Seismic Performance of Reinforced Concrete Coupled Walls

Seismic Performance of Reinforced Concrete Coupled Walls
Author: Richard Clive Malcolm
Publisher:
Total Pages:
Release: 2015
Genre: Buildings
ISBN:

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Following the 2010/2011 Canterbury Earthquakes, an investigation by the Canterbury Earthquakes Royal Commission (CERC) considered the performance of a range of buildings in Christchurch. Several of the buildings investigated by the CERC included reinforced concrete coupled walls, which are comprised of two wall piers linked (or coupled) by a series of coupling beams at each floor level. Notably the coupled wall buildings investigated by the CERC were observed to have performed undesirably when compared to their design intent. It was found by the CERC that these coupled walls tended to display higher strengths and lower ductility capacity than was intended in design. The postulated reason for this behaviour was that interaction between structural components strengthened the coupling beams by restraining the tendency of the coupling beams to axially elongate. To better account for this interaction in design practice, it was recommended by the CERC that the behaviour of coupled walls be investigated further. In this study, structural interaction between coupling beams and floors was first considered using finite element software VecTor2. It was found that the floors tended to restrain the elongation of coupling beams and to cause large coupling beam strength increases. The extent of floor that was activated to restrain coupling beam elongation being found to be dependent upon the arrangement of the floor. Existing provisions of NZS 3101:2006 for upper bounds on floor effective widths were found to be valid for assessment of the maximum coupling beam strength amplification caused by floor interaction. Analysis of a series of seismically loaded coupled walls interacting with floors was undertaken using VecTor2 software. In agreement with the findings of the CERC, axial restraint of coupling beams was found to have a large impact on coupled wall performance. Coupling beam strengths were measured up to 300% of their design strength, which tended to change the strength hierarchy of the coupled wall. In particular it was found that many existing coupled walls would have behaved similarly to a single cantilever wall with penetrations because the coupling beams were too strong to yield. These coupled walls tended to display lower energy dissipation and higher wall pier damage than assumed in design. The coupled wall provisions proposed (at the time of writing) in the 2014/2015 NZS 3101:2006 Amendment were found to over-estimate the impact of the floor systems on restraining coupling beam elongation. However these provisions did not include the effect of the wall piers restraining coupling beam elongation, so overall coupled wall overstrength capacities tended to be under-predicted. As an approximate method of accounting for axial restraint in design of coupled walls, it was recommended that redistribution of design demands be used to reduce the coupling beam design capacity and to achieve a more desirable coupled wall behaviour.

Recommendations for Seismic Design of Hybrid Coupled Wall Systems

Recommendations for Seismic Design of Hybrid Coupled Wall Systems
Author: Sherif El-Tawil
Publisher: Amer Society of Civil Engineers
Total Pages: 70
Release: 2010
Genre: Technology & Engineering
ISBN: 9780784410608

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This report synthesizes the existing information on hybrid coupled wall (HCW) systems into helpful recommendations pertaining to their seismic analysis and design.

Seismic Performance of Concrete Buildings

Seismic Performance of Concrete Buildings
Author: Liviu Crainic
Publisher: CRC Press
Total Pages: 266
Release: 2012-12-10
Genre: Technology & Engineering
ISBN: 0415631866

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This book examines and presents essential aspects of the behavior, analysis, design and detailing of reinforced concrete buildings subjected to strong seismic activity. Seismic design is an extremely complex problem that has seen spectacular development in the last decades. The present volume tries to show how the principles and methods of earthquake engineering can be applied to seismic analysis and design of reinforced concrete buildings. The book starts with an up-to-date presentation of fundamental aspects of reinforced concrete behavior quantified through constitutive laws for monotonic and hysteretic loading. Basic concepts of post-elastic analysis like plastic hinge, plastic length, fiber models, and stable and unstable hysteretic behaviour are, accordingly, defined and commented upon. For a deeper understanding of seismic design philosophy and of static and dynamic post-elastic analysis, seismic behavior of different types of reinforced concrete structures (frames, walls) is examined in detail. Next, up-to-date methods for analysis and design are presented. The powerful concept of structural system is defined and systematically used to explain the response to seismic activity, as well as the procedures for analysis and detailing of common building structures. Several case studies are presented. The book is not code-oriented. The structural design codes are subject to constant reevaluation and updating. Rather than presenting code provisions, this book offers a coherent system of notions, concepts and methods, which facilitate understanding and application of any design code. The content of this book is based mainly on the authors’ personal experience which is a combination of their teaching and research activity as well as their work in the private sector as structural designers. The work will serve to help students and researchers, as well as structural designers to better understand the fundamental aspects of behavior and analysis of reinforced concrete structures and accordingly to gain knowledge that will ensure a sound design of buildings.

