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rahmatii

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تمامی مطالب نوشته شده توسط rahmatii

  1. rahmatii
    روش MPS برای مقیاس کردن شتابنگاشت ها 3.pdf
  2. rahmatii
    آرام سازی ترافیک با بهره گیری از باریک سازی سطح سواره رو NCRRAF03_063_4309968.pdf
  3. rahmatii
    اثرات ریلی کارکردی سامانه ریلی حمل ونقل عمومی بر اقتصاد،محیط زیست واجتماع RTC09_017_4309988.pdf
  4. rahmatii
    نمونه سوالات امتحانی سازه های بتن آرمه پیشرفته دانشگاه آزاد بروجرد
  5. rahmatii
    Comparison of chevron and suspended-zipper braced steel frames Yigit Ozcelik a, Afsin Saritas b,⁎, Patricia M. Clayton a a Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, TX 78712, USA b Department of Civil Engineering, Middle East Technical University, Ankara 06800, Turkey a r t i c l e i n f o a b s t r a c t Article history: Received 22 June 2015 Received in revised form 14 November 2015 Accepted 8 December 2015 Available online xxxx a b s t r a c t Suspended-zipper braced frame is a modified configuration of chevron braced frame inwhich zipper columns are added between story beams and a hat truss is attached between top two stories in order to redistribute the unbalanced vertical forces emerging following the brace buckling to avoid the use of deep beams. In this study, three- and nine-story chevron and suspended-zipper braced frames are analyzed to compare their seismic performances. The beams, columns, braces and zipper columns are modeled using nonlinear force-formulation frame elements and nonlinear geometric effects are included by utilizing corotational transformation. Nonlinear static analyses are performed until reaching a roof drift ratio of 3% and a set of twenty ground motion records scaled to match a 10% probability of exceedance in 50 years is used for nonlinear time-history analysis. The results appear to indicate that the lateral load capacity and drift demands for both low-rise chevron and suspendedzipper braced frames are very similar; however, the mid-rise chevron braced frame has a better performance compared to the mid-rise suspended-zipper braced frame. © 2015 Elsevier Ltd. All rights reserved. Keywords: Steel structures Concentrically braced frames Chevron braced frames Suspended-zipper braced frames Nonlinear static analysis Nonlinear time-history analysis 10.1016_j.jcsr.2015.12.019-Comparison-of-chevron-and-suspended-zipper-braced-steel-frames.pdf
  6. rahmatii
    Analysis of structures convertible to repeated structures using graph products I. Shojaei a,d, A. Kaveh b,⇑, H. Rahami a,c a Engineering Optimization Research Group, College of Engineering, University of Tehran, Iran b Centre of Excellence for Fundamental Studies in Structural Engineering, Iran University of Science and Technology, Tehran, Iran c School of Engineering Science, College of Engineering, University of Tehran, Iran d School of Civil Engineering, College of Engineering, University of Tehran, Iran a b s t r a c t In this paper an efficient method is presented for the analysis of those structures which can be converted to regular forms. The stiffness matrix for such regular structures can easily be inverted using their eigenvalues and eigenvectors. Many non-regular structures can be converted to regular forms. Here the presented method solves not only all the regular forms but also non-regular forms convertible to regular ones. The efficiency of the method is more significant when it is used in reanalyzing and rehabilitating structures where the stiffness matrix should be inverted a r t i c l e i n f o Article history: Received 24 November 2012 Accepted 20 April 2013 Available online 31 May 2013 Keywords: Regular structure Irregular structure Stiffness matrix Graph product Eigenvalues and eigenvectors Reanalysis 10.1016_J.COMPSTRUC.2013.04.018-Analysis-of-structures-convertible-to-repeated-structures-using-graph-products.pdf
  7. rahmatii
    GIS-based system for sight distance analysis of highways María Castro a*, José A. Anta b, Luis Iglesias c, José A. Sánchez d Abstract Analysing the distance visible to a driver on a highway is important for traffic safety, especially in manoeuvres such as emergency stops, when passing another vehicle, or when vehicles cross at intersections. Software that calculates highway distances visible to a driver has been developed. This software is supported by a Geographic Information System (GIS) and can use a trajectory defined by points obtained with a GNSS receiver instead of relying on project information. The software includes specific tools for studying shortcomings in 3D alignment, mainly divings. In this article, the software and its application to a case study are presented. The results are compared with those obtained using an existing validated procedure Keywords: Highways and roads; Design; Sight distances; Geographic information systems; Terrain models. 10.1061-(ASCE)CP.1943-5487.0000317 (1).pdf
