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European norms for civil engineering structures, well known as Eurocodes, are set of highly harmonized codes regarding structural issues. Main rules and recommendations for calculation of wind actions on structures are given in EN 1991-1-4 which is the basic document. Also, some advanced analysis regarding wind actions on towers and masts are given in EN 1993-3-1, with the intention to be transferred in the basic document in the later phase. This paper contains a short presentation of the main rules and recommendations for wind action analysis and their comparison with previous regulations JUS (SRPS). The main focus of the paper is on wind action on buildings and comparative numerical example is also given. Some experiences and conclusions from the process of Serbian National Annex preparation are also presented.

Currently, there is still no explicit design approach for cold-formed stainless steel columns with equal-leg angle sections in Europe. A comprehensive numerical investigation, validated by the available experiments collected in the literature, has therefore been undertaken to provide benchmark data for the assessment of design procedures for cold-formed stainless steel angle columns currently adopted in European and Australian codes. Minor-axis flexural buckling, as well as flexural-torsional buckling have been considered. In total, 27 different cross-section sizes covering both slender and non-slender sections, and a wide range of column slenderness values have been examined including austenitic, duplex and ferritic grades. On the basis of the experimental and numerical results, new design recommendations for cold-formed stainless steel equal-leg angle columns have been made per family of stainless steel. The suitability of the proposals was confirmed by means of a reliability analysis.

New demands towards fast construction resulted in development of different types of prefabricated concrete slabs and shear connectors. Composite action between steel beam and concrete slabs can be achieved with group positioning of shear connectors in envisaged openings of prefabricated concrete slabs. The aim of presented investigation is to promote application of mechanically fastened shear connectors in prefabricated concrete slabs. X-HVB 110 shear connectors fastened to the steel base material with X-ENP-21 HVB cartridge fired pins are used in experimental and numerical analysis presented in this thesis. Presented investigation should improve understanding of X-HVB shear connectors behaviour which is currently based on their application in solid or composite concrete slabs. Also, this investigation should result in extension of currently small basis of experimental results, which are mostly part of the technical reports and are considered as proprietary. Feasibility study presented in this work highlighted the importance of further investigation of X-HVB shear connectors in group arrangement, at distances smaller than minimal recommended, in order to satisfy current recommendations for minimal partial shear connection degree in composite floor structures with profiled steel sheeting. Detail examination of X-HVB 110 shear connectors positioned in envisaged openings of prefabricated composite slabs is performed. The experiment aims at understanding the effects of the spacing between shear connectors, orientation of shear connectors relative to the shear force direction and installation power level used for installation of cartridge fired pins, when they are used for prefabricated composite construction. In order to generate all structural performance data, this investigation included experimental investigation of cartridge fired pins performed through shear and tension tests. Extensive finite element analysis is conducted in this research in order to develop and c, Савремени трендови у грађевинарству се најчешће огледају у повећаним захтевима за убрзаном градњом, што је утицало на развој нових вртса префабрикованих бетонских плоча и средстава за спрезање. Спрезање префабрикованих бетонских плоча и челичних гредних носача најчешће се постиже постављањем можданика у отворе у бетонској плочи, који су за то предвиђени у процесу префабрикације. Предмет научног истраживања је понашање смичућих спојева остварених помоћу X-HVB можданика у префабрикованим бетонским плочама. X-HVB 110 можданици повезани су са челичним профилима уз помоћ два X-ENP-21 HVB механичка спојна средства (ексера) експлозивним упуцавањем. Приказано испитивање треба да допринесе бољем разумевању понашања X-HVB можданика у смичућим спојевима, које је тренутно засновано на испитивањима у пуним и спрегнутим бетонским плочама на профилисаним лимовима. Такође, испитивање треба да допринесе проширењу тренутно мале базе експерименталних испитивања, којa су највећим делом садржанa у техничким извештајима који нису лако доступни истраживачима. Упоредна анализа носивости заварених можданика са главом и X-HVB можданика у спрегнутим плочама са профилисаним лимом, презентована у овом раду, нагласила је потребу за додатним испитивањима ове врсте можданика када су они груписани на растојањима која су мања од минимално препоручених, како би се задовољиле тренутне препоруке у погледу минималног процента парцијалног смичућег споја. Детаљно експериментално испитивање X-HVB 110 можданика постављених у отворе префабрикованих бетонских плоча спорведно је у овом раду. Испитивање је обухватило утицај положаја и међусобног растојања можданика у односу на правац смичуће силе као и различите јачине уградње ексера. У циљу јасног сагледавања понашања ове врсте можданика, експеримeнтално испитивање ескера је спроведено кроз тестове смицања и затезања. Нумерички модели базирани на методи коначних елемената развијени су за потребе симулирања смичућих спојева са X-HVB 110 можданицима као и ескера

