36 research outputs found
Stiffnes and bearing testing of the polyethylene inspection pit
U radu su prikazane metode i rezultati ispitivanja polietilenskih okana (Å”ahtova) na obodni pritisak i vertikalno optereÄenje. Iz rezultata ispitivanja izraÄunana je krutost okna, dopuÅ”teno vertikalno optereÄenje i pritisni modul elastiÄnosti. Rezultati i analize ovih ispitivanja mogu se koristiti pri izradi preporuka za ugradnju i uporabu polietilenskih okana.The paper presents the methods and results of testing of linear low-density polyethylene inspection pits to peripheral pressure and vertical load. From these results stiffness of the pit was calculated as well as permissible vertical load and modulus of elasticity in compression. The results and analysis of these tests are usefull in developement of recommendations for installation and exploitation of inspection pits
RADNI DIJAGRAM I UTJECAJ PARAMETARA ISPITIVANJA NA REZULTATE VLAÄNIH ISPITIVANJA
Tensile steel-coupon testing qualifies as one of the more commonly used experiments for determination of basic parameters for structural design. Such tests are usually performed to determine technical stressāstrain relationships of tested materials. Technical stressāstrain curves are not suitable for various numerical material models that exploit the plastic region of behavior, owing to the necking effect and accompanying change in coupon area being neglected during stress determination. Material ductility is influenced by the choice of gauge length, which may cause different researchers to differently interpret coupon tests of the same material. The proposed research utilizes benefits offered by an optical system for deformation monitoring to track changes in surface area and implement them during stress calculations until fracture. The possibility of adjusting the gauge length the same sample the ability to study its effect on obtained results. Based on analyzed data, these influences were evaluated and possible errors identified.VlaÄno ispitivanje ÄeliÄnih epruveta je jedan od ÄeÅ”Äih eksperimenata, za praktiÄne i znanstvene svrhe, prvenstveno jer daje osnovu za odreÄivanje baznih varijabli koje su potrebne prilikom dimenzioniranja. UobiÄajeni rezultat vlaÄnog ispitivanja je tehniÄki radni dijagram naprezanje - relativna deformacija. MeÄutim, on nije pogodan za razliÄite numeriÄke modele materijala pomoÄu kojih se iskoriÅ”tava plastiÄno podruÄje ponaÅ”anja, vezano uz Äinjenicu da se uÄinak suženja i pripadne promjene povrÅ”ine popreÄnog presjeka epruvete zanemaruju pri odreÄivanju naprezanja. Duktilnost je pod utjecajem odabrane mjerne duljine, Å”to kao posljedicu može imati da razliÄiti istraživaÄi tumaÄe rezultate vlaÄnog ispitivanja istog materijala na razliÄite naÄine. Provedeno istraživanje iskoriÅ”tava prednosti optiÄkog sustava za prostorno snimanje deformacija, tako da se prate promjene ploÅ”tine popreÄnog presjeka i uzimaju u obzir pri proraÄunu naprezanja, sve do loma. MoguÄnost promjene mjerne duljine na uzorku omoguÄila je prouÄavanje tog uÄinka na rezultate. Na temelju analize dobivenih podataka, navedeni utjecaji su procijenjeni i utvrÄene su moguÄe pogreÅ”ke
Konferencija o sadaÅ”njim i buduÄim trendovima u projektiranju, gradnji i održavanju mostova, Peking, 17.ā18. rujna 2007.
