Seismic Design and Performance of Self-Centering Concentrically-Braced Frames PDF Download

Author: Nathan Brent Chancellor
Publisher:
ISBN: 9781321222487
Category :
Languages : en
Pages : 828

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Book Description
The SC-CBF lateral force resisting system has been studied and a first generation design procedure for SC-CBFs has been developed. A laboratory testing program at Lehigh University tested a 4-story, 0.6-scale SC-CBF using hybrid simulation. The 4-story SC-CBF was subjected to 31 intense earthquakes at both the design basis earthquake (DBE) intensity level as well as the maximum considered earthquake (MCE) level. The SC-CBF performed very well.

Author: Mojtaba Dyanati Badabi
Publisher:
ISBN:
Category : Earthquake engineering
Languages : en
Pages : 180

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Book Description
Self-centering concentrically braced frame (SC-CBF) systems have been developed to increase the drift capacity of braced frame systems prior to damage to reduce post-earthquake damages in braced frames. However, due to special details required by the SC-CBF system, the construction cost of an SC-CBF is expected to be higher than that of a conventional CBF. While recent experimental research has shown better seismic performance of SC-CBF system subjected to design basis earthquakes, superior seismic performance of this system needs to be demonstrated for both structural and nonstructural components in all ground motion levels and more building configurations. Moreover, Stakeholders would be attracted to utilize SC-CBF if higher construction cost of this system can be paid back by lower earthquake induced losses during life time of the building. In this study, the seismic performance and economic effectiveness of SC-CBFs are assessed and compared with CBF system in three building configurations. First, probabilistic demand formulations are developed for engineering demand parameters (inter-story drift, residual drift and peak floor acceleration) using results of nonlinear time history analysis of the buildings under suites of ground motions. Then, Seismic fragility curves, engineering demand (inter-story drift, peak floor acceleration and residual drift) hazard curve and annual probabilities of exceeding damage states are used to evaluate and compare seismic performance of two systems. Finally, expected annual loss and life cycle cost of buildings are evaluated for prototype buildings considering both direct and indirect losses and prevailing uncertainties in all levels of loss analysis. These values are used evaluate economic benefit of using SC-CBF system instead of CBF system and pay-off time (time when the higher construction cost of SC-CBF system is paid back by the lower losses in earthquakes) for building configurations. Additionally, parametric study is performed to find acceptable increase in cost of SC-CBFs comparing to CBFs and impact of economic discount factor, ground motion suite and building occupancies on economic effectiveness of the SC-CBF system in three configurations. Results of this study indicates that, SC-CBF system generally shows better seismic performance due to damages to structural and non-structural drift sensitive components but worse performance due to damages to acceleration sensitive components. Therefore, loss mitigation in structural and non-structural damages are major source of economic benefit in SC-CBFs. SC-CBF system is not feasible for high rise buildings and low seismic active locations. If the cost of SC-CBFs are twice as CBF frames, the higher cost is paid back in a reasonable time during the life time of the buildings. SC-CBFs are more feasible for banks/financial institutions than general office buildings.

Author: Vikas Gopagani
Publisher:
ISBN:
Category : Earthquake engineering
Languages : en
Pages : 90

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Book Description
Self-centering concentrically braced frames (SC-CBFs) have been developed to reduce the structural damage caused due to earthquakes. SC-CBF systems have better seismic performance than the conventional concentrically braced frame (CBF) system; SC-CBF systems exhibit less damage to structural and non-structural components under earthquake loading. Recent research has shown that low-rise or mid-rise building seismic performance is better compared to high-rise SC-CBF performance. This study includes the design procedure of the SC-CBF structural members, prototype building, and the analytical procedure considerations in analyses of the prototype structure. The engineering demand parameters (inter-story drift and the peak roof drift) are developed using the nonlinear time history analysis of the structure under a set of ground motions. Then the results are used to evaluate the performance of the structure.In this study, static pushover and dynamic analyses are performed on a 6 story SC-CBF with different numbers of frames in each direction for the same building dimensions (essentially varying the tributary mass per frame). This study proposes to investigate the performance of the structure with varying tributary mass per frame.

Author: David Alan Roke
Publisher:
ISBN: 9781124195391
Category :
Languages : en
Pages : 733

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Book Description
The scope of this study includes the development of a design procedure for SC-CBF systems, a parametric study of different SC-CBF configurations, analytical and experimental studies of a large-scale SC-CBF test structure, and evaluation of the performance of the SC-CBF test structure.

