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Seismic performance comparison of thin steel shear wall and cross brace by Non-linear static analysis Pooria MOSHAVER Department of Civil Engineering, Engineering Faculty, College of Technical and Vocational University Sanandaj Branch, Sanandaj, Iran. Abstract. Steel shear wall system has been rapidly paid into attention as a resistant system against lateral loads within 3 recent decades. This system also is used for construction and retrofitting of important buildings entire the world particularly in seismicity countries such as Japan and the US. In addition, during the recent years, seismic design of the structures through changing design criterion from resistant methods to performance has been considerably welcomed by engineering society. For evaluation of constructed structures based on prior regulations, structures design regulations (regulation 2800) cannot be used and such instructions as instruction for seismic rehabilitation should be employed which evaluate and rehabilitate the structures using performance-based design concept. In present study, general performance parametric assessment of Intermediate Steel Moment Frame was carried out along with evaluation of thin Steel Shear Wall (SSW) and convergent cross brace. For this purpose, several steel frames were modeled using SAP 2000 software package. Performance assessment of each frame was conducted using non-linear static analysis or Push Over and performance point of each frame was specified using the concepts capacity spectrum and demand spectrum. 5000127326-5000205434-1-PB.pdf

COMPARISON OF THE PROGRESSIVE COLLAPSE RESISTANCE OF SEISMICALLY DESIGNED STEEL SHEAR WALL FRAMES AND SPECIAL STEEL MOMENT FRAMES M. R. Sheidaii and S. Jalili Abstract In this study, the progressive collapse potential of seismically designed steel plate shear wall (SPSW) systems is investigated using the alternate path method, and their performances are compared with those of the conventional special moment frame (SMF) systems. Nonlinear static and dynamic analyses are conducted to follow the progressive collapse of the structures, and their ability of absorbing the destructive effects of member loss is investigated. The obtained results show that when a corner or a middle column in the first story of the SPSWs is removed, the rest of the structure is not able to provide an appropriate alternative path for redistributing the generated loads caused by member loss, and therefore the structure presents a high potential for progressive collapse. However, by changing the lateral load resisting system of these buildings with the SMFs, the progressive collapse resisting capacity of the buildings increases significantly. Keywords Progressive Collapse, Alternate Path Method, Nonlinear Static Analysis, Nonlinear Dynamic Analysis, Steel Plate Shear Wall چکیده در این مطالعه پتانسیل خرابی پیشرونده در قاب­های فولادی مقاوم لرزه­ای مجهز به دیوار برشی فولادی (SPSW) با استفاده از روش مسیر جایگزین بررسی شده و عملکرد آن­ها در برابر خرابی پیشرونده با سیستم­های قاب خمشی ویژه رایج (SMF)مقایسه شده است. تحلیل­های غیرخطی استاتیکی و دینامیکی برای تعقیب وقوع خرابی پیشرونده در سازه­ها انجام شده و قابلیت جذب اثرات مخرب حذف عضو، بررسی شده است. نتایج بدست آمده نشان می­دهد زمانی که یک ستون گوشه و یا یک ستون میانی واقع در طبقه اول از سیستم SPSW حذف می­شود، سازه باقیمانده نمی­تواند مسیر جایگزین مناسبی برای بازتوزیع بارهای ناشی از حذف عضو فراهم نماید و سازه پتانسیل بالایی را برای خرابی پیشرونده نشان می­دهد. ولی با تغییر سیستم باربر جانبی سازه از SPSW به SMF، ظرفیت باربری سازه در برابر خرابی پیشرونده بطور چشمگیری افزایش می­یابد. 28-6-7.pdf

به این تاپیک سر بزنید: [Hidden Content]

