@article { author = {Kavand, Ali and Sarkeshikzadeh Motlagh, S. Ahmad and Ghalandarzadeh, Abbas}, title = {Seismic Response of Alluvial Deposits due to Vertical Component of Near-Fault Earthquakes}, journal = {Bulletin of Earthquake Science and Engineering}, volume = {3}, number = {2}, pages = {1-20}, year = {2016}, publisher = {International Institute of Earthquake Engineering and Seismology}, issn = {2476-6097}, eissn = {2476-6100}, doi = {}, abstract = {The characteristics of vertical component of earthquakes are essentially different from those of their horizontal components in terms of amplitude and frequency content. This difference is mainly due to the fact that the vertical component is rather influenced by P-waves while the horizontal component is associated with S-waves. It is widely accepted that the energy of the vertical component of earthquakes is usually concentrated over a narrower range of high frequencies compared to that of the horizontal component. This concentration is destructive to engineering structures having vertical fundamental frequency within the high frequency range. During past earthquakes, the collapse of several buildings and bridges has been found to be directly caused by vertical excitations. Previous researches have illustrated that vertical ground motions are mainly influenced by earthquake magnitude, source-to-site distance as well as local site conditions such as geometry and material properties of subsurface soil layers. Current paper aims to investigate the effects of various local site conditions on vertical component of near-fault earthquakes. To this end, a series of seismic site response analyses based on time-domain equivalent-linear approach were carried out using Quake-W to determine the ground response under simultaneous horizontal and vertical excitations. The site condition was categorized into different soil profiles comprising of different soil types with different Vs30 values rather than the generic site classifications used in seismic design codes. The input seismic motions used in the analyses comprised of 23 acceleration time histories from near-fault earthquakes recorded worldwide in tectonically active regions within distances less than 10 Km from the active faults (RJB ≤ 10 km) and with magnitudes ranging from M = 5.6 to 7.6. The results of numerical analyses were finally presented in terms of 5% damped V/H spectral ratio at the ground surface. The results were also compared with recent empirical V/H attenuation equations developed by other researchers. It was found that the obtained V/H spectral ratios show better agreement with empirical equations in case of higher-magnitude earthquakes at stiff soils than lower-magnitude ones at soft soils. In all of these cases, Poisson ratio (υ) of the soil that controls the ratio of S-waves to P-waves velocities was considered equal to 0.35 as a general value. It should be added that although υ is influenced by parameters like soil type, confining pressure and void ratio, it critically depends on the degree of saturation of the ground as well as the drainage conditions during loading. The saturation of a soil can result in rapid increase in υ, which in turn increases the P-wave velocity. To better understand this issue, some models were analyzed with a constant Vs30 value of 230 m/s but with different υ values or alternatively different P-wave velocity profiles. It was observed that as υ increased, the agreement between V/H spectral ratio predicted by numerical analysis and those obtained based on empirical equations enhanced. It can be concluded that the degree of saturation of the ground can profoundly affect V/H spectral ratio. This issue is not reflected in current V/H empirical relationships. In conclusion, the results of current study demonstrate that V/H spectral ratio depend on parameters such as the natural period of the ground for P-wave, Poisson ratio of the soil and the frequency content of the input shaking. Moreover, it was revealed that the inverse of quarter wavelength impedance contract of P-waves shows a good correlation with V/H spectral ratios and can be used for the implementation of site effects into V/H empirical equations.