Experimental Study on Seismic Performance of Reinforced Concrete Coupling Beams and Rectangular Squat Walls with Innovative Reinforcement Configurations

Experimental Study on Seismic Performance of Reinforced Concrete Coupling Beams and Rectangular Squat Walls with Innovative Reinforcement Configurations
Author: Poorya Hajyalikhani
Publisher:
Total Pages: 213
Release: 2016
Genre: Concrete beams
ISBN:

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Reinforced concrete core walls, coupled by diagonally reinforced coupling beams (DCBs), are a very efficient seismic force resisting system for medium- to high-rise buildings. The diagonal reinforcing bars in DCBs are most effective when the beam has a span-to-depth ratio, ln/h, less than 2. Modern construction, due to architectural requirements, typically requires span-to-depth ratios between 2.4 to 4, which leads to a very shallow angle of inclination of the diagonal reinforcement (generally between 10 to 20 degrees). The lower angles of inclination, combined with the detailing requirements specified in ACI 318, results in reinforcement congestion as well as design and construction difficulties. These issues with DCBs can be considerably minimized by utilizing an innovative and simplistic reinforcing scheme as investigated in this study. This reinforcement scheme consists of two separate cages similar to those used for typical beams in RC special moment frames. The proposed coupling beam has high elastic stiffness and acts like a conventional coupling beam under small displacements. Upon large displacements, cracks begin developing at the mid-span and mid-height of the beams where the narrow gap is located, gradually propagating towards the beam's ends. The cracks eventually separate the coupling beam into two slender beams where each has nearly twice the aspect ratio of the original coupling beam. This essentially transforms the shear-dominated behavior into a flexure-dominated behavior, as conventional slender beams. Because damage initiates from the center of the beam; then spreads towards the ends, the beam's ends maintain their integrity even under very large displacements, thereby eliminating the sliding shear failure at the beam-to-wall interface. Preliminary testing results on half-scale coupling beam specimens with span-to-depth ratio of 2.4 showed that coupling beams with the proposed reinforcement scheme were able to sustain high shear stresses and large rotations before strength degradation occurred. Subsequently, six rectangular squat wall specimens with height-to-length ratio 0.5 and 1, which were designed based the second innovative design concept using discrete confining cages to reinforce the web of the walls, were tested under lateral displacement reversals. Each wall consisted of several separate cages similar to those used for typical beams in RC special moment frames. The response of squat wall specimens showed very high shear strength and stiffness, while maintain adequate ductility due to well confinement of the wall.

Proceedings of SECON'19

Proceedings of SECON'19
Author: Kaustubh Dasgupta
Publisher: Springer Nature
Total Pages: 960
Release: 2019-12-17
Genre: Technology & Engineering
ISBN: 3030263657

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This book gathers peer-reviewed contributions presented at the 3rd National Conference on Structural Engineering and Construction Management (SECON’19), held in Angamaly, Kerala, India, on 15-16 May 2019. The meeting served as a fertile platform for discussion, sharing sound knowledge and introducing novel ideas on issues related to sustainable construction and design for the future. The respective contributions address various aspects of numerical modeling and simulation in structural engineering, structural dynamics and earthquake engineering, advanced analysis and design of foundations, BIM, building energy management, and technical project management. Accordingly, the book offers a valuable, up-to-date tool and essential overview of the subject for scientists and practitioners alike, and will inspire further investigations and research.

Seismic Design of Reinforced Concrete and Masonry Buildings

Seismic Design of Reinforced Concrete and Masonry Buildings
Author: Thomas Paulay
Publisher: Wiley-Interscience
Total Pages: 768
Release: 1992-04-10
Genre: Technology & Engineering
ISBN: 9780471549154

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Emphasizes actual structural design, not analysis, of multistory buildings for seismic resistance. Strong emphasis is placed on specific detailing requirements for construction. Fundamental design principles are presented to create buildings that respond to a wide range of potential seismic forces, which are illustrated by numerous detailed examples. The discussion includes the design of reinforced concrete ductile frames, structural walls, dual systems, reinforced masonry structures, buildings with restricted ductility and foundation walls. In addition to the examples, full design calculations are given for three prototype structures.

