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بهبود شکل پذیری و رفتار چرخه ای مهاربند شکافدار با استفاده از نبشی فولادی مجله علمی، پژوهشی: نشریه علمی و پژوهشی سازه و فولاد-شماره‌ي هفدهم بهار و تابستان 1394 نویسنده: سیدمهدی زهرایی، عبداله چراغی دانلود art-674371220.pdf

SEISMIC DESIGN OF STEEL STRUCTURES BASED ON DUCTILITY AND INCREMENTAL NONLINEAR DYNAMIC ANALYSIS H. Kermani, F. Behnamfar and V. Morsali Abstract In this paper a simple tool for seismic design of steel structures for a selected ductility level is presented. For this purpose, a consistent set of earthquakes is selected and sorted based on the maximum acceleration of ground surface. The selected records are applied as the base motion to a single-degree-of-freedom system with strain hardening and the maximum response acceleration is determined for three levels of ductility. The response results of the incremental nonlinear dynamic analysis are presented in the shape of the maximum acceleration of the system versus the peak ground acceleration for a certain ductility demand. Using these graphs, the maximum acceleration and base shear of the system are calculated accounting for its nonlinear behavior, hence eliminating the need for the response modification factor. This is the main advantage of the presented diagrams for nonlinear seismic design of steel moment frames. Keywords ductility, incremental dynamic analysis, seismic design. چکیده در این مقاله، ابزاری ساده برای طراحی لرزه­ای سازه­های فولادی به ازای سطوح شکل­پذیری انتخاب شده ارائه شده است. برای این منظور، مجموعه­ای از زلزله­های سازگار انتخاب و براساس ماکزیمم شتاب دسته­بندی شده­اند. رکوردهای انتخاب شده به­عنوان حرکت پی به سیستم یک­درجه آزاد با رفتار کرنش سخت شونده اعمال شده و حداکثر شتاب براساس سطوح شکل­پذیری تعیین می­گردد. نتایج پاسخ­های حاصل از تحلیل فزاینده غیرخطی، به­صورت دیاگرام­هایی مربوط به حداکثر بازتاب شتاب سیستم در مقابل ماکزیمم شتاب زمین (PGA) برای یک نیاز شکل­پذیری خاص نشان داده شده است. با استفاده از این شکل­ها، بیشترین شتاب و برش پایه سیستم برای رفتار غیرخطی بدون نیاز به عامل ضریب رفتار محاسبه می­گردد، که از مزایای اصلی این دیاگرام­ها برای طراحی لرزه­ای غیرخطی قاب­های خمشی فولادی است. منبع دانلود 29-1-4.pdf

Mechanical properties of Semi-Rigid Steel Frame- Braced Steel Plate Shear Wall Due to mechanical performances of brace and steel plate, mechanical properties of semi-rigid joints and its construction and installation, semi-rigid steel frame-braced steel plate shear wall system is proposed. Nonlinear static analysis with parameters (thickness of plate, type of brace, size of brace and the ratio of span to height) changed of a single-span and single-floor semi-rigid steel frame-braced steel plate shear wall system illustrates that braced steel plate shear walls contributes obviously to bearing capacity and lateral rigidity of semi-rigid steel frame. Also, the finite element analysis (by ANSYS) show that semi-rigid steel frame-braced steel plate shear wall system has excellent ductility. AMR.1120-1121.1516.pdf

Comparison of plasticity and stiffness of steel shear walls with composite steel plate shear wall Leila Shahryari; Mahdi Esfandiari The steel shear wall and composite steel plate shear wall is introduced in recent three decade and is considered and is spread rapidly. Composite steel plate shear wall which is made of a layer of thin steel sheet with coating of reinforced concrete in one or both sides of steel palate is considered a third generation of resistance shear walls against lateral loads that in addition to increasing the strength, ductility and energy absorption, it is very economical and affordable and it is used in constructing high buildings, retrofitting buildings and tanks. In this paper we have tried to examine the seismic behavior of steel and composite shear walls. For this purpose several models of steel shear and composite walls from one to five stories were constructed and analyzed by Abaqus software. The result show that composite steel plate shear walls has more ability to absorb energy, spread produced stress to different parts of the steel plate and ductile than steel shear walls. The curve hysteresis loop of composite steel palate shear walls is more stable and sustainable than steel shear wall. With increasing the number of stories, the initial strength and stiffness is decreased due to increase in lateral shift but the amount of absorbing energy and ductility is increased. The force tolerance in composite steel plate shear wall models is increased in comparison with steel shear walls منبع دانلود JSEG481443558600.pdf

