پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220Calculation of Design Spectrum for Different Soil Types in Iran, Based on Near Fault Data and its Comparison with Iranian Building Code (Standard 2800)محاسبه طیف طراحی برای انواع مختلف خاک در ایران، بر اساس داده های نزدیک گسل و مقایسه آن با آیین نامه 280011624622210.48303/bese.2021.246222FAمریمصدقیجمعیت هلالاحمر استان تهران و دانشجوی دکتری ژئوفیزیک گرایش زلزلهشناسی، گروه ژئوفیزیک، دانشکده علوم پایه، واحد تهران شمال، دانشگاه آزاد اسلامی، تهران، ایرانمهدیزارعاستاد، پژوهشکده زلزله شناسی، پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله، تهران، ایران0000-0003-1036-4265آرزودرستیاناستادیار، گروه ژئوفیزیک، دانشکده علوم پایه، واحد تهران شمال، دانشگاه آزاد اسلامی، تهران، ایرانJournal Article20190706Near-fault earthquakes have different characteristics comparing to far-field recorded events, they often contain strong coherent dynamic long period pulses and permanent ground displacements. In the recent years, the effects of near-field and far-field earthquakes have been studied separately in various building codes.
Building codes have been revised and updated depending on the improvements in the representation of ground motions, soils and structures. These revisions have been more frequently seen in recent years. One of the key changes in earthquake codes has been performed on the design spectra. Design spectra are used in seismic analysis methods such as equivalent static lateral force analysis, dynamic spectral analysis and time history dynamic analysis. Various seismological and geophysical parameters affect the shape of design spectra. Ambraseys et al. (1996) and Bommer and Acevedo (2004) presented and discussed the effects of earthquake magnitude, source-to-site distance, site classification, and style-of-faulting on the strong-motion accelerograms and consequently design spectra.
The present study shows the results of 214 accelerograms, obtained from shallow crustal earthquakes with epicenral distance less than 80 km from causative fault, to determine the design spectrum in Iran. A comparison is performed with the design spectrum of Iranian building code (Standard No. 2800).
So far, due to the lack of information and registered accelerograms in Iran, as well as the unclear ground conditions at the place of record registration, no effective action has been taken to determine the design spectrum in Iran. The site conditions have been classified into different categories in earthquake codes. These categories are named ground types, soil profile types, local site classes or subsoil classes.
In Iranian Seismic Building Code, four types of soils I, II, III, IV have been determined, Site Class I: Rock, or hard Rock, or thin alluvium on bed rock with Vs30 more than 750 m/s; Site Class II, very dense soil or soft rock with high thickness on rock bed with Vs30 between 375 and 750 m/s; Site Class III stiff soil or soils with medium density or hardness with Vs30 of 175 to 375 meters per second; and Site Class IV, soft soils with a Vs30 of less than 175 meters per second. The accelerograms, obtained from major earthquakes in Iran, United States and Europe have been collected and then processed. After calculating the response spectra, the design spectra was plotted from the average response spectra values for all soil types, (I, II, III, IV) presented in the Standard No. 2800.
To compare the results of this study with spectra presented in Iranian Seismic Building Code, records obtained from event having magnitudes greater than 5.5 and recorded in the epicentral distances less than 80 km were selected and 5% damping was used for calculations. The results show that design spectrum for soil classes I, II, and III, were consistent with Standard No. 2800 for the spectral values of Periods 0.0 to 0.39 seconds, while in the periods longer than 0.39 seconds, the design spectrum of the Standard No. 2800 is more conservative than the present design spectra. Meanwhile, the spectral ordinates for design spectra of vertical component for soil class IV were representative for higher values for the present spectra, comparing to that presented in Standard No. 2800. This might be related to epistemic uncertainty imposed by still few available records for soft soil site (class IV). زلزله های نزدیک گسل نسبت به زلزله های دور از گسل دارای خصوصیات متفاوتی می باشند. در سالهای اخیر در آیین نامه های مختلف اثرات ناشی از زلزله های دور و نزدیک به صورت جداگانه بررسی شده است. مطالعه حاضر نتایج بررسی 214 شتابنگاشت بهدستآمده از زمینلرزههای کمعمق پوست های رخ داده با فاصله کانونی کمتر از 80 کیلومتر از گسل مسبب، جهت تعیین طیف طرح در ایران و مقایسه آن با طیف طرح آییننامه 2800 را نشان می دهد. این شتابنگاشتها از زمین لرزه های بزرگ ایران، آمریکا و اروپا جمع آوری و پردازش شده اند. پس از محاسبه طیف پاسخ، طیف طراحی از میانگین طیف پاسخ شتابنگاشتها برای هر چهار نوع خاک (I، II، III، IV) ارائه شده در آییننامه 2800 محاسبه شد. برای مقایسه نتایج این مطالعه با آییننامه رکوردهایی با بزرگای بیشتر از 5/5 و فاصله رو مرکزی کمتر از 80 کیلومتر انتخاب شد و همچنین پارامتر میرایی 5 درصد مورد استفاده قرار گرفت. نتایج حاصل نشان می دهد که طیف طراحی هر دو مؤلفه خاک نوع یک تا سه در این مطالعه تا پریود 0/39 ثانیه با طیف طراحی آییننامه همخوانی دارد درحالیکه در پریودهای بالاتر از 0/39 ثانیه طیف طرح آییننامه بالاتر از طیف طرح این مطالعه قرار میگیرد. از طرفی طیف طرح مؤلفه قائم خاک نوع IV بالاتر از طیف طرح آییننامه قرار گرفته است که این می تواند به دلیل تعداد کم رکوردهای این نوع خاک باشد.https://www.bese.ir/article_246222_b5a18fbf231f51b6924f1e4a1fbac5cf.pdfپژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220Deformation and Movement of Qom, Alborz and Kushk-e Nosrat Fault Zones in the Northern Part of Qomدگرریختی و جنبایی پهنه های گسلی قم، البرز و کوشک نصرت در محدوده شمال قم172724409310.48303/bese.2021.244093FAهادیطبسیاستادیار، گروه زمین شناسی، دانشکده فنی مهندسی و علوم پایه، واحد دماوند، دانشگاه آزاد اسلامی، دماوند، ایران0000-0001-8298-8099سمیهبهاالدینیدانشجوی کارشناسی ارشد، گروه زمین شناسی، دانشکده فنی مهندسی و علوم پایه، واحد آشتیان، دانشگاه آزاد اسلامی، آشتیان، ایرانJournal Article20201013The placement of the Iranian crust at the junction of the Arabian, Indian and Eurasian plates has caused tectonic disruption. The creation of numerous faults and many folds along with seismicity in the Iranian crust are signs of this disruption. The continental basin of northern Qom is located in central Iran. The general trend of the important faults in this area including Qom, Alborz and Kushk-e Nosrat faults, is northwest-southeast. These faults with a length of more than 50 km affected by Arab-Eurasian plate convergence, and have played an important role in seismicity and deformation of Qom area.