فهرست مطالب

پژوهشنامه حمل و نقل - سال چهارم شماره 1 (پیاپی 10، بهار 1386)
  • سال چهارم شماره 1 (پیاپی 10، بهار 1386)
  • 120 صفحه،
  • تاریخ انتشار: 1386/04/15
  • تعداد عناوین: 9
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  • مقالات
  • علیرضا رهایی، سیدرسول میرقادری، امیر حجت صفحه 1
    پل های قوسی در تحمل و انتقال بارهای قائم عملکرد مناسبی دارند. اما عملکرد این پل ها در برابر بارهای جانبی مانند زمین لرزه، کمتر مورد بررسی قرار گرفته است. در این مقاله، بعد از ارزیابی سطوح مختلف عملکرد و شرایط آسیب پذیری پل های قوسی، عملکرد لرزه ای پل سفید اهواز که یکی از پل های قوسی آویزدار ایران است، مورد بررسی قرار گرفته است. مدل پل شامل یکی از دو دهانه بزرگ اصلی و پایه های دو سوی آن است. با انجام تحلیل طیفی و سپس تحلیل بار افزون، عملکرد پل در برابر زمین لرزه مورد ارزیابی قرار گرفته است و برای رسیدن به سطوح عملکردی مطلوب، روشی برای بهسازی پل پیشنهاد شده است.
    کلیدواژگان: پل قوسی، ارزیابی عملکرد لرزه ای، سطوح عملکرد، بهسازی
  • افشین شریعت مهیمنی، علی منصور خاکی، محسن بابایی صفحه 15
    شبکه های حمل و نقلی ممکن است تحت تاثیر یک سری عوامل خارجی یا داخلی دچار افت عملکرد و ناپایداری جریان ترافیک شوند. عوامل خارجی عمدتا شامل شرایط آب و هوایی خاص (مانند بارش برف، یخبندان و طوفان)، زلزله، بهمن و برخی عوامل دیگرند. عوامل داخلی آسیب پذیری ناشی از خرابی سیستم های کنترل، تصادفات، تعمیرات و ساخت و سازها هستند. تمامی عوامل یادشده می توانند منجر به افت ظرفیت کمان ها شوند و پاره ای از آنها تقاضای پایه موجود در زوج های مبدا- مقصد شبکه را تحت تاثیر قرار می دهند. با توجه به اهمیت حفظ عملکرد شبکه در چنین شرایطی در یک سطح مطلوب، در دهه آخر قرن بیستم تعریفی جدید برای ارزیابی عملکرد شبکه های حمل و نقلی ارایه شده است که اعتمادپذیری شبکه را در شرایط عدم قطعیت بیان می کند. از این رو ارزیابی قابلیت اطمینان عملکرد شبکه های حمل و نقل در طراحی و یا ارتقا و بازسازی آنها نقش بسیار پر اهمیتی پیدا کرده است. در این مقاله روشی ابتکاری برای محاسبه قابلیت اطمینان عملکرد اجزای شبکه در سطوح مختلف سرویس دهی ارایه شده است که از آن می توان برای محاسبه قابلیت اطمینان دسترسی (اتصال) و قابلیت اطمینان ظرفیت شبکه در قالب یک رابطه ریاضی استفاده کرد. همچنین نتایج بکارگیری این روش در یک شبکه شماتیک، جهت نمایش کارآمدی آن، ارایه شده است.
