Proceedings of the Institution of Civil Engineers - Structures and Buildings, 2005
An experimental study on the seismic response of cold-formed steel tubular members functioning as... more An experimental study on the seismic response of cold-formed steel tubular members functioning as bracing members in concentrically braced frames is described. A number of shake table tests were carried out to examine member and storey performance under earthquake loads. Three different square and rectangular hollow cross-sections were utilised for the bracing members. It is shown that maximum brace tensile forces can be over 30% higher than those estimated using the actual yield strength, due to strain hardening and strain rate effects. Moreover, the experimental storey shear can exceed that predicted by design procedures by more than 50%. The tests also indicate that the ductility demand under seismic loading can be estimated reasonably well for the frame models using a conventional equal-energy idealisation. In addition, the results illustrate generally satisfactory performance for braces with member slenderness exceeding typical limits in seismic codes.
Composite steel concrete moment frames are structures for which design guidelines for earthquake ... more Composite steel concrete moment frames are structures for which design guidelines for earthquake resistance are poor worldwide. This is due to the fact that experimental research on such structures was, until very recently, considering only the case of vertical loading, while, under horizontal loading the response of the structure is very different since; in particular, positive bending moments can appear at the beam ends. In order to solve the problems raised by the seismic design of these structures, the European Union has promoted a huge research effort. It involves experimental activity in several large European testing installations. Programs have been run on shaking tables at Bristol, Athens and Bergamo. One huge test of a full scale 3 D structures, 3 storey high and 3 bays by 3 bays in plan has been run at the Elsa facility of the European joint research Centre at Ispra. One plane frame was tested at Saclay. The experimental data have been processed and numerical modelling developed. Design guidelines, based on the results obtained, are prepared. They will be included in the revised version of Eurocode 8 [CEN, 1998] now under way. The main features of the research efforts and of the code developments are set forward in this paper.
Les constructions mixtes acier – beton sont faites de deux materiaux dont l’un est ductile et l’a... more Les constructions mixtes acier – beton sont faites de deux materiaux dont l’un est ductile et l’autre fragile. Concevoir des ossatures dont le comportement plastique global en situation sismique soit ductile implique donc des reflexions particulieres, tant au niveau des mecanismes plastiques locaux qu’en ce qui concerne la reponse globale des structures. Les regles de detail qui assurent la ductilite des divers types d’elements constitutifs des ossatures sont definies et expliquees. Elles concernent les poteaux, les poutres, les dalles collaborant avec des profils en acier et des murs mixtes de divers types. Ces derniers participent a des systemes mixtes qui n’existent pas en charpentes acier classique.
L'article definit les causes des seismes, les caracteristiques des mouvements sismiques et la... more 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 ... more 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.
Les aciers de construction repondant aux normes sont ductiles et cette caracteristique fait a pri... more Les aciers de construction repondant aux normes sont ductiles et cette caracteristique fait a priori des profiles, plats et toles, d'excellents produits pour realiser des constructions stables en zone sismique, car ces produits en acier permettent de realiser une dissipation d'energie elevee et, ce, dans plusieurs schemas de deformation. Les observations effectuees apres des tremblements de terre majeurs confirment generalement le caractere parasismique efficace des constructions metalliques, mais des exceptions existent. Ainsi, le seisme de Northridge (USA), en 1994, et celui de Kobe (Japon), en 1995, ont conduit a des fissurations locales nombreuses dans certains bâtiments. Le caractere metallique d'une construction n'est donc pas necessairement synonyme de qualite parasismique et, seules, des options reflechies permettent d'assurer le comportement global ductile recherche. Le projet de construction devra favoriser la formation de zones dissipatives saines ou se developpent des deformations locales ductiles, lesquelles devront se produire a des endroits choisis. Ceci sera realise par le respect de regles particulieres relatives aux materiaux, aux elements et aux assemblages, ainsi que par l'application de criteres de hierarchie decoulant tous du concept general de « dimensionnement en capacite » specifiques a chaque type d'ossature. Ces regles et criteres, dont le developpement est recent, n'etaient pas inscrits dans la premiere version des regles PS92. On les presente ici dans le contexte de la formulation retenue dans l'Eurocode 8, code parasismique en vigueur dans toute l'Europe en 2011. Le choix a ete fait de garder dans le texte qui suit les symboles utilises dans la version francaise de l'Eurocode 8, qui comprennent parfois des indices en terminologie anglaise. L'aspect des charpentes mixtes acier-beton est aborde dans le [C 2 569].
