Structural performance of a prefabricated concrete beam with longitudinal cavities

Master's thesis in Structural engineeringPrecast concrete elements are getting more and more popular in the construction industry. The precast elements are casted into many different shapes and sizes, which includes walls, beams, columns, slabs and more. There are many advantages of using them, although there are also many limitations. Moreover, concrete elements pass different stages such as casting, storing, transporting and disassembling. Especially the last two stages, brings several limitations regarding size and especially weight to the picture. A specific project turned out to have some problems regarding the weight of a large continuous beam with cross-shaped (special DLB) cross section, carrying hollow decks on both corbels, created the motivation for the topic of this thesis. Many different ideas on how to reduce the weight of the beam were mentioned. Use of lightweight concrete, use pf pre-stressing beams, hollow sections, geometrical changes and many others were proposed. Inspiration from hollow decks and IB-beams created the final idea of using longitudinal cavities as a measure. Originally, the beam was designed using a Gerber system, a system which allows for splitting a continuous beam in parts. It also had transverse cavities. However, for simplicity, the original beam has been re-designed for a case without either Gerber or transverse cavities. The beams have been designed using rules given in Eurocode 2 [1] and design guidelines given in the concrete element book [2] [3]. Also, a publication [4] regarding where the Euler-Bernoulli beam theory is valid for concrete structures has been used in the design phase. Practical design with regards to production has had a very high focus. Preliminary control and calculations for design were mostly done using simple software [5] for design of concrete structures directly towards Eurocode 2 with Norwegian annex. Through discussion and trial & error, a design with a cavity below the neutral axis were proposed, which then maintained almost all its theoretical bending moment capacity (cracked section assumed). As the initial beam were assumed to be sufficiently constrained in the lateral direction, the shear capacity then turned out to be the main issue for design. Reduction in shear capacity introduced further limits to where the design may be used. The initial beam cross section consists of a rectangular beam 520mm*980mm with rectangular corbels 150mm*250mm on each side starting at 350mm above the most bottom part. Space for two layers of ø32 in both top and bottom, shear rebar ø16, and corbel rebar both in the transverse ø12 and longitudinal direction. For the modified cross section, the bottom part of corbels was angled at 45 degrees. A cylindrical cavity ø300 were added and corbel rebar adjusted accordingly. Longitudinal and shear rebar were unaffected. The cavities were added at a distance equivalent to effective depth, “d”, of the cross section from the face of each support, unless the shear capacity of the cross section were violated, in which it was moved accordingly. In sum, these modifications reduced the total weight of the continuous beam by ~9%. To study the structural behavior of the proposed beam, numerical analysis was then carried out using a non-linear finite element software (i.e. ATENA [6]) specifically aimed at concrete structures. Two models were produced for comparison, and two extra for control of shear rebar and mesh size. All the numerical results produced a way too high crack width, though all models mostly passed criteria for deflection, crushing of concrete and yielding of rebar. Comparatively, the higher range of values in the modified beam had mostly ~5-10% higher values for crack width, deflection and compressive stress in concrete. In sum, this design approach seems to be a good measure, though the economical and other aspects have not been analyzed in detail. Further studies must be performed for a proper conclusion

The Implementation of Electricity as Road Transportation Fuel

Road-based electricity increasingly is being considered as an alternative fuel of the future that would replace or reduce dependence on oil and its derivatives, resulting in a reduction at the negative impact on the environment. More and more countries are introducing stricter measures on greenhouse gas emissions, while increasing incentives to buy EVs. This paper looks at the environmental impact of electricity in road transport in ecological, economic, and social terms, highlighting the greater need for more energy efficient EVs than conventional vehicles. The aim of this paper is to emphasize the importance of the application of electricity concerning fossil fuel in road transport, i.e., to describe the impact of EVs on the environment regarding conventional vehicles. Analysis of the use of the EV or the development of electrical infrastructure that is improving and introduced at high speed has shown that only countries with a high standard can monitor trends of EV. Therefore, despite all the advantages of EVs, the strategies and measures adopted by the EU, the implementation of electricity as road transportation fuel does not have a significant echo in countries with a lower standard, at least until the reach and prices of EVs are closer to conventional ones