بهرام‌غفاری در گفت‌وگو با اسکان نیوز تاکید کرد: سازمان نظام مهندسی ساختمان در صف عاملان تخریب شهرها/ مقاومت تمام‌قد شهرداری و وزارت کشور برای اجرای مقررات ملی ساختمان آیین‌نامه ماده 33 قانون نظام مهندسی و کنترل ساختمان شهرداری، را مکلف به تمکین از قانون نظام مهندسی و کنترل ساختمان کرده است و عدم تمکین مدیریت شهری از این آیین‌نامه، در واقع نقض صریح آن خواهد بود. البته بروز رفتارهای اینچنینی ازسوی مدیریت شهری پایتخت، دور از انتظار نبوده، چرا که این نهاد اسناد بسیار بسیار قانونی، الزام‌آور و مهمی همانند طرح‌های جامع تهران را به سهولت و بدون اینکه هیچ‌گونه احساس مسئولیت یا عذاب وجدانی داشته باشد طی 30 سال گذشته زیرپا گذاشته است. محسن‌ بهرام‌غفاری در گفت‌وگو با خبرنگار اسکان نیوز در خصوص مقاومت مدیریت شهری در رابطه با رد ابلاغیه اخیر معاونت شهرسازی شهرداری تهران، گفت: این ابلاغیه و مقاوت برای اجرای آن، همانند دیگر موارد، حلقه‌ای از سلسله حلقه‌های سرپیچی مدیریت شهری از اجرای قوانین جاری بشمار می‌رود. بهرام‌غفاری با اشاره به اینکه وزارت راه و شهرسازی با ارائه پیش‌نویس آیین‌نامه کنترل ساختمان به دولت، درخواست بررسی و در صورت صلاحدید تصویب آن را دارد، اذعان داشت: در حقیقت ارائه این پیش‌نویس در امتداد مسئولیت‌هایی بوده که قانون اساسی در مورد برخودار بودن همه آحاد کشور از مسکن مناسب، حفاظت محیط زیست، تقسیم کار بین دستگاه‌های دولتی با هدف توسعه شهری و... را بر دوش دولت گذاشته است. عضو کمیته پیش‌نویس کنترل ساختمان در ادامه اضافه کرد: ‌ وزارت راه و شهرسازی در راستای مامویت‌های قانونی، آیین‌نامه‌‌ای وضع کرده و در آن تاکید دارد که هر شخص حقیقی یا حقوقی، دولتی یا غیردولتی در صورتی که بخواهد هرگونه تصرفی در زمین یا ساختمان داشته باشد بایستی در چارچوب آیین‌نامه، آن عملیات ساختمانی دارای مجوز باشد تا از طریق کنترل مناسب تاییدیه لازم را برای بهره‌برداری دریافت نماید. به گفته تدوین‌گر قانون نظام مهندسی و کنترل ساختمان، جالب این است که در جلسات رسیدگی وزارت کشور با دوپا و تمام قامت( یک پا خود معاونت فنی، یک پا هم سازمان شهرداری‌ها و شهرداری تهران) و با کمال شگفتنی شورای مرکزی سازمان نظام مهندسی ساختمان کشور و ریاست وقت این سازمان در مقابل دستگاه تخصصی که در تقسیم کار دولت وظیفه کنترل شهرسازی و ساختمان‌سازی استاندارد و... را دارد، ایستاده‌اند. چشم‌پوشی از قانون در سازمان‌ها به یک امر بدیهی تبدیل شده است بهرام‌غفاری در پاسخ اسکان نیوز مبنی بر اینکه آیا هیچ اهرم بالادستی برای ممانعت شهرداری از قانونی‌شکنی وجود ندارد؟