Prediction of the present and future state of Reinforced Concrete (RC) structures suffering from chloride-induced corrosion is important if proper planning for inspection and maintenance is to be made. The majority of research studies have thus far focused on the diffusion process of chloride ions through the concrete cover, the time to corrosion initiation and on the prediction of the surface condition of the structure. However; practical evidence and theoretical analysis suggests that many structures can tolerate considerable corrosion damage without serious reduction to their load carrying capacity. Therefore, visual impression-based maintenance is not an optimum solution particularly when financial resources are limited. To support this notion, accurate models are needed to predict the deterioration rate of the structural load carrying capacity over time. This paper uses existing empirical RC deterioration models to predict the loss in the load carrying capacity of a typical RC T-beam using a reliability based approach. The approach takes into consideration the spatial variability of the deterioration parameters, thereby demonstrating the importance of its inclusion in any such analysis. arabic 13 English 97
Omran Kenshel(1-2009)

Abstract In this study, seepage phenomena through the foundation of Megenin dam are investigated. Most of the recorded dam’s failure around the world are related to seepage problems. Therefore to avoid failure of earth dams due to seepage, settlement, and piping, continuous field observations are essential. The Megenin dam is a 38 m high rock fill dam. A concrete cut-off wall and grout curtain were constructed below the dam body to prevent reservoir seepage through the foundation.The dam was constructed in 1972, for two main purposes; first to control floods for the cultivated fields downstream and to protect Tripoli city, secondly to collect water for irrigation. On 15thMay 2003 during the 3rd filling, the water level in the reservoir reached 271.86 m, while seepage water was observed in the wadi bed downstream of the main dam. This phenomena were also observed in previous times. The Piezometric water level was much higher compared to that previously measured. To assess the seepage phenomena and the impact on dam safety, the folowing were applied: the technique of ground penetrating radar survey (GPR), piezometric analysis, and temperature field evaluation. Constructed a flow net model for the dam.The results of the study showed that: GPR profiles describe critical zones in the dam site. Identify the water seepage paths from dam reservoir to down stream of dam.Determine the amount of total water seepage capacity through the dam foundation (Q= 0.08 Ɩ / s ).The essential points to avoid any problem that may occur in the future in Megenin dam due to seepage problems.
ناجي محمد شكشم (2009)

This research aims to experimentally evaluate the behaviour of multi-layered fibrous cementitious composites with intermediate Glass Fibre Meshes (GFM) under repeated projectile load. The impact load was subjected through a convex edge projectile needle at a low velocity on cylindrical specimens of three-layered fibrous cementitious composites, which have two different steel fibre distributions. In series A mixtures, a constant steel fibre dosage of 2.5% by volume was used. On the other hand, the fibre dosage of the outer layers was 3.0%; while it was 1.5% in the middle layer of series B mixtures. The number of intermediate GFM was the variable that distinguishes the mixtures of each series. The resistance to projectile impacts was evaluated on the basis of penetration depth, near surface distortion, weight loss, damage ratio and failure pattern. The test results showed that due to the combined effect of steel fibre and GFM, significantly lower weight losses were recorded for series A and B specimens compared with reference specimens. However, the different fibre distributions (series B) led to lower penetration depths and weight losses with less surface distortion compared with the fixed fibre distribution (series A). The reduction in the destroyed front surface area of series A specimens compared with reference specimens ranged from 27.8 to 38.1%; while that of series B specimens ranged from 34.8 to 53.4%. In addition, a simplified analytical model was introduced to predict the ejected composite mass. The model predictions were found to be in good agreement with the experimental masses. arabic 9 English 71
Hakim S. Abdelgader (1-2021)