Seismic behavior of code designed steel plate shear walls Jeffrey W. Berman∗ Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195-2700, United States Engineering Structures 33 (2011) 230–244 AbstractThe AISC Seismic Design Provisions now include capacity design requirements for steel plate shear walls, which consist of thin web plates that infill frames of steel beams, denoted horizontal boundary elements (HBEs), and columns, denoted vertical boundary elements (VBEs). The thin unstiffened web plates are expected to buckle in shear at low load levels and develop tension field action, providing ductility and energy dissipation through tension yielding of the web plate. HBEs are designed for stiffness and strength requirements and are expected to anchor the tension field formation in the web plates. VBEs are designed for yielding of web plates and plastic hinge formation at the ends of the HBEs. This paper assesses the behavior of code designed SPSWs. A series of walls are designed and their behavior is evaluated using nonlinear response history analysis for ground motions representing different hazard levels. It is found that designs meeting current code requirements satisfy maximum interstory drift requirements considering design level earthquakes and have maximum interstory drifts of less than 5% for maximum considered earthquakes. Web plate ductility demands are found to be significantly larger for low rise walls than for high rise walls where higher modes of vibrations impact the response. The percentage of story shear resisted by the web plate relative to the boundary frame is found to be between 60% and 80% and is relatively independent of panel aspect ratio, wall height, or hazard level, but is affected by transitions in plate thickness. Maximum demands in VBEs in design level shaking are found to be considerably less than those found from capacity design for SPSWs with 9 or more stories. Research highlights► Steel plate shear walls designed via current building code requirements meet drift limitations. ► Web plate ductility demands in low-rise steel plate shear walls are significantly larger than those in taller steel plate shear walls. ► The percentage of story shear resisted by the web plates was found to range from 60–80% and is independent of aspect ratio, wall height and seismic demand but is affected by transitions in web plate thickness. ► Maximum demands in steel plate shear wall columns from nonlinear response history analysis are found to be considerably less than those determined from capacity design in steel plate shear walls with 9 or more stories. Keywords Steel plate shear walls; Seismic behavior; Ductility; Seismic design; Column demands; Steel structures; Shear walls 10.1016_J.ENGSTRUCT.2010.10.015-Seismic-behavior-of-code-designed-steel-plate-shear-walls.pdf

Experimental and numerical study of unstiffened steel plate shear wall structures Meng Wang a,⁎, Yongjiu Shi b, Jian Xu c,Weiguo Yang a, Yixin Li b a School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China b Department of Civil Engineering, Tsinghua University, Beijing 100084, China c China Southwest Architectural Design and Research Institute Corp. LTD, Chengdu 610081, China a r t i c l e i n f o a b s t r a c t Article history: Received 13 March 2015 Accepted 6 May 2015 Available online 20 June 2015 Keywords: Unstiffened thin steel plate shear wall structure Hysteretic behavior Energy dissipation capacity Ductility Finite element method (FEM) Column stiffness In order to investigate the seismic behaviors of unstiffened thin steel plate shear wall structure, tests of four three-story unstiffened steel plate shear wall specimens under cyclic loads were carried out. Parameters of the specimens included height-to-thickness ratio, span-to-height ratio and middle brace. The carrying capacity, hysteretic behavior, degraded characteristics, ductility, failuremodes, energy dissipation capacity were analyzed and compared deeply. Besides, the nonlinear finite element method of shear wall structure was also established, which was verified by test results. Finally, the effect of column stiffness on load-carrying capacity was studied. The practical requirements of in-plane and out-of-plane stiffness of edge column were suggested. The experimental and numerical results showed that: this kind structure exhibits high strength, good energy dissipation capacity, and good ductility (the ductility coefficients are more than 3.0). When the inter-story drift angle reaches 1/50, the strength degradation is no more than 5%, indicating that the structure has good seismic behaviors. The span-to-height ratio has little effect on load-carrying capacity, while slightly affects the initial stiffness and ductility. The effect of height-to-thickness ratio (thickness) on load-carrying capacity is relatively larger than other factors. The middle braces do not improve the behaviors of structures. The stiffness of edge column has great effect on lateral load-carrying capacity of shearwall structures. The value of column stiffness index could bewithin 2.0–2.5 to achieve the sufficient constraints and economical benefit. 1-s2.0-S0143974X15001406-main.pdf