  8. rahmatii
    Scoping prediction of re-radiated ground-borne noise and vibration near high speed rail lines with variable soils D.P. Connolly a,n, G. Kouroussis b, P.K. Woodward a, A. Giannopoulos c, O. Verlinden b, M.C. Forde c a Heriot-Watt University, Institute for Infrastructure & Environment, Edinburgh, UK b Department of Theoretical Mechanics, Dynamics and Vibrations, University of Mons, 31 Boulevard Dolez, B-7000 Mons, Belgium c University of Edinburgh, Institute for Infrastructure and Environment, School of Engineering, AGB Building, The Kings Buildings, Edinburgh, UK a b s t r a c t This paper outlines a vibration prediction tool, ScopeRail, capable of predicting in-door noise and vibration, within structures in close proximity to high speed railway lines. The tool is designed to rapidly predict vibration levels over large track distances, while using historical soil information to increase accuracy. Model results are compared to an alternative, commonly used, scoping model and it is found that ScopeRail offers higher accuracy predictions. This increased accuracy can potentially reduce the cost of vibration environmental impact assessments for new high speed rail lines To develop the tool, a three-dimensional finite element model is first outlined capable of simulating vibration generation and propagation from high speed rail lines. A vast array of model permutations are computed to assess the effect of each input parameter on absolute ground vibration levels. These relations are analysed using a machine learning approach, resulting in a model that can instantly predict ground vibration levels in the presence of different train speeds and soil profiles. Then a collection of empirical factors are coupled with the model to allow for the prediction of structural vibration and indoor noise in buildings located near high speed lines. Additional factors are also used to enable the prediction of vibrations in the presence of abatement measures (e.g. ballast mats and floating slab tracks) and additional excitation mechanisms (e.g. wheelflats and switches/crossings). & 2014 Elsevier Ltd. All rights reserved. Keywords: ScopeRail High speed rail vibration Environmental impact assessment (EIA) Initial vibration assessment Structural vibration In-door noise Scoping assessment High speed train Urban railway 10.1016-j.soildyn.2014.06.021.pdf
  9. rahmatii
    Quasi-Static Analysis of Geotextile Reinforced Unpaved Road Resting on c- Subgrade Shivraj Meenaa, Lokesh Choudharyb, Arindam Deyb,1 aDepartment of Civil Engineering, KIIT University, Bhubaneshwar, Orissa, India bDepartment of Civil Engineering, IIT Guwahati, Assam-781039, India Abstract This article provides an e stimate of the aggregate thickness required for unpaved roads resting on c- soil. Conventional practice of design of unpaved roads mostly considers the subgrade layer to be purely cohesive such as in soft marshy lands However, a huge bulk of Indian sub-urban and rural unpaved roads rest on c- soil subgrade soil whose strength characteristics are contributed both by cohesion © and angle of internal friction ( ). It is imperative that if cohesion is considered as the sole strength criterion, it will provide lower bearing resistance, and hence, will overestimate the aggregate thickness required, which will eventually lead to undesirable increase in the overall project cost. In this regard, this article reports the result of an attempt made to identify the diminution in the required aggregate thickness of the unpaved road when both the strength characteristics of the subgrade soil are taken into account. Utility of a single geotextile layer beneath the aggregate has also been investigated towards further reduction of the required aggregate thickness. Incorporating bearing capacity estimation of the c- soil, necessary expressions have been developed for estimating the required aggregate thickness as a function of the axle load, tire inflation pressure, cohesion and angle of internal friction of subgrade soil, angle of internal friction and load distribution angle of the aggregate. Extended ranges of the aforementioned parameters, as suitable in Indian context, have been considered and the effect of the same, in the absence and presence of geotextiles, has been reported Efficacy of the geotextiles has been elucidated in terms of the degree of improvement represented as reduction of aggregate thickness. Encouraging improvement up to the level of 70% has been observed in many instances. © 2013 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of International Scientific Committee . Keywords: Unpaved roads;Geotextile reinforcement;; Aggregate thickness; Quasi-static analysis 10.1016-j.sbspro.2013.11.116.pdf
