Design Comparison of Ordinary Concentric Brace Frames and Special Concentric Brace Frames for Seismic Lateral Force Resistance for Low Rise Buildings PDF Download

Author: Eric Grusenmeyer
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Braced frames are a common seismic lateral force resisting system used in steel structures. Ordinary concentric braced frames (OCBFs) and special concentric braced frames (SCBFs) are two major types of frames. Brace layouts vary for both OCBFs and SCBFs. This report examines the inverted-V brace layout which is one common arrangement. OCBFs are designed to remain in the elastic range during the design extreme seismic event. As a result, OCBFs have relatively few special requirements for design. SCBFs are designed to enter the inelastic range during the design extreme seismic event while remaining elastic during minor earthquakes and in resisting wind loads. To achieve this, SCBFs must meet a variety of stringent design and detailing requirements to ensure robust seismic performance characterized by high levels of ductility. The design of steel seismic force resisting systems must comply with the requirements of the American Institute of Steel Construction's (AISC) Seismic Provisions for Structural Steel Buildings. Seismic loads are determined in accordance with the American Society of Engineers Minimum Design Loads for Buildings and Other Structures. Seismic loads are very difficult to predict as is the behavior of structures during a large seismic event. However, a properly designed and detailed steel structure can safely withstand the effects of an earthquake. This report examines a two-story office building in a region of moderately high seismic activity. The building is designed using OCBFs and SCBFs. This report presents the designs of both systems including the calculation of loads, the design of frame members, and the design and detailing of the connections. The purpose of this report is to examine the differences in design and detailing for the two braced frame systems.

Author: Mark D. Denavit
Publisher: John Wiley & Sons
ISBN: 1394222165
Category : Technology & Engineering
Languages : en
Pages : 389

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Book Description
Comprehensive resource on the finite element method in structural steel connection design through verification with AISC 360 provisions Steel Connection Design by Inelastic Analysis covers the use of the finite element method in structural steel connection design. Verification with AISC 360 provisions is presented, focusing on the Component-Based Finite Element Method (CBFEM), a novel approach that provides the global behavior and verification of resistance for the design of structural steel connections. This method is essential for fast and practical design and evaluation of connections with different levels of geometry and complexity. Detailed modeling and verification examples with references to AISC and other relevant publications are included throughout the text, along with roughly 250 illustrations to aid in reader comprehension. Readers of this text will benefit from understanding at least the basics of structural design, ideally through civil, structural, or mechanical engineering programs of study. Written by a team of six highly qualified authors, Steel Connection Design by Inelastic Analysis includes information on: T-stub connections, single plate shear connections, bracket plate connections, beam over column connections, and end-plate moment connections Bolted wide flange splice connections, temporary splice connections, and chevron brace connection in a braced frame Brace connections at beam-column connection in a braced frame and double angle simple beam-to-column connections Semi-rigid beam-to-column connections, covering code design calculations and comparisons, IDEA StatiCa analysis, and ABAQUS analysis Steel Connection Design by Inelastic Analysis is an authoritative reference on the subject for structural engineers, Engineers of Record (EORs), fabrications specialists, and connection designers involved in the structural design of steel connections in the United States or any territory using AISC 360 as the primary design code.

Author: Applied Technology Council
Publisher:
ISBN:
Category : Buildings
Languages : en
Pages : 328

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Author: Ajaya Kumar Gupta
Publisher: CRC Press
ISBN: 1000142493
Category : Technology & Engineering
Languages : en
Pages : 302

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Book Description
Guidelines for Design of Low-Rise Buildings Subjected to Lateral Forces is a concise guide that identifies performance issues, concerns, and research needs associated with low-rise buildings. The book begins with an introduction that discusses special problems with low-rise buildings subjected to wind and earthquakes. Chapter 2 examines probabilistic methods and their use in evaluating risks from natural hazards. It also addresses the characteristics of wind and seismic forces and levels of risk implied by building codes. Wind forces are covered in more detail in Chapter 3, with discussions of wind force concepts and wind-structure interactions. Chapter 4 is devoted to earthquake forces and traces the development of building codes for earthquake resistant design. Chapter 5 describes the main framing systems used to resist lateral forces and discusses the code requirements for drift control. The designs and requirements for connections between building elements are addressed in Chapter 6. It includes examples along with several illustrations of suitable connections. The performance of non-structural elements during wind and earthquake forces is also examined in detail. This book serves as an important reference for civil engineers, construction engineers, architects, and anyone concerned with structural codes and standards. It is an excellent guide that can be used to supplement design recommendations and provide a design basis where there are no current requirements.

