Ponašanje grupe elastičnih moždanika kod spregnutih nosača od čelika i betona

Shear connection with headed studs in group arrangement is simple and frequently used solution for shear connection between steel beam and precast concrete slabs. Reducing the distance between the adjacent headed studs in the group enables smaller holes in the slab to accommodate grouped studs. This paper presents the research about the shear resistance of grouped studs and the main result published in PhD Thesis “The analysis of headed stud group behavior in composite steel-concrete beams” on University of Belgrade Faculty of Civil Engineering.Smičući spoj ostvaren grupom moždanika sa glavom je jednostavno i često korišćeno rešenje za podužni smičući spoj između čeličnog nosača i montažne armiranobetonske ploče. Redukcijom rastojanja između moždanika u grupi omogućava se izvođenje manjih otvora u ploči za smeštaj moždanika. Ovaj rad daje prikaz istraživanja o nosivosti na smicanje grupe moždanika i dobijenih rezultata koji su objavljeni u doktorskoj disertaciji “Analiza ponašanja grupe elastičnih moždanika kod spregnutih nosača od čelika i betona” na Univerzitetu u Beogradu na Građevinskom fakultetu

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 analysis of headed studs group behavior in composite steel-concrete beam

Diskontinualni podužni smičući spoj ostvaren grupama moždanika je jednostavno i široko rasprostranjeno rešenje za sprezanje čeličnih nosača i montažnih armiranobetonskih ploča. Ovaj rad analizira mogućnost primene grupa moždanika sa redukovanim rastojanjima između susednih moždanika u grupi. Osnovni cilj rada je da se istraži mogućnost smanjenja rastojanja između susednih moždanika u grupi u odnosu na minimalno propisana rastojanja. Smanjenje rastojanja između moždanika u grupi i dimenzija grupe, omogućava izvođenje manjeg otvora u armiranobetonskoj montažnoj ploči potrebnog za smeštaj moždanika. Prikazano je sopstveno eksperimentalno istraživanje nosivosti grupa moždanika, sprovedeno na Građevinskom fakultetu Univerziteta u Beogradu. Eksperimentalnim istraživanjem analizirana je mogućnost primene grupe moždanika kod spregnutih greda u zgradarstvu. Ispitana je nosivost, deformabilnost i ponašanje, podužnog smičućeg spoja ostvarenog grupama moždanika. Glavni parametri analizirani u radu su: raspored moždanika u grupi, orijentacija grupe moždanika u odnosu na pravac podužne sile smicanja i međusobno rastojanje moždanika. Istraživanjem je obuhvaćeno pet različitih dispozicija grupa od četiri elastična moždanika sa glavom, kod kojih su međusobna rastojanja manja od minimalno propisanih rastojanja u Evrokodu 4. Cilj istraživanja je i da se utvrdi kako smanjenje minimalnih propisanih rastojanja između moždanika utiče na ponašanje, odnosno nosivost, duktilnost i ukupne deformacije podužnog smičućeg spoja. Korišćeni materijali, polazne pretpostavke i postupak ispitivanja su u skladu sa Evrokodom 4. Metodom konačnih elemenata simulirano je eksperimentalno istraživanje a kalibrisan numerički model sa eksperimentom je poslužio za izvođenje zaključaka o ponašanju veze ostvarene grupom moždanika sa glavom. Uočeni su i definisani modeli loma koji se mogu javiti u podužnim smičućim spojevima, formiranim grupama moždanika. Na uočenim modelima loma definisana su granična stanja nosivosti grupe moždanika. iv Pomoću numeričkih modela urađena je i parametarska analiza koja je obuhvatila različite prečnike i grupe moždanika...Discontinuous shear connection with groups of headed studs is simple and widespread solution for connection between steel beam and precast concrete element. This thesis analyzes the possible applications of headed studs group with reduced distances between adjacent headed studs in the group. The main objective of this study was to investigate the possibility of reducing the spacing between adjacent headed studs in the group compared to the minimum required in Eurocode 4. Reducing the distance between the headed studs in the group and the dimensions of the group, would allow construction of a smaller hole in the reinforced concrete precast plate needed to accommodate the headed studs. The paper presents the results of the experimental research conducted on push-out tests at the Faculty of Civil Engineering at the University of Belgrade. Throughout the experiment there has been analyzed the possibility of using the headed studs group in composite beams for buildings. The capacity, deformability and behavior of shear connection with grouped headed studs was investigated (analyzed). A shape of group arrangement along with its orientation to the applied load and distance between the studs were variables considered. The study includes five different groups of four headed studs, with the distance between headed studs less than the minimum distances required in Eurocode 4. The aim of the research is to determine how the reduce of the minimum required distance between the headed studs affects to the behavior, shear capacity, ductility and total longitudinal shear deformation of the shear connection. The materials, initial assumptions and test set up are in accordance with Eurocode 4. The FEM model is used to simulate the experiment. Calibrated FEM models with push-out tests were used to draw conclusions about the behavior of shear connection with group of headed studs. The fracture models which can occur in longitudinal shear connection with headed studs group were identified and defined in the paper. Ultimate limit state for headed stud group based on the fracture models is defined. Parametric analysis, which included a models with different diameters of headed studs and layout of groups were performed by numerical models. vi Based on the results, the recommendations were derived for determining the shear capacity of the headed studs group, when the distance between studs is less than required by Code. The reduction coefficient was suggested to determine the shear capacity of the headed studs group. Derived recommendations can be applied to shear connections in composite steel-concrete beams applied in buildings..

