The Effective Flexural Modulus of Filament Wound GRP Tapered Poles

The composite lighting poles are filament wound GRP tapered tubes with a variable wall thickness across the length. In this study, the effective flexural properties of GRP poles have been determined, experimentally and theoretically. Cantilever bending tests were performed on full-scale GRP tubes and the effective flexural modulus was calculated from the initial slope of the flexural stress-strain curve based on the classical beam theory. The results show that the strain range corresponding to the linear behaviour is the same as under three-point and four-point tests with smaller specimens. Unlike other methods, the proposed method considers the variation of the crosssectional properties across the pole length. The effective properties of GRP tubes were further determined considering the orthotropic and unsymmetrical layup of the wall segment. A sensitivity analysis was performed at the lamina as well as the laminate level in order to evaluate the influence of material properties of the matrix and the fibres, the amount and orientation of the fibres as well as the layer thickness. Finally, the effective (replacement) flexural modulus of a filament wound tube was determined based on the classical lamination theory and compared to experimentally determined values. It was concluded that the replacement flexural modulus is a matrix dominated property highly influenced by the fibre volume fraction

The Importance of Logistics Distribution Centers as Nodes in Logistics Networks

The emergence of logistics distribution centers has in the past few decades become a mass phenomenon that has emerged as a result of global economic processes. As part of logistics networks, logistics distribution centers are the key link between production and the market, i.e. end users, and function as nodes that facilitate international business activities. For this reason, the aim of this paper is to analyze the characteristics of logistics distribution centers on the example of logistics distribution centers of the selected Western and Central European Union countries and examine the prospects for the development of logistics distribution centers in Croatia. The research results indicate that the Republic of Croatia is less competitive in comparison with Western and Central European countries, although it has a number of logistics distribution centers due to insufficient utilization and renewal of transport infrastructure. Logistics distribution centers are an important center of logistics networks, and the countries will have to devote more attention to their development to attract foreign investment and achieve economic development, because their significance will continue to grow in the future

Viscoelastic properties in seismic insulation

Pomoću puzanja i relaksacije polimernih materijala koji se rabe u potresnoj izolaciji opisana su viskoelastična svojstva. Posebno poglavlje posvećeno je dinamičkim viskoelastičnim svojstvima. Kao primjer primjene viskoelastičnih svojstava kod protupotresnih naprava prikazani su viskoelastični prigušivači. Dinamičkim ispitivanjem elastomernih ležajeva koji se koriste u potresnoj izolaciji određena je količina prigušenja te prikazan dijagram sile i pomaka u ovisnosti o vremenu.Viscoelastic properties of polymer materials used in earthquake insulation are described through creep and relaxation. A special section is consecrated to dynamic viscoelastic properties. Viscoelastic dampers are presented as an example of the use of viscoelastic properties in seismic devices. The damping quantity is determined through dynamic testing of elastomeric bearings used in seismic insulation

Oštećenje vida za boje u radnica izvrgnutih niskim razinama toluena

Colour vision was examined by the Lanthony-D-15 desaturated test in 41 women exposed to toluene and in 29 non-exposed referents. Toluene exposure was evaluated by methods ot environmental and biological monitoring. In the exposed group the median value of toluene in air was 35 ppm (range 11.2-49.9 ppm). Quantitative colour vision impairment was expressed as colour confusion index and colour confusion index corrected for alcohol intake. Qualitative impairment was expressed as normal, yellow-blue, red-green range or complex impairment. Statistical analysis showed the index values to be significantly correlated with age in both groups. In the exposed group they were significantly higher than in the non-exposed group. There was no significant difference in the prevalence of impairment in the blue-yellow range between the examined groups, although the prevalence of impairment in the exposed group was higher than in the non-exposed one. Results suggest that exposure to low toluene concentrations may induce colour vision impairment in women.Desaturacijskim testom Lanthony D-15 ispitivan je vid za boje u 41 radnice izvrgnute prosječnoj koncentraciji toluena u zraku od 35 ppm (raspon 11,2-49,9 ppm) i u 29 radnica kontrolne skupine. Kvalitativni vid za boje izražen je kao indeks pogreške i kao indeks pogreške korigiran za utjecaj alkohola, a kvalitativni vid kao normalan, s oštećenjern u plavo-žutom dijelu spektra ili kao složeno oštećenje. Rezultati su statistički analizirani t-testom i Mann-Whitneyevim U-testom. U obje su ispitivane skupine vrijednosti indeksa pogreške i indeksa pogreške korigiranog za utjecaj alkohola bile značajno povezane s dobi ispitanika. U skupini izloženoj toluenu njihove su vrijednosti bile statistički značajno više (P) nego u kontrolnoj skupini. Nije bilo statistički značajno učestalijeg oštećenja vida u žuto-plavom dijelu spektra. Rezultati upućuju na zaključak da u radnica izvrgnutih niskim koncentracijama toluena indeks pogreške značajno odstupa od očekivanoga, ali da kvalitativno oštećenje vida za boje nije učestalije nego u poredbenoj skupini