New demands towards fast construction resulted in development of different types of prefabricated concrete slabs and shear connectors. Composite action between steel beam and concrete slabs can be achieved with group positioning of shear connectors in envisaged openings of prefabricated concrete slabs. The aim of presented investigation is to promote application of mechanically fastened shear connectors in prefabricated concrete slabs. X-HVB 110 shear connectors fastened to the steel base material with X-ENP-21 HVB cartridge fired pins are used in experimental and numerical analysis presented in this thesis. Presented investigation should improve understanding of X-HVB shear connectors behaviour which is currently based on their application in solid or composite concrete slabs. Also, this investigation should result in extension of currently small basis of experimental results, which are mostly part of the technical reports and are considered as proprietary. Feasibility study presented in this work highlighted the importance of further investigation of X-HVB shear connectors in group arrangement, at distances smaller than minimal recommended, in order to satisfy current recommendations for minimal partial shear connection degree in composite floor structures with profiled steel sheeting. Detail examination of X-HVB 110 shear connectors positioned in envisaged openings of prefabricated composite slabs is performed. The experiment aims at understanding the effects of the spacing between shear connectors, orientation of shear connectors relative to the shear force direction and installation power level used for installation of cartridge fired pins, when they are used for prefabricated composite construction. In order to generate all structural performance data, this investigation included experimental investigation of cartridge fired pins performed through shear and tension tests. Extensive finite element analysis is conducted in this research in order to develop and c, Савремени трендови у грађевинарству се најчешће огледају у повећаним захтевима за убрзаном градњом, што је утицало на развој нових вртса префабрикованих бетонских плоча и средстава за спрезање. Спрезање префабрикованих бетонских плоча и челичних гредних носача најчешће се постиже постављањем можданика у отворе у бетонској плочи, који су за то предвиђени у процесу префабрикације. Предмет научног истраживања је понашање смичућих спојева остварених помоћу X-HVB можданика у префабрикованим бетонским плочама. X-HVB 110 можданици повезани су са челичним профилима уз помоћ два X-ENP-21 HVB механичка спојна средства (ексера) експлозивним упуцавањем. Приказано испитивање треба да допринесе бољем разумевању понашања X-HVB можданика у смичућим спојевима, које је тренутно засновано на испитивањима у пуним и спрегнутим бетонским плочама на профилисаним лимовима. Такође, испитивање треба да допринесе проширењу тренутно мале базе експерименталних испитивања, којa су највећим делом садржанa у техничким извештајима који нису лако доступни истраживачима. Упоредна анализа носивости заварених можданика са главом и X-HVB можданика у спрегнутим плочама са профилисаним лимом, презентована у овом раду, нагласила је потребу за додатним испитивањима ове врсте можданика када су они груписани на растојањима која су мања од минимално препоручених, како би се задовољиле тренутне препоруке у погледу минималног процента парцијалног смичућег споја. Детаљно експериментално испитивање X-HVB 110 можданика постављених у отворе префабрикованих бетонских плоча спорведно је у овом раду. Испитивање је обухватило утицај положаја и међусобног растојања можданика у односу на правац смичуће силе као и различите јачине уградње ексера. У циљу јасног сагледавања понашања ове врсте можданика, експеримeнтално испитивање ескера је спроведено кроз тестове смицања и затезања. Нумерички модели базирани на методи коначних елемената развијени су за потребе симулирања смичућих спојева са X-HVB 110 можданицима као и ескера

