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Direct Displacement-Based Seismic Design of Eccentrically Braced Steel Frames Gerard J. O’Reilly & Timothy J. Sullivan Abstract A series of eccentrically braced frames (EBF) are designed and subjected to nonlinear analyses to highlight ambiguities and differences in current seismic design provisions for EBF structures. This provides motivation to implement better guidance for the checking of local displacement demand considerations and move towards a displacement-based design approach. A recently proposed direct displacement-based design (DDBD) procedure for EBFs is then described and further developed in this paper through the calibration of a spectral displacement reduction factors that relate the displacement of an inelastically responding structure to that of the equivalent linear representation used in the DDBD of EBFs. Such an expression is calibrated as part of this study using an experimentally validated numerical model also proposed here for the EBF links such that the actual hysteretic behaviour of the links is well represented. The DDBD guidelines are applied to EBF systems from 1 to 15 storeys in height and their performance is verified via nonlinear dynamic analyses using two different sets of design spectrum compatible ground motions. The results of the study indicate the robustness of the proposed DDBD method in limiting the interstorey drifts to design limits for a variety of EBF systems with short links, thus demonstrating that the proposed DDBD method is an effective tool for seismic design of EBFs. TandF_1485618928.rar

Seismic Behavior of Direct Displacement-based Designed Eccentrically Braced Frames A. Mohebkhah* , S. Farahani Department of Civil Engineering Faculty of Civil and Architectural Engineering, Malayer University, Malayer, Iran Direct Displacement-Based Design (DDBD) is a performance-based seismic design method that has been proposed and well developed over the past two decades to design RC frame structures, shear walls and bridges. In this method, an equivalent single-degree-of-freedom (SDOF) substitute structure is utilized to estimate seismic displacement demands of a multi-degree-of-freedom (MDOF) system. Although this method has been used to design the above mentioned structures, however, there is just one comprehensive DDBD method to design steel eccentrically braced frames (EBFs) in the literature. The purpose of this study is to investigate nonlinear seismic behavior of the DDB designed EBFs with short, intermediate and long link beams and estimate their seismic demands. To this end, twelve 3, 5, 9 and 12-story EBFs were designed using the proposed DDBD method. To simulate the nonlinear cyclic behavior of link beams, a macro-model proposed in the literature was adopted and validated with the available tests results. In order to describe material nonlinearity of the framing members in the macromodel, distributed plasticity fiber based model was used. After validating the FEM macro-modeling technique of link beams, seismic behavior of the 2D EBFs was investigated with nonlinear time-history analysis under a set of selected earthquake records using the structural analysis software OpenSees (ver. 2.4.0). The results showed that the DDB designed EBFs generally can reach their anticipated performance level. دانلود DDB Designed EBFs.pdf

EVALUATION OF DIRECT-DISPLACEMENT BASED SEISMIC DESIGN METHOD FOR EBFs Amin MOHEBKHAH Assistant Professor of Structural Eng., Dept. of Civil Eng., Malayer University, Malayer, Iran amoheb@malayeru.ac.ir Sina FARAHANI M.Sc. Student of Structural Engineering, Dept. of Civil Eng., Malayer University, Malayer, Iran sina_farahani459@yahoo.com, sina.farahani@stu.malayeru.ac.ir Keywords: Direct displacement-based design, Steel eccentrically braced frame, Seismic behavior, Nonlinear dynamic analysis, Performance level Recent research in the field of earthquake engineering has seen the development of number of different displacementbased seismic design (DBD) methods. Such methods aim to overcome limitations with the force-based design methods incorporated in current codes. The most developed DBD method currently available is the Direct DBD approach, described and investigated in a text by Priestley et al. (2007). While the guidelines in the DDBD code have been relatively well tasted for RC structures, further verification and development is required for steel frame systems. There is just one comprehensive study can be found on DDBD of eccentrically braced frames (EBFs) which has been published recently by Sullivan (2013). The study presented by Sullivan (2013), has been focused of DDBD of EBFs with short (shear) link beams. Therefore, the aim of present study is to evaluate the ability of DDBD method for designing EBFs with intermediate and long link beams. To this end, three five-storey EBFs with short, intermediate and long link beams designed using the DDBD method proposed by Sullivan (2013). Figure 1 shows the case study EBF structures selected for examination in this paper. دانلود منبع 00390-SD.pdf

