The revision of Eurocode 8 is under way. The paper summarizes aspects of the revised rules common to all materials, like new format for the seismic action, enlarged sections on pushover analysis and the redefinition of the ductility classes with limits of applicability in terms of seismic action per structural systems and materials fitting better with the real seismic capacity of each structural type. The range of application of the former lower class DCL is increased for some systems while a class DC2 intermediate between the former DCL and DCM is introduced for more economical design. The revision improves the structural logic of requirements, taking for instance into consideration the force amplification in columns which exists after formation of a first plastic zone.

The SMARTCOCO research project was developed to fill gaps in knowledge and provide design guidance for specific types of composite steel concrete structural elements used in high rise or heavily loaded structures. The targeted elements are composite columns reinforced by several fully encased steel sections, columns of reinforced concrete buildings reinforced by one steel section over the height of one storey, without continuity above and under that storey and concrete flat slabs or beams connected to columns or walls by means of steel shear keys. Those composite elements belong to structures defined as “hybrid” because they are neither reinforced concrete structures covered by Eurocode 2, nor composite steel concrete structures covered by Eurocode 4. Gaps in knowledge are mostly related to the way to evaluate the force transmission between concrete and embedded steel profiles and to design the components to resist those forces. A generic design approach based on the logics of composite sections and of reinforced concrete sections, like equivalent sections and struts and ties mechanisms, was first developed and used to design test specimens. These ones were tested in physical and/or numerical experimentations. The results were used to calibrate or correct the initial proposal for design. The output is written as a design guide which intends to complement Eurocode 2 and 4.

The current EN 1992 provides structured information related to the design of reinforced concrete columns or reinforced concrete column beam connections. On the other hand, EN 1994 gives enough information on the design of composite columns but none of the current codes provide details about a possible transfer zone in the case of usage of RC and composite column solution. The current study tends to fill the gap between these two norms. In the current experimental campaign, carried out in the frame of the European research program SmartCoCo, it is presented as a calibration method for a tentative design method which has been elaborated by one of the authors based on theoretical strut and tie reasoning. The objective of the current paper is to present the results of the experiments and aims to validate the theoretical approach for calculating the force transfer mechanism in the transfer zone. The experimental campaign comprises of 4 columns and 4 column-beam connections, all of them being composed by a RC part and a composite. The tests are performed on vertical column, simply supported with a width of 350mm, length of 380 mm and a height of 3850 mm with a regular concrete quality (C25/30). This contribution describes the test specimens, summarizes their design, presents a selection of the most relevant results from analog and digital measurements and a short interpretation of the obtain results. We concluded from this set of tests that the new design method is able to explain the force transfer mechanism with a good accuracy and can therefore be considered as a suitable solution for designing practical cases.

The European research project SmartCoCo (Smart Composite Components) aims at elaborating a design methodology to be used for all situations in which steel profiles are used to reinforce locally what for else remains a classical reinforced concrete structure. In this framework, an experimental campaign is carried out to study the transfer of compression/tension forces from a steel profile to the surrounding concrete by longitudinal shearing of the steel-concrete interface without creating local disturbances, like transverse cracking or splitting of concrete around the steel profile. The present paper presents the general context and the proposed design methodology. It describes then the test specimens, test procedure and results. It concludes with recommendations for the calibration of the design procedure, including values of the bond resistance, shear resistance associated to a load transfer using mechanical connectors (shear studs or welded plate) and detailing of the transverse reinforcement.

The design of walls or columns with several encased steel profiles as reinforcement has similarities with classical reinforced concrete, but also original aspects which need specific design approaches. Until now there has been experimental research and numerical models, but simple design methods are lacking. In the proposed method, the classical truss model used to design reinforced concrete for shear is extended to bring in the encased profiles contribution to shear stiffness. This allows to distinguish the action effects in the steel profiles and in concrete and to make separate checks for shear of the steel profiles and the concrete section with transverse reinforcements. A method to evaluate longitudinal shear action effects and the compression stresses at the steel profile – concrete interface is developed. Design checks in the format of Eurocodes 2 and 4 are proposed.