، اذعان داشت: این چهار عنصر( چهار عضو مربع مقاومت در برابر اصلاحات) یک دیوار بتنی در مقابل پیشنهادات بسیار بدیهی وزارت راه و شهرسازی ایجاد کرده‌اند که نتیجه آن ده‌ها سال بی‌قانونی و اتفاقات اخیر در حوزه ساخت‌و ساز و مهندسی است. عضو کمیته پیش‌نویس کنترل ساختمان با تاکید بر اینکه مصالحه و چشم‌پوشی از تخلفات بین‌دستگاهی، بده و بستان و معامله‌گری بر سر چشم‌پوشی از اجرای قوانین به یک امر بدیهی تبدیل شده است، اظهار داشت: همه مصیبت‌های کشور ریشه در همین مصالحه‌های بین‌دستگاهی دارد؛ در نتیجه لازم است که وزارت راه و شهرسازی به عنوان مسئول تهیه طرح‌های توسعه شهری ( طرح جامع) و ناظر عالیه برنحوه عمل شهرداری‌ها در انطباق ساختمان با طرح‌های مصوب این وزارتخانه، با رجوع به صحن دولت، پارلمان و هر جای دیگر که لازم باشد، از این بی‌قانونی‌های ممانعت نماید. وی ضمن بیان اینکه دومین راه، انتخاب یک قائم‌مقام خواهد بود، تاکید کرد: بایستی هر شهرداری یک قائم مقام شهرسازی و کنترل ساختمان داشته باشد که آن قائم مقام را وزارت راه و شهرسازی معین کند و یا اینکه اگر شهرداری قصد انتخاب این قائم مقام را دارد، وزارتخانه به عنوان رئیس شورای عالی شهرسازی صلاحیت وی را تایید نماید؛ البته این قائم‌مقام برای اجرای طرح‌های مصوب ناظر عالیه استقلال لازم را خواهد داشت، در غیر این صورت و با شریط فعلی پشت‌سر تهران که تبدیل به یک کلان شهرغیرقابل سکونت شده؛ شهرهای اصفهان، شیراز، تبریز، مشهد و... هم خواهند آمد. بهرام‌غفاری با تاکید بر اینکه وزیر راه و شهرسازی با شجاعت همیشگی باید تمام قامت در هیئت دولت از این واقعیت دفاع نماید، تصریح کرد: راه دیگر این است که تمامی وظایف این وزارتخانه در حوزه شهرسازی را از این نهاد سلب نمایند و یک لایحه با عنوان لایحه معافیت وزارت راه وشهرسازی از امور شهرسازی ارائه شود و در واقع وزارت کشور صاحب تمامی این مسئولیت‌ها شود. در غیر این صورت باید اجازه بدهند این وزارتخانه به عنوان مرجع توسعه کالبدی، قائم مقام مورد نظر را به صورت کاملا مستقل در شهرداری داشته باشد. عضو کمیته پیش‌نویس آیین‌نامه کنترل ساختمان بر این اعتقاد است که شهرداری و وزارت کشور، چهره مخفی در پشت توسعه شهرها بدون توجه به قوانین موجود، تخریب آثار باستانی و باغات و ... هستند، که در واقع شهرها را به این مصیبت بزرگ گرفتار کرده‌اند، اما حالا با گذشت ده‌ها سال بی‌قانونی، تمامی انگشت‌ها به سمت وزارت راه و شهرسازی که در این مدت هیچکاره بوده، نشانه می‌رود. بهرام‌غفاری با انتقاد از اینکه متاسفانه سازمان نظام مهندسی هم از متقاضیان خرید تراکم و بی‌توجهی به قانون است، خاطر نشان ساخت: سازمان نظام مهندسی ساختمان حتی برای ساخت ساختمان‌‌های اداری خودش از شهرداری تراکم می‌خرد. سازمانی که وزیر راه و شهرسازی و برخی دیگر با هزار خون دل برای حفظ ضوابط شهرسازی و مهندسی در کشور بنا نهادند؛، بر اثر سوء مدیریت در صف کسانی قرار دارد که در تمام دهه گذشته عامل تخریب شهرها و نابودی محیط زیست بوده‌اند. منبع: [Hidden Content]