Design of Reinforced Concrete Buildings for Seismic Performance

Design of Reinforced Concrete Buildings for Seismic Performance
Author: Mark Aschheim
Publisher: CRC Press
Total Pages: 576
Release: 2019-04-05
Genre: Technology & Engineering
ISBN: 148226692X

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The costs of inadequate earthquake engineering are huge, especially for reinforced concrete buildings. This book presents the principles of earthquake-resistant structural engineering, and uses the latest tools and techniques to give practical design guidance to address single or multiple seismic performance levels. It presents an elegant, simple and theoretically coherent design framework. Required strength is determined on the basis of an estimated yield displacement and desired limits of system ductility and drift demands. A simple deterministic approach is presented along with its elaboration into a probabilistic treatment that allows for design to limit annual probabilities of failure. The design method allows the seismic force resisting system to be designed on the basis of elastic analysis results, while nonlinear analysis is used for performance verification. Detailing requirements of ACI 318 and Eurocode 8 are presented. Students will benefit from the coverage of seismology, structural dynamics, reinforced concrete, and capacity design approaches, which allows the book to be used as a foundation text in earthquake engineering.

Displacement-based Seismic Design of Reinforced Concrete Buildings

Displacement-based Seismic Design of Reinforced Concrete Buildings
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
Total Pages: 206
Release: 2003
Genre: Technology & Engineering
ISBN: 9782883940659

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A brief summary of the history of seismic design as given in chapter 1, indicates that initially design was purely based on strength or force considerations. When the importance of displacement, however, became better appreciated, it was attempted to modify the existing force-based approach in order to include considerations of displacement, rather than to totally reconsider the procedure on a more rational basis. In the last decade, then, several researchers started pointing out this inconsistency, proposing displacement-based approaches for earthquake engineering evaluation and design, with the aim of providing improved reliability in the engineering process by more directly relating computed response and expected structural performance. The main objective of this report is to summarize, critically review and compare the displacement - based approaches proposed in the literature, thus favouring code implementation and practical use of rational and reliable methods. Chapter 2 Seismic performance and design objectives of this report introduces concepts of performance levels, seismic hazard representation, and the coupling of performance and hazard to define performance objectives. In fact, for displacement analysis to be relevant in the context of performance-based design, the structural engineer must select appropriate performance levels and seismic loadings. A critical review of some engineering limit states appropriate to the different performance levels is therefore proposed. In chapter 3 Conceptual basis for displacement-based earthquake resistant design, the fundamental principles associated with displacement of the ground during an earthquake and the effects, in terms of displacement, in the structure, are reviewed. The historical development guides the presentation with a review of general linear and nonlinear structural dynamics principles, general approaches to estimate displacement, for both ground and structure, and finally a general presentation of the means to measure and judge the appropriateness of the displacements of the structure in section. Chapter 4 Approaches and procedures for displacement-based design can be somehow considered the fundamental part of the report, since a critical summary of the displacement - based approaches proposed by different researchers is presented there. Displacement - based design may require specific characterization of the input ground motion, a topic addressed in Chapter 5 Seismic input. In general, various pertinent definitions of input motion for non-code format analysis are included, while peak ground parameters necessary for code base shear equations are only addressed as needed for the definition of motion for analysis. Chapter 6 Displacement capacity of members and systems addresses the fundamental problem of evaluating the inelastic displacement capacity of reinforced concrete members and realistic values of their effective cracked stiffness at yielding, including effects of shear and inclined cracking, anchorage slip, bar buckling and of load cycling. In Chapter 7 Application and evaluation of displacement-based approaches, some of the many different displacement based design procedures briefly introduced in Chapter 4 are applied to various case studies, identifying and discussing the difficulties a designer may encounter when trying to use displacement based design. Results for five different case studies designed in accordance with eight different displacement based design methods are presented. Although in general case studies are considered a useful but marginal part of a state of the art document, in this case it has to be noted that chapter 7 is possibly the most innovative and fundamental part of the whole report. The conclusions of chapter 7 are the fundamental and essential conclusions of the document and allow foreseeing a bright future for displacement - based design approaches. The state-of-art report has been elaborated over a period of 4 years by Task Group 7.2 Displacement-based design and assessment of fib Commission 7Seismic design, a truly international team of experts, representing the expertise and experience of all the important seismic regions of the world. In October 2002 the final draft of the Bulletin was presented to the public during the 1st fibCongress in Osaka. It was also there that it was approved by fib Commission 7Seismic Design.