Different types of shear connectors, which are used for achievement of steel-concrete composite action, have been developed during decades. Their suitability for various range of structures and loadings is determined by shear resistance, ductility of shear connectors, obtained failure mechanisms and fatigue resistance. Headed studs are widely used for composite construction of buildings and bridges. Perforated shear connectors, mechanically fastened shear connectors or bolted shear connectors with mechanical couplers are alternative solution for achievement of composite action between steel and concrete. Results of experimental and numerical analysis of these types of shear connectors are used for comparative analysis and presented in this paper. Presented analysis included comparison of stiffness and different failure mechanisms for these types of shear connections, with focus on the ductility at different load levels. Besides, results are compared with recommendation given in EN 1994-1-1 for ductile shear connectors.

This paper presents the experimental programme of an extensive research project that deals with analysing the behaviour of compressed stainless steel columns with equal angle sections. The research focuses on different material and geometrical parameters of pin-ended angle columns produced from austenitic and lean-duplex stainless steel alloys. To assess the influences of initial imperfections on column compressive resistance caused by different manufacturing procedures, three types of angle products are included: cold-formed, hot-rolled and laser-welded sections. In order to obtain both elastic and inelastic ultimate responses, including flexural and torsional-flexural buckling modes, the lengths and cross-section geometries of specimens are selected to cover non-slender sections and slender sections covering the entire wide slenderness range. The experimental programme covers all relevant tests: 15 tensile coupon tests, 15 stub-column tests, 48 overall buckling tests on slender columns and 2 residual stress tests, including measurements of initial geometric imperfections. The purpose of these experiments is to provide a reliable database to determine design rules for angle members and extend the scope of procedures currently codified in EN 1993-1-4 (2015), not only to conventional angle profiles, but also to contemporary products such as laser-welded angles.

Even though structural elements of the elliptical hollow section (EHS) have been introduced to the construction market in the past years, the rules for their design were only partially introduced into the suitable codified procedures. The aim of this paper is to present a comparative numerical analysis of behaviour of cold-formed and hot-finished EHS columns exposed to flexural buckling under pure axial compression. Pin-ended columns of a various slenderness without lateral restrains and with incorporated geometrical imperfections are analysed. Material nonlinear behaviour is included through published experimental tensile test results, conducted in previous researches. In addition, numerical simulations of stub column behaviour are performed in order to obtain a cross-section compressive resistance. Results of the finite element analysis are compared to the design criteria defined in the draft version of Eurocode EN 1993-1-1:2015 and in North American specification for cold-formed member design AISI-S100. It is observed that North American standard provides more accurate predictions of both a cross-section resistance and a buckling column resistance. Equivalent diameter method described in Eurocode 3 led to more conservative results. According to the obtained numerical results, similar buckling behaviour is observed for both hot-finished and cold-formed columns of higher slenderness, while in the lower slenderness region, cold-formed compressed members tend to lower buckling curves. Underestimation of a column buckling resistance according to Eurocode regulations is noticed for cold-formed members of a higher slenderness., Iako se poslednjih godina šuplji profili elipsastog poprečnog preseka (EHS) mogu naći na tržištu, pravila za njihovo dimenzionisanje su tek delimično uvedena u odgovarajuće standarde za projektovanje. Cilj ovog rada jeste da prikaže komparativnu numeričku analizu ponašanja centrično pritisnutih hladnooblikovanih i naknadno termički obrađenih EHS stubova, usled fleksionog izvijanja. Analizirani su zglobno oslonjeni stubovi različitih vitkosti bez bočnog pridržanja duž elementa, uzimajući u obzir početne geometrijske imperfekcije. Nelinearno ponašanje materijala modelirano je na osnovu publikovanih eksperimentalnih rezultata testova pri zatezanju, sprovedenih u prethodnim ispitivanjima. Takođe, izvršene su numeričke simulacije ponašanja kratkih stubova kako bi se utvrdila nosivost poprečnog preseka na pritisak. Rezultati numeričke analize sprovedene metodom konačnih elemenata upoređeni su s računskim vrednostima graničnih nosivosti u skladu s revidiranom verzijom Evrokoda EN 1993-1-1:2015 i Severnoameričkom specifikacijom za projektovanje hladnooblikovanih čeličnih elemenata AISI-S100. Uočeno je da Severnoamerički standard daje preciznije predikcije – i za nosivosti poprečnog preseka i za nosivosti stuba na fleksiono izvijanje. Metoda ekvivalentnog prečnika, opisana u Evrokodu 3, daje konzervativnije rezultate. Prema dobijenim numeričkim rezultatima, slično ponašanje pri fleksionom izvijanju uočeno je kod naknadno termički obrađenih i hladnooblikovanih stubova veće vitkosti, dok u oblasti manje vitkosti, hladnooblikovani pritisnuti elementi teže nepovoljnijim krivama izvijanja. Primećeno je da Evrokod potcenjuje nosivosti na izvijanje hladnooblikovanih stubova veće vitkosti.