}, keywords = {Near-fault earthquakes,Vertical component,Site Effects,V/H Acceleration Spectral Ratio}, title_fa = {پاسخ لرزه ای رسوبات آبرفتی ناشی از مؤلفه قائم زلزله های حوزه ی نزدیک گسل}, abstract_fa = {یکی از راهکارهای متداول برای تعیین خصوصیات مؤلفه قائم زلزله طرح به­صورت ویژه ساختگاه استفاده از روابط تجربی نسبت طیفی شتاب قائم به افقی (V/H) است. با این ‌حال اثرات ساختگاهی تاکنون به­صورت دقیق در این روابط وارد نشده است. در این مقاله اثرات محلی ساختگاه بر روی خصوصیات مؤلفه قائم شتاب زلزله‌های میدان نزدیک بررسی شده است.  به این منظور ساختگاه­های مختلف با ویژگی­های دینامیکی متفاوت به­جای دسته‌بندی‌های کلی روابط تجربی در نظر گرفته شده و تحت تحریک مجموعه‌ای از زلزله‌های میدان نزدیک به ‌صورت دو بعدی تحلیل دینامیکی شده‌اند. نتایج به‌دست‌آمده نشان می‌دهد که نسبت طیفی شتاب قائم به افقی (V/H) از عواملی نظیر پریود اساسی ارتعاشی ساختگاه در حالت انتشار موج فشاری، نسبت پواسون خاک (υ) و همچنین مشخصات تحریک ورودی تأثیرپذیر است. مقایسه‌ی نسبت­های V/H به­دست­آمده از تحلیل‌های عددی با روابط تجربی موجود نشان می‌دهد که همخوانی نتایج در حالت اشباع بودن خاک نسبت به حالت خشک بیشتر است و با افزایش نسبت پواسون از میزان تأثیر نوع خاک بر نسبت‌های طیفی شتاب V/H کاسته می‌شود. در نهایت پیشنهاد می‌شود از معکوس امپدانس لرزه‌ای یک‌چهارم طول ‌موج بر مبنای سرعت موج فشاری، در روابط کاهندگی تجربی V/H برای لحاظ نمودن اثرات ساختگاهی استفاده شود.}, keywords_fa = {زلزله میدان نزدیک,مولفه قائم,اثرات ساختگاهی,نسبت طیفی شتاب قائم به افقی (V/H)}, url = {http://www.bese.ir/article_240291.html}, eprint = {http://www.bese.ir/article_240291_89d97abdb6c452f106774331b1684e3c.pdf} } @article { author = {Zafarani, Hamid and Soghrat, Mohammad Reza}, title = {A Database of the Iranian Strong Motion Records}, journal = {Bulletin of Earthquake Science and Engineering}, volume = {3}, number = {2}, pages = {21-34}, year = {2016}, publisher = {International Institute of Earthquake Engineering and Seismology}, issn = {2476-6097}, eissn = {2476-6100}, doi = {}, abstract = {The Iranian plateau, located along the Alpine–Himalayan orogenic belt, is one of the tectonically active regions of shallow crustal earthquakes. Therefore, development of a strong ground-motion dataset with appropriate quality and content is an essential component/tool in local ground-motion studies and for engineering practice. The first strong-motion instruments were installed in 1973. Since then, the number of strong-motion stations has been gradually increased. Currently, the Iranian strong-motion dataset includes more than 10000 three-component time series, which are recorded at about 1100 permanent stations. By probing into the quality of the records and the metadata information, 2286 time series recorded on 743 stations from 461 earthquakes with a maximum moment magnitude of 7.3 are chosen. The moment magnitudes have been provided from international or local seismological agencies or from earthquake-specific literature studies in about 40 % of events. For the remaining events, the empirical magnitude conversion equations are used to obtain the more homogenous magnitude information and increase the number of events associated with moment magnitude values. The calculated moment magnitudes are mainly less than 5. The converted moment magnitudes belong to small earthquakes that are originally reported with magnitude scales of Nuttli (MN), Local (ML), body-wave (mb) and surface-wave (Ms). The bulk of events in the dataset are shallow continental earthquakes with depths less than 30 km. About 75%    of events are in this range of the mentioned focal depth. The number of earthquakes with unknown focal depth is less than 1% in the selected dataset. The events of depths ranging more than 40 km are mainly from the Zagros region. For about 66% of events, there is no information available‌ (NA) about their faulting mechanisms. The dominant faulting mechanisms are reverse (20% of events) and strike-slip faulting (12% of events). A minority of events and accelerograms are related to the normal faulting mechanism.  