  10. rahmatii
    Are totally recycled hot mix asphalts a sustainable alternative for road paving Hugo M.R.D. Silva a,∗, Joel R.M. Oliveiraa, Carlos M.G. Jesusb a C-TAC, Department of Civil Engineering, University of Minho, 4800-058 Guimarães, Portugal b Department of Civil Engineering, University of Minho, 4800-058 Guimarães, Portugal a b s t r a c t The recycling of reclaimed asphalt pavement (RAP) helps road authorities to achieve their goal of a sustainable road transport system by reducing waste production and resources consumption. The environmental and economic benefits of using RAP in hot mix asphalt (HMA) applications could be pushed up to the limit, by producing totally recycled HMAs (100% RAP), but the performance of this alternative must be satisfactory. In fact, these mixtures could possibly present problems of workability and durability higher binder aging and low fatigue cracking resistance. Thus, the objective of this study is to determine if totally recycled HMA mixtures could be a good solution for road paving, by evaluating the merit of some rejuvenator agents (commercial product; used engine oil) in improving the aged binders’ properties and the recycled mixture performance. Several binder samples were prepared with the mentioned rejuvenators and characterized (Pen, R&B and dynamic viscosity), in order to select the best rejuvenator contents. The production temperatures of the corresponding recycled mixtures were evaluated based on their workability. Totally recycled HMAs were produced with the best previously observed combinations and their performance (water sensitivity, rutting resistance, stiffness, fatigue resistance, binder aging was assessed. The main conclusion of this study is that totally recycled HMAs can be a good alternative for road paving, especially if rejuvenator agents are used to reduce their production temperature and to improve their performance. © 2011 Elsevier B.V. All rights reserved. Keywords: Total recycling Reclaimed asphalt pavement (RAP) Rejuvenators Binder properties Asphalt performance 10.1016-j.resconrec.2011.11.013.pdf
  11. rahmatii
    Load Testing and Model Updating of a Single Span Composite Steel-Concrete Railway Bridge Darius Bacinskasa,*, Zenonas Kamaitisa, Donatas Jatulisa, Arturas Kilikeviciusb aDepartment of Bridges and Special Structures, Vilnius Gediminas Technical University, Sauletekio ave. 11, LT-10223 Vilnius, Lithuania bDepartment of Machine Building, Vilnius Gediminas Technical University, J. Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania Abstract Actual static and dynamic response of a newly constructed composite steel-concrete railway bridge with a single span of 32 m is investigated. The m ain objective of this investigation was to increase knowledge on the actual behavior of new innovative structure using field load testing and numerical simulation. Static and dynamic loads were applied by using two heavy locomotives 2M62 with the total load of 2328 kN. Five dynamic tests were conducted at speeds varying from 20 to 100 km/h. The outcomes of the static tests were maximum displacements of the bridge deck and that of dynamic tests were vibration characteristics, and in particular modal parameters such as vibration mode shapes, frequencies, damping ratios as well as dynamic amplification factors. Results of these investigations are presented in this paper . © 2013 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of the Vilnius Gediminas Technical University. . Keywords: railway bridge; composite steel-concrete deck; partial-depth precast deck units; static and dynamic field load testing; FE modeling. 10.1016-j.proeng.2013.04.019.pdf
  12. rahmatii
    Study of road bases construction in Saudi Arabia using foam asphalt Hamad I. Al-Abdul Wahhab a,⇑, Mirza G. Baig a, Isam A. Mahmoud b, Hisham M. Kattan c a Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia bDammam Municipality, Dammam, Saudi Arabia c Roads and Heavy Equipment Department, Saudi Aramco, Dhahran, Saudi Arabia a b s t r a c t This paper summarizes the research carried out to compare the performance of foamed asphalt pavement mixes with conventional crushed aggregate for the construction of road bases. The research work focused on the investigation and evaluation of the feasible use of foamed asphalt technology for Saudi roads using marginal quality construction materials, marl, and reclaimed asphalt pavement (RAP) materials for local applications. Materials included the Ministry of Transport (MOT) granular base class A and B, subbase material class B, and reclaimed asphalt pavement (RAP) material. Foamed asphalt mixes were designed for subbase class B (foamed SB) and RAP (foamed RAP) material