دسته: سمینار و کارگاه

­مدل­سازی ساختاری و عددی رفتار ویسکوالاستیک-ویسکوپلاستیک در بتن آسفالتی و جایگاه آن در عملکرد روسازی های آسفالتی

Constitutive and Numerical Modeling of Viscoelastic-Viscoplastic Behavior of Asphalt Concrete

دکتر محمد محمد کریمی، دانشکده مهندسی عمران، دانشگاه تربیت مدرس

چهارشنبه 26 شهریور 1399، ساعت 13:30 تا 15:00

لینک ورود:

https://vclass.ecourse.sharif.edu/ch/civil-seminar

نحوه ورود: مجانی و بدون نیاز به پسورد، بر روی گزینه “میهمان” کلیک و نام خود را  وارد کنید.

Bio

Mohammad M. Karimi is Assistant Professor of Road and Transportation in the Department of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran. He received his B.Sc. degree in Civil Engineering from Iran University of Science Technology, and M.Sc. and Ph.D. degrees in pavement engineering, both from Sharif University of Technology (Supervisor: Prof. Nader Tabatabaee). Mohammad’s interests lie in the field of thermodynamic-based constitutive relationships, numerical implementation, and computational modeling of pavement materials and structures. Moreover, his research studies are often accompanied by experimental tests to identify the rheological and mechanical characteristics of pavement materials and to validate the numerical simulations. During his M.Sc., Ph.D., and the visiting researcher at University of Kansas, he has developed several kinds of research in the field of computational modeling of asphalt pavement, incorporating viscoelastic, viscoplastic-hardening relaxation, continuum damage, and coupled thermo-electromagnetic constitutive relationships. In recent years, he has been working on smart pavement materials, innovative methods of asphalt healing, and sustainable asphalt concrete and pavement structure using experimental evaluation and computational modeling.

Abstract

The pavement engineers always look for precise and cost-efficient methods to predict the long-term performance of asphalt concrete and pavement structure under the traffic loading and environmental conditions. A comprehensive numerical simulation leads to a precise analysis of pavement materials and structures while taking lower costs compared to accelerated pavement testing machines and test tracks. Given the intricate thermo-mechanical behavior of asphalt concrete, developing an appropriate constitutive relationship becomes the most imperative phase in the computational modeling of asphalt concrete and pavement. Computational scientists often derive constitutive relationships according to the thermodynamic laws and phenomena observed in experimental tests. In this webinar, several findings on the derivation of constitutive relationship, numerical implementation, computational modeling of asphalt concrete and pavement, and relevant experimental tests and field measurement will be presented. A non-linear viscoelastic constitutive relationship was developed to address the different stress transferring mechanisms in asphalt concrete under tensile and compressive stress modes. A viscoelastic-viscoplastic-continuum damage constitutive model was coupled with a hardening relaxation model to simulate the viscoplastic strain and hardening-softening in asphalt concrete under the cyclic loading. Then, a large strain-based viscoelastic-viscoplastic constitutive relationship carried out to predict the compaction process of asphalt concrete in the field will be discussed. As the last case, a coupled-thermo-mechanical-electromagnetic constitutive relationship to compute the temperature rising and crack healing through induction heating-induced healing in asphalt concrete under the electromagnetic field will be covered.

توسعه مشخصات طرح اختلاط عملکردی آسفالت برای بزرگراه عوارضی ایلی نوی

DEVELOPMENT OF A PERFORMANCE-RELATED ASPHALT MIX DESIGN SPECIFICATION FOR THE ILLINOIS TOLLWAY

مهندس بهنام جهانگیری، کاندیدای دکترا در مهندسی عمران در روسازی و تکنولوژی آسفالت، دانشگاه میزوری، آمریکا

سه شنبه 11 شهریور 1399، ساعت 15:00 تا 16:30

لینک ورود:

https://vclass.ecourse.sharif.edu/ch/civil-seminar

نحوه ورود: مجانی و بدون نیاز به پسورد، بر روی گزینه “میهمان” کلیک و نام خود را  وارد کنید.

