In reinforced concrete design, the concrete in the tensile zone is assumed to be ineffective and increase the dead load of the structural elements. In order to reduce the self-weight, this paper examines the structural behavior of reinforced concrete beams containing lightweight concrete in the tensile region and normal weight concrete in the rest of the beam. The lightweight concrete was made from waste polystyrene. Four reinforced concrete beams were prepared with different depth of lightweight concrete. The control beam B1 consists of normal concrete. In Beams B2, B3 and B4, the depth of lightweight concrete was 25%, 50% and 75% of the total depth of the beam measured from the bottom surface respectively. A four-point bending test was conducted on all beams. The beams were loaded in increments until failure. At each load increment, the central deflection was determined. Cracks initiation and the mode of failure were observed during the experiment. The failure load was found to decreases with the increase of depth of lightweight concrete. The presence of lightweight aggregate tends to cause brittle failure. In addition, the mode of failure for reinforced concrete beams containing lightweight concrete was a shear failure. arabic 11 English 79
Hakim S. Abdelgader(6-2020)

Abstract Determination of the in-situ engineering properties of subsurface ground materials has always been a challenge for geotechnical engineers. Several in –situ test methods have been developed. Dynamic cone penetration test (DCPT) is one of the in-situ penetration tests which have been widely used to determine the geotechnical parameters of soil. The dynamic cone penetration test (DCPT) is a quick and easy to set up and run onsite. Due to the economy and simplicity of the test, better understanding of correlations between its results and the geotechnical parameters of soil can reduce significantly the efforts and cost to evaluate the engineering properties of ground materials. In this research, a light weight simple DCP device was used for evaluation of some engineering properties of Tripoli sand. The device consisted of an 8kg hammer that drops over a height of 575 mm and drives a 60o cone tip with 20 mm base diameter into the ground. The intention of this investigation is to obtain sufficient data to establish appropriate and reliable correlations among soil parameters and DCPT results. In order to investigate the effect of fine material content on the correlations between the geotechnical parameters and the penetration index (PI) of the DCPT of Tripoli sand, soil samples of different fine material content have been prepared and tested. This research presents the results of the laboratory tests as well as the analysis and discussion of these results. Based on the analysis of test results, the relationships between the DCPT results (penetration index, PI) and the geotechnical parameters of Tripoli sand such as relative density and CBR value are obtained. In this study penetration index of the dynamic cone penetration test from the laboratory prepared samples were correlated with laboratory CBR,s for a number of different soil types. Unique models were found for each type of soil with good coefficient of determination (R2). The combined data gave also a correlation between CBR and penetration index PI which compare very well with those obtained from other studies. There is no clear correlation between the penetration index and both the dry density (gr/cm3) and relative density, with wide scatter and a low coefficient of determination (R2) value.
نورالدين سالم الكثاري (2011)

The number of deteriorating bridges due to chloride-induced corrosion increases annually as does the cost of inspection, maintenance, repair and where necessary replacement. Meanwhile, budgets made available to bridge owners/managers for repair and maintenance of these bridges are reducing. To optimise and manage their budget spend, bridge owners/mangers need to rely more on rational decision making methods rather than on subjective engineering judgment. In this thesis, the author has developed a probabilistic- based model which aims to predict the lifetime performance of Reinforced Concrete (RC) structures exposed to chloride corrosive environment and consequently to optimise their lifetime management.
Omran Kenshel(11-2009)