Most of the unknown faulting mechanisms are attributed to events with small magnitude (Mw ≤ 5) due to the lack of double-couple fault-plane solutions for these earthquakes. Large events have been studied to determine the faulting mechanisms due to their importance while on the small events are rarely focused. About 743 stations have provided accelerometric data in the selected dataset. The average shear-wave velocity between 0 m and 30 m depth (Vs30) in more than 40% of these stations have been measured and reported by the BHRC. The site classes for about 299 stations have been proposed either by geological surveys or by empirical methods (using H/V method). Therefore, we have no information about the soil categories for only 138 stations because they are either temporary stations or stations that recorded accelerograms less than 5 times. Considering    the Vs30 criteria, the majority of the stations are belonged to site class II while the most of the stations will be in site class III if we use only the above-mentioned empirical method. During the data processing, the records with the following features have been eliminated from the dataset: data from instruments that triggered during the S-wave train; the records with only a single horizontal component; and the records obtained from events with unknown or poor estimates of magnitude (which are attributed to the small events). Furthermore, the records with non-standard error such as very high-frequency spikes, multi-event, and so on are excluded from the dataset. The aim of this paper is first to present the new catalog with comprehensive metadata for engineering and research practices. The record selection for development of new GMPEs for various strong-motion parameters can be performed by using the provided catalog. In addition, the main features of the Iranian strong-motion dataset have been provided in this paper. To this end, a careful revision of the characteristics of the earthquakes such as location, magnitude, style of faulting and fault rupture plane geometry, if available, has been scientifically performed for the first time using the best available information. Finally, we concentrate on special ground-motion records including records with peak ground acceleration PGA > 300 cm/s/s and distances less than 30 km. These are designated as “distinct” records in the Iranian dataset because they include less than 2% of the selected dataset.}, keywords = {Strong Motion,database,Records,Iran}, title_fa = {بانک داده‌های منتخب حرکات قوی زمین برای زلزله‌های ایران}, abstract_fa = {جمع­آوری اطلاعات مربوط به داده‌های ثبت‌شده بر اثر زمین­لرزه و تجزیه‌وتحلیل آنها می‌تواند جهت مطالعات تحلیل خطر، ریسک و یا رویکردهای مهندسی زلزله مفید واقع شود. در این مقاله، گزارشی از روند تهیه یک بانک داده‌ی منتخب از رکوردهای حرکات قوی زمین در ایران ارائه شده است. از مجموع بیش از 10000 رکورد سه‌مؤلفه‌ای که تماماً از رکوردهای ثبت­شده توسط شبکه‌ی شتاب‌نگاری کشوری مرکز تحقیقات راه، مسکن و شهرسازی در بین سال­های 1976 تا 2015 برداشت شده ­است، 2286 رکورد مناسب و دارای کیفیت قابل­قبول انتخاب گردیدند. این رکوردها حاصل از 461 رویداد زلزله می‌باشد که بزرگای گشتاوری آنها در محدوده‌ی 9/3 تا 3/7 قرار دارد و از هر زلزله حداقل دو رکورد در بانک داده‌های معرفی‌شده موجود می‌باشد. برای نخستین بار، فاصله‌ی ایستگاه ثبت­کننده‌ی تصویر افقی سطح گسل در روی سطح زمین برای تعداد زیادی رکورد که بزرگای زلزله‌ی مربوطه عمدتاً بیش از 6 بوده است، در این بانک داده با دقت زیاد گزارش شده است. شایان‌ذکر است که شتاب‌نگاشت‌های ثبت­شده که به‌صورت خام در دسترس بوده‌اند با استفاده از روش پردازش مبتنی بر الگوریتم موجک نوفه­زدایی شده‌اند. پارامترهای مختلفی همچون بیشینه شتاب، شتاب طیفی در دوره تناوب‌های مختلف (تا دوره تناوب 4 ثانیه)، مدت‌زمان مؤثر، مدت‌زمان دوام برای هر سه مؤلفه‌ی رکورد ثبت‌شده محاسبه شده است. همچنین نوع خاک در ایستگاه ثبت­کننده‌ی رکورد و نوع گسلش زلزله نیز گزارش شده است. همچنین یک بازبینی برای مشخصات زلزله شامل موقعیت مرکز زلزله، بزرگا، نوع گسلش و همچنین هندسه‌ی صفحه‌ی گسیختگی گسل (در صورت امکان) صورت پذیرفته است. در نهایت برخی از رکوردهایی که دارای بیشینه شتاب بیش از 3 متر بر مجذور ثانیه و ثبت‌شده در فاصله‌ای کمتر از 30 کیلومتر بوده‌اند، به‌عنوان رکوردهای خاص معرفی شده‌اند.