<br /> Morphological evidence and the existence of numerous fault fragments that have cut Quaternary sediments indicate the activity of these structures around the city of Qom. Despite the valuable studies that have been done on the faults of Qom, Alborz and Kushk-e Nosrat, there are still ambiguous opinions and ambiguities about how these faults move and their seismic potential. Qom fault with a length of more than 50 km, has a northwest-southeast trend that continues from the mountains southeast of Qom to the south of Zefreh in the northeast of Isfahan. Along this fault, Oligo-Miocene limestone and marl are driven on Quaternary sediments. Alborz fault has also a northwest-southeast trend with a dip to the southwest that has cut the northern limb of the Alborz anticline. Alborz fault has also driven Oligo-Miocene units on Quaternary units. Kushk-e Nosrat fault is part of the fault system. It starts from the southeast of Hoz-e Soltan Lake and continues to the Avaj fault. The general direction of Kushk-e Nosrat fault is 280 to 290 degrees, and in most cases, it has a dip more than 80 degrees to the south. One of the objectives of this study is to identify how these faults displacement and activity are occurred.<br /> One of the methods of tectonic assessment is the use of geometric indices. Among these, according to the lithological characteristics and the location and distribution of the basins, the indices of V<sub>f</sub>, hypsometry and S<sub>L</sub> have been selected and the results have been analyzed. Results of morphometric indices with fault geometry and stress orientation data, have been able to elucidate some tectonic features of the area. Morphometric studies show the areas around Saveh fault and Kushk-e Nosrat fault in the northern part of Saveh as well as areas in the south of Qom have the potential to rise. Other zones do not have any significant uplift.<br /> The geometry of the faults and orientation of the maximum compressive stress show that the maximum compressive stress direction is N30 to N330, and according to the direction of the fault, the fault mechanism is estimated to be Dextral. The stress inferred from the seismic event of 2007/06/18 also confirms the right-lateral shear motion along with the reverse motion in the faults.<br /> The low vertical uplifts does not indicate the absence of activities, but can indicate the compressive and shear components or the specific deformation of Central Iran. This type of movement can be easily interpreted by knowing the stress orientation. The shear-compressive deformation of the Qom area is due to the northeastern movement of the Arabian plate and the limitation due to the Caspian hard crust.<br /> Undoubtedly, Qom is an area that is considered and studied by different seismic researchers with different views and study styles. Comparing the results of these studies has helped to discover the Unknown activity zone.<br /> In general, the northern part of Qom is an area with high seismicity in which the mechanism of earthquakes is mostly strike-slip with thrust. Therefore, moderate to large earthquakes are expected to occur in the future.حوزه درونقارهای شمال قم در ایران مرکزی جای گرفته است. راستای عمومی گسلهای مهم این پهنه شامل گسل قم، البرز و کوشک نصرت، شمال باختر- جنوب خاور بوده و همگی با درازای بیش از 50 کیلومتر تحت تأثیر همگرایی صفحه عربی- اوراسیا، در لرزهخیزی و دگرشکلی گستره قم نقش مهمی داشتهاند. یکی از روشهای ارزیابی زمینساختی، بهرهگیری از شاخصهای زمینریختسنجی است. در این میان، با توجه به ویژگیهای سنگشناختی و نحوه قرارگیری و پراکندگی حوضهها، شاخصهای نسبت عرض به ارتفاع دره، هیپسومتری و گرادیان طولی رودخانه برای ارزیابی انتخاب شده و نتایج تحلیل شدهاند. این دادهها، در کنار دادههای هندسه گسلها و جهتیابی تنش توانسته برخی ویژگیهای زمینساختی گستره را روشن کند. مطالعات زمینریختسنجی، گسترههای اطراف گسل ساوه و گسل کوشک نصرت در بخش شمال ساوه و همچنین مناطقی از جنوب شهر قم را دارای توان بالاآمدگی نشان میدهد. سایر پهنهها بالاآمدگی قابل توجهی ندارند.پایین بودن جنبایی قائم در برآوردهای زمینریختسنجی دلالت بر نبود جنبایی نیست بلکه میتواند کارکرد همزمان مؤلفههای فشاری و برشی یا همان دگرشکلی خاص ایران مرکزی را نشان دهد. این نوع حرکت با دانستن جهتیابی تنش بهسادگی قابل تفسیر خواهد بود. دگرشکلی برشی- فشاری گستره قم، ناشی از حرکت رو به شمال خاوری ورقه عربی و محدودشدگی ناشی از پوسته سخت خزر است. حرکتهای راستالغز همزمان با جابهجایی معکوس در طول گسلها باعث شکلگیری چینخوردگیهایی نیز شده است. بدون شک، گسترهی قم محدودهای است که از نظر مطالعات زمینشناسی لرزهای مورد توجه محققین با دیدگاههای مطالعاتی متفاوت بوده که مقایسه نتایج این پژوهشها به کشف مجهولات جنبایی گستره کمک کرده است.https://www.bese.ir/article_244093_0cd29f099f62fa349f327b1c43dbc104.pdfپژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220Effect of Ground Slope on the Dynamic Response of Piles Group in Liquefiable Soil based on 3D Numerical Simulationتاثیر شیب زمین بر روی پاسخ دینامیکی گروه شمعها در خاک قابل روانگرا بر پایهی شبیهسازی سهبعدی عددی294925092710.48303/bese.2022.250927FAفرامرزرنجبردانشجوی کارشناسی ارشد سازه، دانشکده فنی و مهندسی، دانشگاه مازندران، بابلسر، ایرانعلیعسگریاستادیار، گروه مهندسی عمران، دانشکده مهندسی و فناوری، دانشگاه مازندران، بابلسر، ایران0000-0002-2359-8696حبیباکبرزاده بنگردانشیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مازندران، بابلسر، ایرانJournal