Modern monitoring of buildings and civil engineering structures

Przedstawiono wybrane współczesne techniki monitorowania konstrukcji budowlanych. Spośród wielu znanych metod i czujników położono nacisk na systemy światłowodowe. Opisano w zarysie podstawy fizyczne pomiarów tymi rodzajami czujników, które znalazły najszersze zastosowanie do monitorowania odkształceń konstrukcji budowlanych (czujniki interferometryczne SOFO, czujniki Bragga i bazujące na rozpraszaniu Brillouina). Druga prezentowana grupa czujników obejmuje czujniki GPS i Robovec wchodzące w skład systemu monitorowania trójwymiarowych deformacji. Podane są - istotne z punktu widzenia pomiarów budowlanych - właściwości metrologiczne opisywanych czujników i systemów, a także spektrum możliwości ich typowych zastosowań praktycznych.The paper deals with monitoring and measurement concepts followed by discussion and comparison of main features of monitoring systems. Operating principles of fibre optics SOFO, FBG, EFPI and distributed Brillouin sensors used for monitoring of civil engineering structures are presented. There are also discussed monitoring technologies of three dimensional displacements based on GPS and robotized laser distance meter. Each technology is exemplified by describing its application to specific monitoring needs. Examples cover problems of old and new concrete interaction, monitoring of temperature inside concrete block during concrete setting, enlargement of existing structures, stability assessment by crack opening measurement, vertical displacement of a bridge span and monitoring of service loads, strengthening of a harbour wave-breaker and monitoring of strains and deflections of a truss structure. The presented examples show advantages of using modern monitoring systems as tools supporting structural assessment and decisions undertaken by civil engineering experts

The preferences of visitors to selected forest areas for tourism and recreational purposes

Questionnaire surveys were conducted from July 1st to August 15th, 2012 in forests near Gołdap, Białowieża, Pisz, Kraoenik, Warsaw and Zakopane with 335 respondents – 146 residents (43.6%) and 189 tourists (56.4%). The respondents declared that they visit forests throughout the year for various purposes, most often with family or friends and most frequently for the recreational activity of walking. They typically spend about three hours in the forest during a single visit. Respondents perceived the most important functions of the forest as a place where plants and animals live, as well as a place for recreation. In their view, the state budget should be a source of co-financing the recreational management of the forest. Only a small number of respondents (27.5%) would be willing to allocate a portion of their income for recreational forest management. According to the respondents, the most important elements needed in the forest to improve its quality for tourism are information signs and litter bins. Respondents perceive the greatest threats to the forest from tourism to be vandalism, automobiles driving into the forest and wildlife disturbance, whereas the greatest threats to tourists were reported to be biting and stinging animals (snakes, ticks and mosquitoes) and the possibility of getting lost. Respondents indicated clean air, peace and quiet, as well as the ability to harvest wild fruits, plants and mushrooms as the greatest advantages of using the forest for recreation. A large proportion of respondents admitted that they would like to use the services of professional foresters, especially for nature walks and health related purposes, as well as to educate children and youth about nature and the forest

Testowanie miękkiego, samonośnego zbiornika na wodę, używanego dla ochrony przeciwpożarowej obiektów cywilnych

Investigated flexible self supporting water tank is made of fibre reinforced rubber and can be used in fire-extinguishing actions to protect buildings and other civil engineering structures. Its self supporting ability results from the air-tight floating flange. Preliminary investigations of the rubber material done in the laboratory and of a prototype tank led to the tank redesign. Deformations of a new tank were measured under its operating conditions with four tons of water inside. Resulting hoop and longitudinal strains exceed four percent and are in agreement with theoretical considerations. Developed measurement methods can be adapted for testing the shell structures and other coverings made of technical fabrics.Testowany elastyczny, samonośny zbiornik na wodę wykonany jest z gumy wzmocnionej włóknami i może być użyty w akcjach gaśniczych w celu ochrony budynków i innych obiektów cywilnych. Jego samonośna zdolność wynika ze szczelnego samonośnego kołnierza. Wstępne badania materiałowe gumy przeprowadzone w laboratorium, jak i badania prototypu zbiornika doprowadziły do zmian w jego projekcie. Dokonano pomiarów odkształceń w nowym zbiorniku, zawierającym 4 tony wody, w warunkach prowadzenia akcji. Powstałe obwodowe, jak i wzdłużne odkształcenia przekraczają 4% i zgadzają się z teoretycznymi założeniami. Opracowane metody pomiarów mogą być wykorzystane do testowania konstrukcji łupinowych oraz innych pokryć wykonanych z włókien technicznych

Chrząszcze w pokarmie kuny kamionki Martes foina i kuny leśnej Martes martes

The paper is an analysis of 225 excrements of beech and pine martens with regard to species composition of beetles consumed by these animals. On the basis of consumed species a hypothesis was put forward about the penetration of trunks, branches and hollows of trees with loose bark and litter

Structure of carabid communities in forest islands of different size situated in the mosaic landscape