Experimental study of prototypes of construction products

U članku se objašnjava koje se radnje moraju provesti u postupku ocjenjivanja sukladnosti građevnog proizvoda. To su: ispitivanja i nadzor. Dan je tabelarni pregled radnji koje treba provesti s podacima o subjektima koji ih provode. Posebno je opisana prva radnja u sustavu – početno ispitivanje. Prikazani su primjeri istraživanja tipova građevnih proizvoda koji su provedeni u Laboratoriju za ispitivanje konstrukcije Zavoda za tehničku mehaniku Građevinskog fakulteta u Zagrebu.Activities to be undertaken in the scope of conformity assessment for civil engineering products are explained. These activities are: testing and surveillance. A tabular overview of activities, with subjects responsible for their implementation, is given. The first activity in the system - initial testing - is treated as a separate topic. The authors also provide examples of various types of construction products analyzed in the Structural Testing Laboratory operating within the Structural Mechanics Department of the Zagreb Faculty of Civil Engineering

Analysis and Assessment of Efficiency Degree in Operation of Cargo Seaports in the Republic of Croatia

Premda se više desetljeća proučava i unapređuje poslovanje teretnih morskih luka, one u Republici Hrvatskoj još uvijek nisu konkurentne takvim lukama u Jadranskome i Sredozemnom moru, stoga je predmet istraživanja u ovom radu bio da se uz pomoć teorijske i praktične spoznaje utvrde aktivnosti koje će dovesti do unapređenja u poslovanju hrvatskih teretnih morskih luka. Na početku razmatranja, poradi boljeg razumijevanja same problematike, predočene su važnije značajke o pomorskom prometu i morskim lukama, kao što su pojam pomorskog prometa i morskih luka, njihove vrste i funkcije. Nakon detaljno elaboriranih značajki posebna je pozornost posvećena teretnim morskim lukama, iznoseći zakonske odrednice za upravljanje njima, opseg teretnog prometa i, konačno, ocjena upravljanja teretnim morskim lukama u Republici Hrvatskoj. S obzirom na činjenicu da je kontejnerski promet vrlo perspektivan oblik prijevoza tereta, izvršena je analiza kontejnerskog prometa te je predstavljena ocjena upravljanja kontejnerskim prometom u morskim lukama. Na temelju dobivenih pokazatelja izneseno je i elaborirano nekoliko prijedloga kojima bi se poboljšalo poslovanje teretnih morskih luka uz podršku Ministarstva, udruženja luka, lučkih uprava i važnijih sudionika u njihovu poslovanju. Na kraju, zaključeno je da bi pritom bilo prijeko potrebno uspostaviti konzistentnu prometnu i lučku politiku koja će biti usklađena sa standardima i propisima Europske unije.Although in the past decades a number of studies and activities to improve business of cargo ports were carried out, still the cargo seaports in the Republic of Croatia are not competitive in relation to the cargo seaports in the Adriatic and Mediterranean seas, thereby the objective of this thesis was to use theoretical and practical knowledge to establish activities which will lead to improvement in the business activities of cargo seaports in Croatia. At the beginning of this thesis work for a better understanding of the issues, important features of maritime transport and seaports are presented, such as: the concept of maritime transport and ports, types of maritime transport and ports and the function of maritime ports. After thoroughly elaborated features of maritime transport and seaports special attention was paid to the cargo seaports, setting out the legal guidelines of management of seaports, the movement of freight traffic in seaports and assessment of management of cargo seaports in Croatia. Given the fact that container traffic is one of the most promising forms of transport, an analyze has been made in container traffic and an assessment of container traffic management in the seaports of Croatia is presented. Based on the analysis and evaluation of the degree of business efficiency of cargo ports and container traffic in Croatia a few suggestions for improvement of cargo ports are laid out by the Ministry, port associations, port authorities and major actors in the business of cargo seaports. In the end, it was concluded that to improve freight operations of Croatian ports it is necessary to set a consistent transport and port policies that will be consistent with standards and regulations of the European Union