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In this research, an analytical model is presented to study the shear behavior of prestressed hollow core slabs. The study is conducted with respect to the shear considering a concentrated line load (in absence of concrete topping and filling of cores) using finite elements method adopted by the computer program ANSYS. The finite element models are developed using a smeared cracking approach for the concrete and three-dimensional link elements for the prestressing strands. The ANSYS finite element analysis results are compared with the experimental data of two prestressed hollow core slabs. The comparisons are made for load-deflection curves, failure load and crack pattern. The accuracy of the finite element models is assessed by comparison with the experimental results, which are to be in good agreement.

In this study, effects of mineral admixtures on the water permeability and compressive strength of concretes containing silica fume (SF) and fly ash (FA), super pozz (SP) were experimentally investigated. Permeability of concrete was determined through DIN 1048 (Part 5). The research variables included cement type, ordinary Portland cement (OPC) or high slag cement (HSC), and mineral admixtures content were used as a partial cement replacement. They were incorporated into concrete at the levels of 5%, 10%, and15% for silica fume and 10%, 20%, 30% for fly ash, or super pozz by weight of cement. Water-cement ratio of 0.40 was used and tests were carried out at 28 days. From the tests, the lowest measured water permeability was for the 10% super pozz and 10% silica fume or 20% fly ash mixes. Although the highest compressive strengths of concretes determined was 10% silica fume mix for ordinary Portland cement and were reduced as the increase in the replacement ratios for other mineral admixtures than ordinary Portland cement concrete. The main objective of this research was to study the water permeability and compressive strength of concrete containing silica fume, fly ash, and super pozz and high slag cement to achieve the best concrete mixture have lowest permeability. The results were compared to the control concrete ordinary Portland cement concrete without admixtures. The optimum cement replacement by FA, SP and SF in this experiment is 10%SP. The knowledge on the strength and permeability of concrete containing silica fume and fly ash, super pozz and high slag cement could be beneficial on the utilization of these waste materials in concrete work, especially on the topic of durability.

The phenomenon of the punching failure of reinforced concrete slabs and the effect of the pre-stressing on the failure mechanism has been investigated in this paper. This paper deals with the behavior of pre-stressed concrete slabs, subjected to symmetrically static loading. A numerical model based on the finite element method using the computer program "ANSYS" (version 11).Sixteen pre-stressed flat slabs and one conventional flat slab has been analyzed. All the slabs represent an interior slab-column connection. The slabs have dimensions 900x900x80 mm, with interior square column 132x132 mm. The main objective of this research is to study the effect of pre-stressing force and its distribution along the crosssection of slab on the punching failure.

The theme of camouflage and concealment of the most important topics in terms of military strategy, military and field work have brought the importance of the fact that this science has a significant impact on the conduct of hostilities and the scale of profit and loss on the subject of military balance between States.