}, keywords_fa = {ایران,بانک‌داده‌ها,حرکات قوی زمین,خطر لرزه‌ای}, url = {http://www.bese.ir/article_240292.html}, eprint = {http://www.bese.ir/article_240292_cce5a990d14189db570edf3501ed925b.pdf} } @article { author = {Mehrzad, Behrooz and Jafarian, Yaser and Haddad, Abdolhossein}, title = {Centrifuge Study on Progressive Failure of Shallow Foundations due to Soil Liquefaction}, journal = {Bulletin of Earthquake Science and Engineering}, volume = {3}, number = {2}, pages = {35-46}, year = {2016}, publisher = {International Institute of Earthquake Engineering and Seismology}, issn = {2476-6097}, eissn = {2476-6100}, doi = {}, abstract = {The effect of liquefaction depth on co-seismic and post-seismic settlements of shallow foundation has been studied using three centrifuge test series. The models were constructed in 1/80 scale and subjected to the centrifugal acceleration of 80g. They involved two rigid foundations with two different static surcharges and sufficient spacing to minimize the interaction. Poorly graded sand known as No. 306 sand with a relative density of 55% was used. The model was excited with a 15-cycle sinusoidal base motion having constant amplitude and 2 Hz frequency. In the free-field, liquefaction occurred in the shallower layers first, propagated rapidly to the deeper layers. The full depth of soil profile was liquefied in the strongest event. The liquefied depths were about 2.4 m and 7.2 m for amax=0.04g and amax=0.07g, respectively. Liquefaction caused severe deterioration of soil stiffness resulted in significant decay of accelerations. After excitation ceased, upward seepage from deeper layers enforced the shallower layers to remain in liquefied state for longer time. The free-field settlement commenced immediately after the first cycles and accumulated until excitation ceased. Its rate stopped for a while. The free-field settlement began again and continued up to full EPWP dissipation. Large negative EPWP was observed beneath the foundations, which are attributed to the deviatoric stress induced by their surcharge and soil dilation due to lateral movement of subsoil. Amplification was observed in acceleration time histories within the foundation soil, which is attributed to the negative EPWP generated in this zone. Large horizontal and vertical hydraulic gradient was developed during shaking, causing water flow towards the foundations. Once the water pressure equalized in each level, reconsolidation commenced. The foundations settled linearly with time during shaking with decreasing rate after excitation ceased. The extent of liquefaction had a major impact on the foundation settlement in this period. The higher the extent of liquefaction, the more the foundation settlement occurred. It seems that partial bearing failure and the inertial forces are two dominant mechanisms. The settlement and EPWP time histories can be separated into three different phases: (1) shaking, (2) progressive failure, and (3) reconsolidation. The rate of settlement significantly decreased during the second phase. Previous researchers noted that most of foundation settlement occurs during shaking period, but the results of this research show that most of the foundation settlement occurs after shaking. Foundation settlement continued progressively due to partial bearing failure and strength loss in the foundation soil. It seems that liquefaction extent and soil permeability have major impact on Phase (2). The thicker the liquefied layer or the lower the permeability of foundation soil, the longer time the foundation has to settle. Although the foundation settlement is significant in this phase, it has been neglected in geotechnical designs. The foundation settlement mechanisms are clearly different from that of the free-field. Volumetric-induced deformations are dominant mechanisms in the free-field, whereas, deviatoric-induced strains are the main cause of foundation settlement. It seems that the widely used procedure for the estimation of liquefaction-induced settlements of shallow foundations that is based on volumetric strains might be revised.