A numerical study of compressive capacities of stainless steel angle columns is presented in the paper in order to assess the design procedures presented in Eurocode 3. The study focuses on pin-ended hot-rolled equal angle columns made of austenitic stainless steel grade EN 1.4301. The study shows that the implementation of buckling curve b, used for the design of carbon steel hot-rolled angles, gives higher and unsafe buckling resistance of equivalent stainless steel angles in low and intermediate slenderness domains in comparison with numerical results., U radu je prikazano numeričko istraživanje tlačnog kapaciteta elemenata izvedenih kutnicima od nehrđajućeg čelika kako bi se procijenili postupci projektiranja navedeni u Eurokodu 3. Istraživanje je usmjereno na tlačne elemente izvedene kutnicima jednakih krakova sa zglobnim spojevima na kraju, u kvaliteti austenitnog nehrđajućeg čelika EN 1.4301. Utvrđeno je da primjena krivulje izvijanja b, koja se koristi za projektiranje tlačnih elemenata izvedenih kutnicima od toplo valjanog ugljičnog čelika, daje veću i otpornost na izvijanje koja nije na strani sigurnosti u slučaju ekvivalentnih tlačnih elemenata izvedenih kutnicima od nehrđajućeg čelika u područjima niske i srednje vitkosti u usporedbi s numeričkim rezultatima., Die Arbeit enthält eine numerische Studie zum Druckvermögen von Elementen aus Edelstahlwinkeln, um die in Eurocode 3 festgelegten Entwurfsverfahren zu bewerten. Die Forschung konzentriert sich auf Druckelemente, die aus gleichschenkligen Winkeln mit Gelenkverbindungen am Ende in der Qualität des austenitischen rostfreien Stahls EN 1.4301 hergestellt werden. Es hat sich gezeigt, dass die Anwendung der Biegekurve b, die für die Auslegung von Druckelementen aus warmgewalztem Kohlenstoffstahl verwendet wird, bei gleichwertigen Druckelementen aus Edelstahlwinkeln in Bereichen mit geringer und mittlerer Stärke eine höhere und nicht sicherheitsrelevante Biegefestigkeit im Vergleich zu numerischen Ergebnissen ergibt.