Author: M. R. Hasan
Publisher:
ISBN:
Category : Civil engineering
Languages : en
Pages : 139

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Book Description
Conventional concentrically braced frame (CBF) systems have limited drift capacity prior to structural damage, often leading to brace buckling under moderate earthquake input, which results in residual drift. Self-centering CBF (SC-CBF) systems have been developed to maintain the economy and stiffness of the conventional CBFs while increasing the ductility and drift capacity. SC-CBF systems are designed such that the columns uplift from the foundation at a specified level of lateral loading, initiating a rocking (rigid body rotation) of the frame. Vertically aligned post tensioning bars resist column uplift and provide a restoring force to return the structure to its initial state (i.e., self-centering the system). Friction elements are used at the lateral-load bearings (where lateral load is transferred from the floor diaphragm to the SC-CBF) to dissipate energy and reduce the peak structural response. Previous research has identified that the frame geometry is a key design parameter for SC-CBFs, as frame geometry relates directly to the energy dissipation capacity of the system. This thesis therefore considered three prototype SC-CBFs with differing frame geometries for carrying out a comparative study. The prototypes were designed using previously developed performance based design criteria and modeled in OpenSees to carry out nonlinear static and dynamic analyses. The design and analysis results were then thoroughly investigated to study the effect of changing frame geometry on the behavior of SC-CBF systems. The rocking response in SC systems introduces large higher mode effects in the dynamic responses of structure, which, if not properly addressed during design, can result in seismic demands significantly exceeding the design values and may ultimately lead to a structural failure. To compare higher mode effects on different frames, proper quantification of the modal responses by standard measures is therefore essential. This thesis proposes three normalized quantification measures based on an intensity-based approach, considering the intensity of the modal responses throughout the ground motion duration rather than focusing only on the peak responses. The effectiveness of the three proposed measures and the conventionally used peak-based measure is studied by applying them on dynamic analysis results from several SC-CBFs. These measures are then used to compare higher mode effects on frames with varying geometric and friction properties.

Author: Mehdei Kafaeikivi
Publisher:
ISBN:
Category : Earthquake engineering
Languages : en
Pages : 210

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Book Description
Concentrically braced frame (CBF) systems have limited capacity for lateral displacement, causing structural damage that leads to high post-earthquake costs under moderate earthquakes. Self-centering concentrically braced frame (SC-CBF) systems have been developed to soften the lateral force-lateral drift response of the system without causing structural damage; however, the construction cost of SC-CBF systems is expected to be high due to the precision required in fabrication and erection. To take advantage of the ductility of SC-CBFs and the economy of conventional CBFs, a novel dual system has been proposed in which the lower stories of the lateral force resisting system are SC-CBFs and the upper stories are conventional CBFs. The SC-CBF is intended to act as a ductile sub-structure for the CBF, reducing the construction costs and post-earthquake costs. This study presents the design basis of the dual system and an investigation of the influence of dual system configuration on structural performance. To achieve this goal and demonstrate the effectiveness of the proposed dual system, a probabilistic performance assessment is conducted in this study, considering both structural and non-structural components. Firstly, eight prototype buildings are designed with the same configurations and gravity systems but different lateral load resisting systems (CBF and dual systems). Then, nonlinear time history analysis is performed using 3D numerical modeling to obtain seismic responses under a suite of ground motions. Next, probabilistic demand models are developed to predict the selected engineering demand parameters. To develop probabilistic demand models, several intensity measures are investigated to determine the best link between ground motion properties and structural and non-structural responses. The demand model parameters are estimated from regression analysis based on the responses obtained from nonlinear time history analysis of the finite element models. Moreover, hazard analysis is performed to quantify the seismic hazard for the structures. Three different locations inside the United States are considered in the hazard analysis: Los Angeles (high-seismic zone), Seattle (moderate-seismic zone), and Boston (low-seismic zone). Using detailed demand models, the corresponding capacity limits, and calculated intensity hazards, seismic fragility curves and engineering demand hazard curves are developed for three performance levels for structural and non-structural components. Finally, loss analysis is conducted to estimate expected annual loss and pay-off periods for different structural systems. The results of this study show that the dual system can be an efficient structural system for mid-rise buildings in high-seismic zones. Moreover, the time in which the higher initial construction costs of the dual systems are compensated by lower earthquake-induced losses in the lifetime of structures is calculated and presented for different configurations of the dual system.