Article20210124<strong> 1.Introduction</strong><br /><br />During the past earthquakes, liquefaction and the resulting deformations have caused significant damage to the deep foundations of bridges, ports, offshore structures and buildings that these damages have been more severe in mildly sloping grounds due to lateral spreading-induced liquefaction. Lateral spreading-induced soil liquefaction, has imposed significant damage to the deep foundations of bridges, ports, offshore structures and buildings. The behavior of piles in liquefied soil has been investigated by various researchers using field observations, large-scale (1-g) shake table tests, centrifuge tests as well as numerical simulations. Despite various experimental, numerical and field studies by previous researchers, there is also no comprehensive approach to assessing the effects of lateral spreading on pile groups. On the other hand, numerical simulations are an economical tool for investigating and a means of representing the seismic performance of the pile groups at sites with liquefaction-induced lateral spreading.<br />The main purpose of this study is to evaluate the effect of various pile groups (e.g., 1×1, 2×2 and 3×3) on reducing the potential for liquefaction during earthquake are investigated parametrically, applying three-dimensional finite element (FE) simulations using OpenSees software. To examine the ground inclination angle and array of pile groups' effects, different models have been subjected to the El Centro earthquake (1940). This study evaluates the effect of each of these factors on soil acceleration, lateral displacement, excess pore pressure and piles bending moment. The numerical model has been verified and calibrated in the literature through analysis of a well-documented large-scale (1-g) shake-table test.<br /><br /><strong> 2.Numerical Simulations</strong><br /><br />To gain insight into the effect of ground inclination angle on various pile groups in 10-m-thick mildly inclined liquefiable soil above the bedrock (Figure 5). The physical and mechanical properties of the soil layers and the pile respectively, are presented in Tables (1) and (2). Also, all the models in this study have been subjected to the El Centro earthquake (1940) (shown in Figure 9) with 0.15 g scaled peak ground acceleration.<br /><br /><strong> 3.Results and discussions</strong><br /><br />To investigate the effect of the ground inclination angle on the generation and dissipation of pore water pressure, the time history of excess pore water pressure for various pile groups in depths of 6 m is shown in Figure (18). According to Figure (18), as the ground inclination angle increases, the excess pore water pressure disappears sooner, which is due to the increasing effect of the dilatancy phenomenon.<br />Figure (20) shows time history of the pile head lateral displacement for different ground of the slopes (a<sub>f</sub> = 0° to 6°) in the pile group 1×1- 2×2 - 3×3. According to Figure (20) in the initial seconds of the excitation due to the lack of soil liquefaction, the ground of the slope has a little effect on the lateral displacement of the piles but with the occurrence of liquefaction and reduction of soil shear strength, it is observed that with increasing slope, the lateral displacement of piles increases severely. It is also observed that in the horizontal model, the maximum lateral displacement of the pile head occurs in about 2 seconds, which corresponds to the maximum acceleration time of the El Centro earthquake. While in mildly sloping ground due to the increase of lateral pressure from the soil, the maximum deformation occurs at the end of the earthquake and causes permanent displacement in the piles.<br /><br /><strong> 4.Conclusions</strong><br /><br />The main important conclusions drawn from present study are as follows:<br /><br />1. Based on the results, with increasing the ground slope angle in a specified point of the soil, less pore water pressure is produced and the dissipation of pore water pressure starts earlier, but the variations of pore water pressure increased.<br />2. In mildly sloping ground, the amount of pore water pressure in downslope is less than upslope ground and also with increasing ground slope angle, the rate fluctuations of excess pore water pressure increased in the down-slope of the pile group. This behavior is due to the high displacement downslope soil relative to upslope soil in the pile group.<br />3. In mildly sloping ground, despite the reduction of pore water pressure, lateral displacement of piles and soil severely increased. The reason for this contradiction due to the direction of static shear stress is parallel to the direction of soil slope. This shear stress is due to the weight of the soil mass, which increases the displacement of piles and soil in mildly sloping ground.<br /><br />At the last, it should be noted that, the ground slope angle is a very effective parameter in the lateral and vertical displacement of piles that should be considered in design code. گسترش جانبی ناشی از روانگرایی خاک، اغلب باعث ایجاد خرابیهای قابل توجهی در پی های عمیقِ پل ها، بندرها، سازه های دریایی و ساختمانها میشود. با وجود انجام مطالعات مختلف آزمایشگاهی، عددی و صحرایی توسط پژوهشگران پیشین، همچنان رویکرد جامعی برای ارزیابی اثرات گسترش جانبی بر شمعها وجود ندارد. شبیهسازیهای عددی ابزاری مهم و اقتصادی برای بررسی اثرات گسترش جانبی بر شمعها هستند. در این پژوهش، به بررسی اثر شیب زمین بر روی رفتار گروه شمع های 1×1، 2×2 و 3×3 بهصورت پارامتریک و با استفاده از شبیه سازی سه بعدی عددی پرداخته شده است. بدینمنظور، ابتدا مدل عددی ساخته شده با نرم افزار اجزای محدود اپنسیس، با نتایج یک آزمایش میز لرزان بزرگمقیاس، صحت سنجی شده و سپس به ازای شیب های مختلف زمین، پارامترهایی نظیر تغییرات فشار آب حفرهای، تغییرات جابهجایی جانبی شمع و خاک، لنگر خمشی در شمع ها و تغییرات شتاب شمع و خاک تحت زلزله ی السنترو مورد بررسی قرار گرفته است. نتایج نشان می دهد که با افزایش شیب زمین، فشار