One of the most important acceptance issues regarding the implementation of small-scale wind turbines in urban environments is related to human comfort. Turbine-induced vibrations can have a large influence on small-scale turbine implementation for urban wind harvesting. A typical five-storey steel-framed office building with a roof-mounted, horizontal-axis wind turbine was numerically analysed. The aim of the work was to investigate the increase in vibration after the installation of the turbine. A comparison was made between floor vibrations caused by wind action on the building only and by wind action on the building and turbine combined. The results were then compared with requirements given in various design codes. The main outcome of the analysis is that the installation of the turbine did not compromise the building's serviceability.

For the past several decades, codified design of steel connections in civil-engineering is based on the component approach. For a very common end-plate connection, tension component, named T-stub, usually dictates the connections’ behaviour. This T-stub element is greatly investigated in the configuration with two bolts in a row, but configuration with four bolts in a row is usually neglected, both in the studies and codes. This paper presents an experimental investigation of T-stub elements and important aspects of their numerical modelling. Special attention is dedicated to the material testing and modelling since all of the tests were performed until bolt fracture. Uniaxial tests of steel specimens were performed using extensometers, strain gauges, and Aramis system, while bolt material is additionally tested by microscopic examination and hardness testing. In order to obtain satisfactory calibration of numerical models developed in Abaqus, knowing material parameters including damage initiation and propagation is crucial. Several iterative numerical-experimental procedures for obtaining the true stress-strain curves are outlined and compared, along with well-known Bridgman method. The advantages of using Aramis system in calibrating numerical model, for both material and assembly are demonstrated. In the end, comparisons of numerical and experimental behaviour curves are presented and satisfactory results are obtained.

A numerical study of compressive capacities of stainless steel angle columns is presented in the paper in order to assess the design procedures presented in Eurocode 3. The study focuses on pin-ended hot-rolled equal angle columns made of austenitic stainless steel grade EN 1.4301. The study shows that the implementation of buckling curve b, used for the design of carbon steel hot-rolled angles, gives higher and unsafe buckling resistance of equivalent stainless steel angles in low and intermediate slenderness domains in comparison with numerical results.

Savremeni trendovi u građevinarstvu u oblasti spregnutih konstrukcija od čelika i betona najčešće se ogledaju u povećanim zahtevima za ubrzanom gradnjom, razvojem novih vrsta sredstava za sprezanje i prefabrikovanom gradnjom. Mehanički spojena sredstva za sprezanje predstavljaju alternativu tradicionalno korištenim zavarenim moždanicima sa glavom. Veza ovakvih sredstava za sprezanje sa čeličnim nosačima ostvaruje se pomoću različitih mehaničkih spojnih sredstava koji se ugrađuju procesom eksplozivnog upucavanja. U literaturi se ova mehanička spojna sredstva najčešće označavaju kao ekseri sa eksplozivnim upucavanjem. Mehanički spojena sredstva za sprezanje čine jedinstven sistem formiran od samog sredstva za sprezanje, odnosno moždanika i mehaničkog spojnog sredstva, odnosno eksera. Stoga je njihovo ponašanje u spregnutim konstrukcijama u direktnoj vezi sa ponašanjem eksera sa eksplozivnim upucavanjem. Za razliku od zavarenih moždanika sa glavom ili zavrtenjeva kao sredstava za sprezanje koji se često koriste u zgradarstvu, ponašanje mehanički spojenih sredstava za sprezanje u literaturi nije još uvek detaljno objašnjeno. U ovom radu dat je prikaz X-HVB moždanika kao najpoznatijeg predstavnika mehanički spojenih sredstava za sprezanje. Objašnjeno je njihovo ponašanje u spregnutim konstrukcijama i prikazane su osnovne karakteristike eksera sa eksplozivnim upucavanjem.