utilizing low percentage of Portland cement. Foamed asphalt mixes were optimized to meet dry and wet indirect tensile strength (ITS) requirements. Designed mixes in addition to granular base class A and B were evaluated for CBR, dynamic resilient modulus at 25 C and wheel tracking test dry at 50 C and soaked at 22 C. Results indicate that base class A has the lowest rutting followed by base class B then foamed SB and finally foamed RAP for dry condition at 50 C, while foamed RAP has the lowest rutting followed by foamed SB then base class B and finally class A for soaked condition at 22 C. Portland cement was effective in reducing ITS loss of foamed asphalt mixes. Resilient modulus testing indicated that SB mix has behavior comparable to base class A. Foamed RAP mix has shown the best behavior. Saturation has reduced resilient modulus of all mixes significantly. Foamed asphalt technology can be used successfully to construct road bases from locally available marginal or recycled materials. 2011 Elsevier Ltd. All rights reserved. Keywords: Foamed asphalt Recycling Stabilization Granular base Subbase 10.1016-j.conbuildmat.2011.05.010.pdf
  13. rahmatii
    Pavement temperature influence on close proximity tire/road noise M. Bueno ⇑, J. Luong, U. Viñuela, F. Terán, S.E. Paje Laboratory of Acoustics Applied to Civil Engineering (LA2IC), Universidad de Castilla-La Mancha (UCLM), Avda. Camilo José Cela s/n, 13071 Ciudad Real, Spain a b s t r a c t The aim of this work is to analyze the influence of the surface temperature on the acoustical behaviour of a semidense asphalt pavement located in an urban area. The sound levels emitted by the interaction between a reference tire and the asphalt pavement at different surface temperatures were measured with the trailer Tiresonic Mk4 LA2IC-UCLM rolling at a speed of 50 km/h. The analysis of the results shows that increasing pavement temperature leads to a reduction in the close proximity sound levels assessed at a rate of 0.06 dB(A)/C. Moreover, spectral analysis confirms that both the mechanisms associated with vibration and impacts and those related to the friction and adhesion between tire and pavement in the contact patch could be affected by the variation of the surface temperature. 2011 Elsevier Ltd. All rights reserved. Keywords: Road traffic noise Asphalt pavement Temperature Close proximity Acoustic characterization 10.1016-j.apacoust.2011.05.005.pdf
  14. rahmatii
    The effect of traffic tickets on road traffic crashes Roni Factor∗School of Criminology, University of Haifa, Mt. Carmel, Haifa 31905, Israela b s t r a c t: Road traffic crashes are globally a leading cause of death. The current study tests the effect of traffic ticketsissued to drivers on subsequent crashes, using a unique dataset that overcomes some shortcomings ofprevious studies. The study takes advantage of a national longitudinal dataset at the individual level thatmerges Israeli census data with data on traffic tickets issued by the police and official data on involvementin road traffic crashes over seven years. The results show that the estimated probability of involvementin a subsequent fatal or severe crash was more than eleven times higher for drivers with six traffic ticketsper year compared to those with one ticket per year, while controlling for various confounders. However,the majority of fatal and severe crashes involved the larger population of drivers who received up to oneticket on average per year. The current findings indicate that reducing traffic violations may contributesignificantly to crash and injury reduction. In addition, mass random enforcement programs may be moreeffective in reducing fatal and severe crashes than targeting high-risk recidivist drivers.© 2013 Elsevier Ltd. All rights reserved Keywords:Road traffic accidentsTraffic violationsHigh-risk behaviorsSocioeconomic statusDistance traveledEnforcementa. 10.1016-j.aap.2013.11.010.pdf
  15. rahmatii
    Introducing a modified gradient vector method for optimization of accident prediction non-linear functions Shahriar Afandizadeh, Mahmud Ameri, Mohammad Hassan Mirabi Moghaddam ⇑ Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran a b s t r a c t In this paper, a new optimization method has been proposed for accident prediction nonlinear models. This has been achieved by eliminating the Hessian matrix from the equation of optimal pace length in the gradient vector method. One advantage is that it is independent of the starting point in optimization processes and it provides convergence at the highest top as well. This method has been tested on an accident prediction model and its preference over the gradient vector method has been proven. 2011 Elsevier Inc. All rights reserved. Keywords: Accident prediction model Optimization Gradient vector Convergence Optimal pace length Hessian matrix 1-s2.0-S0307904X11002137-main.pdf
