Tihomir Dokšanović

TRŽIŠNA PRIHVATLJIVOST GRAĐEVINSKOG MATERIJALA S MALIM UDJELOM UGLJIKA – DIO I: MATERIJALI I MOGUĆNOSTI SMANJENJA UTJECAJA NA OKOLIŠ

Materijali s malim udjelom ugljika danas su gotovo jednako prihvaceni kao njihove konvencionalne inacice, ali njihova zastupljenost na tržistu nije znacajna, unatoc ocitoj dobrobiti po pitanju zastite okolisa i time ljudskog zdravlja. U okviru održive gradnje pokusava se korisniku prikazati kako umjetno stvoreni, izgrađeni okolis ima skrivene utjecaje te da ucinci proizvodnje, transporta, ugradnje, koristenja i odlaganja materijala mogu biti znacajni za njega i prirodu. Prema nekoliko metoda procjene utjecaja materijala na okolis i prema zastupljenosti u graditeljskoj praksi, beton, asfalt i najcesce koristeni metali, celik i aluminij, predstavljaju podrucje na koje treba djelovati kako bi se trenutacno stanje poboljsalo. Kroz projektiranje, izmjene sastava i intervencije na proizvodni proces, nužno je smanjiti njihov utjecaj na okolis, a osim toga potrebno je bitnim znacajkama novih inacica tih materijala, u ekonomskom i građevinskom kontekstu, opravdavati potreban veci udio u prodaji građevinskog materijala.

State of the art review of the stability and welding of aluminium alloy elements

Iako je aluminij vec dugo prisutan konstrukcijski materijal, uporaba mu nije u skladu s dobrobitima koje se ostvaruju njegovom primjenom. Slican je celiku, no između njih postoje znacajne razlike kako u proizvodnji, tako i u fizikalnim i mehanickim svojstvima. Upravo iz tih razlika proizlaze posebnosti u podrucjima stabilnosti dijelova poprecnih presjeka i konstrukcijskih elemenata te u podrucjima zavara. Ta polja jos uvijek predstavljaju aktivna podrucja istraživanja zbog velikog broja legura, obrada i oblika poprecnih presjeka profila.

Stress–strain relationships and influence of testing parameters on coupon test results

Tensile steel-coupon testing qualifies as one of the more commonly used experiments for determination of basic parameters for structural design. Such

Finite Element Mesh Size Optimization for Steel Bolted Connection

Bolted connections are important components of steel structures and they must be based on good design, with analytical descriptions of failure mechanisms that are thoroughly researched. A robust and reliable analytical description of a failure mode requires a large base of results, collected experimentally or numerically, usually via FEA. The modelling procedure in FEM simulations can significantly influence result accuracy, and one of the most important parameters is spatial discretization. Mesh size presents a delicate balance between accuracy, efficiency and convergence issues, especially in bolted connection analysis with contact, material and geometric nonlinearity. Due to increased complexity, sensitivity studies are difficult to interpret and time expensive, which is why in this study a mesh size optimization procedure is presented. This optimization is based on a previously verified and validated numerical model parametric study of a single-bolt lap connection. The first step included forming of an optimization model based on an artificial neural network, through which results were extrapolated and compared to experimental. However, estimated solving wall time was significantly longer. In the second step, a nonlinear optimization model was structured to determine a mesh size for which the difference between experimental and optimization results would be equal, whilst having a minimal solving wall time. The optimization model provided insights into mesh size quality to efficiency ratios and rendered that the minimal difference between experimental and numerical results is 1.57%, while having a solving wall time of 1.3 h, instead of the step one optimization modelling estimated 36 h.

Applications of aluminium alloys in civil engineering

Although aluminium is a long known structural material, its use is not in accordance with the benefits achieved by its implementation. There are several reasons for such an adverse state. Those that stand out are the late development of a regulative framework for the design of structures, and still the need for improvement, lack of knowledge on application examples and not stressed enough potential areas of use. However, positive trends are present and aluminium alloys are competitive, especially if their positive properties can be utilized and negative properties diminished though purpose oriented design approach. Given examples present good application utilization of aluminium alloys characteristics, and shown new application research can provide directions for further expansion of competitiveness. Structural uses are grouped in suitable areas of application and put into local and global context.

SELF-SUSTAINING MULTIPURPOSE KIOSK FOR UNIVERSITY CAMPUS IN OSIJEK

Sustainable building is growing in importance globally including in Croatia. As green design is gaining rapid recognition in the built environment, th

TRŽIŠNA PRIHVATLJIVOST GRAĐEVINSKOG MATERIJALA S MALIM UDJELOM UGLJIKA - DIO II: ZAKONODAVNI OKVIR

Hrvatska je, kao skorasnja clanica Europske Unije i potpisnica Kyotskog protokola, svoje zakonodavstvo znacajno usmjerila prema smanjenju emisija staklenickih plinova i opcenito zastiti prirodnog okolisa. Zakoni vezani uz prirodni okolis isprepleteni su sa zakonima koji utjecu na građevne proizvode, a naravno time i na materijale s malim udjelom ugljika - oni uvelike utjecu na njihovu tržisnu prihvatljivost. Njihovo aktivno provođenje i popularizacija nužni su kako bi se doprinijelo težnjama unaprjeđenja stanja okolisa i prirode Hrvatske, a posljedicno i položaja unutar Europske Unije i Sustava za trgovinu emisijama. Kroz clanak je pružen pregled zakonodavnog okvira Hrvatske vezanog uz materijale s malim udjelom ugljika koji su predstavljeni u prvom dijelu ovoga rada, a predstavljeni su i određeni prijedlozi za poboljsanje trenutacnog stanja.

PRORAČUN SPREGNUTE REŠETKASTE KONSTRUKCIJE VIŠEKATNE ZGRADE

Composite acti on is a structural solution that has increasing importance due to the significant potential in performance improvement of structural elements, and simplification of the construction technological process. Although steel - concrete composite structures are no w in use for more than a century, certain forms of composite action are still not sufficiently dealt with in modern standards. One of such solutions is a composite truss system, which is the subject of this paper. This type of construction has advantages t hat can be utilized in medium and large spans, and in comparison to steel trusses has a lower height. When it is combined with trapezoidal sheets for composite slabs it provides a number of practical advantages. Relevant literature reports that with the us e of this system load transfer efficiency increases by 20% to 30%, and the shown design example of a building for commercial purposes in composite and non - composite versions supports such a claim.