Review of Good Practices in the Introduction of Traffic Management Systems and Urban Mobility

Mobility, as one of the most significant factors in maintaining the quality of life in cities, faces problems such as traffic congestion and environmental pollution. The rapid population growth in urban areas has had an impact on increased traffic, which is why many cities have decided to implement or improve existing intelligent transport systems (ITS) that reduce traffic congestion with more comfortable and safer pedestrian traffic. Although the population in developed and densely populated cities is familiar with multimodal transportation, inadequate urban transport systems and large individual transport in place continue to pose a major threat. The application of appropriate ITS systems manages traffic and mobility management that are present to residents and facilitate access to all forms of transport. The aim of this paper is to explore urban mobility examples of good traffic management practice for the possibility of their application in cities with issues such as traffic jams and accidents, low pedestrian safety, parking problems, etc

Users’ Perception as a Tool for an Integrated Coastal Management and Beach Quality Assessment

The aim of the paper is to show a brief review of social research methods used in beach user research and coastal zone management. It is argued that this approach may effectively be used from the perspective of Integrated Coastal Zone Management (ICZM). Beaches are one of the most important factors of the sun and sea tourism, and an area where the increased users` pressure is common with the rise of tourist activity. This expansion creates increased pressure on the coastal area, the marine eco systems and, potentially, leads to a degradation of the natural environment. Social research methods provide an invaluable insight into the processes incentivizing beach users in respect to physical, social, economic and natural aspects of beach uses as well as of other parts of the coast, through the concept of the user perception. The intended result is to provide a brief methodological overview of social science research methods applied to and found in literature that can be used to be better informed of the beach management decisions as an area of ICZM interest and, in this way, contributing to the overall sustainable development of the coastal zone and increasing the competitiveness of beach tourism

Cooperative Model for Idle Traffic Optimisation

The growth trend and the trend of population migration into city centres, as well as the continuous increase in the number of motor vehicles cause traffic jams and congestions in most major cities in the world. In order to eliminate the problems caused by the circling in search of available parking space, i.e. by the congestion, different methods and approaches are implemented. First of all, these are the appropriate strategies and policies that are made in order to regulate the existing situation and to demotivate the arrival of part of the population in the city centre, which does not represent a necessity. Another way to eliminate the above problem, which is the most emphasized in this paper, is represented by the intelligent parking systems. Intelligent parking systems are used to guide the driver to the available parking space and to provide information on the characteristics of it. Normally, they are also used for parking reservation and payment, but in most cases they were related exclusively to closed parking lots and garages. With the technological progress and the development of intelligent sensors it has become possible even to control street parking spaces, which is especially emphasized in this paper. Also, an advanced model of guidance to available parking spaces using a cooperative approach is proposed. The simulation model presenting the advantages of this system compared to the classical approach, which are also highlighted in this paper, is developed

Optimizacija kopnene prometne infrastrukture između paneuropskog koridora V i ogranka Vb : doktorska disertacija