نحوه تشکيل و انتخاب اعضاي هيات رئيسه گروه هاي تخصصي سازمان های نظام مهندسی استان ها نامه حامد مظاهریان معاون امور مسکن و ساختمان وزیر راه و مسکن به دکتر ترکان ریاست سازمان نظام مهندسی کشور دانلود نامه در فرمت پی دی اف منبع: سایت سازمان نظام مهندسی استان همدان goroh takhasosi.pdf

ابلاغ وزارتخانه به دکتر ترکان درباره نحوه کنترل شرح خدمات مهندسی منبع : کانال تلگرام مجمع مهندسین ساختمان کرمانشاه

Derivation of Equation of Motion for the Pillow-Shape Seismic Base Isolation System Ali Tayaran; Mahmood Hosseini Rolling-based seismic isolation systems, in which rollers of circular or non-circular section are used, are less expensive and easier to manufacture. However, this type of isolation suffers from either lack of restoring or re-centering capability, or weakness against uplift forces. To resolve the first shortcoming the use of elliptical as well as pillow-shape rolling parts has been suggested, and for the second one, using some uplift restrainers has been proposed. In this paper a kind of base isolating device, called Pillow-Shape Seismic Base Isolation System (PSBIS) is introduced which has both re-centering and uplift-restrained capabilities. The paper is concentrated on derivation of equation governing the motion of PSBIS device. To derive this equation, since the behavior of the device is highly nonlinear the use of Lagrange equation of motion is the most appropriate approach. For this purpose, considering the rotation angle of the pillow-shape roller as the generalized coordinate, the horizontal and vertical components of the pillow-shape roller acceleration have been formulated and the kinetic and potential energy terms as well as the virtual work of the non-conservative, resulted from rolling resistance and seismic forces, have been developed to be substituted in the basic Lagrange equation. To verify the derived equation of motion a simplified sample of the PSBIS device was built and used experimentally, and also the motion of the pillow-shape parts was traced by drawing them in Auto-CAD software. Results show the validity of the derived equation of motion. منبع دانلود JSEG501443558600.pdf

Free vibration analysisof soft-core composite-faced sandwich plates using three-dimensional finite element method Mohammad Mahdi Kheirikhah; Hasan Aghabarati; Pooneh Khosravi In this paper, natural frequencies of the sandwich plates with soft flexible core and composite face sheets are obtained. Three-Dimensional (3D) finite element method (FEM) is used for constructing and analyzing of the sandwich plates to obtain their natural frequencies. Continuity conditions for transverse shear stresses at the interfaces as well as transverse flexibility and transverse normal strain and stress of the core are considered.The effects of plate dimensions such as aspect ratio and thickness ratio are studied. Also, different boundary conditions such as all edges clamped (CCCC), all edges simply supported (SSSS) and combined boundary conditions including (CFCF)are applied to the sandwich plates. Comparison of the present results in special case with those of the accurate plate theories confirms the accuracy of the proposedmodel. منبع دانلود JSEG491443558600.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

Effect of Polypropylene Fibers on Strength and Thermal Resistance of Concrete Jamal Ahmadi; Hossein Aghajanloo In this paper, the effect of Polypropylene Fibers added to concrete on strength and thermal resistance of high strength concrete has been investigated. Therefore, five tests have been carried out to reach this goal which it includes; effect of weight percent of polypropylene fibers on mechanical properties of concrete, effect of fiber’s length on the strength of high strength concrete, effect of fiber’s volume on the thermal stability of high strength concrete, examine the phenomenon of spalling concrete high resistance against heating, determine the changing of compressive strength of high strength concrete in different temperatures. The results present that the compressive strength has declined with the percentage of fiber concrete after 0.7 kg/m3 . Moreover, in all cases the tensile strength and concrete’s bending strength will be increased by fiber content. منبع دانلود JSEG471443558600.pdf