    کلیدواژگان: شبکه حمل و نقل درون شهری، عدم قطعیت، قابلیت اطمینان دسترسی، قابلیت اطمینان ظرفیت
  • محمود صفارزاده، بابک میربهاء صفحه 25
    در این پژوهش نسبت به طراحی الگویی برای پیشبرد معماری منطقه ای سیستم های هوشمند حمل و نقل در کشور اقدام شده است. در الگوی ارایه شده، مهم ترین مرحله را تعیین نیازهای حمل و نقلی منطقه تشکیل می دهد. این نیازها اهداف اصلی پیشبرد معماری در منطقه را تعیین می کند. تبیین مفاهیم اجرایی و ملزومات عملکردی سیستم در حقیقت نحوه ارتباط بین اجزای حقیقی و مجازی سیستم را مشخص می کند که این ارتباطات، منجر به پیدایش اتصال گرها و همچنین جریان های اطلاعاتی بین اجزای سیستم می شوند. پلان به دست آمده در حقیقت مبین شمایی از سیستم نهایی در مقیاس های کوچک تر خواهد بود. الگوی ارایه شده که مستقل از تکنولوژی طراحی شده است، فرآیندی است اقماری که کلیه خدمات قابل دریافت از این الگو را مشخص می کند. در این سیستم اجزای در حین عملکرد تنها با یک مرکز در تعامل اند. فرآیند پیشنهادی قابل اجرا در مناطق مختلف برون شهری کشور بوده و عنصر تکرارپذیری آن، امکان اعمال تغییرات پیشنهادی را مطابق با نظرات طراح فراهم می کند. همچنین، نسبت به بکارگیری الگوی پیشنهادی در قالب یک مطالعه موردی (محور کرج – چالوس) انجام شده است که با مطالعه مقدمات پیاده سازی ITS در این محور و مشکلات حمل و نقلی که محور با آن روبرو ست، نسبت به پیشنهاد فرآیند معماری ITS محور یاد شده اقدام شده است
    کلیدواژگان: سیستمهای هوشمند حمل و نقل، معماری، مشکلات حمل و نقلی، مفاهیم اجرایی، اتصالگرها، ملزومات عملکردی
  • محمد علی گودرزی خویگانی، حسین رجایی صفحه 41
    در طرح و ساخت تیر ورق های با جان عمیق استفاده از جان موج دار به دلیل افزایش سختی خارج صفحه و مقاومت کمانشی آن، بدون بکارگیری سخت کننده های قائم، در دهه های اخیر مورد توجه و استفاده قرار گرفته است. نوع خاصی از جان های فلزی موج دار به همراه بال های بتنی پیش تنیده در قالب تیرهای مرکب در پل ها به طور وسیع به کار گرفته شده است. شکل پروفیل های مختلفی که معمولا برای موج جان این تیرها مورد استفاده قرار می گیرد ذوزنقه ای، زیگزاگ و سینوسی است. این تحقیق با تعبیه یک مدل سه بعدی اجزای محدود، تحلیل تنش های برشی در جان تیر ورق های فولادی با پروفیل موج ذوزنقه ای را با ملاحظه مدهای مختلف کمانشی، مورد مطالعه قرار می دهد. همچنین بررسی پارامتریک جهت ارزیابی تاثیر پارامترهای هندسی مختلف در ظرفیت برشی نهایی جان این تیر ورق ها انجام شده است. این پارامترها برای موج های ذوزنقه ای عبارتنداز: (1) زاویه موج ذوزنقه ای (2) طول قسمت مسطح موج (3) عمق موج (4) ضخامت جان (5) ارتفاع مقطع. با استفاده از مدل یاد شده مطالعات پارامتریک در برش، برای موج های سینوسی نیز دنبال شده و تاثیر طول موج و دامنه موج را در ظرفیت نهایی برش مورد بررسی قرار داده است. مقایسه نتایج حاصل از تحلیل عددی با نتایج حاصل از روابط تحلیلی موجود برای صفحات مسطح، فرض رفتار صفحات ارتوتروپیک را برای جان موج دار در حالت وقوع کمانشی کلی جان مورد تایید قرار می دهد. بر پایه نتایج عددی حاصل شده، مزایا و معایب جان های با پروفیل موج سینوسی و ذوزنقه ای در پایان مورد ارزیابی قرار می گیرد.
    کلیدواژگان: اجزای محدوده، تحلیل غیر خطی، تیرهای با جان موج دار، موج ذوزنقه ای، موج سینوسی، روش عددی
  • سید مرتضی مرندی، پروین صفاپور، محمدحسین باقری پور، مجتبی قاسمی صفحه 57
    امروزه روش های هوشمند در پیش بینی پاره ای از کمیت ها می توانند به عنوان ابزاری قدرتمند برای بهینه سازی مدل های پیش بینی بکار روند. در این تحقیق دو هدف، یکی مدل سازی مقاومت مارشال نمونه های تثبیت شده با امولسیون قیر و سیمان جهت زیرسازی جاده ها و دیگری بهینه یابی هزینه های اجرایی کاربرد امولسیون قیر و سیمان در تثبیت این نوع زیرسازی دنبال شده است. به این منظور 170 آزمایش بر روی نمونه های تثبیت شده برای آموزش شبکه عصبی- فازی انجام شده و مورد استفاده قرار گرفته اند. سپس مقاومت مارشال نمونه ها، توسط شبکه هوشمند عصبی - فازی مدل شده و با استفاده از الگوریتم ژنتیک هزینه های اجرایی بهینه یابی شده است. در مدل سازی انجام شده از نرم افزار MATLAB استفاده شده است. نتایج این تحقیق نشان می دهد که با مدل پیشنهادی می توان تا حدود زیادی در هزینه های ساخت جاده ها صرفه جویی کرد.