The study included 15 isolated islands, grouped in five size classes. Trapped individuals were identified to species and measured and weighted. The number of carabid species was higher in the ecotone zones as compared with the island interior. Reduction in total number of carabid species was observed with increasing size of an island. The share of forest related carabid species was positively correlated with the size of an island; similar was the pattern concerning the large zoophages, the European and brachypterous species. The larger an island, the higher value of the mean individual biomass index (SBO) and the index of Progressive Features Sum (SCP). With the growing size of the islands, the carabid communities are placed still further to the uppermost right hand corner in the SCP/SBO diagram (fig. 2). Response of carabid communities to different size forest islands has shown that the smallest islands which favor the establishment of stable forest communities are 0.63 ha. Hence, it is to consider in the practice of forest management to create islands not smaller than that area (this may be established at the level of about 1 ha, for the practical purposes)

Mortality of invertebrate fauna on hiking trails depends on their width and location

The study tested the following hypotheses: the mortality of invertebrate fauna is higher (1) on wide trails than on narrow ones, (2) on sections near the entrance to the forest than on the parts located within the forest, and (3) during the weekend than during the workdays. To assess the mortality of epigeic fauna trampled on hiking trails, the most frequented trails in the Chojnów Forest District (central Poland) were selected. On each trail, 100 m long segments were designated near the boundary with open terrain (‘entrance' sections) and inside the forest, 500 m from the edge. Paths wide less than 1.5 m were considered as narrow, while those wider than 3 m as wide ones. Data was collected in 2016 and 2017 (8 and 7 inspections, respectively). A total of 752 trampled animals belonging to 25 species or taxa were found. GLM analysis did not reveal significant differences between the number specimens or species trampled on trails with different location or width. However there were more dead individuals and species on the entrance segments. Also, more dead specimens and species were found on wider paths, but the difference was not significant (fig. 1, tab.). The number of trampled invertebrates increased significantly during the weekend (fig. 2, tab.). NMDS clearly ordered the data from fauna collected at the entrance trails to those collected within the forest (fig. 3). 74.9% of the variation in species data was explained by the first PCA axis and 14.0% by the second one. The first axis was associated with the trail location (fig. 4). Points representing invertebrate fauna found on narrow paths (especially inside the forest stand) are located closer together than points representing fauna on wide trails (especially those bordering on open areas). The PCA correlated the most significant trampling of the dor beetle (A. stercorosus) with narrow trails within the stand and trampling of the spring dor beetle (T. vernalis) with wide paths near the entrance. The impact of hiking on the forest and all of its fauna is still little known. In order to effectively counteract its negative effects and protect organisms present on trails, research should be continued

Spontaneous regeneration of a stand disturbed by a hurricane in July 2002

Spontaneous regeneration in the hurricane−disturbed stand in the Pisz Forest District (N Poland) was registered in the years 2007−2008 and 2011−2012. Breast height diameter and crown size were measured on 10×10 m plots. The analysis also included the soil respiration rate, the decomposition rate of organic matter, soil pH, leaf area index (LAI), content of Mg, Ca, C, N and P in soil, and vegetation coverage of the forest floor. The natural regeneration was dominated by birch, followed by pine, which recolonized the disturbed stand in smaller extend, possibly because of the thick cover of organic material hindering germination and making it difficult for pine sprouts to reach the mineral soil. Spontaneous regeneration of the stand was most severely inhibited by Deschampsia flexuosa, whose growth over the entire surface was linked to the capture of excess released nitrogen resulting from the decomposition of organic matter. Mosses and lingonberry did not delay the spontaneous appearance of seedlings. The development of the natural regeneration suggests the possibility that an uneven−aged stand will emerge

Zastosowanie fali Raylegha do diagnostyki degradacji historycznych materiałów konstrukcyjnych

Paper presents results of degradation modelling of historical construction materials based on Rayleigh surface wave velocity (CR) measurement for two marbles widely used as the structural and decorative material in historical constructions. Environmental loading is modelled by freezing and thawing cycles performed in laboratory. Rayleigh wave measurement method does not need any coupling medium between the stone and ultrasonic probe and is 100% non-destructive. It is shown that exponential law can be used to model the proces of degradation of elastic properties of the tested materials.Praca przedstawia wyniki modelowania degradacji historycznych materiałów konstrukcyjnych na podstawie pomiarów prędkości fali Rayleigha dla dwóch marmurów szeroko stosowanych w zabytkowych budowlach jako materiał konstrukcyjny i dekoracyjny. Obciążenia środowiskowe modelowane są cyklami zamrażania i rozmrażania przeprowadzonymi w laboratorium. Metoda pomiaru fali Rayleigha nie wymaga żadnego ośrodka sprzęgającego pomiędzy materiałem a sondą ultradźwiękową i jest w 100% nieniszcząca. Wykazano, że proces degradacji właściwości sprężystych badanych materiałów dobrze modeluje prawo wykładnicze