Numerical Modeling of the Effect of Geocell Elements’ Dimensions on Behavior of Circular Footings Soheil Ghareh Use of auxiliary elements in refining and betterment of engineering properties of soil have gained attention since a long time ago. Nowadays the effectiveness and capability of the soil reinforcing technique for giving proper practical solutions in various projects have resulted in this technique quickly gaining a place in geotechnical engineering. In this paper, the results of laboratory studies on such characteristics as width and height of the geocell element on load-bearing capacity and settlement of footings have been modelled numerically. It should be noted that the laboratory studies have been carried out in the uniaxial apparatus and analytical studies have been carried out utilizing the finite element software ABAQUS 6.11. by investigating the results it can be seen that in the case of using a geocell element in reinforcing the soil, the load-bearing capacity of the footing increases 1.65 times in comparison with the non-reinforced sample, while settlement in the reinforced footing – with geocell – is only 1.15 times more than the non-reinforced footing. Furthermore when the increase in load-bearing capacity of the footing has a significant importance, the best scenario is increasing the height of the geocell element. But when the footing’s settlement is of significant importance, we can have more effective results by changing the width of the geocell element. By comparing the results from numerical and laboratory studies, an appropriate agreement is observed and in all cases the analytical studies have more conservative results compared to the results from laboratory studies. منبع دانلود JSEG461443558600.pdf

Performance of industrial facilities and lifelines during the October 23rd, 2011 Van, Turkey Earthquake Kiarash Nasserasadi; Mehran Seyed Razzaghi Damage to essential facilities (e.g. lifelines and industrial facilities) due to extreme loads may cause remarkable indirect impact as well as direct physical loss. Hence understanding seismic performance of essential facilities is very important in high seismic risk regions. On October 23, 2011 an earthquake of magnitude Mw7.2 occurred in Van province in eastern Turkey. Several damages occurred at industrial plants. Damage to equipment and buildings caused work abandon in some industrial plants. In this paper the observed damage to essential facilities such as transportation systems, silos and gas stations are presented. منبع دانلود JSEG451443558600.pdf

Effect of Adding Nanoclay on the Mechanical Behaviour of Fine-grained Soil Reinforced with Polypropylene Fibers Alireza Tabarsa; SeyedJassem Hosseini In this study the performance of clay nano-particles on the soil reinforced with Polypropylene fibers (PP-fiber) has been investigated. Also a series of investigations concerning the effect of random orientation of fibers on the engineering behaviour of soil were conducted. Soil mixtures were modified with varying percentages of nanoclay and Fibers. Unconfined compressive strength (UCS), Compaction, Atterberg limits, and microstructural (scanning electron microscopy) tests were conducted. In order to understand the micromechanical behaviour of nanoclay in fiber reinforced soil, the microstructure and morphology of fracture surfaces of samples were studied using Scanning Electron Microscopy (SEM). It was found that the addition of nanoclay significantly improves the performance of fiber reinforced soil in a unique way. This paper presents the understanding of nanoclaybehaviour and its impact on the overall mechanical characteristic and laboratory performance of fiber reinforced soil. منبع دانلود JSEG441435606200.pdf

The Effect of Recurring on Physical Properties of Concrete Containing Silica-Fume with Improper First Curing Ali Delnavaz; Mohammad Reza Pezeshkian As regards if curing stops for some time and then resumes again, then strength gain will also stop and reactive, in this study with choose suitable curing conditions after improper first curing (recurring) for normal and silica-fume concrete, Effect of this curing conditions on strength and permeability was investigated. The results from tests such as compressive strength, capillary water absorption and water penetration under pressure, indicates that curing after 28 days for concretes with improper first curing, especially for silica-fume concretes could be effective and reduction permeability and increase compressive strength of concretes was observed منبع دانلود JSEG431435606200.pdf