    کلیدواژگان: مدل سازی مقاومت مارشال، تثبیت خاک، امولسیون، سیمان
  • محمود عامری، احمد منصوریان صفحه 69
    به طور کلی روسازی ها پس از گذشت چند سال از بهره برداری (کمتر از عمر بهره برداری)، به خرابی هایی از جمله قیر زدگی، انواع مختلف ترک ها، ناهمواری و یا تلفیقی از آنها دچار می شوند. به همین دلیل متولیان راهسازی همواره به دنبال راه حل هایی بوده اند که عمر روسازی راه ها را بیشینه و هزینه تعمیر و نگهداری آنها را کمینه کند. از جمله خرابی هایی که معمولا در روسازی راه ها مشاهده می شوند، ترک های خستگی هستند. برای تهیه مخلوط آسفالتی مقاوم در برابر بروز ترک های خستگی زودرس، آزمایش هایی پیشنهاد شده اند که معمولا انجام آنها نیاز به تجهیزات ویژه و صرف زمان طولانی دارد. به همین دلیل پژوهشگران روابط متنوعی را برای پیش بینی عمر خستگی مخلوط های آسفالتی ارایه کرده اند که البته این روابط نیز برای شرایط خاص انجام آزمایش (نوع مصالح، دما و...) معتبرند، اما باید برای شرایط دیگر اعتبارسنجی و صحت کاربرد آنها مورد بررسی قرار گیرد. در این پژوهش سعی شده است با توجه به امکانات آزمایشگاهی موجود در کشور و استفاده از آزمایش کشش غیرمستقیم رابطه ای برای پیش بینی عمر خستگی مخلوط های آسفالتی رایج که در رویه آسفالتی راه های کشور مورد استفاده قرار می گیرند ارایه شود. نتایج به دست آمده در این پژوهش نشان می دهند که با استفاده از درصد فضای خالی مصالح سنگی پرشده با قیر و ضریب برجهندگی نمونه های آسفالتی می توان رفتار خستگی مخلوط های آسفالتی را مورد بررسی قرار داد.
    کلیدواژگان: ترک خستگی، عمر خستگی، مخلوطهای آسفالتی، آزمایش کشش غیر مستقیم
  • یادداشت فنی
  • محسن پورسیدآقایی، جعفر محمودی، محمود ذوالقدری صفحه 83
    امروزه از خصوصیات یک سازمان موفق، خلاق و کارآمد آن است که از خواسته های مشتریان خود اطلاع یافته و با در نظر گرفتن آنها در بهبود کیفیت کالاها یا خدمات خود، در جهت رضایتمندی مشتریان خود گام بردارد. یکی از روش هایی که می تواند به این منظور مورد استفاده قرار گیرد، تکنیک QFD است که مبنای این مقاله است. در این مقاله برای جمع آوری خواسته های مسافران قطارهای ویژه شرکت رجاء از مصاحبه ساخت یافته و پرسشنامه، که روایی و پایایی آن سنجیده شده، استفاده شده است. پس از جمع آوری خواسته های مسافران، این خواسته ها در 7 دسته گروه بندی شده و سپس بر اساس درجه اهمیت و میزان رضایتمندی اختصاص یافته به هر یک از آنها از طرف مسافران، تعدادی از آنها برای بررسی و تحلیل انتخاب شده اند. برای تجزیه و تحلیل خواسته ها و الزامات مسافران و تعیین خدمات و الزامات عملیاتی مربوط به آنها از رویکرد 3 ماتریسی سازگار شده QFD استفاده شده و در نهایت الزامات عملیاتی مورد نیاز برای اجرای خدمات برآورده کننده خواسته های مسافر در داخل قطارهای شرکت استخراج و ارایه شده است.