آب حفرهای کمتری تولید شده و زایل شدن اضافه فشار آب حفرهای زودتر آغاز می شود اما جابهجایی جانبی شمع و خاک افزایش می یابد. از طرفی دو عامل در روند تغییرات و میزان جابهجایی ها نقش دارد، عامل اول تنش برشی استاتیکی در راستای شیب که اثر افزایشی بر میزان جابهجایی دارد و عامل دوم رفتار اتساعی خاک ناشی از تغییر شکل است که اثر کاهشی بر روی روند جابهجایی دارد.https://www.bese.ir/article_250927_63148cb8a9f0542892477ce9b2741c5f.pdfپژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220An analytical study of the effect of non-uniform excitation on the seismic response of Sadr Bridgeتعیین پاسخ لرزه ای پل صدر تحت اثر اندرکنش خاک-سازه و تحریک غیر یکنواخت516524608010.48303/bese.2021.246080FAشیما الساداتحسینیدانشجوی دکتری، گروه مهندسی عمران، دانشگاه خوارزمی، تهران، ایرانعلیقنبریاستاد، گروه مهندسی عمران، دانشگاه خوارزمی، تهران، ایران0000-0002-8264-0540محمدداودیدانشیار، پژوهشکده مهندسی ژئوتکنیک، پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله، تهران، ایرانJournal Article20180802<strong> 1. Introduction</strong><br /><br />Large-dimensional structures, such as long-span bridges, receive different ground motions at different supports in earthquake events. Seismic wave propagation and local site conditions cause spatial variation of ground motion. It may result in pounding or even collapse of adjacent bridge decks owing to the out-of-phase response. In addition, dynamic Soil-Structure Interaction (SSI) resulting from the interaction of the bridge with the surrounding soil also affects the dynamic bridge response. In most bridges, shallow foundations are not appropriate, because they do not provide the required capacity or may experience excessive settlements or deformations. In such structures, pile groups are used as foundation systems. Pile foundations have to be designed to support not only vertical loads, but also lateral loads due to the earthquake, wind and vehicle impact loads. Therefore, soil-pile interaction is added to above factors in dynamic behavior of long-span bridges. From the above reasons, it is very important to consider both Soil-Pile-Structure interaction (SPSI) and Spatially Varying Earthquake Ground Motions (SVEGM) effects in evaluation of the seismic response of long-span bridges.<br />Material and methods<br />This paper presents a study about the spatial variability effects of ground motion and Soil-Pile-Structure Interaction (SPSI) on the dynamic response of a long bridge. Two decks of the considered bridge with length d<sub>1</sub> = 100 m and d<sub>2</sub> = 150 m are supported by four isolation bearings connected to three elastic piers standing on the pile foundations. The structure of the bridge continues from both sides. The decks are considered as lumped mass model with the total mass of m<sub>1</sub> = 1.2´10<sup>6</sup> kg and m<sub>2</sub> = 1.8´10<sup>6</sup> kg. All of the bearings have the same dynamic properties with an effective stiffness Kb<sub>1</sub> and equivalent viscous damping Cb<sub>1</sub> for the left span, and Kb<sub>2</sub> and Cb<sub>2</sub> for the right span. The concrete piers with heights of h<sub>1</sub> = 14 m, h<sub>2</sub> = 16 m and h<sub>3</sub> = 15 m are modelled as elastic columns with lumped mass m<sub>3</sub> = m<sub>4</sub> = m<sub>5</sub> = 2´10<sup>5</sup> kg at the top of each pier. The lateral stiffness of the piers are Kp<sub>3</sub> = 2´10<sup>8</sup> N/m, Kp<sub>4</sub> = 10<sup>8</sup> N/m and Kp<sub>5</sub> = 3´10<sup>8</sup> N/m. To simplify the analysis, a constant damping ratio of 5% is used for bearings and piers. The most widely used model to perform the analysis of piles under lateral loads, consists in modeling the pile as a series of beam elements and representing the soil as a group of unconnected-concentrated springs perpendicular to the pile that is known as Discrete Winkler Model. The Spatially Varying Earthquake Ground Motion (SVEGM) is simulated by SIMQKE-II record generator. Target response spectrum and power spectral density function used in the simulation are determined depending on the January 17, 1994, Northridge earthquake. To evaluate the effect of SPSI, the soil surrounding the pile foundation is modelled by frequency-independent springs and dashpots in the horizontal and rotational directions. The effect of soil-pile mass is considered by lumped-mass soil-pile model. A new analytical model is proposed to study the effect of both SVEGM and SPSI on dynamic response of long bridges.<br /><br /><strong> 2. Results and Discussion</strong><br /><br />The results indicate that considering the effect of non-uniform excitation and soil-structure interaction can increase the relative displacement of the deck in the longitudinal and transverse directions by 275% and 176%.<br />Also, considering the interaction effect, on average, shows a reduction of 67% and 75% of the base shear and moment considering non-uniform excitation, shows an increase of 37% and 29%, respectively.<br /><strong> </strong><br /><strong>3. Conclusion</strong><br /><br />The main conclusions drawn from this study can be written as:<br /><br />1. Based on the results obtained from the proposed analytical model, SVEGM affects the seismic behavior of long-span bridges. Influence of SVEGM on decks displacements and maximum shear forces in piers is more significant in softer soil types. It means soil condition as an important factor affects the dynamic response of long bridges.<br />2. The importance of the SPSI effect on the dynamic response of the bridge is also investigated in comparison with fixed-base case. It is observed that the results obtained from the SPSI case are usually amplified in comparison with the fixed-base case. This effect is more significant in softer soil types. It means that the variation of the soil conditions where the bridge supports are located on, has important effect on the bridge dynamic response. Since the proposed model is very similar to real soil-pile-structure systems, suggested equation derived from it, can be used to simulate the seismic behavior of long-span bridges.