Assessment of Subsurface Explosion caused by Tunnel Construction in Urban Areas Hossein Haghighimanesh; Mohammad Azadi Nowadays, tunneling in urban areas is a common activity for a variety of transportations such as subways, water supply, lifelines andsewers that may require blast operations. The characteristics of stress waves of the blast are quite different from earthquake waves. The blast waves are usually of high frequency content, short duration, equality of amplitudes in horizontal and vertical directions and large range of magnitude from ten to thousands of the gravitational constant. However few papers can be found to discuss about the effect of soil characteristics under blast loading. In this paper, numerical models based on finite element method is used to simulate stress wave at soil sites under explosion effect in an underground linear chamber and then characteristics of the ground movement and the explosion effect on soil-structure interaction is analyzed. In this study, numerical results of area deformations in every region are compared together and parameter sensitivity of the soil is analyzed. Results presented in this paper can be used in a more detailed assessment of ground motion effect on structures. منبع دانلود JSEG421435606200.pdf

Performance Evaluation of Viscoelastic and Friction Passive Damping System in Steel Structures Mohammad Taghi Kazemia; Hosein Hoseini Additional dampers are employed in order to decrease the dynamic response of structure against the earthquake and wind loading recently. In this study, two types of systems related to waste of inactive energy, i.e. frictional damper which is categorized in dampers dependent on movement and viscoelastic damper which is categorized in dampers dependent on velocity, in making steel structures resistant are investigated and evaluated. Results of structures with dampers (viscoelastic damper, friction damper and combination of both dampers) were compared with the results of structures without damper. Increasing trend in dissipating energy was observed. Then, the behavior of these dampers in frames of 4, 8 and 12 stories was studied by modeling the damper directly. The analyses were conducted via nonlinear time history technique and by using earthquake records (near fault and far fault) scaled with peak acceleration and SAP 2000 14.2.2 software. The results indicate the appropriate function of the selected dampers in controlling and decreasing the seismic responses of the structure. Given that in frictional dampers the maximum force created in the damper is specified, the use of this damper in resistance building of structures is very effective especially by considering the limitation of structure capacity. منبع دانلود JSEG391435606200.pdf

Influence of the Isolator Characteristics on the Response of the Isolated Buildings in the Near-Fault Earthquakes Beytollah Taromi; Kiarash Nasserasadi; Asghar Vatani Oskouei Seismic base isolation are devices that used to limit the human and material damage caused by an earthquake. This devices diffuse the energy induced at the time of the earthquake before being transferred to the structure.The base isolated structures when subjected to the near-fault eathquakes which contain long-period velocity pulses that may coincide with the period of base isolated structures resulting in excessive deformation and rupture of isolators. Parameters of base isolation such as the yield strength and post yield stiffness ratio have significent effect on the displacement of isolation system. To study this effect, influence of these parameters on the dynamic response of the isolated structures in term of displacment, acceleration, base shear and absorbed energy has been studied. The results show that the increase in the bearing yield strength can reduce the bearing displacment signficantly without much alterning to the superstructure accelerations. Also the optimum yield strength and post yield stiffness ratio of the LRB is found to be in range of 0.8% - 1% of the total weight of the building and 0.08 – 0.12 of the ratio of plastic stiffness to elastic stiffness of base isolation respectively under near fault motions. منبع دانلود JSEG411435606200.pdf

Pillow-Shape Base Isolation System and Its Seismic Behavior Ali Tayaran; Mahmood Hosseini In this paper a new isolating system is introduced for short to mid-rise buildings. In comparison to conventional systems such as LRB and HRB, the proposed system has the advantage of no need to cutting edge technology and has low manufacturing cost. This system is made up of two orthogonal pairs of pillow-shaped rollers that are located between flat bed and plates. By using this system in two perpendicular directions, building can move in all horizontal directions with respect to its foundation. Due to the pillow shape of the roller, this system has self-centering capability which causes it to return to its original position after the earthquake. The rolling friction force between pillows and their bed creates some damping in the system which prevents it from further oscillation after earthquake excitations diminish. The purpose of this study is to evaluate the proposed isolation system’s performance under different earthquake excitations. First of all general features of the proposed isolators have been introduced followed by the analytical equations of the system. Vertical bearing capacity and the effects of the thickness of pillows has been investigated using ABAQUS software. It has been shown that for a pair of pillows of 58 cm width, 45 cm height and 100 cm length the vertical load bearing capacity of the system is more than 300 tons. The period of system with respect to the height and radius of curvature of the rollers, and seismic response of a building, assumed as a rigid body resting on isolators, has been studied subjected to simultaneous effects of horizontal and vertical excitations. It has been shown that the proposed system can reduce the absolute acceleration in the building around 78% in average, while the building’s maximum displacement is around 1.77 times of the ground in average. منبع دانلود JSEG401435606200.pdf