    کلیدواژگان: بکارگیری کارکرد کیفی، qfd و قطار، صدای مشتری
  • داریوش دریایی، علی پیردوانی صفحه 91
    یکی از مهم ترین حرکاتی که در تقاطع ها صورت می گیرد، حرکت گردش به چپ است. هنگامی که حرکت گردش به چپ در یک فاز به صورت حفاظت نشده انجام می شود، احتمال برخورد و تصادف این حرکت ها با حرکت مستقیم رویکرد مخالف نیز افزایش می یابد. در این تحقیق برای رفتار حفاظت نشده، مطابق استاندارد HCM، تاخیر در حرکت گردش به چپ به صورت نمودارهایی با متغیرهای حجم گردش به چپ، حجم حرکات مستقیم رویکرد مخالف، تعداد خطوط حرکات مستقیم رویکرد مخالف، و نسبت زمان سبز موثر توسط تحلیل با نرم افزار Hicap رسم شده است. نمودارهای روند تغییر تاخیر به ازای تغییر حجم در هر یک از حالات گوناگون رسم شده است. از روی نمودارهای روند تغییر تاخیر، منحنی های هم تاخیر برای سه سطح سرویس D و E و F بر اساس حجم گردش به چپ و حجم حرکات مستقیم برخوردی برای شرایط مختلف رسم شدند. با مقایسه تاخیر در حجم های مختلف در شرایط رفتار حفاظت نشده و حفاظت شده، یک مرز پیشنهادی بین استفاده از این دو شرایط ارایه شد.
    کلیدواژگان: رفتار حفاظت نشده، تاخیر و حرکت گردش به چپ، تقاطع ها
  • چکیده انگلیسی
    صفحه 1
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  • A. Rahaiee, R. Mirghaderi, A. Hojjat Page 1
    Arch bridges have a desirable behavior under gravity loads. They transfer the gravity loads of the deck, through the axial performance of arches. But the performance of these bridges, under lateral forces requires special analysis. Seismic forces are known as the most important lateral forces in most of the engineering structures. In this study, the seismic performance of a steel arch bridge has been evaluated, using a finite element model. The "White Bridge" in Ahwaz, in south east of Iran is selected as the case study.In part 1, a general description of the paper is provided.In part 2, different performance levels from different bridge codes and specifications have been studied. Performance levels are different conditions that are expected to occur, after earthquakes of different return periods, for bridges of different levels of importance.Part 3 is a review on rehabilitation of the bridges. Bridge rehabilitation, contains three main steps of determining the bridges critical in need of repair, evaluating the structure and site conditions of the bridges and planning a procedure to perform the rehabilitation.In part 4, the case study has been introduced. Ahwaz “White Bridge” is a pass-through steel arch bridge which has been constructed on the Karoon River in Khuzestan, Iran in 1936. The bridge has two main arch spans with 130 and 136 meters length and is one of the largest and oldest engineering designed bridges in Iran. The steel arches, have I shape sections and the deck, is a composite slab which has been rehabilitated in 1999. Two ends of the arches are pinned to the supports and the abutments are huge concrete boxes, filled by rock fill.Part 5 describes the finite element model of the structure, which is generated by SAP2000 software to model the performance of the bridge under seismic forces. Arches, hangers and braces, have been modeled by "Beam" elements and the deck and abutments, has been modeled using "Shell" elements. Dead load, is applied to the shell elements of the deck and live load, is applied to the longitudinal beams of the deck, based on Iran "139-bridge loading code". Seismic analysis has been performed using the response spectrum method, based on the first 12 mode shapes of the bridge. Accelerations in the three longitudinal, transverse and vertical directions have been applied based on Iran Earthquake "Seismic design of bridge" specifications.In part 6, results of the response spectrum analysis have been studied. Regarding the modal analysis, first deformation mode shape of the structure is longitudinal with a period of 2.87 seconds. Response spectrum analysis in longitudinal direction results in allowable displacements and stresses in different parts of the bridge. In vertical direction, same results are obtained, but in transverse direction, displacements and stresses in some parts of the bridge, are greater than the allowable quantities. Especially at un-braced parts of the arches (traffic route), stresses may exceed the yield limit and plastic hinges may be formed. Evaluating the transverse behavior of the bridge requires a non-linear analysis. In this study inelastic static analysis, pushover method, has been utilized.Part 7 describes the pushover analysis procedure. To evaluate the behavior of the bridge under transverse horizontal loads, point loads of certain magnitudes are applied to deck nodes and stresses in different parts of the slab and steel structure is monitored. The quantities of the loads is increased step by step and in each step, elements having stresses larger than yield, buckling and fracture limits, have been omitted. This process has been repeated until the structure becomes globally instable. Instability occurs when applied load is greater than what is applied to the structure in transverse response spectrum analysis. So, the bridge may not become unstable after a design earthquake.In part 8, results of the response spectrum analysis, have been verified through comparison with a time history analysis, which had performed using Naghan earthquake accelerations, scaled for the site specific conditions. Nodal displacements in different parts of the structure in the three directions are almost equal for two response spectrum and time history methods. Regarding the results of different analysis methods which have performed, In part 9, seismic performance of the bridge has been compared with the performance levels of different codes and specifications. It can be seen that at the existing conditions, the bridge performance is not acceptable and probable damages would require fundamental and long time rehabilitation.Part 10 briefly demonstrates the strengthening method which is proposed to improve the seismic performance of the bridge to acceptable levels.The strengthening plan is concentrated on the non braced parts of the arches and this stresses that traffic area of the arch bridges is the most vulnerable part in an earthquake.