Experimental and analytical investigations on seismic behavior of ductile steel knee braced frames Seyed Mehdi Zahrai 1a and Meysam Jalali 2 1 Center of Excellence for Engineering and Management of Civil Infrastructures, School of Civil Engineering, the University of Tehran, Tehran, Iran 2 Department of Civil Engineering, Faculty of Engineering, University of Damghan, Damghan, Iran (Received November 11, 2011, Revised August 30, 2013, Accepted September 16, 2013) Abstract. Knee Braced Frame (KBF) is a special form of ductile eccentrically braced frame having a diagonal brace connected to a knee element, as a hysteretic damper, instead of beam-column joint. This paper first presents an experimental investigation on cyclic performance of two knee braced single span one-story frame specimens. The general test arrangement, specimen details, and most relevant results (failure modes and hysteretic curves) are explained. Some indexes to assess the seismic performance of KBFs, including ductility; response reduction factor and energy dissipation capabilities are also subsequently discussed. Experimental results indicate that the maximum equivalent damping ratios achieved by test frames are 21.8 and 23% for the specimens, prior to failure. Finally, a simplified analytical model is derived to predict the bilinear behavior of the KBFs. Acceptable conformity between analytical and experimental results proves the accuracy of the proposed model. Keywords: knee braced frames; cyclic behavior; ductility; equivalent damping ratio; response reduction factor; simplified model Steel and Composite Structures, Vol. 16, No. 1 (2014) 1-21 DOI: [Hidden Content] منبع: [Hidden Content] دانلود: [Hidden Content] AoJV84uc.pdf

Analytical study on cyclic behavior of chevron braced frames with shear panel system considering post-yield deformation S.M. Zahrai and A. Moslehi Tabar Abstract: An analytical investigation is performed on chevron braced frames using the shear panel system (SPS) and verified based on experimental results. This paper aims to determine key issues influencing the cyclic behavior and energy dissipation capacity of this kind of ductile braced frame. An extended analytical model is presented to evaluate the lateral stiffness of the SPSs at different levels of nonlinear deformation. The expressions developed in this model may be used to select the geometric properties of the SPS based on the desired ductility. Finally, the results obtained from testing on five full-scale braced specimens are used to verify the validity of the proposed model. The experimental specimens showed approximately 30% hysteretic damping ratio and their SPSs reached a plastic rotation of about 0.15 rad. Key words: shear panel, inelastic deformation, earthquake, damping, energy dissipation, post-yield behavior, ductility. . دانلود: [Hidden Content] منبع: [Hidden Content] QSN7obHy.pdf

8. مهرداد حجازی, پرهام معمارزاده, علی محمدیان, , "Study of the Effect of the Length and Position of Knee Elements on Structural Behavior of Knee-Braced Steel Frames and Comparison with X-Braced Frames", 4th International Conference on Seismic Retrofitting, تبريز, 2012 Abstract In optimum design of steel frames that are resistant to lateral loads it is necessary to provide stiffness and ductility, along with financial considerations. Lateral resistant systems like bending frames or concentric braced frames normally cannot provide liable stiffness and ductility. To solve this problem, it can be helpful to use knee bracing. In a knee bracing system a diagonal member is connected to a knee element that works like a plastic fuse. In this situation, ductility is provided through yielding of the knee element, and stiffness is supplied by a diagonal member. In this study, a number of three-span steel frames with different number of floors have been analysed using nonlinear dynamic method in order to investigate the effect of the length and position of the knee element on the stiffness and ductility of the frames. Obtained results have been compared with those of x-braced steel frames. Keywords : knee bracing, nonlinear dynamic, ductility, stiffness. منبع: [Hidden Content] دانلود: [Hidden Content] PaperC_8873.pdf

DUCTILITY BEHAVIOR OF A STEEL PLATE SHEAR WALL BY EXPLICIT DYNAMIC ANALYZING P. Memarzadeh Faculty of Civil Engineering, Islamic Azad University, Najafabad Branch, Iran Email: p-memar@iaun.ac.ir, parham_memarzadeh@yahoo.com The 14 th World Conference on Earthquake Engineering October 12-17, 2008, Beijing, China ABSTRACT : AISC-341 provides requirements for designing of SPSWs by means of a capacity-design method in which boundary elements are designed for forces corresponding to the fully yield strength of the web plate. In present research, an explicit dynamic analysis is conducted to a typical multi-storey SPSW designed according to AISC requirements. The SPSW model is subjected to a base earthquake acceleration record to simulate the time history response of the structure. The analysis utilizes a finite element method involving both material and geometric nonlinearities. The energy dissipation and ductility behavior of the structure are investigated through time history response of the system. KEYWORDS: Steel Plate, Shear Wall, Transient, Ductility, Energy Dissipation PaperC_5125.pdf