The objective of the present contribution is to present the outcomes of an experimental campaign carried out in the frame of the European research program Smartcoco and aiming at validating a design approach for determining the shear performances of RC wall reinforced by multiple encased steel profiles. The experimental campaign comprises 6 walls, ranging from a classical RC wall taken as a reference to configurations with multiple profiles with studs or plate stiffeners to ensure the transfer of the longitudinal shear at the steel-concrete interface. Vertical cantilever tests were performed on the specimens specifically detailed to fail in shear. Tests are carried out on walls with a width of 240 mm, a length of 880 mm and a height of 2250 mm with a regular concrete quality (C25/30). This contribution describes the test specimens, summarizes their design, presents a summary of the most relevant observations and a short interpretation of the obtain results. It is concluded from this set of tests that the new design method is able to predict the shear capacity with a good accuracy and can therefore be considered as a suitable solution for designing practical cases.

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.

The SMARTCOCO research project was developed to fill gaps in knowledge and provide design guidance for specific types of composite steel concrete structural elements used in high rise or heavily loaded structures. Those composite elements belong to structures defined as “hybrid” because they are neither reinforced concrete structures covered by Eurocode 2, nor composite steel concrete structures covered by Eurocode 4. A generic design approach based on the logics of composite sections and of reinforced concrete sections, like equivalent sections and struts and ties mechanisms, was first developed and used to design test specimens. These ones were tested in physical and/or numerical experimentations. The results were used to calibrate or correct the initial proposal for design. The output is written as a design guide which intends to complement Eurocode 2 and 4.

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The current state of EN 1994 and EN 1992 does not provide correlated solutions related to the design of concrete walls reinforced by multiple steel profiles. Explicitly, Eurocode 4 is setting clear boundaries in the design of composite walls by limiting the possibilities to elements reinforced by a single profile or multiple connected profiles. A number of previous studies have shown that the method proposed by Eurocode 2 regarding classical reinforced walls provides a good prediction of the bending capacity of the wall; however limited information regarding their shear capacity can be found. The current paper is having as starting point a theoretical approach for determining the shear performances of RC wall reinforced by multiple steel profiles, coupled with an experimental campaign. The experimental campaign comprises 6 walls, ranging from a classic RC wall taken as a reference to configurations with multiple profiles with studs or plate stiffeners to ensure the transfer of the longitudinal shear at the steel-concrete interface. The FE model is going to try to reproduce the behavior showed by the walls. The objective of the present paper is to present a comparative analysis between results obtained using a FE software and results from the experimental campaign carried out in the frame of the European research program SmartCoCo. The obtained results will be used to confirm once again the design method based on theoretical reasoning, proposed by the authors and presented in previous papers. This contribution contains a brief description of the test specimens, presents a selection of the most relevant experimental results in parallel with the FE results and a set of conclusions regarding the results. It can be concluded from this set of tests that the new design method is able to predict the shear capacity with a good accuracy and can therefore be considered as a suitable solution for designing practical cases.

The design of concrete walls or columns reinforced by several encased steel profiles, also called hybrid walls, is similar to the one of classical reinforced concrete, although specific features require adequate design approaches. Experimental research and numerical models demonstrated the feasibility and validity of such structural components, but simple and practical design methods are still lacking regarding their shear resistance. The evaluation of longitudinal shear action effects at the steel profile–concrete interface is a key aspect: research results have been achieved in a more or less recent past for different types of connection but without leading to design conclusions. In this paper, the classical equivalent truss model for reinforced concrete subjected to shear is extended to take into account the contribution of the encased profiles to the shear stiffness and strength. Resulting action effects in the steel profiles, in the concrete and at the steel profile–concrete interfaces are established which allows performing design checks for those three components. In particular, it is evidenced that friction is one of the main component of the resistance to longitudinal shear at the steel profile-concrete interface. It can be directly checked since the proposed method clearly identifies the compression stresses at that location. The validity of the method is assessed by referring to tests results from experimental campaigns in China and in Europe. Some of these tests were carried out without shear connectors welded to the encased steel profiles allowing however achieving the full bending resistance of the element without any apparent problem related to longitudinal shear, like slippage between concrete and steel profile. For some other tests, failure was observed as a consequence of an insufficient shear connection. A detailed assessment of these results shows that the new design proposal is perfectly consistent with all the experimental observations.