  • A. Shariat Mohaymany, A. Mansourkhaki, M. Babaei Page 15
    A transportation network, subject to some internal or external events, may be involved in performance degradation and traffic flow instability. The external events mainly include weather conditions and natural disasters like snowfall, ice, hurricane, earthquake and avalanche. Internal degradations are due to traffic related factors such as control systems failure, accidents, and maintenance and construction operations. All aforementioned circumstances can severely decrease links’ capacities, and some of them affect the base demand of the origin-destination pairs; hence, the network cannot perform as well as that in normal situation.When a transportation network or a number of its components (links) is vulnerable pertain to the foregoing incidents or disasters, its performance cannot be evaluated through the conventional methods in which we calculate deterministic measures such as average travel speed, average delay per vehicle and vehicle-kilometer traveled. In such situations the capacity of degraded links has not certain values, and they must be referred to as probability distribution functions; we therefore will face with a probabilistic network whose performance index ought to be assessed in reliability terms. Until now different types of performance reliability have been established to evaluate the reliability of degradable transportation networks. The first one is the connectivity reliability which considers the probability that a special origin-destination (OD) pair of the network remains connected. The other measure addressed frequently in previous studies is travel time reliability, which is defined as the probability that a trip performs successfully between a given OD pair within a specified time interval. Recently, another challenging measure has been introduced in order to estimate that at what level of a certain demand the network can perform accurately. This measure is known as capacity reliability and, in other words, is the probability that a network can accommodate a certain traffic demand at a required service level.This paper presents a heuristic method to calculate the connectivity (terminal) reliability and the capacity reliability. The capacity of each link is assumed to have a normal distribution function that is verified by a proposed method in order that a lower bound and an upper bound can be assigned to the function. Using these modified normal distribution functions the performance reliability of each link is obtained based on the integration of its probability density function from to: where is the traffic volume on link that is computed through the application of user equilibrium assignment with respect to the expected link capacities. and are respectively upper bound and probability density function of capacity of link. Notice the link performance reliability will be zero if the volume exceeds the upper bound of link capacity.Having calculated the links performance reliabilities, the capacity and connectivity reliability of the network are calculated by means of the closed formulas presented in this paper for each type of considered performance reliability measures. Another contribution of this paper is that the presented method has the ability of taking into account a required level of service for each link, namely it would be possible to assess the network performance when there exist especial expectations for maximum volume per capacity ratios (s). Therefore, it might be said that in the proposed method the travel time reliability is considered along with evaluating the two explained performance reliability measures because the travel time of each link is a function of its. Finally, for the sake of comparing the numerical results obtained from proposed method and from the other previous works, we have examined a simple test network employed repeatedly in network reliability analysis, particularly in the case of capacity reliability studies.
