Estimating the Reliability (Probability of Failure) of Reinforced Concrete (RC) structures in marine environments has been of major concern among researchers in recent years. While General (uniform) corrosion affects the reinforcement by causing a uniform loss of its cross-sectional area, Pitting (localized) corrosion concentrates over small areas of the reinforcement. Many studies have focused on the effect of general corrosion, the effect of pitting corrosion on the structure reliability has not been fully investigated. Furthermore, due to the variability associated with the parameters involved in the reliability estimation of the corroded structure, this paper focuses on the effect of variability of pitting corrosion on the structure reliability. The analysis also takes into consideration the Spatial Variability (SV) of key deterioration parameters often neglected in previous studies. The authors have used their experimental data in modeling SV parameters of a specific deterioration parameter. The analysis adopted here used Monte Carlo (MC) simulation technique to construct a Spatial-Time Dependent model to estimate the girder reliability. The results showed that pitting corrosion potentially has a far more aggressive effect on the structure reliability than general corrosion and that pitting corrosion affects shear resistance far more severely than it would affect flexure resistance. The analysis showed that after 50 years of service, the reduction in the beam reliability due to pitting corrosion was 51% higher than that caused by general corrosion and that considering SV has caused the reliability predicted in terms of pitting corrosion to decrease by 12%. In the case of general corrosion, the decrease in beam reliability was only about 2% for the SV scenario.
Omran Kenshel, Mohamed Sulieman (12-2021)

Multi-layered Prepacked aggregate fibrous composite (MLPAFC) is a new type of concrete, which is prepared in two subsequent stages of aggregate-fibre skeleton prepacking and cementitious grouting. In this study, ten MLPAFC mixtures were prepared in three subsequent layers incorporating different contents of four different types of steel fibres. Long and short hooked-end and crimped steel fibers were adopted with 3.0 and 1.5% dosages for the outer and interior layers, respectively. In-between the three MLPAFC layers, two layers of Glass Fiber Mesh (GFM) were inserted in five of the ten mixtures. The impact response of the MLPAFC mixtures was evaluated using two test methods. In the first, the ACI 544-2R repeated free-falling weight test was followed using disk specimens, while flexural free-falling weight on prism specimens was the second adopted impact test. Moreover, Weibull distribution was used to statistically analyse the discrepancies of the obtained experimental impact records. The impact tests results revealed that MLPAFC can absorb significantly high energy under falling weight impact due to its structure and the dual crack arresting activity of both steel fibers and GFM. The cracking number of impacts of MLPAFC cylindrical specimens without GFM was increased by approximately 530–870% compared reference specimens, while increment percentages reaching 1350% were recorded at failure stage. The impact resistance of MLPAFC prisms under flexural impact was noticeably improved, yet with lower percentages than cylindrical specimens. The insertion of intermediate GFMs let to additional developments in the impact strength of both cylindrical and prism specimens. arabic 14 English 97
Hakim S. Abdelgader (12-2020)

تتضمن هذه الورقة دراسة عن الجسور وتوظيف برنامج نظم المعلومات الجغرافية GIS لأرشفة معلومات عن هذه الجسور، فمن خلال البحث عن معلومات عن الجسور لدي مؤسسات الدولة المعنية بجسور داخل مدينة طرابلس تبين عدم وجود أي بيانات، مما تطلب حصر معظم الجسور داخل مدينة طرابلس وجمع المعلومات العامة والمتمثلة في ( الاسم، الاحداثيات، الطول، العرض، ومنطقة ربط الجسر) لعدد 51 جسر، وتم عمل دراسة تفصيلية عن ثلاث جسور واجراء فحص بصري ظاهري وجمع البيانات عن حالتها ووظائف عناصرها اذا كانت تشتغل بالشكل المطلوب وما بها من عيوب ام بصحة جيدة وبعد جمع بيانات الفحص البصري وتقييم حالة الجسور تم وضع هذه البيانات في بطاقات وربط كل البيانات التي تم جمعها في برنامج نظم المعلومات الجغرافية لأرشفتها الكترونيا ليسهل الوصول اليها في أي وقت من قبل المهتمين للحصول علي معلومات عن الجسور داخل مدينة طرابلس بطريقة سهلة وميسورة وفي اسرع وقت وتكون خطوة للاستغناء عن الارشفة الورقية. arabic 135 English 3
هيفاء علي رجب ابوحليقة(3-2020)