S obzirom da je Jadransko more najdublje uvučeno u europsko kopno, srednjoeuropskim zemljama sjeverni Jadran omogućuje najbliži pristup svjetskom moru kroz Tršćanski i Riječki zaljev. Glavni smjer V Paneuropskog koridora kao i njegov ogranak V.B omogućuju sjeveroistočni ulaz Južnih vrata Europe povezujući taj dio europskog kontinenta s lukama na Sjevernom Jadranu. Morski putovi koji se nadovezuju na sjevernojadranske luke Rijeka, Kopar i Trst, a odnose se, kako na Mediteran, tako i na velika tržišna područja istočno od Sueza, upravo su tim pravcem najkraći i najpovoljniji. Znanstveni problem ovog istraživanja sastoji se u tomu da, usprkos činjenici da je kopneno povezivanje ishodišnih točaka V Paneuropskog koridora i ogranka VB značajan segment razvoja sjevernojadranskog prometnog pravca, tematika koja obuhvaća pripadajuću kopnenu prometnu infrastrukturu nije dovoljno istražena i analizirana. Svrha ovog rada je sustavno istražiti i analizirati kopnenu prometnu mrežu sjevernojadranskog prometnog pravca, predložiti kriterije radi optimalnog odabira kopnene prometne trase, željezničke pruge i ceste te izraditi model optimizacije kopnenog povezivanja ishodišnih točaka Paneuropskog koridora V i ogranka VB. Značenje Paneuropskog koridora V i ogranka VB za integraciju sjevernojadranskog prometnog pravca u europski prometni sustav elaborirano je putem detaljne analize kopnenih prometnih pravaca. Determinirani su i analizirani postojeće stanje i planovi razvoja kopnene prometne infrastrukture na sjevernojadranskom prometnom pravcu. Provedena je iscrpna analiza razvoja i poslovanja sjevernojadranskih luka Rijeka, Kopar i Trst kao i njihove zemljopisne, prometne i logističke značajke. Utvrđivanje konkurentne sposobnosti sjevernojadranskog prometnog pravca obavljeno je analizom gospodarskog okruženja i potencijalnog tržišta, elaboriranjem integracije sjevernojadranskih luka kroz logističke principe te analizom konkurentnosti u odnosu na alternativne prometne pravce. Budući da postupci planiranja i projektiranja prethode odluci o izboru optimalne kopnene prometne trase, prikazana je metodologija i analiza postupka prostornoprometnog planiranja i projektiranja te je definirano značenje vrednovanja i optimizacije prostorno-prometnih rješenja. U skladu sa svrhom i ciljem istraživanja, između više postupaka višekriterijske analize za optimizaciju izbora trase kopnene prometnice koja će povezivati ishodišne točke Paneuropskog koridora V i ogranka VB, primijenjen je PROMETHEE postupak te računalni program za višekriterijsko rangiranje varijanti D-sight 3.2.4. Značajka te metode je da na osnovu unošenja egzaktnih podataka omogućuje djelomično i potpuno rangiranje većeg broja varijanti u odnosu na veći broj kriterija. Cilj istraživanja bio je izraditi model za odabir trase željezničke pruge ili ceste koji će biti primjenjiv na svim razinama odlučivanja. Pri tomu su istraženi svi činitelji koji su omogućili utvrđivanje kriterija i potkriterija za odabir trase željezničke pruge i ceste na teorijskoj i operativnoj razini. Problem vrednovanja željezničke ili cestovne trase se svodi na donošenje odluke o odabiru trase kojoj prethodi detaljna analiza mogućih varijantnih rješenja te njihovo stručno ocjenjivanje. Optimizacija kopnene prometne infrastrukture između Paneuropskog koridora V i njegovog ogranka VB provedena je determiniranjem relevantnih tematskih skupina kriterija i potkriterija za odabir željezničke i cestovne prometne trase. Kriteriji su subjektivno definirani uz pomoć domaće i strane stručne i znanstvene literature. Provedeno anketno istaživanje, koje je obuhvatilo analizu mišljenja stručnjaka iz područja planiranja i projektiranja kopnene prometne infrastrukture, korišteno je za ocjenjivanje i vrednovanje definiranih tematskih skupina kriterija i potkriterija. Definiran je težinski koeficijent za svaku tematsku skupinu kriterija i za svaki pojedini potkriterij te je postavljen model za odabir trase željezničke pruge i model za odabir cestovne prometne trase. Kvantitativnim i kvalitativnim ocjenjivanjem kriterija i potkriterija te primjenom višekriterijske analize testirana je efikasnost i djelotvornost modela na primjeru povezivanja ishodišnih točaka Paneuropskog koridora V i ogranka VB, odnosno odabira optimalne trase željezničke pruge i autoceste Rijeka – Kopar – Trst. S obzirom na primjenjivost predloženih modela u praksi, naglašena je mogućnost njihove univerzalne primjene prilikom izbora odgovarajuće kopnene prometne trase, željezničke pruge ili ceste.Owing to the fact that the Adriatic Sea is the one most indented in the European continent, the Northern Adriatic provides the central European countries with the shortest access to deep sea through the Gulf of Trieste and the Gulf of Quarnero / Rijeka. The main route of the Pan-European V corridor as well as its VB branch provide a NE entrance through the European