Uvođenje evrokodova u građevinsku regulativu Srbije – prikaz trenutnog stanja

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

Metalne konstrukcije

U ovom radu su ukratko prikazana najnovija ostvarenja u oblasti čeličnih konstrukcija. Obuhvaćeni su neki od najznačajnijih objekata, kao i savremeni propisi za proračun čeličnih konstrukcija - Evrokod 3. Pored toga, ukratko su predstavljana četiri rada iz oblasti čeličnih konstrukcija koja su prispela na XXIII Kongres i Simpozijum Jugoslovenskog društva za ispitivanje i istraživanje materijala i konstrukcija

A contribution to the bearing analysis of the fasteners in thin gauge steel members

У овом раду приказана су теоријска и експериментална истреживања у области веза танкозидних челичних елемената остварених помоћу механичких спојних средстава: обичних завртњева, високовредних завретњева и самонарезујућих завртњева. Испитивани су смичући спојеви и спојеви оптерећени на затезање. Код смичућих спојева анализиране су везе на преклоп и са подвезицама. Варирана су четири параметра: дебљина лима (2 и 4 mm), ивично растојање (20 и 40 mm), тип везе (на преклоп или са подвезицама), као и врста спојног средства. Да би се прецизније утврдило понашање основног материала код оваквих веза, поред експерименталне извршена je и нумеричка анализа, применом методе коначних елемената. Коришћени су готови софтверски пакета (програч ПАК). На основу поменутих теоријско-експерименталних истраживања утврђени су потенцијални видови лома и дате препоруке за прорачун носивости. Због свог специфичног понашања испитиване су само везе оптерећење затезање остварене помоћу самонарезујућих завртњева. Испитивање je спроведено у уређају који je посебно конструисан за ову прилику. Установљени су могући видови лома као и фактори од којих зависи који ће се тип лома појавити.Theoretical and experimental researches in the field of connections of steel thin gauge members made with fasteners (bolts, high resistance bolts and screws) are shown in this paper. Both of shear and tension connections have been examined. In shear connections, lap connections and connections with splices have been analysed. Four parameters have been varied: thickness of the steel plate (2 and 4 mm), edge distance (20 and 40 mm), type of the connections (lap or splices) and kind of fastener (simple bolts, high resistance bolts and screws). Numerical analysis by finite element method has been done in the sense of precise establishing of the basic material behavior in such a kind of connections. Existing computer programs have been used (PAK). According these, mentioned, theoretical-experimental research potential types of failure have been defined and some recommendations for calculation of the bearing capacity have been given. Only tension connections with screws have been examined, because of their specific behavior. Testing procedure has been carried out in special device, which had been designed for this dissertation. Possible types of failure have been defined, and factors that influence which type of failure will appear, have been given, as well

Metalne konstrukcije

U ovom radu su ukratko prikazana najnovija ostvarenja u oblasti čeličnih konstrukcija. Obuhvaćeni su neki od najznačajnijih objekata, kao i savremeni propisi za proračun čeličnih konstrukcija - Evrokod 3. Pored toga, ukratko su predstavljana četiri rada iz oblasti čeličnih konstrukcija koja su prispela na XXIII Kongres i Simpozijum Jugoslovenskog društva za ispitivanje i istraživanje materijala i konstrukcija

Fleksiono izvijanje naknadno termički obrađenih i hladnooblikovanih stubova elipsastog poprečnog preseka: Numerička uporedna analiza

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

Recent research on ductility of perforated shear connectors

Significant implementation of Perfobond shear connectors in construction of composite steel-concrete structures resluted in development of entirely new type of shear connectors, denoted as perforated shear connectors. Except the shear resistance of this type of shear connector, the overall behaviour of shear connection is strongly influenced by shear connector geometry. Ductility of shear connector, which is strongly influenced by connectors geometry, defines the behaviour of shear connection. The results of resent research on ductility of perforated shear connectors are obtained from numerical models which are calibrated with results of experimental investigation of this type of shear connector. The results of extensive numerical analysis were used for definition of direct relation between connectors ductility and geometry and presented in this paper

The influence of a roof mounted small-scale HAWT on headed studs fatigue resistance

Installation of small-scale wind turbines in urban regions can gain higher energy efficiency, considering that energy production takes place at the place of its consumption. The aim of this work is to investigate effects of installation of a small-scale horizontal axis wind turbine (HAWT) on a roof structure of an existing building. This paper is focused on fatigue resistance of headed studs that are preinstalled in the building roof composite steel-concrete deck to ensure shear connection and that are indirectly dynamically loaded during wind turbine operation. Turbulent wind profiles with mean wind speeds from 3 m/s up to 15 m/s are generated and applied on the model of HAWT with 5 m rotor diameter using Ashes software package. Time-dependent forces and bending moments induced by wind turbine operation are applied on the composite roof deck model. Based on the time-history of transverse force in the composite steel-concrete beam and wind speed records during a year, fatigue cumulative damage of headed studs is calculated according to Eurocode. It is obtained that installation of HAWT do not significantly affect residual life of headed studs with reference to fatigue

The influence of a roof mounted small-scale HAWT on headed studs fatigue resistance

Installation of small-scale wind turbines in urban regions can gain higher energy efficiency, considering that energy production takes place at the place of its consumption. The aim of this work is to investigate effects of installation of a small-scale horizontal axis wind turbine (HAWT) on a roof structure of an existing building. This paper is focused on fatigue resistance of headed studs that are preinstalled in the building roof composite steel-concrete deck to ensure shear connection and that are indirectly dynamically loaded during wind turbine operation. Turbulent wind profiles with mean wind speeds from 3 m/s up to 15 m/s are generated and applied on the model of HAWT with 5 m rotor diameter using Ashes software package. Time-dependent forces and bending moments induced by wind turbine operation are applied on the composite roof deck model. Based on the time-history of transverse force in the composite steel-concrete beam and wind speed records during a year, fatigue cumulative damage of headed studs is calculated according to Eurocode. It is obtained that installation of HAWT do not significantly affect residual life of headed studs with reference to fatigue

Design recommendations of floor vibrations induced by human activities

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

Najnovije evropske preporuke za proračun širokih veza greda-stub sa čeonom pločom

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