DIRECT DISPLACEMENT-BASED SEISMIC DESIGN OF CONCRETE BUILDINGS MJN Priestley, MJ Kowalsky - Bulletin of the New Zealand National …, 2000 - cat.inist.fr Abstract A seismic design procedure is developed to enable concrete buildings to be designed to achieve a specified acceptable level of damage under the design earthquake. The acceptable limit is defined as a displacement profile related to limit material strains or code specified drift limits. In this procedure, the elastic properties, including initial stiffness, strength and period, are the end product of the design rather than the starting point. It is shown that the procedure is simple to apply, and results in significant differences from the more conventional force-based procedure. Designs for multi-storey frame and wall buildings are presented, and target displacements are compared with results from inelastic time-history analysis. Source 2000, vol. 33, no4, pp. 421-444 (14 ref.) Publisher New Zealand National Society for Earthquake Engineering, Wellington, NOUVELLE-ZELANDE (1974-1998) 33(4)0421.pdf

TWO IMPORTANT ISSUES RELEVANT TO TORSIONAL RESPONSE OF ASYMMETRIC 8-STORY RC BUILDINGDESIGNED WITH DIRECT DISPLACEMENT BASED DESIGN APPROACH E. Izadi Z. and A. S. Moghadam Abstract Direct displacement based design (DDBD) is a conceptual framework that directly design a structure to achieve an expected performance level under specified seismic intensity. In this study, two important issues relevant to torsional response of mass eccentric 8-story RC building designed with DDBD approach are investigated. These issues are including the effects of unbalanced mass distribution scenario on the torsional response parameters and the study of these parameters with reference to diagonal displacement. Diagonal displacement is the SRSS combination of the displacement demands along the direction of excitation and orthogonal direction. Three different unbalanced mass distribution scenarios which produce the same mass eccentricity were applied to the plan of the generic structural model to determine the general range of the mass moment of inertia (MMI) variation due to different unbalanced mass distribution scenarios. Expressions were established to correlate MMI and mass eccentricity in each scenario. Results show for slight eccentricities the variation of the MMI is negligible but as eccentricity is increased the range of the variation is extended. Then sensitivity analyses based on finite element method and inelastic time history analysis have been carried out on 8-story RC building frame designed with DDBD approach with different level of mass eccentricity and different MMI. Torsional response parameters in terms of maximum displacement demands of edge elements, maximum diaphragm rotation, maximum nominal relative displacement and maximum nominal rotation is compared with considering diagonal and horizontal displacement demands along seismic excitation. Keywords Asymmetric, Direct displacement based design, Diagonal displacement, Seismic, RC Frames, Torsional response چکیده روش طراحی مستقیم بر اساس تغییرمکان،یک روش مفهومی است که سازه را بمنظور رسیدن به یک سطح عملکرد مورد انتظار تحت شدت لرزه ای معین طراحی می‌کند. در این مطالعه بمنظور مشارکت در توسعه بیشتر روش یاد شده در سازه‌های نامتقارن، دو مقوله مهم در ارتباط با پاسخ پیچشی ساختمان 8 طبقه قاب خمشی بتن آرمه نامتقارن جرمی طراحی شده به روش طراحی مستقیم بر اساس تغییرمکان مورد مطالعه قرار می‌گیرد. یکی مطالعه تآثیر سناریوی توزیع نامتوازن جرم بر پارامترهای پیچشی سازه نامتقارن و دیگری مطالعه این پارامترها با در نظر گرفتن اثر تغییرمکانهای مورب می‌باشد. در اینجا تغییرمکان مورب به ترکیب جذر مجموع مربعات تغییرمکانها در امتداد اعمال تحریک زلزله و امتداد متعامد آن اطلاق می‌گردد. در این ارتباط تعداد سه سناریوی مختلف توزیع نامتوازن جرم بمنظور تعیین محدوده تغییرات ممان اینرسی دورانی در نظر گرفته شده و معادلاتی برای مرتبط نمودن خروج از مرکزیت جرمی و ممان اینرسی دورانی استخراج گردیده است. نتایج نشان می‌دهد در محدوده خروج از مرکزیتهای کم، تغییرات ممان اینرسی دورانی بسته به سناریوهای مختلف کم می‌باشد اما هر چه مقدار خروج از مرکزیت افزایش می‌یابد محدوده تغییرات آن نیز بشدت افزایش می‌یابد. در ادامه آنالیز حساسیت بر مبنای روش المان محدود و تحلیلهای تاریخچه زمانی غیر ارتجاعی برای سطوح مختلف خروج از مرکزیت و مقادیر مختلف ممان اینرسی دورانی بر روی سازه 8 طبقه بتن آرمه طراحی شده به روش طراحی مستقیم بر اساس تغییرمکان انجام شده است. پارامترهای پاسخ پیچشی سازه شامل ماکزیمم نیازهای تغییرمکانی لبه‌ها، ماکزیمم دوران دیافراگم، ماکزیمم تغییرمکان نسبی اسمی و ماکزیمم دوران اسمی دیافراگم با در نظر گرفتن اثر تغییرمکانهای نیاز مورب و همچنین تغییرمکانهای نیاز افقی در امتداد اعمال تحریک لرزه‌ای مورد مطالعه و مقایسه قرار گرفته است. منبع دانلود 28-9-2.pdf