  • M. Saffarzadeh, B. Mirbaha Page 25
    In this research, a pattern for developing a regional ITS architecture has been presented for Iran. In presented pattern, the most important phase is specifying the transportation requirements of the region. These requirements define main objectives of developing the regional architecture. The operational concept and functional requirements of the system actually defines the communications between the real and virtual elements of the system. The gained plan in this stage describes the final system functions in smaller scales. The presented pattern which is designed dependent from technology is a satellite process which determines all the receivable services of this pattern. In this system the performing elements are interactive only with one center. The proposed process is executable in different rural areas, and its iterative function enables the designer to apply the suggested changes in accordance to regional transportation needs. Moreover, it has been tried to use the suggested pattern in the framework of a case study (Karaj – Chaloos), which by studying the preliminary steps in applying ITS in this road and considering the transportation problems in the area, The ITS architecture process has been proposed for this road.Generally, an ITS architecture should have the following characteristics:- Information compatibility, transmitted to the final users by means of various media,- Compatibility of equipment and facilities, with the infrastructures, and consequently accessibility to the integrated trips,- Developing a basis for comprehensive planning and presentation of strategies, for facilitating the ITS development,- Developing a market for provided services and facilities, compatible with ITS systems, and- Considering the economic aspects of the produced equipment, which finally will result in developing a competing environment in the market and reducing the prices of the equipment when the comprehension process is terminated.The main objective of advancing the regional – architectural ITS is execution and writing down the steps that should be taken for comprehension of ITS systems in the regional level.In this research, the extended preliminary studies determined the main structure of the plan for choice of operators and consequently the main ITS objectives were determined. The traffic management services are very important for implementation of all the proposed services in each region. In this very concern, the traffic management center is regarded as the heart of the system. Therefore, all the involved members and proposed system in the region can continue their performance by gaining compatibility with other elements of the system.
  • M. A. Goudarzi Khoygani, M.A. Rajaie, B. Baradaran Page 41
    Long span beams with heavy load require increasing the thickness of web and in many cases using a number of stiffeners needs to improve the lateral buckling difficulty. Development and application of corrugated steel web provides facilities to modify the web thickness of beam girders in the design and construction procedure. The attractiveness for using corrugated webs in bridges and composite sections has been increased in recent years. The new system combines the usage of either corrugated steel plates as webs or steel or reinforced/ prestressed concrete slabs as flanges.The application of corrugated steel web may reduce the thickness of webs and restricts it between 2 to 5mm while increases the portion of height/thickness of corrugated web girders in industrial structures up and about 260 and even for long span bridges up to 400.Manufacturers have produced different corrugated profiles such as sinusoid, trapezoid and other forms. The investigations show that the most significant weakness of application of the corrugated web beams is failure due to shear stress. The flanges are assumed to provide the flexural strength of the girder with no contribution from the corrugated web, which is assumed to provide the entire shear capacity of the girder. The corrugated web is thus, subjected to an “almost” pure shear stress state. Failure of a corrugated steel web plate may occur by the classical steel yielding of the web under a pure shear stress state. It may also occur by web buckling due to either local instability of any “panel” between two folds or overall instability of the web over two or more panels. An interactive failure mode between these different failure criteria represents another possibility of failure and so many researchers have considered global, local and semi global buckling in phenomena due to shear strength in their research work. In this paper nonlinear 3D Finite Element Model with regarding buckling modes phenomena for shear analysis of different profile shape of available manufacture corrugated webs is intended. The model is verified with published experimental results and sensitivity of the involved parameters is investigated. As presented in the following figure, the post-buckling strength of girders with corrugated steel webs could be investigated by this model. Figure 1: Typical nonlinear load-deflection curve for corrugated web beam under shear stress The geometric parameters that influence the shear resistance of trapezoidal corrugated web girders investigated in this study, involve:1) Corrugation angle 2) Width of the plane sub panel of the web 3) Web thickness 4) Height of the web 5) Corrugation depth of the web. The parameter study is developed for the sine corrugated web by focusing on amplitude of the central curve of the web and the wave length of the central curve of the web. Corrugated web shear capacity is changed by altering of the amplitude and wave length of the sinusoidal corrugated web. These changing manners are presented in the following figures respectively: Figure 2: Shear capacity versus sinusoidal web wave length Figure 3: Shear capacity versus sinusoidal web amplitude Results show, the sinusoidal webs have better performance than trapezoidal webs in the same conditions. The optimum size of trapezoid and sinusoid dimensions depends to the thickness of applied plate for producing the profile. Concerning to the manufacture restriction for production of profile, the study shows that the maximum shear strength will appear in the sinusoid profile for amplitude of 3 to 4 centimeter while in the trapezoid profile the equal dimension for flat and inclined part in the profile provides maximum shear strength.