<br />3. If the effects of SPSI and SVEGM are considered simultaneously, it should be noticed that the results will not be the same as what obtained from the addition of the response determined from these effects separately. The effects of SPSI and SVEGM amplify each other especially in softer soil conditions. It is also observed that considering the effect of SPSI with respect to the SVEGM can change the dynamic response of long-span bridges in comparison with the cases in which one of these factors or none of them is considered.<br />4. In general, the recommendation of fixed-base case with uniform ground excitation in dynamic design regulations of bridges is valid only if SPSI and SVEGM effects are negligible. These assumption can be used in seismic design of bridges on very stiff soil conditions and not very long bridges. Otherwise, this recommendation leads to usually underestimating the dynamic response or even bridge structure damage.چکیده<br /><br />در سازههای عظیم و طویل مانند پلها فرض گیرداری پی و تحریک یکنواخت لرزهای در تمام تکیه گاه های سازه موجب انحراف پاسخها از واقعیت میشود. هدف از انجام این مطالعه ارزیابی پاسخ لرزه ای یک پل طویل تحت اثر اندرکنش خاک- سازه و تحریک غیر یکنواخت می باشد که در آن یک مدل تحلیلی جدید جهت مدل سازی اثر اندرکنش خاک-سازه ارائه شده است. همچنین تحریکات غیر یکنواخت در محل تکیه گاه های مختلف محدوده ی مطالعه ی پل صدر به عنوان یک پل طویل شبیه سازی شد و بر مدل اعمال گردید. مقایسه پاسخ های دینامیکی سازه در شرایط اندرکنش و تحریک غیر یکنواخت با حالت پایه گیردار و تحریک یکنواخت حاکی از تأثیر بسزای هر دو عامل اندرکنش و تحریک غیر یکنواخت در تحلیل و طراحی پل های طویل بوده و نشان داد که عدم در نظرگیری این عوامل ممکن است منجر به پاسخ های دور از واقعیت شود. نتایج بیانگر این مطلب است که در نظر گیری اثر اندرکنش و تحریک غیر یکنواخت می تواند تا 275 و 176 درصد باعث افزایش تغییر مکان نسبی عرشه در راستای طولی و عرضی شود. همچنین لحاظ نمودن اثر اندرکنش به طور میانگین کاهش 67 و 75 درصدی برش و لنگر پایه و در نظر گیری تحریک غیر یکنواخت افزایش 37 و 29 درصدی آن مقادیر را نشان میدهد.https://www.bese.ir/article_246080_108d9a3c1ae3fd4bd66cf168acc304c3.pdfپژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220Seismic Performance Assessment of Substituting RC Coupling Beams with Replaceable Perforated Steel Type in Tunnel Form Concrete Building Structuresبررسی عملکرد لرزه ای جایگزینی تیر همبند بتن آرمه با نوع فولادی سوراخدار تعویضپذیر پیشنهادی در ساختمانهای بتنی قالبتونلی678325092810.48303/bese.2022.250928FAسید بهرامبهشتی اولدانشیار، دانشکده مهندسی عمران، دانشگاه صنعتی خواجهنصیرالدین طوسی، تهران، ایران0000-0001-8919-2923سیدعلیحسینیدانش آموخته کارشناسی ارشد سازه، دانشکده مهندسی عمران، دانشگاه صنعتی خواجهنصیرالدین طوسی، تهران، ایرانJournal Article20190326The coupled-shear wall system has been proven to be an outstanding lateral-load resisting system in the medium- to high-rise buildings. In this system, several individual shear walls are coupled with coupling beams. Thus, the walls show an integrated performance in resisting the earthquake loads by providing control over lateral displacements. In tunnel form buildings, the strength and the lateral stiffness are influenced by the coupling beam. In this system, the coupling beams act as a fuse in this system; they are the first elements to undergo inelastic deformations. The proper design of the concrete coupling beams (CCBs) leads to the use of diagonal reinforcements and high-level of detailing. There is a problem in construction of RC tunnel form buildings related to inserting the diagonal reinforcing shear bars, which is practically difficult and in most cases, this reinforcement is ignored. Therefore, these elements as the structural fuses have a minor contribution in dissipation of seismic input energy. Recent researches showed that the steel coupling beams (SCBs) exhibit better performance than the CCBs in terms of ductility and energy absorption during cyclic loadings. The pinching effect was not observed in the hysteretic loops for SCBs, which implied a more stable post-elastic behavior and a higher energy dissipation capacity than the CCBs. Also, the energy dissipation capacity of SCBs was more than three times larger than that of the CCBs. In this study, a regular symmetric plan seven-story tunnel form building was used. The coupling beams with a length of 1 m and a depth of 0.7 m above the openings were inserted. The building was assumed to be residential and located in Tehran. The story height was 3 m, and the soil was considered type B based on the regulatory seismic code of Iran. The building was designed according to ACI 318-14 by using ETABS software. The thickness of the walls and the slabs were 20 cm and 15 cm, respectively. No. 8 rebar with spacing of 20 cm was designed for the vertical and horizontal reinforcements in two layers. In the first two stories, only the vertical reinforcements were of No. 12 rebar. The compressive strength of concrete and the yield strength of reinforcements for structural members were 25 MPa and 400 MPa, respectively. The diagonal reinforcements of the CCBs were designed to provide the ductility and the improvement of the shear strength. In this research, the CCBs were substituted by SCBs with circular holes. The shear strength of the beam was improved with diagonal stiffeners. The holes in the web of the beam were used to convey installations and to avoid perforating shear walls in tunnel form buildings. The diagonal stiffeners prevented the buckling of the beam’s web. Also, the shear strength and the tension field action were improved. Therefore, the seismic performance of the coupling beam was overall enhanced. As the main design equipment the SCB, the relations related to determining the shear capacity of the steel beam were exploited. Then, the seismic behavior of tunnel-form structures with regular RC coupling beams against the same structures designed with the proposed steel beams