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Kod veza tankostijenih elemenata je, zbog male debljine lima, prisutno niz specifičnosti. U radu su prikazana teorijska i eksperimentalna istraživanja ponašanja spoja tankostijenih čeličnih elemenata ostvarenih pomoću mehaničkih spojnih sredstava: vijaka i samonarezujućih vijaka. Analizirani su posmični i vlačno opterećeni spojevi. Rezultati ispitivanja uspoređeni su s aktualnim europskim i američkim propisima. Određene su i karakteristične nosivosti samonarezujućih vijaka na posmik i vlak., Due to small plate thickness, thin-walled members are characterized by some specific features. The theoretical and experimental study of behaviour of thin-walled member connections with mechanical fasteners, bolts and selftapping screws, is presented in the paper. The shear and tensile behaviour of connections is analyzed. Experimental results are compared with current European and American design codes. Characteristic shear and tensile resistance values of selftapping screws are also defined.

Prefabrication of steel-concrete composite decks can improve their competitiveness and sustainability. This paper presents recent studie of longitudinal shear connection at the University of Belgrade, Faculty of Civil Engineering. Grouped welded headed studs and bolted shear connectors, suitable for prefabricated composite construction, has been examined in push-out tests. Totally 30 tests were conducted, and advanced Finite Element Analysis (FEA) were made using Abaqus/Explicit dynamic solver. Influence of the bolt-to-hole clearance in case of the composite beam with bolted shear connectors is examined using FEA, as well. Based on the experimental and numerical studies behaviour those two shear connectors are compared. Prefabrikacijom spregnutih konstrukcija od čelika i betona može se povećati njihova konkurentnost i smanjiti uticaj konstrukcije na životnu sredinu. Ovde su prikazana istraživanja podužnih smičućih spojeva koja su nedavno sprovedena na Građevinskom fakultetu Univerziteta u Beogradu. Rešenja podužnog smičućeg spoja sa grupisanim moždanicima sa glavom i zavrtnjevima kao sredstvima za sprezanje koja su pogodna za prefabrikaciju spregnutih konstrukcija su ispitivana standardnim eksperimentom smicanja. Eksperimentalno je ispitano ukupno 30 uzoraka i vršene su analize na bazi MKE korišćenjem softverskog paketa Abaqus/Explicit. Primenom MKE analizirano je i ponašanjenosača sa zavrtnjevima kao sredstvima za sprezanje i uticaj zazora između rupe i zavrtnja. Na bazi eksperimentalnih i numeričkih ispitivanja izvršeno je poređenje ponašanja ova dva sredstva za sprezanje i razvijene su nove preporuke za proračun i konstruisanje.

The design rules in EN 1993-1-8 (the Eurocode) for beam-to-column joints in steel frames with endplate are based on the component method. Generally, three different zones of the joint are considered: tension, shear and compression. The component method given in Eurocode is comprehensive, but quite complicated for engineering practice. The possibility of development of simplified recommendations for the design of beam-to-column joints is investigated in this paper. The aim is to define the limiting, critical, values of the dimensions of some joint components in the tension zone, such that the major failure mode becomes failure of the bolts in tension. This would lead to more simple calculation of the bending moment resistance of the joint which is valuable for engineers in practice. Three often use joint layouts are defined and parameterized. For those joint layouts the critical thicknesses of the joint components in the tension zone are analytically derived. A short parametric study is conducted verifying the proposed critical thicknesses of the endplate, column and beam flanges and webs. A design flowchart is provided following the proposed simplified design procedure and the design example is given, as well.

Recent activities undertaken on adoption and implementation of European norm for structures in Serbia are presented in this article. Besides the review of European standards that have until now been adopted as national standards in all areas of civil engineering structures, activities on making of National annexes for their application are presented as well. Problems, which occur during the making of National Annexes and technical regulations by which mandatory application of standards and period of transition are defined, are emphasized.

Continuous strength method is a contemporary approach to calculation of resistance of stainless steel cross-sections which has been recently developed at the Imperial College of London. The basis of the method is the continuous relation between the slenderness and strain capacity of a cross-section, nonlinear relation between the stress and strain and the strengthening effects of cold forming. In the paper are presented the fundamental rules for calculation of cross-section resistance according to continuous strength method; the comparative analysis of design resistance of the compressed cross-section was conducted through a numerical example according to this method and EN 1993-1-4.

Structural engineers are now facing with new demands towards long spans, lightweight floors in steelconcrete composite construction and big open interiors. Thеsе new design trends аrе leading to the extensive problems related to the serviceability limit state, especially problems with unwanted floor vibrations. Annoying vibrations caused by human activities are an important serviceability problem, which can significantly affect the comfort of people, quality of life and structures functionality. Over past years many design recommendations of floor vibrations induced by human activities have been published. This paper presents a short overview of dynamic loads modeling and design recommendations of floor vibrations induced by human activities.

