23 research outputs found
Ronald Reagan a wyzwania epoki
Z wprowadzenia: "艢mier膰 Ronalda Reagana w czerwcu 2004 r. zamkn臋艂a znacz膮c膮 epok臋 w dziejach
Europy i 艣wiata. Reagan symbolizowa艂 pokolenie polityk贸w, kt贸rym przysz艂o dzia艂a膰
w czasach szybkiej dekompozycji dw贸ch, wydawa艂oby si臋 niepodwa偶alnych pewnik贸w
politycznych dominuj膮cych po drugiej wojnie 艣wiatowej w 艣wiecie zachodnim.
Z polityk贸w tych by艂 tym, kt贸ry przyczyni艂 si臋 w olbrzymiej mierze do podwa偶enia
obu z nich."(...
Bending tests on lighting poles made of glass fiber reinforced polymer composites
Celem artyku艂u jest przybli偶enie tematyki s艂up贸w kompozytowych polimerowych wzmocnionych w艂贸knem szklanym, a tak偶e zaprezentowanie materia艂贸w sk艂adowych kompozytu i wybranej technologii produkcji s艂up贸w o艣wietleniowych. S艂upy te coraz cz臋艣ciej zast臋puj膮 s艂upy wykonane z tradycyjnych materia艂贸w, takich jak stal oraz beton. W artykule przedstawiono wyniki bada艅 wytrzyma艂o艣ciowych kompozytowych s艂up贸w o艣wietleniowych o wysoko艣ci L = 12,0 m. Podczas badania na zginanie o艣wietleniowe s艂upy kompozytowe przej臋艂y bezpiecznie minimalne obci膮偶enia graniczne w klasie A dla eksploatacji s艂up贸w ze wspornikiem jednostronnym i dwustronnym. Stwierdzono, 偶e s艂upy ze wzgl臋du na ugi臋cie mo偶na zaliczy膰 do 3 klasy wed艂ug normy PN-EN 40-3-3:2013-06.The aim of this paper is to introduce the subject of glass fiber reinforced polymer composite poles, to present the composite component materials and the chosen technology for the production of lighting poles. These poles are increasingly replacing poles made of traditional materials such as steel and concrete. This paper presents the results of strength tests of composite lighting poles with height L = 12.0 m. During the bending test, the composite lighting poles safely took the minimum limit loads in class A for the operation of the poles with single-sided and double-sided booms. It was found that the columns due to deflection can be classified as class 3 according to PN-EN 40-3-3:2013-06
Use of passive safety supporting structures
Road safety issues have been raised for many years in subsequent national and EU documents. An example of a Polish document is the National Road Safety Program for 2013-2020 [1]. The priorities and measures adopted in the document [1] relate mainly to the environment and road furnishings making up the so-called passive road safety. In accordance with PN-EN 12767: 2008 [2], road lighting columns, as well as supporting structures for vertical road marking and traffic safety devices should be constructed in such a way that they do not pose a threat to road users in case of unforeseen situations ending up in a collision. Three categories of passive safety of support structures depending on the level of energy absorption during vehicle impact can be distinguished: high energy absorbing (HE), low energy absorbing (LE) and non-energy absorbing (NE) energy. The article presents an overview of solutions of several countries (USA, Norway, Sweden, Finland, Great Britain, Slovakia and Poland) in the use of support structures that minimize the impact of a collision. Particular attention was paid to the fact that due to the potential risk of secondary injuries sustained by other road users (pedestrians and cyclists) in relation to a specific installation site and designated speed limit, constructions in the HE or NE absorption class or even Class 0 constructions should be used
Variation in Compressive Strength of Concrete aross Thickness of Placed Layer
Is the variation in the compressive strength of concrete across the thickness of horizontally cast elements negligibly small or rather needs to be taken into account at the design stage? There are conflicting answers to this question. In order to determine if the compressive strength of concrete varies across the thickness of horizontally cast elements, ultrasonic tests and destructive tests were carried out on core samples taken from a 350 mm thick slab made of class C25/30 concrete. Special point-contact probes were used to measure the time taken for the longitudinal ultrasonic wave to pass through the tested sample. The correlation between the velocity of the longitudinal ultrasonic wave and the compressive strength of the concrete in the slab was determined. The structure of the concrete across the thickness of the slab was evaluated using GIMP 2.10.4. It was found that the destructively determined compressive strength varied only slightly (by 3%) across the thickness of the placed layer of concrete. Whereas the averaged ultrasonically determined strength of the concrete in the same samples does not vary across the thickness of the analyzed slab. Therefore, it was concluded that the slight increase in concrete compressive strength with depth below the top surface is a natural thing and need not be taken into account in the assessment of the strength of concrete in the structure
Realization of post-tensioned concrete retention tanks on Wroclaw鈥檚 sewer network system
W artykule zaprezentowano technologi臋 realizacji czterech kablobetonowych zbiornik贸w retencyjnych na sieci kanalizacyjnej na terenie przepompowni Port Po艂udnie we Wroc艂awiu, ka偶dy o nominalnej pojemno艣ci 15 000 m3. Zbiorniki stanowi膮 g艂贸wn膮 cz臋艣膰 nowego uk艂adu retencyjnego i przeznaczone s膮 do okresowego magazynowania nadmiarowych og贸lnosp艂awnych 艣ciek贸w pogody burzowej. Obiekty zosta艂y wykonane w latach 2019-2022 w technologii tradycyjnej jako monolityczne, wolnostoj膮ce zbiorniki cylindryczne z betonu spr臋偶onego o promieniu wewn臋trznym 23,25 m, wysoko艣ci 艣ciany 11,82 m i grubo艣ci 艣ciany 0,40 m. 艢ciany zbiornik贸w na wysoko艣ci zosta艂y odcinkowo spr臋偶one po obwodzie kablami zbudowanymi ze splot贸w Y1860S7 - 15,7 mm kotwionych w pilastrach. 艢ciany zbiornik贸w zosta艂y monolitycznie utwierdzone w p艂ytach fundamentowych. Zbiorniki przykryte zosta艂y samono艣nymi kopu艂ami aluminiowymi.The article presents the technology of realization of the four post-tensioned concrete retention tanks on the sewer network system located in the Port Po艂udnie pumping station in Wroclaw, each with a nominal capacity of 15000 m3. The tanks are the main part of the new retention system and are intended for periodical storage of redundant storm sewage. The structures were constructed between 2019 and 2022, along with traditional technology, as monolithic, above ground cylindrical tanks made of prestressed concrete. Dimensions of the structure are as follows: internal radius 23.25 m, wall height 11.82 m and wall thickness 0.40 m each. The tank walls were sectionally prestressed around the perimeter with cables made of Y1860S7 - 15.7 mm strands anchored in pilasters. Tank walls were monolithically restrained in the bottom slabs (foundations) and covered with self-supporting aluminum domes attached to the cylindrical walls of the tanks