Author: Jack Porteous
Publisher: John Wiley & Sons
ISBN: 047069792X
Category : Technology & Engineering
Languages : en
Pages : 556

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Book Description
Structural Timber Design to Eurocode 5 is a comprehensive book which provides practising engineers and specialist contractors with detailed information and in-depth guidance on the design of timber structures based on the common rules and rules for buildings in Eurocode 5 - Part 1-1. It will also be of interest to undergraduate and postgraduate students of civil and structural engineering. The book provides a step-by-step approach to the design of all of the most commonly used timber elements and connections using solid timber, glued laminated timber or wood based structural products. It features numerous detailed worked examples, and incorporates the requirements of the UK National Annex. It covers the strength and stiffness properties of timber and its reconstituted and engineered products; the key requirements of Eurocode 0, Eurocode 1 and Eurocode 5 - Part 1-1; the design of beams and columns of solid timber, glued laminated, composite and thin-webbed sections; the lateral stability requirements of timber structures; and the design of mechanical connections subjected to lateral and/or axial forces as well as rigid and semi-rigid connections subjected to a moment. The Authors Jack Porteous is a consulting engineer specialising in timber engineering. He is a Chartered Engineer, Fellow of the Institution of Civil Engineers and Member of the Institution of Structural Engineers. He is a visiting scholar and lecturer in timber engineering at Napier University. Abdy Kermani is the Professor of Timber Engineering and R&D consultant at Napier University. He is a Chartered Engineer, Member of the Institution of Structural Engineers and Fellow of the Institute of Wood Science with over 20 years' experience in civil and structural engineering research, teaching and practice. The authors have led several research and development programmes on the structural use of timber and its reconstituted products. Their research work in timber engineering is internationally recognised and published widely. Also of Interest Timber Designers' Manual Third Edition E.C. Ozelton & J.A. Baird Paperback 978 14051 4671 5 Cover design by Garth Stewart

Author: Ramin Golesorkhi
Publisher:
ISBN: 9780939493562
Category : Buildings
Languages : en
Pages : 116

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Book Description
Performance-Based Seismic Design (PBSD) is a structural design methodology that has become more common in urban centers around the world, particularly for the design of high-rise buildings. The primary benefit of PBSD is that it substantiates exceptions to prescribed code requirements, such as height limits applied to specific structural systems, and allows project teams to demonstrate higher performance levels for structures during a seismic event.However, the methodology also involves significantly more effort in the analysis and design stages, with verification of building performance required at multiple seismic demand levels using Nonlinear Response History Analysis (NRHA). The design process also requires substantial knowledge of overall building performance and analytical modeling, in order to proportion and detail structural systems to meet specific performance objectives.This CTBUH Technical Guide provides structural engineers, developers, and contractors with a general understanding of the PBSD process by presenting case studies that demonstrate the issues commonly encountered when using the methodology, along with their corresponding solutions. The guide also provides references to the latest industry guidelines, as applied in the western United States, with the goal of disseminating these methods to an international audience for the advancement and expansion of PBSD principles worldwide.

Author: Felix C. Blebo
Publisher:
ISBN:
Category : Damping (Mechanics)
Languages : en
Pages : 172

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Book Description
Conventional concentrically braced frame (CBF) systems have limited drift capacity prior to brace buckling, and related damage leads to deterioration in strength and stiffness. CBFs are also susceptible to weak story failure. A pin- supported self-centering friction-damped braced frame system with buckling-restrained columns (FDBF-BRC) is being developed to provide significant drift capacity while limiting damage due to residual drift and soft-story mechanisms. The FDBF-BRC system consists of beams, columns, and braces branching off a central column, with buckling restrained columns (BRCs) incorporated into the system at the first story external column positions. The BRCs and friction generated at lateral-load bearings at each floor level are used to dissipate energy to minimize the overall seismic response of the FDBF-BRC system. Vertically aligned post-tensioning bars provide additional overturning moment resistance and aid in self-centering the system to eliminate residual drift. The pin support condition and the lateral stiffness of the system enable it to exhibit a nearly uniform inter-story drift distribution. In this study, a suite of 44 DBE-level ground motions used in FEMA P695 is numerically applied to several FDBF- BRCs to demonstrate the seismic performance of the system. The results show that the FDBF-BRC system has a nearly uniform inter-story drift response, high ductility, and a high energy dissipation capacity, and is an effective seismic-resistant system.

Author: Federico Mazzolani
Publisher: CRC Press
ISBN: 1439859418
Category : Technology & Engineering
Languages : en
Pages : 1667

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Book Description
Behaviour of Steel Structures in Seismic Areas comprises the latest progress in both theoretical and experimental research on the behaviour of steel structures in seismic areas. The book presents the most recent trends in the field of steel structures in seismic areas, with particular reference to the utilisation of multi-level performance bas