The Railway road bridge in Novi Sad is situated on the international railroad Belgrade-Budapest. The bridge is designed for two railway tracks (with design speed of 160 km/h), two road lanes and two footpaths. The bridge structure consists of four structures: two approach composite bridges at the banks and two steel tied network arch bridges over the river and transition structure between two arches. The spans are 27.0+177.0+ 3.0+219.0+48.0 m, totally 474.0 m in length. The rises of arches are 34.0 m and 42.0 m respectively. The width of the bridge is 31.440 m. The arches and ties, as well as the girders of the approach spans, are steel box girders. The decks of all bridge structures are the composite reinforced concrete slabs with thickness of 300 mm, locally 400 mm. The launching was very complex, in both analysis and construction. The arch bridges were fully assembled on the banks and launched by skids over the bank and by pontoons over the river, to the final position on piers. The bridge was designed fully according to European standards and additionally - according to requirements of German codes DIN-Fachbericht 101 to 104 Edition 2009 and Deutsche Bahn Richtlinie 804, Edition 2003. The bridge is, despite of heavy loads and structural complexity, very rational in steel volumes and construction costs as well. The bridge is also, with the arch span of L = 219 m, the bridge with the longest span in the world in the category of tied network arch bridges with two rail tracks. The bridge is open to rail traffic at 7th April 2018.

Different types of shear connectors which assure composite action between steel profile and concrete slabs have been developed during decades, considering different shapes, installation equipment and installation process. Also, three main characteristics of shear connectors, shear resistance, stiffness and ductility are specific for each type of shear connector. Widely used shear connectors for composite constructions of buildings and bridges are headed studs and different types of perfobond shear connectors. Different behaviour of these types of shear connectors, mainly reflected in unsatisfactory behaviour of headed studs resulted from fatigue problems, reflects in their various applications. Numerous experimental and numerical investigations performed with headed studs and perfobond shear connectors through standard push-out tests resulted in development of design procedures which are proposed by different authors or can be found in current design codes such as EN 1994-1-1, ANSI/AISC-360-05 and JSCE. Comparison of heads stud’s and perfobond shear connector’s beahviour through experimental results of standard push-out tests are presented in this paper. Experimentally obtained shear resistance of four headed studs with 16 mm diameter and 100 mm height, positioned in one row into envisaged openings of prefabricated composite decks, with shear resistance of perfobond shear connectors are compared. Main differences in respect of ductility, stiffness and different failure modes which can be noticed for these types of shear connections, obtained from experimental investigation are analyzed in this paper. Comparative analysis includes different shapes, dimensions and specimen’s layout of perfobond shear connectors, experimentally investigated through standard push-out tests which results are available in different literature. Numerical analysis included perfobond shear connectors positioned into envisaged openings of prefabricated composite decks with same dimensions and

Although all metals lose strength and stiffness when they are exposed to fire, the reduction of mechanical properties considerably varies between different metals. In contrast to carbon steel, austenitic stainless steel has better response at elevated temperatures due to relatively high content of alloying elements. The type of metallurgical microstructure crucially affected on material response and global behaviour of structural elements under fire conditions. Despite the fact that carbon steel and stainless steel have different constitutive patterns, EN 1993‐1‐2 states that resistance of structural elements made from these materials should be checked using the same fire design procedure. This paper presents numerical analysis of buckling resistance of compressed members exposed to fire, without fire protection. Finite element analysis is conducted using the ABAQUS software. The study points out the structural performance of columns made of stainless steel cold‐formed hollow section and hot‐rolled I‐section in grade 1.4301 and identical columns from carbon steel grade S235 at high temperatures. Sensitivity to initial imperfections is also assessed. The thermal and mechanical properties of carbon and stainless steel are taken from EN 1993–1‐2. Development of temperature into the columns in fire condition is obtained from standard fire curve, according to ISO834. The numerical predictions of buckling response are compared with results of design procedure according to Eurocodes EN 1991–1‐2 and EN 1993–1‐2. The aim of this paper is estimation of acceptability and accuracy level of the mentioned design guidelines in the treatment of buckling phenomena of stainless and carbon steel structural elements at elevated temperatures.

