J. Georgi

The further environmental development of Polyphyto Hydroelectric Project reservoir in Kozani prefecture and its contribution to the life quality improvement

The Polyphyto Hydroelectric Project was constructed in 1974 and it has been operating since on the Aliakmonas River, Kozani prefecture, by the Greek Public Power Corporation. The construction of the Ilarion Hydroelectric Project, upstream from the Polyphyto Reservoir, has been recently completed and will start operating in the near future. Apart from hydroelectric power production, the Polyphyto reservoir provides flood control to the areas below the Polyphyto dam. It is also used to manage water provision to the city of Thessaloniki and adjacent agricultural plain, providing at the same time cooling water to the Thermo Electric Projects in Ptolemaida. The Polyphyto reservoir has potential for further development as an economic fulcrum to the region in which is located. The Kozani and Servia–Velvendos Municipalities have proceeded to the construction of several touristic, nautical – athletic and fishing projects. In order to promote such developments, while preserving the artificial wetland, flora and fauna of the Polyphyto Reservoir, it is important to reduce the fluctuation of the reservoir elevation which according to its technical characteristics is 21m. The aim of this paper is to propose the combined operation of the two Hydroelectric Project reservoirs to satisfy all the present Polyphyto Hydroelectric Project functions and to reduce the annual fluctuation of the Polyphyto Reservoir. The HEC-5, Version 8 / 1998 computer model was used in our calculations, as developed by the Hydrologic Engineering Center (HEC) of the US Army Corps of Engineers for reservoir operation simulation. Five possible operation scenarios are tested in this paper to show that the present fluctuation of the Polyphyto Reservoir can be reduced, with some limitations, except during dry weather periods.

Unmanned aerial vehicle (UAV) application to the structural health assessment of large civil engineering structures

This paper summarizes the experience gained in the structural assessment of an existing Thermal Power Plant (TPP) located near Pristina, focusing on the cooling tower and the flue gas stack, which are the main structures of the TPP. Scope of the work was the evaluation of the actual conditions of the structures and to identify the eventual repair measures in order to guarantee a safe and reliable operation of the TPP in view of the extension of its operational lifetime for the next 30 years. With this aim, a sequence of different activities was performed, like: a topographic survey to compare the actual geometrical configuration with the design one, an investigation of the material properties, an in depth visual inspection in order to detect any visible existing damage. Due to the very high elevations of the constructions and to the lack of appropriate structures aimed to their inspections and maintenance, this activity could not be performed without using Unmanned Aerial Vehicle (UAV). This resulted the safest, most economical and less time-consuming solution identified to map the surface damage in the reinforced concrete elements of these large structures including zones that could not be inspected because out of reach by other means.

Management and protection of peri-urban forests of three towns in Greece

The satisfaction of continuous leisure demand in suburban forest requires a proper management of space so as on the one hand to provide better services to visitors and on the other hand to protect against excessive and improper use by guests. In the present study we investigated and analyzed the current situation of the suburban forests of Drama, Limni and Elassona and proposed the appropriate future management. The views of residents are reflected in primary research using a questionnaire (personal interview). The results focus, regardless of the region, to the multiple roles played by suburban forests for urban and suburban areas. The integration of suburban forests and especially of all the urban green as key elements of spatial planning and urban reconstruction of large and small urban centers, are the means that will create favorable conditions for future upgrading of suburban forests in order to sufficiently accomplish a modern triple role; productive, ecological and social.

SEISMIC RETROFIT OF INDUSTRIAL SILOS BY MEANS OF BASE ISOLATION DEVICES

Abstract. Silos are industrial facilities used for storing a huge range of different materials. In the last decades, many silos were damaged by natural events, among which the seismic events are the most significant. Indeed many plants are located in territories in which seismic risk is not negligible. Furthermore, most of these plants have been designed, and built before the latest updates of the seismic design codes took place, and most of them are prone to earthquakes. In this study, seismic behaviour of an existing industrial steel silo system in Italy has been investigated, and a retrofit solution has been proposed making use of seismic isolation technology. Curved surface single sliding pendulums have been designed as a base isolation retrofitting solution. Incremental dynamic analysis method has been used in order to evaluate the seismic performance of both the non-isolated and isolated cases. Structural benefits of the seismic isolation retrofitting solution has been quantified in terms of inelastic deformations, base shear, floor drifts, isolator displacements, and residual drifts, and comparisons between the original and retofitted solutions are presented. The impact of vertical ground accelerations on the global behaivour of seismic isolated silos has been highlighted, which showed that a fully elastic superstructure behaviour can be achieved only when the vertical component of earthquake is not significant. Uplift has been investigated and stated as a limiting parameter for the design of seismically isolated silos. The study has been realized thanks to EU-RFCS research fund for PROINDUSTRY project [1].