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    Prediction of ground vibrations generated by a falling-weight pavement breaker Mohammad Amin LAK, Stijn FRANC¸OIS, Geert DEGRANDE, Geert LOMBAERT Department of Civil Engineering, KU Leuven Kasteelpark Arenberg 40, B-3001 Leuven - Belgium email: amin.lak@bwk.kuleuven.be Abstract— Pavement breaking generates a high level of ground vibration that is potentially damaging to nearby buildings and infrastructures. In this paper, a numerical model for the estimation of the impact load due the blow of a falling-weight pavement breaker is first developed. The estimated impact load is in good agreement with the experimental result. Next, the fracturing of the concrete road is investigated and the amount of dissipated energy is found to be only a small fraction of the impact energy. The large part of the impact energy is transferred to the soil and causes ground vibrations. Finally, a non-linear road-soil interaction model is developed and numerically verified. The model accounts for both road-soil separation as well as the inelastic behaviour of the soil. The model is used to predict ground vibrations generated by the operation of a multi-head pavement breaker. Up to 25m from the road, the predicted ground vibrations agree with the experimental results while at large distances the model underestimates the response . Keywords—pavement breaking, ground vibration, fallingweight impact, non-linear road-soil interaction 1_Lak.pdf
  17. rahmatii
    Potential Energy Savings by Reducing Rolling Resistance of Dutch Road Pavements Berthe van Haaster1; Ernst Worrell2; Jan Paul F. Fortuin3; and Willem-Jan van Vliet4 Abstract: The current study focuses on options to improve vehicle energy efficiency by reducing rolling resistance on Dutch national highways. Different studies of pavement materials have been evaluated, and models have been compared to experimental data to review rolling resistance indicators. The study shows that texture parameters MPD (mean profile depth) and RMS (root mean square) are relevant indicators for rolling resistance, whereas the effect of road roughness (IRI) is found to be larger than indicated in the evaluated models. The effects of other wavelength regions, texture orientation, and road wear need further investigation. The rolling resistance assessment shows that single-layer porous asphalt concrete (PAC) with aggregate size 6=16 (which is most currently used on Dutch highways) has rolling resistance levels that are 8–10% higher than the levels of double-layer porous asphalt concrete (DPAC) with aggregate size 2=6. Switching to DPAC 2/6 for highways would result in energy savings of 2–2.5%. These calculations are based on estimations and results with high uncertainty and should therefore be taken as a rough estimate of the potential energy savings. Further research is recommended to further refine and validate the results of this study. DOI: 10.1061/(ASCE)MT.1943-5533.0000999. © 2014 American Society of Civil Engineers . Author keywords: Rolling resistance coefficient; Dense asphalt concrete; Porous asphalt concrete; Road wear; Road texture; Fuel consumption. elearnica.ir-Potential_Energy_Savings_by_Reducing_Rolling_Resistance_of_Dutch_Road_Pavem.pdf
  18. rahmatii
    PERFORMANCE OF WARM ASPHALT MIXTURE MODIFIED BY THE NEW ADDITIVE XU Zhoucong, LIU Liping, LI Di and JIANG Zilong Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji University, 4800 Cao’an Rd., Shanghai, 201804, China; email: xuzhoucong@163.com Abstract: Warm mix asphalt (WMA) has been increasingly applied in pavement project due to its environmentally friendly and low-carbon. Therefore, more and more WMA additives appeared on the market. In order to validate the new domestic warm mix additive’s pavement performance, in this paper, the new additive (A or made in China is added to the mixture (AC-13, AC-20), and the mixture’s pavement performance is tested. The test results show that, the mixing and compaction temperature of mixture could be decreased by 30~40℃ if additive A or B is used, it achieves the effect of energy saving and emission reduction. And the mixture’s performance indicators meet the requirement in current specification. In addition, compared with the corresponding HMA, the low temperature performance and fatigue performance of WMA containing additive A or B are improved Key Word: highway engineering, WMA mixture, the new additives, pavement performance, fatigue performance elearnica.ir-Performance_of_Warm_Asphalt_Mixture_Modified_by_New_Additives.pdf
  19. rahmatii
    مقایسه حمل و نقل ریلی مترو با مونوریل فایل پاورپوینت مترو و منویل.ppt
  20. rahmatii

    در مورد فروم جدید ؟!

