Effect of the steel material variability on the seismic capacity design of steel-concrete composite structures : a parametric study

International audienceModern seismic codes recommend the design of ductile structures able to absorb seismic energy through high plastic deformation. Since seismic ductile design relies on an accurate control of plastic hinges formation, which mainly depends on the distribution of plastic resistances of structural elements, efficiency of the design method strongly depends on the actual mechanical properties of materials. The objective of the present contribution is therefore to assess the impact of material variability on the performance of capacity-designed steel-concrete composite moment resisting frames

The SMARTCOCO design guide for hybrid concrete-steel structures

[EN] Standard buildings in steel and in reinforced concrete are constructed by two different industrial sectors with little interaction. Even steel-concrete composite buildings remain designed as steel structures, with a limited benefit of the presence of concrete slabs. For some years however, a more integrated design between both materials is used, merely in high rise and heavy loaded structures. This new trend is not supported by actual standards that give little guidance for the specific arrangements that come from this new practice. The RFCS SMARTCOCO research project is intended to fill these gaps in knowledge and provide design guidance for some composite elements covered neither by Eurocode 2 nor by Eurocode 4 : composite columns or walls reinforced by several fully encased steel sections, reinforced concrete columns reinforced by one steel section over the height of one storey and concrete flat slabs or beams connected to columns or walls by means of steel shear keys. Gaps in knowledge are mostly related to force transmission between concrete and embedded steel profiles. A generic design approach has been developed and then used to design test specimens. The results have been used to calibrate the design proposals. The output is a design guide which complements Eurocode 2 and 4.This paper was developed in the frame of the SMARTCOCO project funded by RFCS, the Research Fund for Coal and Steel of the European Commission, Research grant agreement RFSR-CT-2012-00031 Smartcoco. The companies BESIX and ArcelorMittal are also acknowledged for their involvement in the project.Somja, H.; Hjiaj, M.; Nguyen, QH.; Plumier, A.; Degee, H. (2018). The SMARTCOCO design guide for hybrid concrete-steel structures. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 749-755. https://doi.org/10.4995/ASCCS2018.2018.7023OCS74975

Influence of variability of material mechanical properties on seismic performance of steel and steel-concrete composite structures

Modern standards for constructions in seismic zones allow the construction of buildings able to dissipate the energy of the seismic input through an appropriate location of cyclic plastic deformations involving the largest possible number of structural elements, forming thus a global collapse mechanisms without failure and instability phenomena both at local and global level. The key instrument for this purpose is the capacity design approach, which requires an appropriate selection of the design forces and an accurate definition of structural details within the plastic hinges zones, prescribing at the same time the oversizing of non-dissipative elements that shall remain in the elastic field during the earthquake. However, the localization of plastic hinges and the development of the global collapse mechanism is strongly influenced by the mechanical properties of materials, which are characterized by an inherent randomness. This variability can alter the final structural behaviour not matching the expected performance. In the present paper, the influence of the variability of material mechanical properties on the structural behaviour of steel and steel/concrete composite buildings is analyzed, evaluating the efficiency of the capacity design approach as proposed by Eurocode 8 and the possibility of introducing an upper limitation to the nominal yielding strength adopted in the design

EXPERIMENTAL TESTING ON MODERN CLAY MASONRY STRUCTURES

During the past few years, the authors of this paper, in close collaboration with Wienerbergermain European producer of clay masonry units -and with other academic partners (University of Bristol, LNEC, University of Mons), have been involved in a number of experimental campaigns aiming at a good characterization of modern clay masonry structural elements in the perspective of an accurate prediction of load-bearing clay masonry buildings subjected to seismic loading. These test results are covering different scale of specimens as well as different loading procedures. More precisely, the list of tested configurations is the following: 11 horizontal cyclic tests on walls or wall combinations under pre-compression, including: o 1 reference plain wall; o 3 walls comprising acoustic isolation devices; o 4 walls with a door opening; o 3 walls with a perpendicular flange wall. 4 shaking table tests on single walls with and without acoustic isolation systems; 2 shaking table tests on two-storey full-scale houses; A full set of out-of-plane pushover and semi-cyclic bending tests on 1 m² wallets. The detailed test results have been presented in various publications, included in other papers submitted in the present ECEES conference for what regard the most recent ones. The objective of the present contribution is therefore: To give a synthetic overview of this extensive corpus of experimental results; To evidence the advantages, drawbacks and complementarities of the different size and configurations of specimens and of the different testing procedures; To summarize the main outcomes that can be taken out of these results in the perspective of efficient prediction of the seismic behaviour of modern masonry buildings

Impact of the material variability on the efficiency of seismic capacity design of steel-concrete composite structures

International audienc

Shear capacity of slabs with voiding elements

In the current version of EN 1992-1-1, the shear and punching capacity of beams and slabs without shear reinforcement is governed by the smallest width of the cross section in the tensile area. The semi-empirical formula in this code is appropriate for rather deep beam elements without contribution of the flanges and transfer stiffeners to the shear capacity. However, it can be presumed that for rather stocky beams or slabs with small void formers these components contribute and improve the shear capacity of the global element. To evidence the increased capacity of such slabs in comparison with the single beam theory, a limited test program was set up by Airdeck Building Concepts and Hasselt University (Belgium). Four-point bending tests were carried out on elements with a width of 600 mm, span of 2400 mm and thicknesses of 220 and 340 mm with or without void formers. Because these systems are mostly composed by a precast plank with a thickness from about 60 to 70 mm (with fixed void formers) and a topping cast on site, special attention was taken to the interface to avoid an early failure at the shear interface. Different approximations are investigated for deducing the resistance of the slab with voiding elements by application of a reduction factor on the resistance of a solid slab. It appears from this preliminary set of tests that a volumetric reduction ratio provides the best though safe estimate for this slabs.status: publishe