Construction industry is constantly facing new demands towards fast construction and smallest possibly quantity of work at the construction site. These increasing demands, in the field of composite construction of buildings and bridges, resulted in development of different types of prefabricated composite decks during decades and group arrangement of different types of shear connectors. Positioning of shear connectors into envisaged openings of prefabricated composite decks contributes to smaller quantity of concrete needed to infill openings of prefabricated composite decks. Composite action between steel profile and concrete decks can be achieved using X‐HVB shear connectors with powder‐actuated fasteners. Anchorage mechanisms developed between steel profile and fasteners during installation process of powder‐actuated fasteners are resulting in composite action between steel and concrete. Relatively simple and fast installation process, without requirements for additional equipment and electrical power on the site is characteristic for this type of shear connectors. Experimental investigation of X‐HVB shear connectors in prefabricated composite decks through standard push‐out tests, according to EN 1994‐1‐1 is presented in this paper. Shear connectors are positioned at the envisaged openings of prefabricated composite decks at the minimal longitudinal and transversal distances, recommended by the manufacturer. Two different orientations of shear connectors, forward and backwards to shear force direction are experimentally investigated and presented in this paper. Experimentally obtained characteristic shear resistance are compared with recommendations given by manufacturer. Characteristic slip at failure obtained from experimental investigation is compared with requirements given in EN 1994‐1‐1 in order to determine if this type of shear connector is considered as ductile. Eight specimens in two series are experimentally investigated through standard push‐out test

This paper presents parametric linear-elastic analysis of flexural buckling of idealised non-uniform member and nonlinear analysis of flexural buckling with equivalent imperfections, using software package Abaqus. The analysis includes hinged and cantileverstepped members, where the stiffness ratio of the upper and lower segments and the ratio of the values of axial forces at the top and at the change in the cross-section are varied. The aim of this paper is to define graphic and table models for determining effective lengths coefficients of non-uniform members' segments based on a relevant and reliable database that was obtained using the Finite element method. In addition, the reliability of the method for calculating the flexural stability of the compressed columns according to EC3 was evaluated in which the critical load value was determined in the previous step using the Elastic buckling analysis of idealised elements., Rad prikazuje parametarsku linearno-elastičnu analizu fleksionog izvijanja idealizovanog neuniformnog elementa i nelineranu analizu fleksionog izvijanja sa ekvivalentnim geometrijskim imperfekcijama, urađenu u programu Abaqus. Analizom su obuhvaćeni zglobno oslonjeni i konzolni elementi sa stepenastom promenom poprečnog preseka, kod kojih je variran odnos krutosti gornjeg i donjeg segmenta i odnos vrednosti aksijalnih sila na vrhu i na mestu promene preseka. Rezultat rada je definisanje grafičkih i tabelarnih modela za određivanje koeficijenata dužine izvijanja segmenta neuniformnih elemenata na osnovu relevantne i pouzdane baze podataka koja je dobijena primenom Metode konačnih elemenata. Kao dodatak, ocenjena je pouzdanost metode proračuna fleksione stabilnosti pritisnutih stubova prema EC3 u kojoj je vrednost kritične sile izvijanja određena u prethodnom koraku primenom Elastične analize izvijanja idealizovanog elementa.

Grouped headed studs may be successfully utilized to achieve the longitudinal shear connection between prefabricated slabs and steel beams. The behaviour of the studs and the ultimate resistance of the group were analysed using the results of experimental push tests and by employing advanced FE analyses. Different arrangements of studs in the group were investigated, focusing on minimal distance between the studs. It is demonstrated that the full shear resistance of a group of headed studs is achieved even when the distances between the studs are less than the minimum requirement according to EN 1994-1-1. Concrete class C30/37 is the minimum that should be used. Furthermore, the paper presents a new model for calculating the shear resistance of grouped headed studs. The proposed design model is based on an equivalent stud diameter and can be used for various arrangements of headed studs in a group. The shear resistance formula and the requirements for ductility are consistent with the existing Eurocodes. Fatigue loading is not considered in this paper, so the proposed recommendations are valid for buildings including multi-storey car parks.