L'article definit les causes des seismes, les caracteristiques des mouvements sismiques et la theorie de ces mouvements, ainsi que l'action dU calcul sur un site donne. Sont decrits brievement deux effets particuliers : tsunamis et liquefaction des sols. Les methodes d'analyse des structures soumises a une action sismique sont exposees. Sont ainsi detaillees les analyses lineaires, utilisant les spectres de reponse en acceleration (analyses modales et par forces laterales), puis les analyses non lineaires, statiques en poussee progressive ou «pushover» et chronologiques.

L'article decrit l'evolution des concepts presents dans les normes parasismiques, depuis les origines jusqu'a la troisieme generation de code actuellement en vigueur. Le pourquoi et le comment de l'objectif «mecanisme plastique global», qui sous-tend les regles favorisant la ductilite locale et globale des structures, sont expliques ici, avec des exemples d'implication pratiques. Sont decrites notamment les dispositions architecturales souhaitables et les donnees des tremblements de terre recents, dans une optique d'amelioration optimale de la conception des bâtiments. Enfin, le cadre legislatif et reglementaire de la prevention sismique en vigueur en France est rappele.

The existing methods for predicting of the buckling strength of reinforced concrete are satisfactory for the usual cases of use. However their applicability remains limited. The approximate methods apply only for shorts columns with a small eccentricity of a compression force. The other existing methods impose restrictive conditions: a partially loaded column cannot be modelled by the known methods; concentrated horizontal load or a concentrated moment applied in an unspecified point of the column cannot be treated. The restrictions on the modes of fixing of the supports limit the studies to hinged-hinged columns or to cantilever. The interest of the matrix transfer method for the calculation of the buckling strength of reinforced concrete columns is its flexibility. It allows studying all the external loading cases and all conditions of supports.

This publication describes and discusses the aspects and issues in EN 1998-1:2004 that need clarification and/or further development. This book is the result of the activities carried out by Technical Committee "Seismic Design" (TC13) of the European Convention for Constructional Steelwork (ECCS) in the field of codification and technical specifications. The publication is organized into 12 sections and one annex. The basic topics discussed in the text are material overstrength, selection of steel toughness, local ductility, design rules for connections in dissipative zones, new links in eccentrically braced frames, behaviour factors, capacity design rules, design of concentrically braced frames, dual structures, drift limitations and second-order effects, new structural types and low-dissipative structures. URI: Authors: LANDOLFO Raffaele NEGRO Paolo [1] BEG Darko ARIBERT Jean-Marie CASTRO Jose Miguel DEGEE Herve DINU Florea DUBINA Dan ELGHAZOULI Ahmed ELNASHAI Amr GERGELY VIGH Laszlo GIONCU Victor HJIAJ Mohammed HOFFMEISTER B. MARTIN Pierre-Olivier MAZZOLANI Federico PILUSO Vincenzo PLUMIER Andre REBELO Carlos SEDLACECK Gerhard STRATAN Aurel Publication Year:

According to the current standards, unreinforced masonry may only be used in regions of low seismicity as the material for the lateral-load resisting system. This requirement may be too safe-sided and leading to not cost-effective solutions for moderately seismic regions. This chapter presents overview of experimental results from shake table tests on unreinforced masonry shear walls carried out in the EQUALS Laboratory of Bristol University, in order to assess, and possibly enhance, the current seismic design rules. The study also includes as additional parameter the presence of soundproofing devices required in buildings with numerous dwellings, in order to achieve the acoustic isolation recommended by recent standards. In practice the required level of acoustic isolation is obtained by locating horizontal rubber layers in the wall. These layers are likely to influence significantly the dynamic response of the wall and hence of the whole structure under seismic actions. Tests are performed on walls realized with masonry units and construction methods typical of North-Western Europe.