بناءً على ما جاء في نتائج برنامج البحث الاستراتيجي للطرق Strategic Highway Research Program (SHRP) والذي تم في امريكا 1994 وهو إعادة النظر في و دراسة كل ما كان يجري من عمليات في تصميم وإنشاء الطرق والذي كان من أهم نتائجه إلغاء التصنيف السابق للمادة الرابطة الإسفلتية والمعتمد على درجة الغرز(Penetration Grades) ودرجة اللزوجة (Viscosity Grades) وأستبدل بتصنيف جديد يعتمد على درجة أداء (Performance Grades) (PG) المادة الرابطة الإسفلتية أثناء الخدمة وعلى الظروف المناخية بالحقل حيث يتم تحديد المادة الرابطة الإسفلتية المناسبة لإنشاء طريق بأي موقع بناءً على درجة حرارة الرصف القصوى والدنيا والتي يتم الحصول عليها بالقياس المباشر أو باستخدام معادلة رياضية تحسب درجة حرارة الرصف بالاعتماد على كل من ( درجة حرارة الهواء و دائرة العرض محل المشروع) لموقع الطريق يأتي هذا البحث للرصد المباشر لكل من ( درجة حرارة الرصف ودرجة حرارة الهواء وكمية الإشعاع الشمسي ) من خلال تنفيذ محطة رصد لهذا الغرض بشمال غرب ليبيا ضمن برنامج شامل يغطي جميع اقاليم ليبيا المختلفة وذلك للحصول على درجة الرصف القصوى والدنيا بموقع المحطة وقد انتج الباحث عدد من النماذج الرياضية ( معادلات ) تمثل العلاقة بين درجة حرارة الرصف وكل من درجة حرارة الهواء وكمية الإشعاع الشمسي وإنتخاب أفضل هذه النماذج لتكون نماذج محلية يمكن إستخدامها لتوقع درجة حرارة الرصف بجميع مناطق شمال غرب ليبيا ومقارنة النماذج المحلية بالنماذج المستخدمة بنظام الرصف الممتاز (Superpave) ونموذج برنامج (LTPP) وهو إختصار ل ((Long Term Pavement Performance فكانت النتيجة إنَّ النماذج المنتجه بهذه الدراسة أكثر ملائمة لتقدير درجة حرارة الرصف بشمال غرب ليبيا من النموذجين المذكورين وبالإعتماد على درجة حرارة الرصف القصوى والدنيا المتحصل عليها بالرصد المباشر بمحطة الرصد تم تحديد المادة الرابطة الإسفلتية المناسب استخدامها بالطرق بموقع المحطة وبشمال غرب ليبيا وفقاً لنظام الأداء (Performance Grades) . Abstract According to the results of the strategic highway research program in the U.S.A. (SHRP) Known as Superpave System ,that has been introduced in the nineties of last century The previous methods that still used for mix design and selection of binder use in our country proved to be not suitable and replaced with modern methods that depends on the performance of the binder according to the climate of the area According to the new procedure the selection of the binder depends on the maximum and minimum pavement temperature. The required pavement temperature could be measured actually or estimated by using a special mathematical model. Considering that asphalt pavements in Libya suffers from many distresses, much of them related to the environmental factors .Hence it was necessary to investigate the applicability of the models developed for this method to Libya’s environmental conditions and more generally to the hot arid climate. This research is part of a Comprehensive study aims to develop models to predict high and low Flexible pavement temperatures in Libya. A pavement monitoring station was set-up at the North West of Libya to monitor air, pavement temperatures and solar radiation. The temperatures were recorded at different points through the pavement depth. Collected data were analyzed to develop the low and high temperature models by using air temperature and solar radiation as independent variables. The developed models were compared with the SHRP and LTPP models. The Local models were found to be more suitable than the SHRP and LTPP models for predicting pavement temperatures in the Northern west part of Libya.
أحمد حسن المختار (2008)

Abstract Behavior of constant thickness circular plates under axisymmetric uniform loading and for different edge boundary conditions may be obtained analytically, but for the case of variable thickness and transverse shear effect is usually difficult to follow analytically. Since the numerical analysis has become an essential tool in engineering mechanics, where the use of numerical methods enables the engineer to expand his or her ability to solve practical design problems, where the engineer may now treat real shapes as distinct from the somewhat limited variety of shapes amenable to simple analytic solution. That is why developing an appropriate numerical analysis becomes a more suited procedure to solve such problems. The standard stiffness procedure of finite element method may encounter some difficulty in formulation when dealing with both cases of variable thickness and transverse shear effect. The usually followed procedure is to utilize ring elements of constant thickness and increase the number of elements to reach an accurate solution. Mixed finite element formulation utilizing curved ring element with linearly varying thickness as well as considering the shear effect has proved to be successful to obtain accurate results for shells of revolution with small number of elements, due to the fact that the mixed formulation allows for nodal values in the form of global displacement components (ur, uz) and bending moment (Mr, M) as field variables, where second order polynomials may be used allowing for shear deformation effect to be considered as a function of moments and does not require higher order polynomials.
ايناس عبدالمولي المصراتي (2009)

Building and infrastructure damages, such as tunnels, have become a more important issue because of the continuous expansion of rural and urban constructions. It is well-known that when high-strength concretes (HSCs) are exposed to high temperatures; it is more likely to experience explosive fire-induced spalling than conventional strength concrete. Spalling might result in catastrophic loss of life and damage to nearby critical infrastructure. The exposure of reinforcement bars to elevated temperature, decreased permeability, higher density, moisture transfer, and brittleness of the HSC contribute to spalling. The concrete on a structural member's surface may be violently ripped apart by a high and fast rising temperature during a fire. Despite being a non-combustible material, the physics-chemo-mechanical properties of concrete deteriorate when subject to high temperatures. The magnitude and duration of a fire in a concrete structure define the severity of the fire. The resistance to fire spalling of HSCs under different fire conditions, extremes, and tendencies must be explored urgently. Cementitious materials exhibited a positive impact as an alternative to cement in HSC because they are known as environmentally friendly concrete materials with superior fire-resistant properties. In addition, the inclusion of fibers as an additive reinforcement is adopted to prevent and mitigate fire spalling in HSCs. Therefore, the establishment of appropriate fire-safety measures is a fundamental requirement in building design to ensure the safety of its inhabitants. While the process of fire spalling for HSC during a fire has not yet been completely understood. For this reason, a critical literature study on recent developments in HSC fire-resistance performance should be conducted to determine the present fire spalling behavior of HSC in the event of high temperatures and/or a fire. This article systematically reviews the mechanisms, influential factors, and types of fire spalling. This literature also reviews the behavior, fire spalling modelling, and strategies to prevent spalling in HSC applications. Given the advantages of the research subject, several hotspot research topics for scientific investigations are also suggested to facilitate the widespread use of HSCs in advanced construction applications.
Hakim S. Abdelgader (5-2022)