  • S.M. Marandi, P. Safapour, M. H. Bagheripour, M. Ghasemi Page 57
    Intelligent methods for predicting some quantities are powerful tools for optimization of predicting models these days. The bitumen emulsion is able to easily mix with wet soil so that the bitumen may be easily distributed and scattered in the soil. The aggregates with PI<6 are quite suitable for stabilization of soils with bitumen emulsion. In this research, two aims are followed, one is Marshal Stability modeling for samples stabilized with emulsion bitumen and cement for roads sub-layers, and the other is cost optimization of using these binding materials in roads construction. 170 stabilized samples were made and tested for training the fuzzy neural network. The Marshal Stability of these samples were modeled by fuzzy neural network and also with using genetic algorithm, the roads execution costs were optimized. For modeling, the MATLAB software programming was used. The results showed that, with presented model, the construction costs decrease considerably.The overall conclusions of this research are summarized as follows:1. The fuzzy neural network presented, is able to determine the Marshall Stability of the samples stabilized by bitumen emulsion and cement with an accepted error %, and establishes a logical relation between the portions of used cement and emulsion.2.The fuzzy neural network model is a suitable tool for modeling and estimating the natural problems. 3.The genetic algorithm optimization model presented in this research is able to optimize the performance costs of soil stabilization by cement and bitumen emulsion, and consequently reduces total costs of road projects, considerably.4.The presented diagram for Marshall Stability – cement and emulsion content is able to specify the required cement and emulsion portions as compared to Marshall Stability.
  • M. Ameri, A. Mansourian Page 69
    Fatigue cracking is one of the major forms of distress that directly influences the service life and ride quality of pavements. The fatigue resistance of asphalt mix is defined as the ability of asphalt mix to withstand repeated bending without fracture. A traditional approach to dealing with cracking in asphalt pavements is based on the assumption that cracks initiate at the bottom of the asphalt layer due to tensile stresses developed from the flexure of the layer and propagate to the pavement surface under repeated load applications(bottom-up cracking). However, recent field studies suggest that fatigue cracks may also initiate at the pavement surface and propagate downward under traffic (top-down cracking).Several methods have been developed for the fatigue testing of asphalt mixes that repeated flexural beam, indirect tensile or direct tensile tests are usually used. Since determination of this characteristic is time consuming and it is difficult to measure, some predicting models have been developed. The results of these models are usually differ from each other because of material types, test methods and tests conditions. In general, there are two approaches to analyze and design against fatigue failure: conventional (traditional) approach, which bases on the analysis on the nominal (average) stresses in the region of the component being analyzed; and fracture mechanics approach, which specifically treats growing cracks using the method of fracture mechanics. In recent years other approaches such as viscoelasticity and continuum damage, has been considered. In this paper, based on traditional approach and by using indirect tensile test (for measuring the fatigue life and resilient modulus) a simplified model is developed for estimation of fatigue life of common asphalt mixes which are ordinary used in Iran. The loading pattern used in the indirect tensile fatigue test was a haversine load. The loading time was 0.1-second, and the rest period was 0.9-secend. The amplitude of the load for a specific tensile stress was kept constant during the test. The asphalt mix variables were bitumen content, bitumen type, air void content and aggregate gradation. For resilient modulus and fatigue tests, the Universal Testing Machine (UTM) was applied. The statistical analysis for each data set (resilient modulus and fatigue response) included the following sequences:- Test for correlation among the independent variables.- Analysis of variance (ANOVA) of full models (all main factors and two-factor interactions) to determine the sensitivity of resilient modulus and fatigue life to mix variables.- General Linear Modeling (GLM) to develop models for resilient modulus and fatigue life.- Summarizes of the effects of the experimental variables included in the experiment on resilient modulus and fatigue life based on the results of GLM.The experimental design used in this study was a fractional factorial which permitted the estimation of the main effects of experimental factors and all the two-factor interactions. On the basis of the statistical analysis the following equation was obtained: R2=0.800 Where:Stress = tensile stress (KPa)Mr = resilient modulusVFB = voids filled with bitumenFigure 1 shows the fatigue life for specimens resulting from proposed model and indirect tensile fatigue test. As shown in this figure, the predicted values and observed values(results of fatigue tests) are near to each other.Verification of the proposed model indicates that it can be used to estimate fatigue life of asphalt mixes as a function of their void filled with asphalt, resilient modulus and the tensile stress. The proposed model was compared with Shell model and Asphalt Institute model. For predicting the stiffness of asphalt mixes in Shell model, equations developed by bonnaure et al. were used and for predicting the dynamic modulus of asphalt mixes in Asphalt institute model the equations developed by Hwang and Witczak were used. The results of proposed model are usually between results of Shell model and Asphalt Institute model.