Steel presents intrinsic qualities which make it a more adaptable material than others for constr... more Steel presents intrinsic qualities which make it a more adaptable material than others for construction in seismic zones. Its rational use requires respect for a certain number of principles related as much to the form of the aggregate structure and to the distribution of resistant elements as to the constitution of couplings or the choice of profiles and nuances of the steel. These principles are developed by locating the problem in a general context and treating seismic actions and the methods of computation.
The SMARTCOCO research project was developed to fill gaps in knowledge and provide design guidanc... more 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.
The existing methods for predicting of the buckling strength of reinforced concrete are satisfact... more 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.
The paper covers the seismic evaluation and upgrading of an existing 20 - storey hotel building f... more The paper covers the seismic evaluation and upgrading of an existing 20 - storey hotel building for compliance with a peak ground acceleration of 0.4g in the city of Istanbul. The assignment was performed by SECO. It was finalised only recently and lasted for about 6 years. The implementation of the strengthening design into an operating hotel proved to be an exciting challenge. The standard storey area of the building is about 35.000 m². The building’s structure comprises an (in plan view) S-shaped classical reinforced concrete frame of beams, columns and slabs, divided by 2 joints in 3 independent blocks, but disturbed by the presence of some major irregularities. Quite an experience …
LA CECM (CONVENTION EUROPEENNE DE LA CONSTRUCTION METALLIQUE) A INTRODUIT UN CLASSEMENT DES DIFFE... more LA CECM (CONVENTION EUROPEENNE DE LA CONSTRUCTION METALLIQUE) A INTRODUIT UN CLASSEMENT DES DIFFERENTS PROFILES SELON LEUR RESISTANCE AU FLAMBEMENT. CE CLASSEMENT EST TRES CONSERVATIF EN CE QUI CONCERNE CERTAINES CLASSES DE PROFILES, A CAUSE DU MANQUE DE RESULTATS EXPERIMENTAUX CORRESPONDANTS. POUR COMBLER UNE DE CES LACUNES, DES ESSAIS DE FLAMBEMENT ONT ETE EFFECTUES RECEMMENT SUR PROFILES LAMINES EN H AVEC DES EPAISSEURS DE SEMELLE ATTEIGNANT 80MM. LA PRESENTE RECHERCHE EST UN COMPLEMENT THEORIQUE A CES TRAVAUX AINSI QU'UNE EXTENSION AUX EPAISSEURS ENCORE PLUS FORTES. PAR LA SIMULATION NUMERIQUE D'ESSAIS DE FLAMBEMENT, EFFECTUEE SUR LA BASE DE MESURES DE CONTRAINTES RESIDUELLES, CETTE RECHERCHE A PERMIS DE CONFIRMER LES RESULTATS DES ESSAIS ET DE JUSTIFIER UN CLASSEMENT NETTEMENT PLUS FAVORABLE DE CES PROFILES QUE CELUI ADOPTE DANS LE PROJET EUROPEEN DE REGLES DE CONSTRUCTION EUROCODE 3 (A).
This paper deals with the seismic behaviour of bracing members. An experimental investigation inv... more This paper deals with the seismic behaviour of bracing members. An experimental investigation involving shake table tests on idealised concentrically braced single-storey frames is decribed. The testing arrangement, specimen configuration and choice of seismic input are summarised. Typical results are presented and the main experimental observations are highlighted. Elastic tests were first conducted to examine basic dynamic characteristics, followed by large amplitude seismic tests to assess the inelastic behaviour. The frames incorporated hollow steel bracing members with three different square and rectangular cross-sections sizes in order to provide a range of section and member slenderness. In addition, a number of hollow members were in-filled with mortar for comparison purposes. An assessment of a number of key design aspects is undertaken on the basis of experimental observations and findings as well as consideration of underlying response mechanisms. The main differences in the interpretation and simplification of response within codes of practice are discussed, particularly in terms of dealing with the brace buckling in compression. The implications of these differences on the overall behaviour, primarily in terms of the expected lateral overstrength as well as the level of inelastic ductility demand on the bracing members, are pointed out. The limiting criterion for the bracing members was illustrated in some of the tests, in which brace failure occurred through fracture of the cross-section following the onset of local buckling. Depending on the section and member slenderness level, beneficial effects may be realised by in-filling the hollow braces which could delay or inhibit local buckling. The tests also indicated that bracing members with slenderness exceeding the limits imposed by some seismic codes demonstrated generally satisfactory performance. Despite their lower energy dissipation capabilities, there are several practical and design advantages that merit their utilisation.