When analysing slip resistance connections, which are commonly used in-situ assemblied joints of structures dominantly loaded by cyclic loading, for example in bridges, telecommunication towers, towers for wind turbines, we may say that preloaded high strength bolts are their most important part. A level of pretension force in a bolt influences the strength of a slip resistance connection, therefore it is very important to attain a design level of a pretension force. This paper tackles most frequently used methods for measuring of a pretension force in high strength bolts both on site and in a laboratory. Primarily usage of ultrasonic methods, washer like load cells (with strain gauges and piezoelectric), strain gauges installed on the bolt shank and strain gauges installed inside of the bolt shank. The emphasis is both on a use of strain gauges which measure pretension force inhigh strength bolts and on a bolt calibration procedure prior to pretensioning. Installation process of strain gauges in the bolt shank is described in detail and all its specificities are bring to the attention based experimental research conducted on 126 bolts.

Basic distinctive characteristics of stainless steels are reflected in the nonlinear relationship of stress and strain, prominent ductility, strain hardening due to cold forming, asymmetry and anisotropy of material. These properties lead to a different behavior of structural elements of this material than the equivalent elements made of carbon steel. Implementation of a design concept based on an ideal elasto-plastic model of material such as carbon steel, often produces conservative results in case of stainless steel, which is already at a disadvantage due to its cost in construction engineering. Proper defining of recommendations for design and their implementation in technical codes requires a precise and accurate mathematical interpretation of nonlinearity of stainless steel. This paper presents the most important analytical models for description of the relationship of stress and strain of various alloys of stainless steel which have lately been developed worldwide. Most of these models are based on the original Ramberg-Osgood analytical expression.

Nehrđajući čelik odlikuje niz specifičnosti koje određuju drugačije ponašanje konstrukcijskih elemenata od ovog materijala u odnosu na ekvivalentne od ugljičnog čelika. Ova svojstva, osobito izražena kod tlačnih elemenata, očituju se u nelinearnom odnosu naprezanja i deformacija i izraženim utjecajima očvršćenja materijala uslijed hladnog oblikovanja. U radu su prikazani osnovni principi proračuna tlačnih hladno oblikovanih elemenata od nehrđajućih čelika koji su obuhvaćeni suvremenim tehničkim propisima ili su rezultat aktualnih istraživanja., Stainless steel has a number of features that define different behaviour of structural elements made of this material, as related to equivalent carbon steel elements. These properties, especially prominent in case of compression elements, are manifested through the nonlinear stress and strain relationship, pronounced influences of material hardening due to cold forming. Basic principles for the analysis of cold-formed stainless steel compression elements, either included in modern technical regulations, or resulting from current research, are presented in this paper.

U radu je izvršen kontrolni proračun vrelovoda s korozijskim oštećenjem prema normi DNV-RP-F101 i pomoću SINTAP postupnika, uz pretpostavku postojanja polueliptične pukotine. Izračunat je maksimalni unutarnji tlak kojem vrelovodna cijev smije biti opterećena uz prisustvo pukotine poznatih dimenzija. Isto tako je određena kritična vrijednost polueliptične pukotine za zadane uvjete režima rada vrelovoda.

Connections made by use of wide end plates, i.e., by means of four bolts in one row are widely used in steel structures, i.e., in building engineering. On the other hand, the applicable version of European standard EN 1993-1-8, does not provide recommendations for designing of such connections but rather limits itself to application of somewhat narrow bonds). Extensive research has been conducted in recent years throughout Europe in order to extend implementation of Eurocode with regards to connections made by wide end plates. This paper will show the latest research conducted in this engineering field, as well as key calculation points relating to resistance of a rigid joint made by use of four bolts in one row. Veze sa širokom čeonom pločom, odnosno sa četiri zavrtnja u redu imaju značajnu primenu u čeličnim konstrukcijama u zgradarstvu. Međutim, trenutna verzija evropskog standarda EN 1993-1-8, ne daje preporuke za projektovanje ovakvih veza, već se ograničava samo na primenu uskih veza. Proteklih godina širom Evrope su vršena istraživanja sa ciljem da se proširi primena evrokoda i na veze sa širokim čeonim pločama. U ovom radu su prikazana najnovija istraživanja u ovoj oblasti, kao i osnovne specifičnosti proračuna nosivosti momentne veze sa četiri zavrtnja u jednom redu.