Bio:

Behnam Jahangiri is a PhD candidate in the Department of Civil and Environmental Engineering at the University of Missouri-Columbia (MU, Advisor: Bill Buttlar). He also holds an MSc degree in Pavement Engineering from Sharif University of Technology (Advisor: Nader Tabatabaee), and a BSc degree in Civil Engineering from Isfahan University of Technology. As a Graduate Research Assistant at Missouri Asphalt Pavement and Innovation Lab (MAPIL), he has been working on cutting-edge research areas related to smart infrastructure systems and innovative construction materials to address real-world concerns in the asphalt industry. Currently, his research is focused on the development of performance specifications for the Illinois Tollway.  He is also involved in the characterization of a wide variety of modern and heterogeneous asphalt mixtures containing recycled materials RAP, RAS, rubber, and waste plastic for the Missouri Department of Transportation and for industry. Finally, he conducts research in advanced machine learning/artificial intelligence methods for material characterization, and deployment of sensors for civil infrastructure condition assessment.

Abstract:

In the past, traditional asphalt mixtures involved relatively simple combinations of virgin asphalt binder and aggregates to meet performance requirements. However, modern, heterogeneous asphalt mixtures exhibit more complex behavior due to proliferation of new ingredients and because of the interactions that subsequently occur. As a result, recent asphalt mixes require advanced performance tests to account for the effects of the added components, increased traffic loads, and prevailing environmental conditions. In this presentation, different mixtures produced in 2018 for the mainline and shoulder sections across Tollway system in Chicago were selected to characterize trends of the performance tests conducted on the new Tollway mixtures and to study the ability of different performance tests to predict pavement performance. To this end, performance tests were performed on the collected plant produced mixtures, and later, on selected field-cored sections. The latter included both good and poor performing sections, which were determined based on an extensive survey of the Illinois Tollway in May of 2019. Evaluation of Tollway asphalt surface pavement management data indicated excellent overall performance vs. time, with minor amounts of several cracking forms developing gradually over time. These included transverse cracking, usually associated with reflective cracking on the mainline and/or thermal and block cracking on shoulders, and longitudinal cracking (typically along the construction joint between lanes). Rutting, on the other hand, was not observed to be a significant form of distress on modern Tollway sections. The Disk-shaped Compact Tension (DC(T)) test was chosen to be retained in the performance related specification (PRS) for the design of crack-resistant mixtures because of its excellent repeatability and its high correlation with field results. A systematic approach was developed, which allowed different reliability levels to be addressed in the specification, along with a consensus step to take advantage of the experience of local practitioner.

آزمایش های عملکردی پس از تولید مخلوط آسفالتی در انتاریوی کانادا  

مهندس سید محمد طبیب، مهندس ارشد بخش قیر و مواد قیری در  MTO

چهارشنبه 5 شهریور 1399، ساعت 13:30 تا 15:00 

لینک ورود:

https://vclass.ecourse.sharif.edu/ch/civil-seminar

نحوه ورود: مجانی و بدون نیاز به پسورد – بر روی گزینه “میهمان” کلیک کنید و نام خود را  وارد کنید.

Bio:

Seyed Mohammad Tabib, M..Sc., P.Eng. is a senior bituminous engineer with the Bituminous Section of the MTO. He completed a M.Sc. degree in 1996 from Sharif University of Technology in Transportation Engineering , majored in asphalt technology, and another M.Sc. in 2001 in Traffic Engineering from U of T. Seyed has a broad range of background experience in materials engineering and research, pavement, geotechnical, and traffic engineering in Ontario and overseas. He joined MTO in 2003 and has provided effective support to regional and head office programs ever since. 

Seyed is a licensed engineer with the Professional Engineers Ontario (PEO). He has authored and co-authored several research papers in asphalt technology, pavement, and traffic engineering.

Abstract:

The Ministry of Transportation of Ontario (MTO) uses a PG plus specification to mitigate premature pavement cracking. Due to complex nature of the various asphalt mixture components and binder additives, testing the tank asphalt cement (AC) alone may not be sufficient and there is a need for testing post-production products for acceptance.

The MTO is evaluating various asphalt mix performance tests with the goal to establish acceptance criteria for post-production asphalt mix that relates to long term pavement performance (i.e., to achieve a balance between resistance to cracking and rutting). Loose asphalt mix and pavement cores were collected and tested from various paving contracts using the following tests:

• Flexibility Index Test (FIT)

• Disk-Shaped Compact Tension (DC(T)) test

• Hamburg Wheel Tracking (HWT) test

Work to date has revealed that, in general, these tests were able to differentiate asphalt mixes based on PGAC, asphalt mix type, and presence of RAP.

MTO has also evaluated cores taken from good and poor performing pavements 5-13 years old using FIT and DC(T) tests and obtained reasonable results. Both recovered AC grading and mix performance tests are considered effective tools in evaluating pavement performance.

This presentation will provide an overview of the test procedure, results, and preliminary threshold values for acceptance of post-production asphalt mixes.