  • M. Poureseyed Aghaiee, J. Mahmoudi, M. Zolghadri Page 83
    In this era one of the specifications of a successful, innovative and effective organization is to get familiar to its customer's requirements to use this information for improving the quality of the goods and services. This specifications may help the mentioned organization to take steps toward customer's content. One of the effective instruments applied for this purpose is a technique called QFD which forms the base of this study.To acquire information about requirements of passengers in trains with specific facilities, organized interviews and questionnaires were use in this research, which their constancy were evaluated and approved. The information about the travelers requirements were then sorted and organized. The next step was to analyze the requirements according to their priority and based on their significance as well as the quality of content in the view of customers who, in this paper, are passengers. The paper applied to three matrix models matched QFD to analyze the passenger's requirements. The paper, in conclusion, introduces the operational methods needed for providing services which is required to satisfy passengers who use trains with special facilities. IntroductionQuality function deployment (QFD) is "an overall concept that provides a means of translating costumer requirements in to the appropriate operation requirements for each stage of service deployment".Three approaches of quality function deployment to improve the quality of product/service are: the 4-matrix model or the 30-matrix model or 3-matrix model The 4 and 30 matrix models use in the product industries and the third one using the service industries.Steps of the completion of house of quality in 3-matrix modelThis model has many steps to follow, all of which are interconnected to from the house of quality matrices. The HOQ matrix whose name drivers from its house-like appearance is a combination of sub-matrices used increase customer satisfaction by developing services exactly demanded by customers. The sections constituting the HOQ matrix are namely:1- Customer needs and requirements (voice of customer) 2- Service specification 3-relationship matrix 4- Planning matrix 5-correlation matrix 6- Benchmarks 7- weights & targets.Application of 3-matrix model of QFD in train and its conclusion For using QFD in special trains, first, passenger requirement have been collected. For this aim personal and structural interview with 23 person of special trains has been done and with conclusion of this interview and received complains from passengers, a questionnaire has been designed for evaluating the importance of the passenger requirements and satisfaction of the passengers by likert scales and the reliability and validation of the questionnaire has been checked and the number of reliability that calculated from the coefficient Kronbakh was 0.987. Whereas the number of the requirements of the experimental QFD project must be between 20 and 30 and with this notification that the amount of collected requirement from passenger was 58, so the 23 requirements with priority has been collected.The 3-matrix model of QFD has been used for this project. In first matrix, requirements of the passengers in the brain storming meeting has been translated to service specifications then after filling the sections of the services planning matrix, in the second matrix services specifications with priority has been translated to key process operation and finally in the third matrix each of collected key process operation from the second matrix, has been translated to operation requirement.
  • D. Daryaee, A. Pirdavani Page 91
    According to the HCM standards of signalized intersections, when there is a permitted phase, delay of left-turns will grow with increasing of through-turn volume of the opposing approach. In many countries, among them Iran, left-turn movement will not look for an acceptance gap and cuts into the through movement of opposing approach in a later time according to standards. Left-turn movements cause increasing the delay of through-turn movements of opposing approach. This fact will occur in a permitted condition, when volumes of left and through-turn movements prosper a certain limit. To determine these boundaries of left-turn movements and through-turn movements of the opposing approach, we should do the sensitivity analysis of “left-turn movement delay” against increasing of volumes of left-turn movements and through-turn movements of the opposing approach.According to accident statistics of many countries, %45 of accidents, at intersections, pertains to left-turn maneuvers. Most accidents occurr when left-turn movements are done in a permitted condition. Statistics indicate that %85 of these accidents will reduce, if permitted left-turn movements changed into protected left-turn movements.In addition, existence of permitted left-turn movements will increase the intersection delay. This paper presents relation between left-turn movements and volume of through-turn movements of opposing approach considering various numbers of opposing approach lanes and effective green time ratio (g/C).In this research, delay of left-turn movements is drawn in different charts with variables like left-turn movement volumes, effective green time ratio and opposing approach through-turn movement volumes and number of lanes, as a result of analysis with HICAP Software, for permitted condition. Also same-delay curves are drawn for three LOS es (D, E, F), according to volumes in different conditions. In comparison to delays, based on different volumes in permitted and protected conditions, we will present a proposed boundary that shows us when to use, which of these conditions.