}, keywords = {Shallow Foundation,Settlement Mechanism,Progressive failure,Liquefaction Depth,Centrifuge Study}, title_fa = {ارزیابی خرابی های پیش‌رونده پی های سطحی در شرایط روانگرایی با استفاده از مطالعات سانتریفیوژ}, abstract_fa = {در این مقاله با استفاده از نتایج سه سری آزمایش سانتریفیوژ چگونگی اثر گسترش عمق روانگرایی و خرابی­های پیش‌رونده بر نشست حین و پس از تحریکات دو پی­ سطحی با فشارهای استاتیکی متفاوت مورد مطالعه قرارگرفته است. اعماق مختلف گسترش روانگرایی با اعمال تحریکات ورودی هارمونیک با دامنه­های شتاب مختلف به مدل سانتریفیوژ به‌دست‌آمده است. نتایج بیانگر سه مکانیسم (فاز) مجزا در نشست پی است که عبارتند از: (1) حین تحریک، (2) خرابی پیش‌رونده و (3) باز تحکیم. بر خلاف میدان آزاد که در آن نشست­ها از نوع حجمی بوده، بیشتر نشست پی­ها از نوع برشی بوده و در فازهای (1) و (2) اتفاق افتاده است. عمق گسترش روانگرایی رفتار پس از تحریک را به‌طور قابل­ملاحظه­ای تحت تأثیر قرار داده است. پاسخ شتاب پی­ها تحت تأثیر گسترش عمق روانگرایی بوده، به‌گونه‌ای که پی­ها در قوی­ترین تحریک علیرغم تجربه‌ی نشست بزرگ­تر پاسخ ضعیف­تری داشته­اند. به نظر می­رسد که نشست­های پس از تحریک و خرابی­های پیش‌رونده در پی­های سطحی از اهمیت بالایی برخوردار باشند که در کاربردهای مهندسی مورد ارزیابی قرار نمی­گیرند.}, keywords_fa = {پی سطحی,سازوکار نشست,خرابی پیش‌رونده,عمق روانگرایی,مطالعات سانتریفیوژ}, url = {http://www.bese.ir/article_240293.html}, eprint = {http://www.bese.ir/article_240293_4e230d0c9ac08359bc7f2db593f2a13a.pdf} } @article { author = {Manie, Salar and S. Moghadam, Abdoreza and Ghafory-Ashtiany, Mohsen}, title = {Probabilistic Collapse Behavior Evaluation of Low-Rise In-Plan Irregular Buildings}, journal = {Bulletin of Earthquake Science and Engineering}, volume = {3}, number = {2}, pages = {47-69}, year = {2016}, publisher = {International Institute of Earthquake Engineering and Seismology}, issn = {2476-6097}, eissn = {2476-6100}, doi = {}, abstract = {The present paper aims at evaluating the post-peak and collapse behavior of low-rise irregular buildings. Irregularity -in this study- is defined as the unidirectional mass irregularity in plan to produce torsional models. In previous earthquake events, most of torsional buildings have suffered from extensive damages and even total collapse. To investigate the performance and collapse behavior of the considered buildings from the probabilistic point of view, three-dimensional three and six-story reinforced concrete models with unidirectional mass eccentricities ranging from 0% to 30% (of the building overall plan dimension) were subjected to nonlinear static (pushover) as well as extensive nonlinear incremental dynamic analysis (IDA) under 21 two-component ground motion records. Currently, FEMA P-695 is the reference document to evaluate the collapse behavior of common structural systems in a completely probabilistic framework that contains a step-by-step procedure to examine the seismic design parameters including the response modification (R), the structural over-strength (W) and the structural ductility (m) factors. All models were built and analyzed using the OpenSees simulation platform. The SP version of the software, which is able to efficiently solve large systems of equations using the capacity of multi-processors was utilized in this study. For performing nonlinear analyses, the structural system was modeled using concentrated plasticity nonlinear modeling approach in which concentrated hinges are modeled and defined at the ends of each frame element. All degradation sources including the loading and reloading stiffness, peak-strength and hardening zone stiffness degradation effects in each cycle of response have been taken into account in the modeling process. The hysteretic model known as "peak-oriented hysteretic model" which is based on kinematic hardening rules were used for the modeling of the structures to assess their dynamic behavior. All models were created in the OpenSees platform by using CECARC-3D; a graphical pre- and post-processor for OpenSees designed by the authors for modeling and analyzing nonlinear static and dynamic response of 3D reinforced concrete structural systems. Geometric nonlinearities including the global P-∆ as well as the local p-delta effects were also