Dana je vijest o održanoj konferenciji o sadaÅ”njim i buduÄim trendovima u projektiranju, gradnji i održavanju mostova, Peking, 17.ā18. rujna 2007
Ductility analysis of laminated timber beams of small section height
Svrha je rada analizirati odnosno utvrditi primjenjivost modela koji uzimaju u obzir duktilnost drvenih elemenata pri savijanju. Ispitani su i prikazani gredni elementi male visine, dakle elementi kod kojih je raspon viÅ”estruko veÄi od visine. Osim ispitivanja grednih elemenata, dani su rezultati ispitivanja mehaniÄkih karakteristika osnovnog materijala i prikazana su ispitivanja provedena metodom konaÄnih elemenata (numeriÄki modeli). NumeriÄki modeli napravljeni su u programskom paketu Abaqus.The purpose of this paper is to analyze and determine the applicability of the models that take into account the ductility of timber elements in bending. Beam elements whose span is many times higher than the height are experimentaly tested. In addition to the tested beam elements, paper presents the mechanical properties of the timber material and the results obtained by finite element method (numerical models). Numerical models are made in the software package Abaqus
Measurement of bridge dynamic displacements and natural frequencies by RTS
U radu je prikazana primjena RTS-a za mjerenje pomaka na željezniÄkom mostu "Sava" tijekom pokusnog optereÄenja nakon rekonstrukcije mosta, s posebnim naglaskom na odreÄivanje pomaka pri dinamiÄkom djelovanju optereÄenja te vlastitih frekvencija mosta. Rezultati mjerenja su usporeÄeni s rezultatima numeriÄkog proraÄuna i s rezultatima vlastitih frekvencija odreÄenih operacionalnom modalnom analizom (OMA).The use of RTS for measuring displacements at the Sava railway bridge during load testing after bridge rehabilitation is presented in the paper, and a special emphasis is placed on the determination of displacements when the bridge was subjected to dynamic load and natural frequencies. Measurement results are compared to numerical analysis results and to natural frequency results obtained by the Operational Modal Analysis (OMA)
Centrifugally-cast concrete poles with non-metallic reinforcement
U radu se prikazuje ispitivanje stupova namijenjenih elektrodistribuciji, koji se proizvode postupkom centrifugiranja, od betona vrlo visoke tlaÄne ÄvrstoÄe i koji su prednapeti Å”ipkama od polimera armiranog ugljiÄnim vlaknima (Carbon Fibre Reinforced Polymer - CFRP). Prikazani rezultati ispitivanja stupova savijanjem do sloma upuÄuju na moguÄnost primjene ovog graÄevnog proizvoda, napose u okoliÅ”u u kojemu dolazi do pojaÄane korozije konvencionalne ÄeliÄne armature. Dio ispitanih stupova imao je posmiÄnu armaturu u obliku ovijene mrežice od polimera armiranog staklenim vlaknima (Glass Fibre Reinforced
Polymer - GFRP), a dio je uzoraka bio bez posmiÄne armature, ali je betonska matrica ojaÄana sintetiÄkim makro vlaknima. Dan je osvrt na dosadaÅ”nja ispitivanja sliÄnih proizvoda, na metode proraÄuna, kao i naznaka smjernica za daljnja istraživanja.The article describes the testing of poles for electric power transmission lines, which are made of centrifugally-cast concrete and ultra-high strength concrete, and which are prestressed with Carbon Fibre Reinforced Polymer tendons (CFRP). The presented results of pole ultimate load testing suggest the potential for usage of this construction product, particularly in aggressive environments with high probability of steel corrosion. Part of the tested poles had shear reinforcement in the form of confined Glass Fibre Reinforced Polymer (GFRP) grid, while one share of samples had no shear reinforcement, but the concrete matrix was strengthened with synthetic macro fibres. A review is given on similar product testing, calculation methods, and guidance is provided for further research
Dynamic analysis of cable-stay and suspension bridges
DinamiÄka ispitivanja zavjeÅ”enih i viseÄih mostova prikazana su na primjerima Mosta Franja TuÄmana u Dubrovniku i pjeÅ”aÄkog mosta u Osijeku. Kako je utjecaj dinamiÄkih djelovanja na zavjeÅ”ene i viseÄe mostove veÄi nego na druge tipove mostova veÄa je i potreba za njihovu eksperimentalnu verifikaciju. Prikazani su rezultati eksperimentalno odreÄenih dinamiÄkih parametara (vlastitih frekvencija i priguÅ”enja) prikupljenih u razliÄitim vremenskim intervalima te njihove usporedbe.The dynamic analysis of cable-stay and suspension bridges is presented through case studies of the Franjo TuÄman Bridge in Dubrovnik, and the pedestrian bridge in Osijek. As the impact of dynamic actions on cable-stay and suspension bridges is greater when compared to other bridge types, the need for their experimental verification is also greater. The results of experimentally defined dynamic parameters (eigenfrequency and damping), measured at various time intervals, are presented and compared
The Impact Analysis of Lateral Restraint on the State of Stress and Strain in the Thin-Walled Z-Section Beam
The behaviour of thin-walled Z-section beam subjected to gravity load for different variants of lateral restraints is analyzed. For the basic variant of the laterally restrained beam the one defined in Eurocode 3 (EN 1993-1-3:2006) is taken. The Z-section beam which is laterally restrained along the flange by trapezoidal steel sheeting is observed, shown as a Z-section beam laterally restrained with linear stiff connection and rotary elastic connection. Variant of laterally restrained Z-section beam with a linear stiff connection, a variant of laterally restrained Z-section beam with rotary elastic connection and beam without lateral restraints are analyzed. Based on the research, analysis and comparison of the results for individual variants of thin-walled Z-section beams, with and without lateral restraints, is conducted