Author: Brandon W. Fuqua
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
The hazards of seismic activity on building structures require that engineers continually look for new and better methods of resisting seismic forces. Buckling restrained braced frames (BRBF) are a relatively new lateral force resisting system developed to resist highly unpredictable seismic forces in a very predictable way. Generally, structures with a more ductile lateral force resisting system perform better in resisting high seismic forces than systems with more rigid, brittle elements. The BRBF is a more ductile frame choice than special concentrically braced frames (SCBF). The ductility is gained through brace yielding in both compression and tension. The balanced hysteretic curve this produces provides consistent brace behavior under extreme seismic loads. However regular use of the BRB is largely limited to Japan where the brace type was first designed. The wide acceptance of buckling restrained braced frames requires the system to become easily designable, perform predictably, and common to engineers. This report explains the design process to help increase knowledge of the design and background. This report also details a comparison of a BRBF to a SCBF to give familiarity and promote confidence in the system. The design process of the BRBF is described in detail with design calculations of an example frame. The design process is from the AISC Seismic Provisions with the seismic loads calculated according to ASCE 7 equivalent lateral force procedure. The final members sizes of the BRBF and SCBF are compared based on forces and members selected. The results of the parametric study are discussed in detail.

Author: J. Paul Guyer, P.E., R.A.
Publisher: Guyer Partners
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 29

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Book Description
Introductory technical guidance for civil and structural engineers interested in design of steel braced frames in buildings to resist seismic forces. Here is what is discussed: 1. GENERAL 2. CONCENTRIC BRACED FRAMES 3. ECCENTRIC BRACED STEEL FRAMES (EBF).

Author: Chen Wang
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
"In low and moderate seismic regions, low-ductility concentrically braced frames (CBFs) are widely used as the seismic force-resisting system for steel structures. Unlike high-ductility CBFs, the capacity-based design principle and additional seismic detailing are not required for such systems, which are referred to as conventional CBFs (CCBFs) in this study. In CCBFs, the brace-to-gusset connections are inherently weaker than the adjoining gusset plates and braces when loaded in tension. This occurs because both the gusset plates and the braces are most often selected based on their respective compressive buckling resistances, and hence, typically have a much greater resistance in tension. As such, brace connections are critical for the seismic behaviour and collapse prevention performance of CCBFs. However, brace connections have received little research attention because they are usually assumed to remain elastic in most capacity-based designs, and as such, their inelastic behaviour is not fully understood at a fundamental level. This is reflected in the different code provisions: in Canada, the seismic design force must be amplified by 1.5 for brace connections in CCBFs unless these connections are proven to be ductile as per CSA S16-19; in New Zealand, for connections in CCBFs, a structural performance factor of 1.0 is required, compared with 0.9 for structural members, which effectively increases the seismic design force demand on connections as per NZS 3404; no analogous requirements exist for CCBFs in the USA as per ANSI/AISC 341-16 or in Europe as per Eurocode 8.The inelastic behaviour of and the seismic deformation demand on CCBF brace connections were studied through a two-level numerical simulation approach, which is presented in this thesis. The bolted flange plate connection of the I-shape brace, which is a common design choice for CCBFs, was selected as the subject of this study.At the connection level, a high-fidelity finite element (FE) simulation procedure was developed for the bolted flange plate connection and validated against laboratory test results. The force transfer mechanism within the branches of the connection was characterized. Subsequently, a parametric study based on the validated numerical simulation procedure was carried out. Three key design parameters, namely, the gusset plate thickness, the flange lap plate thickness, and the web lap plate thickness, were varied to study their effects on both the compressive and tensile behaviour of the brace and the connection assembly. Various deformation mechanisms and failure modes were revealed under both compression and tension. Design recommendations are proposed with regards to attaining better deformation capacity.Based on the knowledge gained from the high-fidelity numerical simulations, a computationally efficient component-based modeling method was developed for the bolted brace connection. The connection was discretized into individual components, and modeled by means of organized springs, which each simulate the behaviour of a component. After validation against experimental test results, the component-based connection model was incorporated into a system-level numerical model for a series of prototype CCBFs. Through nonlinear static and dynamic structural analyses, the seismic behaviour and collapse prevention performance of CCBFs were studied. When loaded in tension, the brace connections deformed much more than the brace, and amplifying the design force by 1.5 was effective in reducing the seismic deformation demand on brace connections. In some cases, a secondary seismic force-resisting mechanism developed and prevented the system from collapse after the primary seismic force-resisting mechanism had failed"--

Author: Federico Mazzolani
Publisher: CRC Press
ISBN: 020311941X
Category : Technology & Engineering
Languages : en
Pages : 1147