    rahmatii پاسخی برای alen18 ارسال کرد در موضوع : انتقادات و پیشنهادات

    باسلام وادب خدمت استاد عزیز جناب آقای مهندس جعفری وهمکاران محترم ایرانسازه در ادامه نقل قول مهندسین گرانقدر،دراین فروم از همکاری و نشاط علمی (برخلاف فروم قبلی ایرانسازه) خبری نیست .در رگ وخونش زندگی جریان ندارد،خیلی سرد وبی روح و حتی قابل تحسیین و مقایسه نیست،چون در فروم قبلی محیط خیلی دلچسب و پیگیری مباحث بسیار سریع ومفید ودوستانه صورت میگرفت انگار همه اعضاء یک خانواده بودند.و همین که صفحه اصلی نمایش داده میشد لذت میبردی وبا اشتیاق از همه مباحث سایت اطلاع پیدا میکردی.حقیقتش آدم بغض میکنه وقتی ایرانسازه رو به این شکل دور از روزهای ناب خودش میبینه؟!!!!!!! در نهایت ضمن تشکر از شکیبایی مدیر محترم،اگر امکان تجدید نظر وجود دارد، برگشت به فروم قبلی را مورداولولیت وعنایت ویژه قرار دهند. ما بی صبرانه منتظریم تا رنگ ولعاب فروم قدیم ایرانسازه را دوباره در جلوی چشمانمان نظاره گر باشیم. با آرزوی موفقیت برای همه عزیزان
  21. rahmatii
    با سلام درسقف کامپوزیت معمولاٌ بعلت کم نمودن سربار، تیرهای اصلی در دهانه های کوتاهتر قرار می گیرند،از این روتیرهای فرعی عمود بر آنها(تیرهای اصلی) ودر جهت بلندتر قرا خواهند گرفت. البته اگرسقف بصورت شطرنجی اجرا گردد این امر نقض میگردد وتیرهای فرعی در دهانه های کوتاه و بزرگ قرار میگیرند.
  22. rahmatii
    Investigation and Prediction Model for the Dynamic Modulus of Asphalt Emulsion Cold Recycled Mixtures Jinhai Yan, Ph.D.1; Zhixiang Zhang, Ph.D.2; Stephane Charmot, Ph.D.3; Wuyang Ding4; and Feng Li5 Abstract: The stiffness characteristics of four types of asphalt emulsion cold recycled mixtures (AECRMs) were evaluated using the simple performance test (SPT). Factors influencing the dynamic modulus and the applicability of theWitczak model were investigated. Based on the time-temperature superposition principle, the dynamic modulus jEj master curves of recycled mixtures were constructed using nonlinearleast squares regression techniques. Statistical significance on the basis of one-way analysis of variance was evaluated as a function of cement aggregate gradation, frequency, temperature, and confining pressure. The Witczak model is suitable for AECRMs and cement-treated AECRMs, and its prediction accuracy was improved by modifying the original Witczak model. The accuracy of the predicted models was evaluated on the basis of the statistical analysis. The one-way analysis of variance results indicated that the constructed master curves were consistent with the experimental test data. Frequency and temperature significantly affected the dynamic modulus, while confining pressure was not significant. Cement and aggregate gradation had a significant effect on the dynamic modulus at high temperatures or at low frequencies, while the effect was not significant at low temperatures or at high frequencies. Furthermore, the results of the statistical analysis showed that the modified and the original Witczak models resulted in a satisfactory fit between the predicted jEj results and the laboratory measured jEj data. The modified Witczak model was more accurate than the original model for AECRM. DOI: 10.1061/(ASCE)MT.1943- 5533.0001048. © 2014 American Society of Civil Engineers. Author keywords: Asphalt emulsion; Cold recycling; Dynamic modulus; Time-temperature superposition principle; Master curve; Witczak model; Mixture stiffness. elearnica.ir-Investigation_and_Prediction_Model_for_the_Dynamic_Modulus_of_Asphalt_Emuls.pdf
  23. rahmatii
    EVALUATION OF STONE MATRIX ASPHALT (SMA) For AIRFIELD PAVEMENTS (BOOK فایل لاتین صفحات 28-23 کتاب عنوان شده، همرا با ترجمه آن (موضوع:ارزیابی مصالح سنگی آسفالت (SMA) جهت آسفالت فرودگاه (کف سازی فرودگاه)) RAHMATI.rar