Proceedings of the Institution of Civil Engineers - Structures and Buildings, 2005
An experimental study on the seismic response of cold-formed steel tubular members functioning as... more An experimental study on the seismic response of cold-formed steel tubular members functioning as bracing members in concentrically braced frames is described. A number of shake table tests were carried out to examine member and storey performance under earthquake loads. Three different square and rectangular hollow cross-sections were utilised for the bracing members. It is shown that maximum brace tensile forces can be over 30% higher than those estimated using the actual yield strength, due to strain hardening and strain rate effects. Moreover, the experimental storey shear can exceed that predicted by design procedures by more than 50%. The tests also indicate that the ductility demand under seismic loading can be estimated reasonably well for the frame models using a conventional equal-energy idealisation. In addition, the results illustrate generally satisfactory performance for braces with member slenderness exceeding typical limits in seismic codes.
Composite steel concrete moment frames are structures for which design guidelines for earthquake ... more Composite steel concrete moment frames are structures for which design guidelines for earthquake resistance are poor worldwide. This is due to the fact that experimental research on such structures was, until very recently, considering only the case of vertical loading, while, under horizontal loading the response of the structure is very different since; in particular, positive bending moments can appear at the beam ends. In order to solve the problems raised by the seismic design of these structures, the European Union has promoted a huge research effort. It involves experimental activity in several large European testing installations. Programs have been run on shaking tables at Bristol, Athens and Bergamo. One huge test of a full scale 3 D structures, 3 storey high and 3 bays by 3 bays in plan has been run at the Elsa facility of the European joint research Centre at Ispra. One plane frame was tested at Saclay. The experimental data have been processed and numerical modelling developed. Design guidelines, based on the results obtained, are prepared. They will be included in the revised version of Eurocode 8 [CEN, 1998] now under way. The main features of the research efforts and of the code developments are set forward in this paper.
Les constructions mixtes acier – beton sont faites de deux materiaux dont l’un est ductile et l’a... more Les constructions mixtes acier – beton sont faites de deux materiaux dont l’un est ductile et l’autre fragile. Concevoir des ossatures dont le comportement plastique global en situation sismique soit ductile implique donc des reflexions particulieres, tant au niveau des mecanismes plastiques locaux qu’en ce qui concerne la reponse globale des structures. Les regles de detail qui assurent la ductilite des divers types d’elements constitutifs des ossatures sont definies et expliquees. Elles concernent les poteaux, les poutres, les dalles collaborant avec des profils en acier et des murs mixtes de divers types. Ces derniers participent a des systemes mixtes qui n’existent pas en charpentes acier classique.
L'article definit les causes des seismes, les caracteristiques des mouvements sismiques et la... more 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 ... more 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.
Les aciers de construction repondant aux normes sont ductiles et cette caracteristique fait a pri... more Les aciers de construction repondant aux normes sont ductiles et cette caracteristique fait a priori des profiles, plats et toles, d'excellents produits pour realiser des constructions stables en zone sismique, car ces produits en acier permettent de realiser une dissipation d'energie elevee et, ce, dans plusieurs schemas de deformation. Les observations effectuees apres des tremblements de terre majeurs confirment generalement le caractere parasismique efficace des constructions metalliques, mais des exceptions existent. Ainsi, le seisme de Northridge (USA), en 1994, et celui de Kobe (Japon), en 1995, ont conduit a des fissurations locales nombreuses dans certains bâtiments. Le caractere metallique d'une construction n'est donc pas necessairement synonyme de qualite parasismique et, seules, des options reflechies permettent d'assurer le comportement global ductile recherche. Le projet de construction devra favoriser la formation de zones dissipatives saines ou se developpent des deformations locales ductiles, lesquelles devront se produire a des endroits choisis. Ceci sera realise par le respect de regles particulieres relatives aux materiaux, aux elements et aux assemblages, ainsi que par l'application de criteres de hierarchie decoulant tous du concept general de « dimensionnement en capacite » specifiques a chaque type d'ossature. Ces regles et criteres, dont le developpement est recent, n'etaient pas inscrits dans la premiere version des regles PS92. On les presente ici dans le contexte de la formulation retenue dans l'Eurocode 8, code parasismique en vigueur dans toute l'Europe en 2011. Le choix a ete fait de garder dans le texte qui suit les symboles utilises dans la version francaise de l'Eurocode 8, qui comprennent parfois des indices en terminologie anglaise. L'aspect des charpentes mixtes acier-beton est aborde dans le [C 2 569].