considered in the model utilizing the co-rotational formulation. Performance of each model was then examined via the calculation of conventional seismic design parameters including the response modification (R), structural overstrength (W) and structural ductility (m) factors; the calculation of probability distribution of maximum inter-story drift responses in two orthogonal directions (and their combination); and also by the calculation of the collapse margin ratio (CMR) defined as the ratio of the median of all collapse-level spectral intensities (determined by the IDA results) to the MCE-level spectral intensity of the building at the fundamental period of vibration in the direction of interest. Basically, all performance checks in the procedure of FEMA-P695 is based on CMR. Results of this study demonstrate that substantial differences exist between the behavior of regular and irregular buildings in terms of the lateral load capacity and collapse margin ratio. Besides, results indicate that current seismic design parameters (including R, W and m) are non-conservative for buildings with high degrees of plan eccentricity, and such structures cannot satisfy the target “life safety” performance level based on the calculated safety margin against collapse. It appears that design codes need to address more precisely the torsional effects on seismic design parameters as well as on analysis and design procedures for irregular structures to provide the required safety margin against collapse under severe seismic loading conditions.}, keywords = {Torsional Buildings,Collapse,Fragility Curves,Performance-based design,IDA}, title_fa = {ارزیابی احتمالاتی رفتار فروریزش ساختمان‌های کوتاه نامتقارن در پلان}, abstract_fa = {این مقاله به ارزیابی احتمالاتی رفتار فروریزش ساختمان‌های کوتاه پیچشی می‌پردازد. طی زلزله‌های گذشته، بسیاری از این ساختمان‌ها در معرض خرابی‌های گسترده و حتی انهدام کلی قرار گرفته‌اند. برای این منظور، مدل‌های طراحی‌شده‌ی ساختمان‌های سه‌بعدی 3 و 6 طبقه‌ی بتن‌آرمه با برون‌محوری‌های جرمی یک‌جهته معادل صفر درصد (متقارن)، 10، 20 و 30 درصد به روش‌های بار افزون (پوش‌اور) و تاریخچه زمانی فزاینده (IDA) غیرخطی تحت اثر 21 رکورد دو مؤلفه‌ای قرار گرفته و عملکرد آنها از طریق محاسبه‌ی پارامترهای طراحی از جمله ضرایب رفتار و اضافه مقاومت، شکل‌پذیری و نیز محاسبه‌ی مقادیر حاشیه‌ی ایمنی در برابر فروریزش و منحنی‌های شکنندگی، ارزیابی شده است. نتایج نشان می‌دهد که تفاوت اساسی بین رفتار سازه‌های متقارن و نامتقارن از نظر ظرفیت شکل‌پذیری، حاشیه‌ی ایمنی در برابر فروریزش، پارامترهای طراحی و نیز منحنی‌های شکنندگی وجود دارد. همچنین نتایج حاکی از آن است که پارامترهای آیین‌نامه‌ای برای طراحی لرزه‌ای ساختمان‌های دارای برون‌محوری زیاد غیرمحافظه‌کارانه بوده و حتی با افزایش برون‌محوری سازه‌ها از یک مقدار مشخص عملکرد ایمنی جانی در آنها با توجه به معیارهای فروریزش تأمین نمی‌شود. بازنگری در پارامترهای طراحی این نوع ساختمان‌ها برحسب میزان برون‌محوری ضروری به نظر می‌رسد.}, keywords_fa = {ساختمان های پیچشی,فروریزش,منحنی شکنندگی,طراحی براساس عملکرد,تحلیل IDA}, url = {http://www.bese.ir/article_240294.html}, eprint = {http://www.bese.ir/article_240294_d50726d7e26c39064b042f8073ada3e1.pdf} } @article { author = {Peyrovan, Melika and Sabouri, Saeid}, title = {Plate Zipping in Major Deformation of Rectangular and Square Shape Steel Shear Panels}, journal = {Bulletin of Earthquake Science and Engineering}, volume = {3}, number = {2}, pages = {71-85}, year = {2016}, publisher = {International Institute of Earthquake Engineering and Seismology}, issn = {2476-6097}, eissn = {2476-6100}, doi = {}, abstract = {Plate in steel plate shear walls has high capability for earthquake energy damping. The experimental investigations show that the plate zipping in corner and edge of plate causes damage and failure in steel plate shear walls. The main objective of this research is to prevent plate zipping with using four stiffeners at steel plate corners. For this reason, 24 rectangular steel plate shear walls and 24 square steel plate shear walls, with four stiffeners in edge of the plate as one-story frame and unite snap were modeled by ANSYS 15.0. Corner stiffeners have rectangular shapes. All samples are subject to 