Experimental study of composite concrete cellular steel beams

The main objective of this study is to compare the structural behavior of composite steel– concrete beams using cellular beams with and without steel ring stiffeners placed around the web openings. An IPE140 hot rolled I-section steel beam was used to create four specimens: one without openings (control beam); one without shear connectors (non-composite); a composite steel–concrete beam using a cellular beam without strengthening (CLB1); and a composite steel–concrete beam using a cellular beam (CLB4-R) with its openings strengthened by steel ring stiffeners with geometrical properties Br = 37mm and Tr = 5mm. CLB1 was fabricated with openings of 100mm diameter and a 1.23 expansion depth ratio, while CLB4-R was fabricated with openings of 130mm diameter, a 1.42 expansion depth ratio. Both beams were 1700mm in length with ten openings. The results of this experiment revealed that the loads applied to CLB1 and CLB4-R at deflection L/360 exceeded the load applied to the control specimen at the same deflection by 149.3% and 177.3%, respectively. The results revealed that the non-composite beam had an ultimate load 29% lower than that of the control beam. The ultimate load on CLB1 was 5.3% greater than that of the control beam, and failure occurred due to web-post buckling. While the ultimate load of the CLB4-R beam was 18.43% greater than that of the control beam, the Vierendeel mechanism was indicated as the failure mode.

Shrinkage-Induced Response of Composite Steel–Concrete Slabs: A State-of-the-Art Review

Composite steel–concrete slab is a floor typology widely used for building applications. Their design is usually governed by serviceability limit state requirements associated with the time-dependent response of the concrete. In this context, this paper presents a state-of-the-art review of research carried out to date on the long-term behavior of composite steel–concrete slabs. The particularity of this time-dependent response relies on the fact that the concrete cannot dry from the underside of the slab due to the presence of the profiled sheeting while it can dry from its upper surface. In the first part of the paper, a review of the work carried out on the identification of the time-dependent response of the concrete is presented by considering the peculiarities that occur due to the non-symmetric drying condition related to composite slabs. Particular attention is given to shrinkage effects and to the occurrence and influence of the non-uniform shrinkage gradient that develops in this form of construction over time. This is followed by the description and discussion of the experimental work performed on both simply-supported and continuous static configurations of composite slabs. In particular, the work published to date is summarized while highlighting the key parameters of the test samples and of the testing protocols adopted in the experiments. In the last part of the paper, available theoretical and design models proposed for the predictions of the shrinkage-induced behavior of composite slabs are presented and discussed.

Push-out tests of shear dowels

Continuous shear connectors in a shape of dowels are one of the newer shapes of composite steel-concrete bridges. In this article results of push-out tests of such a dowel with geometry designed at Faculty of Civil Engineering, Technical University of Kosice are presented and compared to the previous research.

Push-Out Test and FEM Analysis of Continuous Shear Connector

Composite steel concrete bridges with embedded continuous shear connectors are one of the newer popular options for short span (up to 20 m) bridges. They can be used for both road and railway bridges and due to their low structural height, nowadays, they are also a welcome alternative for bridge reconstructions – the concrete part serves as the bridge deck as well as the main structure. Unfortunately, In the Slovak Republic, no such bridges have been built as of yet (2020). At Technical University of Kosice, Department of Steel and Timber Structures, an extensive research regarding the steel shear connectors have been launched. Its goals are to bring new, easier for construction (due to prefabrication process), more resistant with even lower structural height, and more economical (due to lesser usage of materials and quick construction) geometrical solutions for composite steel concrete bridges as well as to open and popularize this solution for developers in the Slovak Republic. In this article, one of the new types is presented. It has a cross-section in a shape of a trapezoid, with holes in all its sides, except the bottom flange. Their purpose is to create concrete studs and secure full shear transmission with higher shear resistance, but they also serve to create space for transverse reinforcing bars. Its geometrical and material characteristics are closely specified. Results and process of push-out tests performed in Laboratory of Excellent Research onto three specimens are described and compared to results of finite element analysis simulation performed in Abaqus software.