جستجوی مقالات مرتبط با کلیدواژه « field effects » در نشریات گروه « عمران »
تکرار جستجوی کلیدواژه «field effects» در نشریات گروه «فنی و مهندسی»-
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.Keywords: Seismic Responses, Regular, Irregular Structures in Plan, Vertical Component, Near, field Effects, Iranian Code of Practice for Seismic Resistant Design of Buildings (Standard No.2800)}
-
آیین نامه های معتبر ساختمانی در یکی دو دهه ی اخیر، روابطی را برای محاسبه ی نیروی وارد بر اجزای غیرسازه یی ساختمان ها ارائه کرده اند. در این مطالعه، روابط پیشنهادی آیین نامه ی یوروکد با مقادیر حاصل از تحلیل های تاریخچه ی زمانی قاب های فولادی 3، 5 و 7 طبقه ی خمشی، مهاربندی هم محور و برون محور با رفتار کشسان و خمیری تحت رکوردهای حوزه ی دور و نزدیک قایسه و نشان داده شده است که مقادیر حاصل از این روابط در بسیاری از موارد، غیرمحافظ کارانه و کمتر از حد لازم است. بر این اساس و با استفاده از نتایج تحلیل های ذکرشده برای اصلاح مقادیر این آیین نامه، اصلاحاتی پیشنهاد می شود. این اصلاحات عمدتا مرتبط با اثر محل قرارگیری عضو غیرسازه یی در ارتفاع سازه و نیز ضریب تشدید ارائه شده در آیین نامه ی مذکور است. در این نوشتار، همچنین اثر زلزله های حوزه ی نزدیک و شدت زلزله در نیروی وارد بر اعضای غیرسازه یی نشان داده شده است.
کلید واژگان: اجزای غیرسازه یی, شدت زلزله, قاب برشی, زلزله ی حوزه ی نزدیک, طیف پاسخ طبقه, ضریب تشدید, بیشینه ی شتاب طبقه}The importance of non-structural components in the seismic performance based design of buildings is well known nowadays. Impaired Non-Structural Components (NSC) in earthquakes could cause heavy loss of life and property and loss of serviceability. The response of NSC depends on various parameters, among them are the behavior of the primary structure, location of non-structural elements in the structure, interaction between NSC and the structure, type and number of NSC attached points, the geometry, shape and condition of the mass distribution of NSC and etc. Researchers have used different methods for calculating NSC responses. Among them are the direct method and the Floor Response Spectrum (FRS) method. In the first method, analysis is performed by modeling the primary structure and NSC simultaneously. In case the weight of the NSC is less than 10% of the total weight of the structure and 20% of the weight of the floor, then, the effect of NSC on the structure can be neglected and simpler methods can be implemented. One of the simpler methods is the FRS method. In this method, the behavior of the primary structure at the attached point or points of NSC is etermined, eglecting their interaction. Then, the obtained FRS is used as an input for analyzing non-structural elements. This method is used in many design codes in order to determine the design force on the NSC. The present research studies the effect of various parameters, including the inelastic behavior of the system, natural periods of primary and secondary systems and type of structural system, on NSC response. A method for calculating the NSC response is suggested, which accounts for the location of the NSC and the inelastic behavior of the structure more precisely. For this research, a variety of moment resisting frames, eccentric and concentric braced frames were examined. These frames are designed in accordance with ASCE 2005 requirements. 15 records of far-field earthquakes and 15 records of near-field earthquakes were chosen for performing parametric studies. To perform expanded parametric studies on various frames with different stiffness and strength, modified shear building models for these frames were constructed. The shear building frame is set to have an equivalent lateral force-deformation behavior in each storey of a given MRF, CBF or EBF frame. Consequently, the base shear-roof displacement curve of both frames became approximately the same. It has been demonstrated that the structure system type does not significantly affect the suggested relations. Moreover, in this study, it has been shown that earthquake intensity causes minimum acceleration (in the first floor) to decrease, and peak cceleration (in higher floors) to increase.