Effect of the Cylindrical Reinforcing Element’s Filling Materials on the Soil’s Resistance Seyed Vahid Mojtahed Sistania; Soheil Ghareh; Mehdi Siavoshnia In this paper a laboratory study has been carried out on the effect of changing the type of soil filling cylindrical reinforcing elements from SM to GM on behavior of sandy soil. In this study the primary tests for evaluation of the impact of reinforced sand and gravel columns with diameters of 5 cm and heights of 15 cm subjected to vertical stresses of 50, 100, and 150 KPa were carried out in a large-scale direct shear apparatus (300×300×150 mm). Results showed that the shear stress and settlement of the reinforced sample with geogrid and a gravel column increases by 45.4% and decreases by 23.9% respectively compared to the non-reinforced sample. منبع دانلود JSEG381427657400.pdf

The Investigation of Effective Factors in the Removal of Bentonite Jelly from the Joints of Cut-off Wall Panels Seyed Majdeddin Mir Mohammad Hosseini; Abdolhossein Azadmaneshb In the construction process of a plastic concrete cut-off wall, concreting is usually performed using the termie pipe method. In this method, concreting is performed from the lowest point in the excavated trench (containing the slurry) using a funnel and the pipe connected to it. The concrete poured in the funnel gradually settles in the panel through the termie pipe which is beneath the slurry and the end of the pipe has always been in the concrete. Because of its unit weight which is less than that of the concrete, the slurry goes up and the height of its column reduces. As the construction continues the length of the termie pipe is cut down so that the remaining operation is carried out more easily. In this process there are three types of flows to be considered: concrete flow in the termie pipe, concrete flow in the panel and slurry flow in the panel. Using the fundamentals of hydraulics, this paper tries to study the interactions among these fluids. It also examines the influential factors in removing the bentonite jelly in order to provide the plastic concrete with homogeneity and consistency (slump 22-16 cm) in primary and secondary panels of cut – off wall as a most reliable water tightening system in most dam foundations. منبع دانلود JSEG371427657400.pdf

Evaluating Response Modification Factors of Concentrically Braced and Special Moment Steel Frames in Duplex Buildings Leila Kalani Sarokolayi; Sirous Gholampour dehkordib; Masoud Shafaghati sefidabc Response modification factor (R-factor) is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake. Relying on this, many seismic design codes led to reduce earthquake loads imposed to the structure. The present paper tries to evaluate the R-factors of conventional concentric braced frames (CBFs) and special moment frames (MRFs) in duplex steel buildings with level difference in their floors. Since, the R-factor depends on ductility and over strength, the incremental nonlinear static analysis, push over analysis, has been performed on 4, 7 and 10 storey building models with three floor level differences and including CBFs and special MRFs systems in x and y directions of buildings respectively. The results showed that the R-factors for CBFs system in duplex buildings were higher than ones in conventional buildings without floor level differences while for MRFs system it was found that on 4 and 7 storey duplex buildings, the R-factors were decreased and with the increase in building height to 10 storey, they were increased compared to conventional models. منبع دانلود JSEG361427657400.pdf