15% drift, which occurs gradually applied to samples. In this study, interaction plate and frame theory has been used to design the shear panel. Thickness of steel plate shear walls are 0.003, 0.005, 0.007 and 0.01 meter. To find the optimum height and thickness dimensions of stiffeners, 557 times of trial and error is done in the software. The results show that by putting above-mentioned stiffeners, plate zipping can prevented. According to von Mises stress values in rectangular and square steel shear walls, the optimum mode for stiffener length is 8.5% and 6% of plate steel length respectively, which can be considered the length of stiffener an average 7% of the steel plate length. In present research, the smaller dimensions of square steel plate shear wall than rectangular ones have obtained. The results also show, by increasing the thickness of the steel plate, because of the large dimensions of stiffeners von Mises stress in the corners of the plate is reduced. In square steel shear walls, the post buckling field, is diagonally created, and therefore its condition is more critical than the rectangular steel shear wall.}, keywords = {Steel Plate Shear Wall,stiffener,Post Buckling Field,Zipping}, title_fa = {مطالعه‌ پدیده‌ی زیپ شدن ورق در تغییر شکل های بزرگ پانل های برشی فولادی مستطیل و مربع شکل}, abstract_fa = {ورق در دیوارهای برشی فولادی دارای توانایی بالایی در جذب انرژی زلزله است. مطالعات آزمایشگاهی نشان می­دهد که علت خرابی و ضعف تعدادی از این نوع دیوارها، زیپ­شدگی ورق ازگوشه و لبه‌ی ورق واسط می­باشد. برای جلوگیری از زیپ­شدگی در این تحقیق، از چهار سخت­کننده در گوشه­های ورق فولادی استفاده شده است. با نرم­افزار ANSYS15.0، 24 مدل دیوار برشی فولادی مستطیل شکل و 24 مدل دیوار برشی فولادی مربع شکل به‌صورت قاب یک طبقه‌ی یک دهانه، مدل‌سازی شده است. تمام نمونه­ها تحت تغییر مکان جانبی 15درصد قرار دارد، که به‌صورت تدریجی به نمونه­ها اعمال می­شود. در این تحقیق برای طراحی پانل برشی از تئوری اندرکنش ورق و قاب استفاده شده است. شکل سخت­ کننده­ ها، مستطیل شکل می­باشد. ضخامت دیوار­های برشی فولادی شامل 003/0، 005/0، 007/0 و 01/0 متر می­باشد. برای پیدا کردن ابعاد بهینه‌ی ارتفاع و ضخامت سخت­ کننده­ ها، 557 بار سعی و خطا در نرم­افزار انجام شده است. نتایج نشان می­دهد با قرار دادن سخت­کننده­های یاد شده می­توان از زیپ­شدگی ورق جلوگیری کرد. با توجه به مقادیر تنش فون‌میسز در دیوار برشی فولادی مستطیل شکل و مربع شکل، بهینه­ترین حالت برای طول سخت­کننده به ترتیب 5/8 درصد و 6 درصد طول ورق فولادی می­باشد که به­طور میانگین می­توان طول سخت­کننده را 7 درصد طول ورق فولادی در نظر گرفت. در این تحقیق ابعاد سخت­کننده­ها در دیوار برشی فولادی مربع شکل کمتر از مستطیل شکل به­دست آمده است. همچنین نتایج نشان می­دهد با افزایش ضخامت ورق فولادی، به دلیل بزرگ شدن ابعاد سخت­کننده­ها تنش فون‌میسز در گوشه­های ورق کاهش می­یابد. در دیوار برشی فولادی مربع شکل موج­ها به‌صورت قطری ایجاد می‌شوند که حالت بحرانی­تری نسبت به دیوار برشی فولادی مستطیل شکل است.}, keywords_fa = {دیوار برشی فولادی,سخت کننده,میدان پس کمانش,زیپ شدگی}, url = {http://www.bese.ir/article_240295.html}, eprint = {http://www.bese.ir/article_240295_ea6ada5a47a3e8e56f5900e924ded3f4.pdf} } @article { author = {Ahmadpour, Behrouz and Amel Sakhi, Masoud}, title = {Static and Pseudo Static Study of Loose Clay Layer Effects on Steel Sheet Pile Walls Behaviors}, journal = {Bulletin of Earthquake Science and Engineering}, volume = {3}, number = {2}, pages = {87-100}, year = {2016}, publisher = {International Institute of Earthquake Engineering and Seismology}, issn = {2476-6097}, eissn = {2476-6100}, doi = {}, abstract = {IntroductionUsually, the construction of new multi-story buildings require deep supported excavation. Steel sheet pile wallsare being widely used in civil engineering projects for excavation support systems. Many researches have performedabout various problems of steel sheet piles, like steel sheet pile behaviors; using of sheet pile as a permanentstructure; long term performance of sheet piles; Vertical bearing capacity; construction of steel sheet pile walls onsloping ground; performance of steel sheet pile wall for supporting an excavation in urban environment. Soil is notuniform in depth, sometimes loose soil layer may exist in various