemental damping. There is renewed interest in the use of sustainable timber buildings, and masonry structures still represent a popular choice in many areas. Moreover, seismic isolation and supplemental damping can offer low-damage solutions which are being increasingly considered in practice. The book stems primarily from practical short courses on seismic design which have been run over a number of years and through the development Eurocode 8. The contributors to this book are either specialist academics with significant consulting experience in seismic design, or leading practitioners who are actively engaged in large projects in seismic areas. This experience has provided significant insight into important areas in which guidance is required.
Author: Gustavo Alejandro Acuna Alegria
Author: Gustavo Alejandro Acuna Alegria
Author: Jeroen Jose Julien Houbrechts
Author: Md Kobir Hossain
Author: Jan Weckendorf
Author: Sven Thelandersson
Author: United States. Federal Emergency Management Agency
Author: Erol Karacabeyli
Author: Wei Song
Author: Simon Aicher
Author: Ahmed Elghazouli