Numerical Analysis of Cyclic Behavior of Beam-To-Column Bolted Connections in Steel Frames Morteza Rastian; Asghar Vatani Oskouieb; Hassan Aghabaratic This article considers the seismic behavior of beam-to-column joints in steel frames for different bolt arrangements by using of finite element modeling. As the most important beam-to-column joint type, the beam-to-column joints with end-plate is chosen for the analysis. Four different specimens have been analyzed. These models had some differences such as bolt arrangement and the presence or absence of end-plate stiffeners. Design of bolts arrangement and stiffeners have been done based on the AISC standards. Two vertical bolt arrangements, with or without stiffener and two other models with horizontal bolt arrangement, with or without stiffeners have been considered. Different aspects such as energy absorption, ductility, initial stiffness and effective stiffness for all specimens have been compared. Finally effect of pre-stressing of all specimens has been assessed. As a result, comparison between vertical bolt arrangement and horizontal bolt arrangement has shown that the vertical bolt arrangement is more advantageous, especially in energy absorption منبع دانلود JSEG351427657400.pdf

Development of Seismic Criteria for Seismic Responses of Regular and Irregular Structures in Plan considering Vertical Component of the Near-field Records Maryam Firoozi Nezamabadi; Fariborz Yaghoobi Vayeghan Field observations of the incurred damages to the buildings and bridges due to earthquakes in near field show there are various failure modes which are in relation to the forces caused by vertical component. While vertical component of earthquake for ordinary buildings in most seismic regulations and standards is not considered. Therefore, in the current study the effects of vertical and horizontal components of earthquake on regular and mass asymmetric structures are investigated simultaneously. The study considers a model of one-story structure with 3 degrees of freedom, lateral displacement, torsional displacement of roof level and vertical displacement, on a rigid foundation. It is concluded that for all such structures in the near-fault zones, the effect of vertical component must be considered. In case of stiff structures, the effect of the force on displacement of such structures is of importance and the effect of vertical component can be disregarded. The use of vertical design response spectrum to calculate the vertical forces caused by near field earthquakes is also recommended. منبع دانلود JSEG341427657400.pdf

A methodology for Determining the Seismic Vulnerability of Old Concrete Highway Bridges by Using Fragility Curves Araliya Mosleh; jose jara; Humberto Varum Past earthquakes have demonstrated that old RC bridges may be seismically vulnerable. Bridge responses during the last decades illustrated the necessity of the seismic assessment of bridges especially those which were designed with old codes. In this research an existing concrete bridge representative of the most common bridges in the highway system in Iran are studied. Push over and nonlinear time history analyses using refined 3-D structural models are performed for each sample. Bridge structural systems are identified and quantified to establish a set of earthquake-site-bridge samples. The superstructure was assumed to remain elastic and the nonlinear behavior in piers was modeled by assigning plastic hinges in columns. The soil flexibility was considered by using elastic spring elements. Displacement ductility and peak ground acceleration (PGA) were selected as seismic performance indicator and intensity measure, respectively. Ten time history records from the past earthquakes were selected. They were scaled and applied incrementally to the 3-D model to evaluate seismic performance of the bridge. Furthermore, bridge damage states were defined and the probabilistic characteristics of structural capacity corresponding to each damage state were established. Then, the conditional probabilities of specific structural demand to exceed the structural capacity were computed and the results were displayed as fragility curves. منبع دانلود JSEG331427657400.pdf

Evaluation of Autogenous Shrinkage in High-Performance Concrete Jamal Ahmadi; Reza Naghdi2 Recent tendencies in concrete technology have been towards to high- performance concrete with a low water-cement ratio. However, high performance concretes have some problems. One of the problems is early-age cracking due to autogenous shrinkage. This study presents the results of an experimental investigation carried out to evaluate the autogenous shrinkage of high-strength concrete. According to this, effects of water/binder ratio, cement content, fine to coarse aggregate ratio and silica fume content were evaluated. From the results of this investigation, it can be concluded that the autogenous shrinkage strain of high strength concrete increases with reduction of w/b ratio. The results show also that the variation of cement content and fine to coarse aggregate ratio had only a limited effect on the autogenous shrinkage. منبع دانلود JSEG581419885000.pdf