has been evaluated and compared in a nonlinear range. Finite element modeling and nonlinear analyses were conducted in PERFORM-3D. The incremental dynamic analysis regarding the probable ground motions was performed on the buildings to consider the effects of amplitude variation, frequency content, and the duration of ground motions on the response. The results showed that the use of the proposed SCB reduces the system stiffness and thus increases story drifts. In addition to decreasing the probability of the walls to attain the first levels of failure slightly, under the design earthquake and the maximum probable earthquake, the reliability of buildings in achieving predetermined performances was increased. Indeed, the use of this proposed coupling beam also increases the ductility of the tunnel form structures. Easy to implement and easy to repair or replacement of this steel coupling beam after a destructive earthquake are its other advantages compared to RC type.به علت مشکلات اجرایی در ساختمانهای بتنی قالبتونلی، تعبیه میلگردهای برشی قطری عملاً دشوار بوده و در اکثر موارد، از این تسلیح صرفنظر میشود. لذا این المانها بهعنوان فیوز خرابی، در اتلاف انرژی ورودی زلزله عملکردی ضعیفی خواهند داشت. در این مطالعه، طرح جایگزینی تیرهمبند بتنی با نوع فولادی برشی تعویضپذیر پیشنهاد شده است. بدینمنظور ضمن ارائه روابط مربوط به تعیین ظرفیت برشی این تیر، رفتار لرزهای ساختمانهای قالبتونلی طراحی شده با تیرهای همبند فولادی پیشنهادی و بتنی، در محدوده غیرخطی مورد ارزیابی و مقایسه قرار گرفته است. نتایج نشان می دهد استفاده از تیر همبند فولادی پیشنهادی سبب کاهش سختی در سیستم و بالطبع افزایش تغییر مکانهای نسبی طبقات می شود. در این سیستم پیشنهادی علاوه بر اینکه احتمال رسیدن دیوارها به اولین سطوح خرابی کاهش یافته، تحت زلزله طرح و بیشینه زلزله محتمل قابلیت اعتماد ساختمانها در حصول به عملکردهای از پیش تعیین شده افزایش یافته است. همچنین استفاده از این نوع تیر همبند فلزی، باعث افزایش شکل پذیری ساختمانهای قالب تونلی می شود. اجرای آسان و سهولت در تعمیر یا تعویض این نوع تیر همبند فلزی بعد از یک زلزله مخرب از مزایای دیگر آن در مقایسه با نوع بتنی می باشد.https://www.bese.ir/article_250928_8a278bdcbd793bab1c44f1c4e2edadaa.pdfپژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220Evaluation of the Effects of Topography on the Horizontal and Vertical Displacement of Semi-Sine Shaped Hills against Ricker Wavesﺑﺮﺭﺳﯽ ﺍﺛﺮﺍﺕ ﺗﻮﭘﻮﮔﺮﺍﻓﯽ بر روی جابهجایی افقی و قائم تپههای ﻧﻴﻢﺳﻴﻨﻮﺳﯽ تحت برخورد ﺍﻣﻮﺍج ﺭﯾﮑﺮ859224599610.48303/bese.2021.245996FAمهیارنوبختدانش آموخته کارشناسی ارشد ژئوتکنیک، دانشگاه صنعتی قم، قم، ایرانمسعودعامل سخیاستادیار، گروه مهندسی عمران، دانشگاه صنعتی قم، قم، ایران0000-0002-5894-0404فاطمهشش پریدانش آموخته کارشناسی ارشد ژئوتکنیک، دانشگاه صنعتی قم، قم، ایرانJournal Article20200712This study presents the results of a numerical study on seismic behavior of two-dimensional semi-sine shaped hills that were subjected to vertically propagating incident SV wave of the Ricker wavelet. In the case of 2D response analysis of hills, different researchers studied the seismic response of triangular shaped hills under vertically propagating SH waves. Earthquakes are natural events that can have considerable economic and social injuries and have effects on people life and their environment. Geotechnical earthquake engineering has been noticed particularly in recent decades. Soil mass and soil structure response analysis against earthquake movements is one of the most important practical concepts in geotechnical earthquake engineering. This paper used finite difference method and represented that topography has specific effect on acceleration distribution in different points of roughness. The finite difference software is used to model and analyze the different sizes of the hills. Concentration is on topographic effects, so parameters such as the shape factor (the ratio of the height to half width of the hill) and the type of ground took into account in this research. The medium was assumed to have a linear elastic constitutive behavior. An important factor that affects on numerical results is the shape factor of the hills. Therefore, we modeled semi-sine hills with different shape factors (0.1, 0.4 and 0.8) subjected to Ricker wavelet with constant frequency on grounds with different properties that differ from each other in density and shear velocity (three types). The finite difference software used to run the numerical analyses was Flac 2D. The aim of this project was to investigate the response of topography effects on semi-sine shaped hills under Ricker wavelet, which is the second derivative of Gauss function. In this research, the horizontal and vertical displacements of different points on hills were calculated. Also, amplification factors were calculated from the ratio of horizontal components of motion to displacements of free-field model. The results are shown that both horizontal and vertical displacements were increased with a change in the shape factor as well as the amplification. It is shown that changing ground type from one to three, the displacements were reduced. Obtained results show that most horizontal displacement occurs in the top of the hill and as we reach the lowest height of the hill, this displacement decreases. Thus it can be seen that most amplification occurs in the top of the hill for different numerical models. The vertical displacement in top of the hill is zero and with decreasing the height of the hill, this vertical displacement increases and then decreases. Based on obtained results, the most vertical displacement occurs in the height between the top and down of the hill for different finite difference numerical models. Another important result is that these vertical and horizontal displacements depend mostly on soil geotechnical behavior of the hill. It is obvious that the shape factor of the hill affects on the obtained numerical results. An important factor that is studied in this research is the shape factor of the hill. Another important factor on which results are dependent is input motion frequencies. It is clear that when natural frequencies of the hill and the input motion frequencies are near to each other, the vertical and horizontal displacement increases. When the hill steep increases, the obtained results increase because of gathering most energy on top of the hill in a narrow band area.