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

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

Experimental investigation of X-HVB shear connectors in prefabricated composite decks

Increasing demands towards fast construction and smallest possible quantity of work resulted in development of different types of prefabricated composite decks and group arrangement of shear connectors. Short presentation of basic characteristics of X-HVB shear connectors and powder-actuated fasteners is given in this paper. Experimental investigation of X-HVB shear connectors through standard push-out tests, according to EC4:2004, is presented in this paper. Two different orientations of shear connectors, forward and backwards to the shear force are experimentally investigated

Non-linear lateral buckling analysis of aluminium alloy channel beams

This research paper presents the comparative analysis of lateral-torsional buckling resistance of structural aluminium alloy members, accounting for the effects of initial geometrical imperfections. The results of non-linear numerical analysis, conducted using ABAQUS software, are compared with the results obtained by utilizing the procedure for calculation of LTB resistance suggested by EN 1999-1-1. The purpose of the analysis is the assessment of accuracy of the above-mentioned code-prescribed design method using the real Al channelsection members with initial imperfections on which the load does not act in the shear centre

Numerical parametric study on steel-concrete composite floor beams vibrations due to pedestrian traffic

Human perception of floor vibrations and uncompromised serviceability of equipment are two most important acceptability criteria considering floor vibrations. While verification of deflection is a simple and well-known procedure in structures’ design for serviceability limit state, the fulfilment of floor vibrations acceptability criteria are presented in different standards in the form of various calculation procedures. Results achieved through those calculation procedures are presented in the form of various classification of floor structures. Classification of composite floor structures due to vibrations is inconsistent considering different calculation procedures. Comparison of various calculation procedures for the definition of composite floor vibrations is presented in this paper. In addition, a parametric analysis is performed on the wide range of steel-concrete composite floor structures, through analysis of various composite floor layouts and a wide range of imposed loads values. The analysis of the relation between deflection, vertical vibrations and accelerations of steel-concrete composite floor beams is presented in this paper. The results of the parametric analysis are given through direct relation between deflections of composite beams and achieved floor class for the fulfilment of vibrations acceptability criteria due to the pedestrian walking

Demountable composite steel-concrete floors: A state-of-the-art review

U skladu sa zahtjevima za održivi razvoj u svim segmentima industrije, brojna su istraživanja u području spregnutih čelično-betonskih konstrukcija usmjerena na razvoj demontažnih sredstava za sprezanje. Proteklih godina predlagana su različita demontažna sredstva za sprezanje koja su različitim mehanizmima prenosila posmičnu silu između čeličnog profila i betonske ili spregnute ploče. U ovom radu prikazana su najnovija dostignuća na tu temu dajući sažetke eksperimentalnih i numeričkih rezultata istraživanja vezano uz potisna (push-out) ispitivanja i ispitivanja na nosačima.In keeping with current demands for sustainable development in all segments of the industry, numerous research in the field of steel-concrete composite structures has been focused on developing demountable shear connectors. In the past years, various demountable shear connectors have been suggested, with various mechanisms for transferring shear force between a steel profile and a concrete or composite slab. In this paper, a state of the art on the topic is given, and experimental and numerical research results of push-out and beam tests are summarized