  24. rahmatii
    Design and seismic response of modified suspended zipper braced frames Haifeng Yu ⁎, Yaran Guo, Yan Zhang, Xin Wang Hebei University of Science and Technology, Shijiazhuang 050018, China a b s t r a c t In a conventional suspended zipper braced frame (SZBF), the required strength of zipper columns and top story braces increases rapidly with the number of stories, resulting in unacceptable cross sections for these members. To overcome these drawbacks, a new modified suspended zipper braced frame (RZBF) is proposed in this paper. Compared with SZBF, the two central ideas of RZBF are that the unbalanced vertical forces at each story do not reach the maximum values simultaneously, and that the braced beams can transfer part of the unbalanced vertical forces during earthquakes. In order to understand better the seismic performance and design advantages of RZBF, nonlinear time history analyses were conducted on 3, 6, 10, 15, and 18-story RZBF and SZBF models. Comparison of the results obtained demonstrates the efficiency and viability of RZBF. Moreover, it is shown that the RZBF saves more steel material as the number of stories increases. © 2015 Elsevier Ltd. All rights reserved. Keywords: Braced frame Seismic design Zipper column Nonlinear time history analysis Seismic performance 10.1016_j.jcsr.2015.12.025-Design-and-seismic-response-of-modified-suspended-zipper-braced-frames.pdf
  25. rahmatii
    Validated finite element techniques for quasi-static cyclic response analyses of braced frames at sub-member scales M. Lotfollahi a,1, M.M. Alinia a,2, E. Taciroglu b,⇑,2 a Department of Civil Engineering, Amirkabir University of Technology, Tehran, Iran b Department of Civil and Environmental Engineering, University of California, Los Angeles, CA 90095, USA a b s t r a c t In this study, a numerically robust finite element procedure is described, which is based on explicit time-stepping, for high-fidelity simulations of inelastic and post-buckling cyclic responses of braced frame systems. The use of an explicit time-stepping method with properly chosen increments permits accurate results while avoiding (implicit) equilibrium iterations throughout the entire loading history, during which multiple yielding and buckling events occur. A number of essential techniques for properly calibrating the discrete models and to constrain their responses in order to obtain quasi-static outcomes are provided. The procedure is globally and locally validated (verified) using experimental data (implicit numerical simulations) from three types of specimens—namely, individual braces, and single and multi-story braced frame systems with diagonal and X-brace arrangements—under both monotonic and cyclic loading protocols. Results from these validation and verification studies indicate that the proposed simulation methodology can accurately capture sub-member (i.e., plastic hinges), member, and system behavior very accurately; and thus, it can be confidently used—e.g., as a virtual laboratory—to predict the responses of braced frames with configurations and dimensions other than those tested, and to seek optimum designs beyond those offered by basic guidelines. 2015 Elsevier Ltd. All rights reserved. Keywords: Finite element verification and validation Dynamic explicit analysis Static implicit analysis Quasi-static solution Buckling Braced frame systems Cyclic loading [Hidden Content] gh.part1.rar gh.part2.rar

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