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In the past few decades, demountable connectors have often been used for connections in composite and mixed steel-concrete structures to reduce construction time and costs. Furthermore, the application of demountable connectors enables the reuse of structural elements in these structures, which leads to sustainable design and a circular economy. In this paper, the demountable connector is made out of two parts: (1) mechanical coupler and rebar anchor placed in formwork before casting the concrete element, and (2) steel bolt used for connecting steel to the RC element. Although this connector is increasingly being used in contemporary building structures, its behaviour in composite connections is still insufficiently defined. The paper presents the results of experimental tests and numerical analysis of the connector with a mechanical coupler, focusing on the local behaviour of the tapered threaded connection between the mechanical coupler and rebar anchor.

Modern conustructions of pedestrian bridges must satisfy functional and increasingly complex architectural requirements. In order to achieve the attractive design of pedestrian bridges, modern constructions generally differ from older, conventional solutions. The vibration problem of such structures shows that the dynamic response of the structure is governing for the design. This paper presents the comparative analysis of several dynamic models of pedestrian loads, described in various standards, guidelines, and recommendations. On the example of an arched pedestrian bridge, comparative analysis of the structure behavior due to the effect of pedestrian load was performed using numerical simulations in the SOFISTIK software, with the results obtained by analytical calculation procedures.

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.

Thin-walled cylindrical and conical shells represent one of the most complex structural elements considering their behaviour and susceptibility to buckling. A brief theoretical review including the presentation of different currently available design recommendations is given in this paper. Influence of initial imperfections on nonlinear behaviour of cylindrical and conical shells is also presented through numerical analysis. Shells with different wall thicknesses and different values of initial imperfections, but constant length and diameter of shell are analysed. Numerical analysis includes materially and geometrically nonlinear analysis of cylindrical and conical shells, using experimentally obtained stress-strain relation of carbon steel and stainless steel. Material nonlinearity and initial geometrical imperfections resulted in significantly lower buckling resistance of shells.

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.

The latest demands in construction design towards slender structures with large spans, large open interiors, unconventional shapes and constructional solutions are leading to the extensive problems related to the serviceability limit state. Slender structures with large spans have lower natural frequencies and lower natural damping, considerably influencing the dynamic response of the structure. Annoying vibrations induced by human activities can significantly affect the structure's functionality, comfort of people and quality of life. Design recommendations for composite steel-concrete floor vibrations can be found in different standards. This paper presents a short overview of design procedures for vibrations of composite steel-concrete beams and design recommendations of floor vibrations induced by human activities, through two design criteria.

Implementation of demountable beams in steel‐concrete composite floors enables structure reuse during several life cycles, consequently leading to savings in material consumption and reduction of emissions, providing overall ecological benefits. The behaviour of the innovative demountable beam with a shear connection consisting of headed studs and bolts is analysed in this paper. The proposed beam is formed of a steel profile and a steel‐concrete composite slab cast in open trough profiled steel sheeting. Headed studs, welded to the additional steel angles, are placed in sheeting ribs, whereas bolts are installed between ribs, connecting the steel angles and profile flange. A numerical FE model of a full‐scale steel‐concrete composite beam has been developed to analyse the beam behaviour under service loads. Experimental results of push‐out tests have been used to describe the load‐slip behaviour of headed studs, whereas bolt response has been simulated according to the experimental investigations of lap joints with preloaded bolts and oversize holes. The parametric study has been conducted by varying the bolt diameter, grade and bolt hole size. The results have validated the applicability of the proposed system, confirming the fulfilment of serviceability limit state requirements. [ABSTRACT FROM AUTHOR]

Cartridge fired pins, also known as powder actuated fasteners, have a wide application in different construction industry fields, mostly for joints of cold‐formed structural elements and profiled steel sheeting, or for installation of shear connectors in composite steel‐concrete structures. Installation of cartridge fired pins is mostly governed by high energy introduction from installation device and mechanical fastener to the steel base material, without initial predrilling of holes. Therefore, large plastic deformations of base material are developed through installation procedure, together with various anchorage mechanisms between fastener and base material. This paper presents experimental investigation of most important influence parameters on behaviour and resistance of cartridge fired pins, such as adjusted installation power level on installation device and steel base material strength. Experimental investigation involved X‐ENP‐21 HVB cartridge fired pins through double‐sided shear tests, tension tests with fasteners installed over X‐HVB shear connector with two different steel grades (S275 and S355) and two installation power levels (2 and 3.5), and tension tests with fasteners installed over two thicknesses of profiled steel sheeting (0.8 mm and 1.0 mm). Cartridge fired pin resistances together with corresponding failure mechanisms were experimentally quantified and presented in this paper. [ABSTRACT FROM AUTHOR]

Multi-storey car park buildings with steel–concrete composite floor structures are widespread in construction due to the distinct benefits of the implemented structural system. Although there are various possibilities for accomplishing composite action between a steel beam and a concrete slab, some solutions, such as friction-grip bolts commonly applied in the 1970s, did not show good durability. An example is the multi-storey car park building "Obilićev venac" in Belgrade. This case study presents two methods for life extension of the car park building structure. Both approaches focus on applying welded headed studs with the primary intention of providing a durable shear connection. While the first method has been applied during the structure's reconstruction, the second method is proposed as a novel solution for implementation in steel–concrete composite floors. The application of the proposed connection is discussed and the results of the experimental and numerical research conducted are presented. [ABSTRACT FROM AUTHOR]

For obtaining shear resistance of a welded headed stud in profiled steel sheeting, EN 1994‐1‐1:2004 defines reduction factors that should be multiplied with the resistance of a headed stud in a solid concrete slab. Two reduction factors are prescribed, for sheeting ribs that are parallel and transverse to the supporting beam. However, the design code does not recognise cases when the angle between ribs and the beam is in the range between 0° and 90°. This research is focused on the specific case in the steel‐concrete composite beam design when the angle between profiled sheeting ribs and the beam is 45°. The experimental investigation has been conducted through push‐out tests, comparing the response of the connection with a rib‐to‐beam angle of 45° and the connection with ribs transverse to the supporting beam. In addition, numerical models based on finite element analysis have been made and validated against experimental data. According to the obtained results, similar failure mechanisms manifested through concrete pull‐out failure and separation of the concrete cone are observed in shear connections with rib‐to‐beam angles of 45° and 90°. An increase in the connection resistance is noticed with the decrease of a rib‐to‐beam angle. [ABSTRACT FROM AUTHOR]

During the assembling of a steel structure with anchors, grout should be used in connections between steel elements and a reinforced concrete support element. In horizontal and vertical joints, grout is used as a good construction practice for solving geometric tolerance problems. Grout can be used with cast‐in anchors or post‐installed anchors. However, the relation between anchor shear resistance and characteristic grout compressive strength is not described in detail in technical regulations. The behaviour of a connection considering achieved slip tolerances should match the boundary conditions set in the global analysis. In the support joint, grout properties could influence the value of the slip between a steel part and a concrete part of the joint. Slip value could be significant for the relevant design cases featuring the interaction of shear force and tension force. In this paper, results of the push‐out test conducted on anchors are presented. Based on the experimental test, the finite element analysis was performed to investigate the shear connection behaviour. According to the preliminary results, it can be concluded that a grout strength and a grout thickness influence the connection response when serviceability loads are applied, although they do not influence the ultimate load bearing capacity of anchors. In some cases, using the contemporary solutions of high strength grout materials, the slip between steel and concrete parts in the connection could be reduced. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]