Keywords: Non, Structural Components, Earthquake Intensity, Shear Building, Near, Field Effects, Floor Response Spectrum} -
در این تحقیق، محاسبه شتاب وارد بر اجزای غیرسازه ای واقع بر طبقات سازه های قاب خمشی و مهاربندی شده هم محور و برون محور تحت اثر زلزله بررسی شود. برای بررسی این موضوع از تحلیل های تاریخچه زمانی غیرخطی قاب های فولادی 3، 5 و 7 طبقه با پریودها و ضرایب کاهش مقاومت مختلف تحت اثر رکوردهای حوزه دور و نزدیک استفاده شده است. برای انجام مطالعات پارامتری از مدل برشی اصلاح شده قاب های فلزی استفاده شده که تحقیقات قبلی میزان صحت نتایج حاصل از آن را در حد قابل قبول به اثبات رسانده است. در آیین نامه های معتبر ساختمانی معمولا روابطی که برای محاسبه نیروی وارد بر اجزای غیرسازه ای ارائه می شود، به صورت ضریبی از بیشینه شتاب زمین بیان می شود. نتایج این تحقیق به ارائه روشی منجر شده است که طبق آن شتاب وارد بر عناصر غیرسازه ای براساس طیف شتاب زمین محاسبه می شود. به این ترتیب اثر محتوای فرکانسی زلزله طرح نیز در محاسبه شتاب لحاظ خواهد شد. همچنین اثر عوامل مختلف بر شتاب وارد بر طبقات سازه از جمله اثر زلزله های حوزه نزدیک و سیستم های سازه ای مختلف بررسی می شود.
کلید واژگان: اجزای غیرسازه ای, مدل ساختمان برشی, زلزله حوزه نزدیک, طیف پاسخ طبقه, طیف زلزله}The importance of non-structural components in seismic Performance Based Design of buildings is well known nowadays. In this research calculation of absolute acceleration applied on non-structural components located on floors of moment-resisting، eccentric braced and concentric braced frames subjected to earthquake ground motions has been studied. The results of nonlinear time-history analyses of 3، 5 and 7-story steel frames with 8 different periods and 5 reduction factors subject to 15 records of near-field earthquakes and 15 records of far-field earthquakes has been used to investigate the effects of different parameters on absolute acceleration induced in each floor of the structures. The effect of inelastic behavior of system، natural periods of primary and secondary systems، structural system type and near-field ground motions have been studied with use of modified shear-building models of steel frames. The shear building models are set to have an equivalent lateral force-deformation behavior in each story to the one’s of given steel frames. Reliability of these models to estimate the maximum roof displacement and the maximum inter-story drift of steel frames has been investigated elsewhere through probabilistic analysis of the results obtained from comprehensive incremental dynamic analyses. The relationships that are presented in building codes to calculate the force applied on non-structural components has been usually expressed as a ratio of peak ground acceleration. This method of calculating of input acceleration to non-structural elements ignores the effect of frequency content of design ground motion. The results of the present study have been used to introduce a new method for calculation the force applied on non-structural components based on ground acceleration spectrum. In this method the input acceleration to non-structural components has been expressed as a ratio of earthquake response spectrum (instead of the peak ground acceleration). For this ratio which is entitled as “spectral amplification factor” two different expressions have been proposed for use in structures with linear and nonlinear behavior. This approach explicitly accounts for the frequency content of design earthquake in calculation of peak floor acceleration. The results of this study show that Euro-code 8 and ASCE 7-2010 recommendations need to modify specially for the precise location of the non-structural element and inelastic behavior of the structure. It has been demonstrated that structural system type does not significantly affect the amount of induced acceleration on each floor of steel frames.Keywords: Non, structural components, Shear, building models, Near, field effects, Floor response spectrum, Ground response spectrum}
- نتایج بر اساس تاریخ انتشار مرتب شده‌اند.
- کلیدواژه مورد نظر شما تنها در فیلد کلیدواژگان مقالات جستجو شده‌است. به منظور حذف نتایج غیر مرتبط، جستجو تنها در مقالات مجلاتی انجام شده که با مجله ماخذ هم موضوع هستند.
- در صورتی که می‌خواهید جستجو را در همه موضوعات و با شرایط دیگر تکرار کنید به صفحه جستجوی پیشرفته مجلات مراجعه کنید.
©2000-2024 magiran.com All Rights Reserved.