Southern Gate, thus linking that part of the European continent to the Northern Adriatic ports. It is through this very route that the sea routes, which are the continuation of the Northern Adriatic ports of Rijeka, Koper and Trieste toward the Mediterranean and toward large markets east of Suez, represent the shortest and most cost effective trading routes. The scientific problem of this study features the fact that, for all the linking of starting points of the Pan-European V corridor and the VB branch by land representing a significant segment in the development of the Northern Adriatic traffic route, the issue comprising the pertaining land traffic infrastructure has not been adequately studied and analysed. The purpose of the study is to carry out a systematic survey and analysis of the Northern Adriatic land traffic route, to propose criteria for an optimal selection of the land traffic marked route, railway line and road and to prepare a land connection optimization model for starting points of the Pan-European corridor V and the VB branch. The significance of the Pan-European corridor V and the VB branch for integration of the Northern Adriatic traffic route in the European traffic system has been elaborated through a detailed analysis of land traffic routes. The present situation and development plans concerning the land traffic infrastructure on the Northern Adriatic traffic route have been determined and analysed. A comprehensive analysis has been carried out comprising the development and operation of the Northern Adriatic ports of Rijeka, Koper and Trieste as well as their geographical, traffic and logistic features. Competitiveness of the Northern Adriatic traffic route has been determined through the analysis comprising its economic environment and potential market areas, elaborated integration of the Northern Adriatic ports through logistic principles, and analysis of competitiveness with regard to alternative traffic routes. Whereas the planning and designing processes precede the decision on the selection of the optimal land traffic marked route, the methodology and analysis of the traffic related regional planning and designing have been presented and the significance of evaluation and optimization of traffic related regional designing has been defined. In accordance with the purpose and aim of the study, the PROMETHEE method has been selected as well as the computer programme for multicriteria ranking of variants D-sight 3.2.4 among a number of multicriteria analytical methods for optimization of selection concerning the land traffic marked route to link the starting points of the Pan- European corridor V and the VB branch. The significant feature of this method is that using the exact data it enables either partial or complete ranking of a large number of variants with regard to a larger number of criteria. The aim of the study was to develop a model for the selection of the railway line or road marked route to be applicable at any decision-making level. The study included all the facts enabling the criteria and subcriteria to be determined for the selection of the railway line and road marked routes at both theoretical and operational levels. The problem concerning evaluation of railway line or road marked routes becomes reduced to the decision-making process dealing with the selection of the marked route preceded by a detailed analysis of possible variants and their evaluation by experts. Optimization of the land traffic infrastructure between the Pan-European corridor V and its VB branch has been carried out by determining relevant thematic groups of criteria and subcriteria for the selection of the railway line and road marked route. The criteria have been subjectively defined with the aid of domestic and foreign technical and scientific literature. The conducted survey comprising the analysis of expert opinions in the field of the land traffic infrastructure planning and designing was used in the assessment and evaluation of defined thematic groups of criteria and subcriteria. The weight coefficient has been defined for each thematic group of criteria and for every single subcriterion and a model has been prepared for the selection of railway line and road marked routes. Using the quantitative and qualitative assessment criteria and subcriteria and applying the multicriteria analysis, the efficiency and effectiveness of the model was tested by way of example for linking the starting points of the Pan-European corridor V and the VB branch and, respectively, for selecting optimal railway line and motorway Rijeka – Koper – Trieste marked routes. With regard for the widely applicable nature of the proposed models in practice, their universal applicability has been emphasized as eligible in the selection of the appropriate land traffic marked route, be it a railway line or a road