Steel presents intrinsic qualities which make it a more adaptable material than others for constr... more Steel presents intrinsic qualities which make it a more adaptable material than others for construction in seismic zones. Its rational use requires respect for a certain number of principles related as much to the form of the aggregate structure and to the distribution of resistant elements as to the constitution of couplings or the choice of profiles and nuances of the steel. These principles are developed by locating the problem in a general context and treating seismic actions and the methods of computation.
The SMARTCOCO research project was developed to fill gaps in knowledge and provide design guidanc... more 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.
The existing methods for predicting of the buckling strength of reinforced concrete are satisfact... more 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.
The paper covers the seismic evaluation and upgrading of an existing 20 - storey hotel building f... more The paper covers the seismic evaluation and upgrading of an existing 20 - storey hotel building for compliance with a peak ground acceleration of 0.4g in the city of Istanbul. The assignment was performed by SECO. It was finalised only recently and lasted for about 6 years. The implementation of the strengthening design into an operating hotel proved to be an exciting challenge. The standard storey area of the building is about 35.000 m². The building’s structure comprises an (in plan view) S-shaped classical reinforced concrete frame of beams, columns and slabs, divided by 2 joints in 3 independent blocks, but disturbed by the presence of some major irregularities. Quite an experience …
LA CECM (CONVENTION EUROPEENNE DE LA CONSTRUCTION METALLIQUE) A INTRODUIT UN CLASSEMENT DES DIFFE... more LA CECM (CONVENTION EUROPEENNE DE LA CONSTRUCTION METALLIQUE) A INTRODUIT UN CLASSEMENT DES DIFFERENTS PROFILES SELON LEUR RESISTANCE AU FLAMBEMENT. CE CLASSEMENT EST TRES CONSERVATIF EN CE QUI CONCERNE CERTAINES CLASSES DE PROFILES, A CAUSE DU MANQUE DE RESULTATS EXPERIMENTAUX CORRESPONDANTS. POUR COMBLER UNE DE CES LACUNES, DES ESSAIS DE FLAMBEMENT ONT ETE EFFECTUES RECEMMENT SUR PROFILES LAMINES EN H AVEC DES EPAISSEURS DE SEMELLE ATTEIGNANT 80MM. LA PRESENTE RECHERCHE EST UN COMPLEMENT THEORIQUE A CES TRAVAUX AINSI QU'UNE EXTENSION AUX EPAISSEURS ENCORE PLUS FORTES. PAR LA SIMULATION NUMERIQUE D'ESSAIS DE FLAMBEMENT, EFFECTUEE SUR LA BASE DE MESURES DE CONTRAINTES RESIDUELLES, CETTE RECHERCHE A PERMIS DE CONFIRMER LES RESULTATS DES ESSAIS ET DE JUSTIFIER UN CLASSEMENT NETTEMENT PLUS FAVORABLE DE CES PROFILES QUE CELUI ADOPTE DANS LE PROJET EUROPEEN DE REGLES DE CONSTRUCTION EUROCODE 3 (A).
This paper deals with the seismic behaviour of bracing members. An experimental investigation inv... more This paper deals with the seismic behaviour of bracing members. An experimental investigation involving shake table tests on idealised concentrically braced single-storey frames is decribed. The testing arrangement, specimen configuration and choice of seismic input are summarised. Typical results are presented and the main experimental observations are highlighted. Elastic tests were first conducted to examine basic dynamic characteristics, followed by large amplitude seismic tests to assess the inelastic behaviour. The frames incorporated hollow steel bracing members with three different square and rectangular cross-sections sizes in order to provide a range of section and member slenderness. In addition, a number of hollow members were in-filled with mortar for comparison purposes. An assessment of a number of key design aspects is undertaken on the basis of experimental observations and findings as well as consideration of underlying response mechanisms. The main differences in the interpretation and simplification of response within codes of practice are discussed, particularly in terms of dealing with the brace buckling in compression. The implications of these differences on the overall behaviour, primarily in terms of the expected lateral overstrength as well as the level of inelastic ductility demand on the bracing members, are pointed out. The limiting criterion for the bracing members was illustrated in some of the tests, in which brace failure occurred through fracture of the cross-section following the onset of local buckling. Depending on the section and member slenderness level, beneficial effects may be realised by in-filling the hollow braces which could delay or inhibit local buckling. The tests also indicated that bracing members with slenderness exceeding the limits imposed by some seismic codes demonstrated generally satisfactory performance. Despite their lower energy dissipation capabilities, there are several practical and design advantages that merit their utilisation.
Uploads
Papers by André Plumier