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Book Description
Behaviour of Steel Structures in Seismic Areas is a comprehensive overview of recent developments in the field of seismic resistant steel structures. It comprises a collection of papers presented at the seventh International Specialty Conference STESSA 2012 (Santiago, Chile, 9-11 January 2012), and includes the state-of-the-art in both theore

Author: Sara M. Ibarra
Publisher:
ISBN:
Category :
Languages : en
Pages : 318

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Book Description
Chevron-braced frames are preferred structural systems by architects and contractors in low to mid-rise buildings for seismic design because they accommodate architectural elements while providing the necessary lateral stiffness and resistance. This system was more common prior to the advent of Special Concentrically Braced Frame (SCBF) seismic provisions based on capacity design in the late 1980’s, which require that the beam develop the idealized expected unbalanced capacities of full yielding of the tension brace and degraded capacity of the compression brace. This results in large and costly beams, which deter their use in construction. Previous experimental tests of chevron SCBFs with beam strengths that do not satisfy the theoretical unbalanced force prescribed by AISC SCBF Seismic Provisions result in a yielding beam plastic mechanism. These tests suggest that the current beam strength requirement is not necessary for assuring life safety and collapse prevention. Three single-story chevron SCBFs were tested at the University of Washington to further evaluate the beam yielding mechanism. One of the tested specimens had a beam weaker than any previously tested to establish a lower bound for comparison of seismic performance. A second specimen had A500 Gr. C braces to determine the impact of brace steel type on seismic performance. The third single-story specimen used a deeper beam to determine the effect of beam stiffness on frame resistance and ductility. Finally, a capstone 3-story chevron SCBF was tested at the National Center for Research on Earthquake Engineering in Taiwan to evaluate the system’s performance with a yielding beam. Results show that the beam yielding mechanism improved the deformability of the SCBF and the weaker beam did not compromise the capacity of the system if the beam was not excessively weak.

Author: Liang Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 149

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Book Description
The chevron braced frame is a widely used seismic force resistant system in North America in areas subjected to moderate-to-severe earthquakes. However, the chevron braced frame system is limited in term of lateral loads redistribution over the building height. Khatib et al (1988) proposed to add zipper columns to link together all brace-to-beam intersecting points with the aim to drive all compression braces to buckle simultaneously and as a result to enlarge the energy dissipation capacity of the system. Although the Commentary of AISC Seismic Provisions for Structural Steel Building (AISC 2002) contains recommendations regarding this innovative zipper steel frame systems, no design provisions are included yet. The scope of this thesis is to refine the design method for the Zipper Braced Frame System which was initially proposed by Tremblay and Tirca (2003) and to study the system's behaviour under seismic loads by means of accurate inelastic time-history analysis. The main objective of this research project is three-fold: To develop accurate computer brace models by using Drain2DX and OpenSees and to validate the accuracy of computations with experimental test results for slender, intermediate and stocky braces; To refine the existing design method for CBFs with strong zipper columns; To validate the refined design method by studying the performance of CBF systems with strong zipper columns in Drain2DX and OpenSees environment for low-, middle- and high-rise buildings. Through this research, the overall understanding of the CBF system with strong zipper columns is improved by means of accurate numerical predictions. The outcome of this study will be further used as input data for experimental tests. The design procedure has been divided into two phases: design of braces, columns and beams according to NBC 2005 and CSA-S16-09 and design of zipper columns. A spreadsheet was developed for a 4-, 8- and 12-storey buildings and six different pattern loads related to the distribution of internal brace forces over the structure height were proposed. Based on this study, the best suited pattern load distribution is selected and considered for zipper column design. In order to evaluate the accuracy of modeling assumption in OpenSees, parametric studies were carried out. Comparisons between analytical and available test results have validated the accuracy of the computer models and analysis results. Three ground motion ensembles such as: regular, near-field and Cascadia were scaled to match the design spectrum for Victoria, B.C., have been considered in these analyses. In conclusion, good seismic performance was found for all studied buildings. The forces in the zippers were equal to or lower than predicted in the design method. All zipper columns performed in elastic range while buckling of braces propagated upward or downward within seconds. It was clearly demonstrated that by using CBF's with zipper columns the storey mechanism was mitigated and in almost all cases the interstorey drift was uniformly distributed over the structure height. In addition the median estimations of the interstorey drifts were below than 2.5% hs limit prescribed in the NBC-05 code for buildings of normal importance. The outcomes of this research project will be further used as input data for a future experimental test planned to be conducted on an 8-storey braced frame with zipper columns sample.