Prefabrication of steel-concrete composite decks can improve their competitiveness and sustainability. This paper presents recent studies of longitudinal shear connection at the University of Belgrade, Faculty of Civil Engineering. Grouped welded headed studs and bolted shear connectors, suitable for prefabricated composite construction, has been examined in push-out tests. Totally 30 tests were conducted, and advanced FEA were made using Abaqus/Explicit dynamic solver. Based on the experimental and numerical studies behaviour those two shear connectors are compared. Prefabrikacijom spregnutih konstrukcija od čelika i betona može se povećati njihova konkurentnost i održivost. Ovde su prikazana istraživanja podužnih smičućih spojeva koja su nedavno sprovedena na Građevinskom fakultetu Univerziteta u Beogradu. Grupisani moždanici sa glavom i zavrtnjevi kao sredstva za sprezanje koja su pogodna za prefabrikaciju spregnutih konstrukcija su ispitivani standardnim eksperimentom smicanja. Eksperimentalno je ispitano ukupno 30 uzoraka i vršene su analize na bazi MKE korišćenjem softverskog paketa Abaqus/Explicit. Na bazi ekserimentalnih i numeričkih ispitivanja izvršeno je poređenje ponašanja ova dva sredstva za sprezanje.

Alcoa Fastening Systems, introduces the Huck BobTail, representing the most advanced fastening technology to date. Recognized as the next-generation lockbolt, the Huck BobTail delivers 5 times the fatigue strength of conventional nuts and bolts, and is engineered to provide the highest level of strength, reliability, and vibration-resistant performance. Engineered to meet the challenges of a wide range of assembly applications, BobTail offers high performance and easy, quick installation. Firma 'Alcoa Fastening Systems' konstruisala je 'Huck BobTail' sistem mehaničkih spojnih sredstava i predstavila ga kao jednu od najnaprednijih tehnologija spajanja do danas. Prepoznat kao zaključavajući zavrtanj (antivandal) naredne generacije, 'Huck BobTail' donosi pet puta veću čvrstoću na zamor od standardnih zavrtnjeva sa navrtkom, a konstruisan je tako da pruži visoku čvrstoću, pouzdanost i otpornost na vibracije i u najekstremnijim uslovima. Konstruisan da zadovolji širok spektar sistema za spajanje, 'BobTail' odlikuju visoke performance kao i jednostavna i brza ugradnja.

The construction of Railway Road Bridge across the Danube in Novi Sad is in progress. The bridge is designed for two railway tracks, two road lanes and two footpaths, with total width of 31,440 m. The distances of the piers are 27+178,5+220,5+48 m and total bridge length is 474 m. On the cetral two spans are steel tied arches with network hangers and composite decks. In the article is presented the rationality of the bridge structure – main bearing systems, hangers and deck structures – according to steel material quantities and total construction costs. Železničko-drumski most preko Dunava u Novom Sadu je u toku gradnje. Most ima dva koloseka, dve drumske trake i dve pešačke staze i širok je 31,440 m. Razmaci stubova su 27+178,5+220,5+ 48 m, pa je ukupna dužina mosta 474 m. Na dva centralna raspona su čelični lukovi sa zategom, dijagonalnim vešaljkama i spregnutom kolovoznom konstrukcijom. Konstrukcija mosta (glavni noseći sistemi, vešaljke i kolovozne konstrukcije) je vrlo racionalna po količini materijala i koštanju izgradnje.

У овом раду су презентоване основне специфичности алуминијумских легура и њихова примена у грађевинским конструкцијама. У уводном делу су, поред историјата примене алуминијума у грађевинарству, прегледно и илустративно описани поступак добијања примaрног и секундарног алуминијума, као и најзначајнији поступци технолошке обраде алуминијумских легура. Поред тога, описана су основна својства алуминијума као материјала и његове сличности и разлике у односу на челик као традиционални метал за грађевинске конструкције. Истакнуте су најзначајније специфичности алуминијумских легура као што су мала специфична тежина, нелинеарна веза напон-дилатација, ниска вредност модула еластичности, понашање на високим и ниским температурама, отпорност на дејство корозије, пад механичких својстава услед заваривања у зони утицаја топлоте (ЗУТ). Посебан пажња је посвећена могућностима рециклирања и процесу добијања секундарног алуминијума уз истицање несумњивих предности које овај поступак производње алуминијума има у односу на производњу примарног алуминијума. Такође су истакнуте и могућности примене алуминијумских конструкција у грађевинарству уз конкретне илустративне примере из праксе. У последњем делу рада приказане су основне специфичности пројектовања и прорачуна конструкција од алуминијумских легура. Детаљно су приказани поступци прорачуна према стандарду EN 1999-1-1 за најзначајније случајеве напрезања као што су притисак, смицање и савијање. Такође је представљен и концепт ефективног пресека помоћу кога се узмају у обзир ефекти избочавања и (или) заваривања у ЗУТ-у. Укратко су презентовани и најзначајнији аспекти граничних стања употребљивости. This paper is concerned with the basic specificities of aluminium alloys and its use in constructions. Besides the use of aluminium in constructions, the introduction depicts the process of primary and secondary aluminium production in a clear and illustrative manner, as well as the most important aluminum alloy processing technology. In addition, basic properties of aluminium are described, including its similarities and differences with steel, which is a traditional metal for construction. The most important specificities of aluminium alloys are highlighted, such as small specific weight, nonlinear tension-strain relationship, low modulus of elasticity value, behavior at high and low temperatures, corrosion resistance, and reductions of mechanical properties due to welding in heat-affected zone (HAZ). Special attention is given to recycling possibilities and the production of secondary aluminium, emphasizing its indubitable advantages over the production of primary aluminium. Furthermore, possible applications of aluminium constructions are highlighted, followed by practical examples. The final part of the paper presents the basic specificities of design and calculation aluminium alloy structures. The procedures of design for the most significant cases of load, such as compression, shear and bending, according to EN 1999-1-1 are given in detail. What is also discussed is the concept of effective cross-section, by which the effects of buckling and (or) reduction in HAZ are considered. The most important aspects of serviceability limit states are concisely summarized.