depth and situations. This issue can cause differenteffects on ground surface displacements, forces and moments acting on sheet pile and struts during excavationprocedure, compared with status that soil is uniform in depth, especially in seismic conditions that must beconsidered in design of sheet piles and struts.MethodologyIn this study a deep excavation by using finite element method is analyzed. Excavation’s depth is divided tothree clayey layers. One of three layers is loose clay layer that its positions is modelled in three different situations,top, middle and bottom. Obtained results are compared with excavation without loose layer. Since excavationsupport system may be a permanent structure, long term stability must be considered. Pseudo static analysis isperformed by applying 0.3g horizontal acceleration.Models are analyzed in different situations, dry and saturation. Width and depth of considered excavation are 10and 12 meters, respectively. The first strut is installed beneath one meter of ground surface and subsequent struts aremodeled in 3 meters spacing from each other so that finally, four struts are considered along the depth of excavation.Change percent of different parameters in models with clay loose layer is calculated in comparison with modelwithout clay loose layer.ResultsAccording to comparative obtained results it can be concluded that:1. Existence of a loose clay layer on two stiff clay layers that thicknesses of all three layers are same, generallyhas reducing effects on soil and sheet piles deformations, forces and bending moments of sheet piles.2. With increasing depth of loose clay layer, lateral deformation, shear force and bending moment acting onsheet piles are increased. In depth equal to two times of loose layer thickness, these parameters havemaximum values. In fact, with increasing sheet piles horizontal displacement, bending moments are increased.3. Maximum horizontal displacement of the soil is in condition that loose clay layer is bottom layer.4. When loose clay layer is located on the middle or bottom layer, shear forces acting on sheet piles are greaterdue to loose layer located on upper layer. 5. Generally, it can be said, with increasing depth and location of loose clay layer, affecting parameters on sheetpiles and struts behaviors are increased.6. Existence of loose clay layer changes axial force of struts. This issue must be considered in design of sheetpiles, especially in design of middle struts.7. Saturated situations increase axial force of struts.}, keywords = {Sheet Piling,deformation,Strut,Pseudo Static Analysis}, title_fa = {مطالعه ی استاتیکی و شبه استاتیکی اثر وجود لایه ی سست رسی بر رفتار سپری های فلزی}, abstract_fa = {سپری­های فلزی به‌طور گسترده در پروژه­های مهندسی عمران به‌عنوان سازه نگهبان مورد استفاده قرار می­گیرد. مشخصات پروفیل خاک در عمق متفاوت بوده و در برخی مواقع ممکن است لایه­ی سست در عمق­ها و موقعیت­های مختلف وجود داشته باشد. این مسئله می­تواند اثرات متفاوتی را در طی عملیات گودبرداری بر تغییر شکل سطح زمین، نیروها و لنگرهای وارد بر سپرهای فولادی و مهارها نسبت به حالتی که خاک نسبتاً یکنواخت است داشته باشد که در طراحی سپری­ها و مهارها بایستی در نظر گرفته شود. در این تحقیق یک گود عمیق تعریف و مدل‌سازی شده و با استفاده از روش اجزای محدود مورد تحلیل قرار گرفته است. عمق گود به سه لایه­ی رسی تقسیم شده است. یکی از این سه لایه، لایه­ی سست رسی می­باشد که موقعیت آن در لایه­ی بالا، وسط و پایین در مدل­هایی به‌طور جداگانه تغییر می­کند. نتایج حاصل از تحلیل با نتایج مدلی که فاقد لایه­ی سست می­باشد مقایسه می­شود. ازآنجاکه سازه نگهبان ممکن است دائمی‌ باشد، پایداری بلندمدت آن نیز بایستی مد نظر قرار گیرد. ازاین‌رو در نظر گرفتن نیروهای لرزه­ای ضروری است. بدین منظور در این تحقیق از تحلیل شبه استاتیکی با شتاب g 3/0 استفاده شده است. نتایج نشان می­دهد که وجود لایه­ی سست فوقانی بر تغییر شکل­های سطح زمین و سپری اثرات کاهنده دارد. همچنین وجود لایه­ی سست رسی زیر لایه­های سخت خاک رس سبب افزایش لنگر خمشی و نیروهای وارد بر سپری می­شود.}, keywords_fa = {سپرکوبی,تغییر شکل لرزه ای,مهار,تحلیل شبه استاتیکی}, url = {http://www.bese.ir/article_240296.html}, eprint = {http://www.bese.ir/article_240296_64913750828e21e1f76a89eaddbd3f8d.pdf} }