این پژوهش مطالع های است روی رفتار لرزهای تپه های نیمسینوسی شکل که در معرض امواج برشیِ قائمِ ریکر قرار گرفتهاند. برای مدلسازی از نرمافزاری که بر مبنای روش تفاضل محدود میباشد، استفاده شده است. چون تمرکز بر روی تأثیرات توپوگرافی است، از پارامتر ضریب شکل (نسبت ارتفاع به نیمپهنای تپه) و پارامترهای زمین بهعنوان متغیر استفاده شده است. رفتار محیط مدلسازی الاستیک خطی در نظر گرفته شده است؛ در نتیجه تپه های شبهسینوسی با ضریب شکل های متفاوت (0/1، 0/4 و 0/8)، در زمین با جنس های متفاوتِ تیپ I، II و III (که تفاوت آنها طبق استاندارد 2800 در چگالی و سرعت موج برشی در محیطِ پیوسته است) مدل شدهاند که هرکدام از آنها تحت موج ریکر با فرکانس ثابت قرار گرفتهاند. در این تحقیق جابهجاییهای افقی و عمودی برای نقاط مختلف روی تپه محاسبه شده اند. همچنین بزرگنماییِ جابهجایی با توجه به مدل میدان آزاد به دست آمده است. نتایج نشاندهندهی این مطلب است که با افزایش ضریب شکل، هم جابهجایی افقی و هم جابهجایی قائم و درنتیجه بزرگنمایی در تمام موارد افزایش می یابد. همچنین از نمودارهای حاصله می توان دریافت که با تغییر جنس زمین از تیپ I به تیپ II جابهجایی ها کاهش مییابد.https://www.bese.ir/article_245996_9dbca5b4314659455d110bd755bfc256.pdfپژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220Statistical Modeling of the Migrating Pattern of the Occurrence of Successive Earthquakes in the Zagros Regionمدلسازی آماری الگوی مهاجرتی رخداد زلزلههای متوالی در ناحیه زاگرس9310324381210.48303/bese.2021.243812FAسید ناصرهاشمیاستادیار، گروه زمینشناسی، دانشکده علوم زمین، دانشگاه دامغان، دامغان، ایرانJournal Article20191230<strong>1. Introduction</strong><br />Most of the seismic energy (or tectonic loading) accumulated in lithosphere of active regions is released through the occurrence of large earthquakes that usually show complex spatio-temporal patterns. Hence, the study of the spatial and temporal pattern of these occurrences is very important for revealing the seismotectonic nature of these regions. Over the past decades, the statistics of the waiting times between consecutive earthquakes (so-called inter-event times) have become the focus of research. Statistical analysis of inter-event times of earthquakes allows the derivation of useful information that can allow the development of earthquake forecasting strategies, and inter-event time statistics for moderate to small events may be used to extrapolate inter-event time behaviour at larger scales. Assuming that the release of seismic energy (by occurring earthquakes) is stationary in the whole region of Zagros, in this research, the spatio-temporal relationships of the occurrences of large earthquakes that occurred in this region have been studied.<br /><br /><strong> Methodology</strong><br /><br />In this study, the migration pattern of successive earthquakes in the Zagros region during the period 1976-2019 has been studied for earthquakes with magnitude 4.5 and greater. In order to carry out this work, the earthquake data of the examined region with M ≥ 4.5 (1976-2019) have been obtained from the USGS catalog. Then, the inter-event time, migration distance, and migration trend of successive earthquakes with different lower magnitude thresholds of 4.5, 0.5 and 5.5 were calculated and the statistical distribution of these data was analyzed and modeled.<br /><br /><strong> Results and Discussion</strong><br /><br />Statistical analysis of the inter-event times between consecutive earthquakes in the Zagros region shows that among the different models used in statistical modeling of data, Weibull and Gamma models show the best agreement with the statistical distribution of inter-event time data. In addition, it is observed that larger earthquakes are less compatible with these models. Furthermore, migration distance data from successive earthquakes also shows a decreasing pattern, similar to the inter-event time distribution data. In addition, the study of the relationship between the two variables of migration distance and time interval between events shows that it is not possible to find a significant relationship between these two variables especially for earthquakes of smaller magnitude, but for larger earthquakes, it seems that a positive correlation between these two variables exists. This finding indicates that earthquakes with more inter-event times are expected to occur farther apart from each other, which could be a reason for seismicity migration behavior of earthquakes in this region. Also, the directional pattern of earthquakes migration data shows a pattern consistent with the general trend of active faults in the Zagros region, which confirms the idea that the activation of discrete segments of fault systems in this region plays a key role in the temporal and temporal pattern of seismicity. Based on the results of this study, it is expected that earthquakes with magnitude 5.5 and greater, tend to occur with an average migration distance of about 418 km and an average waiting time of 198 days, and in the dominant directional azimuth of N62W or S62E, compared to their previous events.<br /><br /><strong> Conclusions</strong><br /><br />The results of this study can be considered as an effective step to better understanding the temporal-spatial pattern of seismicity in the Zagros region and also as an attempt to achieve earthquake prediction in a regional scale.<br />It is expected that in the future, with the possibility of access to more accurate data and the use of other new methods such as neural network modeling and artificial intelligence, it will be possible to better understand the temporal and spatial pattern of earthquakes, which undoubtedly is an important and effective step to achieve earthquake prediction on a regional scale.