Seismic Analysis and Design of Type FR Steel Frames Using Displacement-Based Design and Advanced Analysis Authors: Harris, John Leroy III Advisors: Mervyn Kowalsky, Committee Chair James Nau, Committee Member Tasnim Hassan, Committee Member Keywords: Capacity Design Earthquake Engineering Seismic Steel Moment Frames Steel Design Displacement-Based Design Advanced Analysis Performance-Based Seismic Engineering Issue Date: 17-Sep-2002 Degree: MS Discipline: Civil Engineering Abstract: Current design office methodologies for seismic design of steel moment frames include forced-based methods for calculating equivalent lateral forces and a static elastic analysis. Research has revealed erroneous assumptions in forced-based methods and proposes that displacement-based methods, due to modeling inelastic systems, result in more reasonable lateral force distributions. Additionally, LRFD1 member design interaction equations implicitly account for geometric and material non-linear effects. This philosophy does not satisfy compatibility between the actual inelastic member response and the elastic system as assumed by conventional elastic analysis. Displacement-based lateral force distributions in combination with a second-order inelastic static analysis that sufficiently determines the limit state strength and stability of a structural system, or "Advanced Analysis," is advantageous to the design of steel moment frames. Second-order geometric and inelastic effects are directly accounted for in the analysis. This allows engineers to predict actual frame behavior with greater accuracy and results in a more efficient and economical frame. Another advantage is that force reduction factors outlined in current seismic codes are not required since the frame is designed for inelastic behavior. This approach eliminates discrepancies between initially assumed force reduction factors and final frame ductility capacity. Also, individual member capacity checks outlined in design specifications are similarly not required. The goal of this research is to advance the validity and accuracy of displacement-based design methods and Advanced Analysis for the engineering of seismic resistant steel moment frames. This research will allow the development of alternate seismic analysis and design procedures, as well as refined practical methods that can be incorporated in a design office. 1) Manual of Steel Construction – Load and Resistance Factor Design, American Institute of Steel Construction URI: [Hidden Content] Appears in Collections: Theses دانلود: [Hidden Content] Seismic Analysis and Design of Type FR Steel Frames Using Displacement-Based Design and Advanced.pdf

Displacement based design of reinforced concrete structural walls: an experimental investigation of walls with rectangular and t-shaped cross-sections Thesis (Ph. D.)--Clarkson University, 1995. Includes bibliographical references (p. 134-141) and abstract. Thomsen__Wallace-Disp-based_design_of_RC_structural_walls_An_experimental_investigation_of_walls_with_rectangular_and_T-shaped_cross-sections_NSF_report-1995.rar