Today, wind power is second largest available renewable resource of energy, after sun and before geothermal and hidrologic energy resources. According to data from 2008. for expected bulding of wind farms with capacity 27 GW it is required to pay 1,35 million euro per MW. The construction of steel tower is about 15-20% of total investment so construction of wind farms is great opportunity for development of civil engineering industry. The aim of this paper is to introduce civil engineers with the specific problems of design of steel towers for wind turbines.

SINTAP procedure gives a comprehensive approach to assessing the integrity of structural components with damage. In this investigation SINTAP procedure has been applied to the hot water pipe with detected corrosion damage that is in operation for more than 15 years of centmlized hot water system, in the City of Osijek. It is a steel pipe 273 x 5 with the measured corrosion damage of 1, 5 mm in depth and 68 mm in length, which is loaded in the exploitation of internal overpressure of 12 bar. Performed analysis based on the FAD approach given in SINTAP procedure shows that for a specified load and measured size of the pipe corrosion damage is sill running deep into the safe area and there is no danger of leak.

Stainless steels get wider application in engineering structures. Apart from many advantages such as corrosion and fire resistance this material has some special characteristics in compare to regular carbon steels. In this paper short preview of basic characteristics of stainless steels, as also the design procedure according to latest European code, EN 1993-1-4, is shown. . Nerđajući čelici nalaze sve veću primenu u građevinarstvu. Pored niza prednosti kao što su otpornost na koroziju i poboljšana vatrootpornost, ovaj materijal odlikuju i određene specifičnosti u odnosu na klasične ugljenične čelike. Ovaj rad daje kratak prikaz osnovnih karakteristika nerđajućih čelika, kao i postupke proračuna prema najnovijem evropskom propisu, EN 1993-1-4. .

The towers represent about 15 to 20% of the total installation costs and optimized design may therefore lead to substantial savings with regard to costs and use of materials. Some of the most interesting design and manufacturing details are connections used to assemble sections of tubular steel towers supporting wind turbines. There is traditional flange ring connection and on the other side, as a new proposal, friction connection. In this paper theoretic basis of design of friction connection of wind towers is given. Tornjevi predstavljaju 15 do 20% ukupne cene vetrogeneratora pa se optimizacijom u projektovanju može doći do značajne uštede u materijalu. Među najinteresantnijim projektantskim i izvođačkim detaljima je montažni nastavak tornja vetrogeneratora. Postoje tradicionalni nastavci sa čeonim pločama i sa druge strane, kao novi predlog, tarni spoj. U ovom radu date su teorijske osnove projektovanja tarnih spojeva kao montažnih nastavaka tornjeva vetrogeneratora.

This paper describes the basic philosophy of the design aluminium structures according to the new European standard EN1999: Design of aluminium structures, Part 1-1: General structural rules. Comparison of the properties of aluminium as a material for structural elements is given in relation to the carbon steel. Special attention is given to the buckling effect in compressed parts of the cross section as well as the thermal effects of welding process, resulting in reduction of the mechanical properties in the heat-affected zones. These effects are illustrated through a brief numerical example.

Today, wind power is second largest available renewable resource of energy, with 870 TW (terawatts). Large wind farms, with hundreds of wind towers are big opportunity for steel production industry. Designers and manufacturers of wind towers pay special attention on every single detail, always looking for some new solutions, trying to reduce price of wind towers. Some of the most interesting design and manufacturing details are connections used to assemble sections of tubular steel towers supporting wind turbins. There is traditional and actually more used flange ring connection and on the other side, as a new proposal which is used more and more, friction connection. In this paper theoretic basis of design of flange ring connection of wind towers is given