در این تحقیق، الگوی مهاجرت زلزلههای متوالی رخ داده در ناحیه زاگرس، در بازه زمانی 1976 تا 2019 و برای زلزلههای با بزرگای مساوی و بیش از 4/5 ریشتر مورد مطالعه قرار گرفته است. به این منظور، زمان بین رخداد، فاصله مهاجرت رومرکزی و راستای مهاجرتی زلزلههای متوالی، برای زلزلههای با بزرگیهای مساوی و بیش از 4/5، 5/0 و 5/5 محاسبه شده و توزیع آماری این دادهها مورد تحلیل و مدلسازی آماری قرار گرفته است. بررسی توزیع آماری زمان بین رخدادی زلزلهها حاکی از تطابق خوب این دادهها با توزیعهای آماری گاما و ویبول است. دادههای فاصله مهاجرتی زلزلهها نیز بهخوبی الگوی کاهشی، مشابه با توزیع زمان بین رخدادی زلزلهها را نشان میدهد. همچنین، دادههای روند مهاجرت زلزلههای متوالی نیز الگویی کاملاً همراستا با روند کلی گسلهای فعال ناحیه زاگرس را نشان میدهد که تأیید کننده این نظر است که فعال شدن قطعات مجزای سیستمهای گسلی در این ناحیه، نقش اصلی را در توالی زمانی و مکانی رخداد زلزلهها ایفا میکند. نتایج حاصل از این تحقیق میتواند گامی مؤثر برای شناخت بهتر الگوی زمانی- مکانی لرزهخیزی در ناحیه زاگرس و تلاشی برای دستیابی به پیشبینی زلزله در مقیاسی ناحیهای محسوب شود.https://www.bese.ir/article_243812_2f2dea22c5d9e870f71925a65709c09f.pdfپژوهشگاه بین المللی زلزله شناسی و مهندسی زلزلهفصلنامه علوم و مهندسی زلزله2476-60978420220220Presenting a Model of Earthquake Wave Velocity Changes (VPn ) Based on Genetic Algorithm (Case Study - Iran)ارائه مدل تغییرات سرعت امواج زلزله ( VPn) بر اساس الگوریتم ژنتیک (مطالعه موردی- ایران)10511324432910.48303/bese.2021.244329FAرسولمظلومدانشآموخته کارشناسی ارشد، پژوهشکده زلزلهشناسی، پژوهشگاه بینالمللی زلزلهشناسی و مهندسی زلزله، تهران، ایراناحسانمعانی میاندوآباستادیار، دانشکده علوم مهندسی، پردیس دانشکدههای فنی دانشگاه تهران، تهران، ایرانJournal Article20200515Earthquake is one of the most dangerous natural disasters of the present age, which has always shown its importance objectively. An earthquake is a natural disaster that, depending on its magnitude, can cause massive catastrophes in a short time. In this study, the authors seek to provide a simple analytical form for the propagation speed of waves, which despite previous studies, has not received much attention. Therefore, the purpose of this paper is to extract and present a model for earthquake wave velocity changes ( VPn) using Genetic Algorithm (GA).<br /><strong>Research Methods</strong><br /> The data used in this study were received from the National Seismological Center of the Institute of Geophysics, University of Tehran. In this study, three provinces of Kermanshah, East Azerbaijan and Kerman were selected. Earthquake event characteristics of each of these three provinces in the period between 2006 and the end of 2018, with a focal depth of up to 30 km and magnitude between 4 and 8 were selected. In order to use the Genetic Algorithm (GA), first the data received from the National Seismological Center for these three provinces were merged, which was estimated at 1863 earthquake events. After extracting the relevant data, the earthquake wave velocity (VPn ) was calculated. Then, ignoring about 25% of this data, a mathematical model for earthquake velocity was extracted. Finally, the obtained formula was applied to the initial ignored data (25%), which had similar results. To model the changes in wave velocity according to distance changes, a mathematical relation was considered as an exponential function and the unknown parameters of the model were determined using a Genetic Algorithm (GA). To find a suitable model between distance and speed, the following relation is considered for it.<br />V(X)=a+b<sup>-kX</sup> (1) <br />In this regard, a, b and k are constant coefficients and x is the distance from the earthquake site in terms of one thousand kilometers. In the above equation, the coefficients must be determined so that the output of this model with the recorded data has the least amount of error. For this purpose, the Genetic Algorithm (GA) optimization method is used, and the error between the model output and the actual data was considered as the objective function of the optimization problem, and the optimization variables were determined with the aim of minimizing this objective function. The objective function is defined as follows:<br /> (2)<br />In this connection,V<sub>i</sub> is the velocity obtained as a measure and V(X<sub>i</sub>) the amount of speed obtained according to the Equation (1). For implementation, the Genetic Algorithm (GA) has been used 2000 populations and 30 generations. Also the coefficient of crossover is equal to 70% and coefficient mutation is equal to 2%.<br /> The output of the model for training and test data showed that the proposed model has acceptable accuracy for modeling the velocity of longitudinal waves. This model can be used to determine the arrival time of waves of an earthquake to different points. It is also possible to estimate the location of the earthquake by recording the occurrence of the earthquake at several different points and using the provided relationship.زلزله یکی از خطرناکترین بلایای طبیعی عصر حاضر به شمار میرود که همواره اهمیت خود را بهطور عینی نمایان کرده است. زلزله سانحهای طبیعی است که بر اساس میزان بزرگی خود میتواند در مدت کوتاهی فجایعی عظیم به وجود آورد. هدف این مقاله، استخراج و ارائه مدلی برای تغییرات سرعت امواج زلزله (VPn) با استفاده از الگوریتم ژنتیک میباشد. دادههای مورد استفاده در این تحقیق از مرکز لرزهنگاری کشوری مربوط به مؤسسه ژئوفیزیک دانشگاه تهران دریافت شده است. در این تحقیق، سه استان کرمانشاه، آذربایجان شرقی و کرمان انتخاب شدند. به منظور استفاده از الگوریتم ژنتیک، ابتدا دادههای دریافت شده از مرکز لرزهنگاری کشوری برای این سه استان با هم ادغام شده که بالغ بر تعداد 1863 رخداد زلزله برآورد گردید. پس از استخراج دادههای مربوطه، نسبت به محاسبه سرعت امواج زلزله( VPn) اقدام شد. سپس با نادیده گرفتن حدود 25 درصد از این دادهها، نسبت به استخراج مدل ریاضی برای سرعت امواج زلزله، اقدام شد. در انتها، فرمول بهدستآمده در مورد دادههای چشمپوشی شده اولیه (25 درصد) اعمال گردید که نتایج مشابهی به دست آمد.https://www.bese.ir/article_244329_5e3ca3b35eade6a86b3c5f721f340744.pdf