Seismic behavior of bidirectional-resistant ductile end diaphragms with buckling restrained braces in straight steel bridges

Celik, Oguz C.; Bruneau, Michel

doi:10.1016/j.engstruct.2008.08.013

Cited by 51 publications

(13 citation statements)

References 14 publications

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“…To check numerical results obtained from computer analysis using simple models, closed-form solutions are also presented. To help reduce the complexity of the derived expressions, an ideal elastic-plastic hysteretic model with equal tension and compression capacities T y ¼ C y is used for the BRBs (Black et al 2002;Sabelli et al 2003;Celik and Bruneau 2007). Furthermore, the BRBs are assumed to have pinned end connections and are not active under gravity loading.…”

Section: Modeling Assumptionsmentioning

confidence: 99%

Skewed Slab-on-Girder Steel Bridge Superstructures with Bidirectional-Ductile End Diaphragms

Celik

Bruneau

2011

J. Bridge Eng.

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Specially designed ductile end diaphragms of steel bridge superstructures have previously proved, both theoretically and experimentally, to dissipate seismic input energy, protecting other substructure and superstructure members. Although ductile diaphragms have been introduced in the latest AASHTO guide specifications as a structural system that can be used to resist transverse earthquake effects, no guidance is provided on how to implement these ductile diaphragms in skewed bridges. To address this need and to resolve some shortcomings of the known end diaphragm systems (EDSs), two bidirectional end diaphragm configurations, namely, EDS-1 and EDS-2, with buckling restrained braces (BRBs) are proposed and numerically investigated. Bidirectional end diaphragm is a new concept, and can be implemented both in straight and skewed steel bridge superstructures to resist bidirectional earthquake effects. To assess the relative effectiveness of the proposed systems and to investigate how various parameters relate to seismic response, closed-form solutions are developed using nondimensional bridge geometric ratios. Numerical results indicate that skewness more severely affects end diaphragm behavior when φ ≥ 30°. Also, comparisons reveal that although both end diaphragm systems can be used with confidence as ductile seismic fuses, each of the two systems considered have advantages that may favor its implementation, depending on project-specific constraints.

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Section: Modeling Assumptionsmentioning

confidence: 99%

Skewed Slab-on-Girder Steel Bridge Superstructures with Bidirectional-Ductile End Diaphragms

Celik

Bruneau

2011

J. Bridge Eng.

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“…In 2009, a new type of bidirectional-resistant ductile end diaphragm using BRBs was introduced for bridges (Celik and Bruneau, 2009). BRB devices cased with steel tubes and mortar have been investigated, and the results indicate that it is possible to acquire reasonably efficient and economical performance during cyclic loading (Palazzo et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Non-compression X-bracing system using CF anchors for seismic strengthening of RC structures

Lee

Sim

et al. 2014

Magazine of Concrete Research

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Cross-bracing (X-bracing) is one of the most popular methods of seismic retrofitting. Research results indicate that X-bracing significantly increases structural stiffness and enhances the strength of the structures. However, researchers have also noted that conventional steel X-bracing methods can involve brittle failure at the connection between the brace and the building, as well as buckling failure of the braces. The current research thus investigated the structural properties of a new type of non-compression carbon fibre (CF) X-bracing system with the goal of overcoming the brittle and buckling failures that can occur with conventional steel X-bracing methods. The proposed non-compression X-bracing system uses CF bracing and anchors to replace the conventional steel bracing and bolt connection. This paper reports on the seismic resistance of a reinforced concrete frame strengthened using CF X-bracing. Cyclic loading tests were carried out, and the structural stiffness and ductility were investigated along with the hysteresis of the lateral load-drift relations. CF is less rigid than the conventional materials used for seismic retrofitting, resulting in some significant advantages: the strength of the structure increased markedly with the use of CF X-bracing and no buckling failure of the bracing was observed. NotationD depth of column f c concrete compressive strength h o clear height of column K secant stiffness between yield and zero points (V y /ä y ) M u ultimate flexural strength N axial force R strength ratio, defined as V max /V y V max maximum shear strength V mu shear force at point of ultimate flexural failure V su ultimate shear strength V u ultimate lateral load-carrying capacity V y yield shear strength ä max displacement at the maximum point ä y displacement at the yield point ì ductility ratio, defined as the maximum displacement divided by yield displacement (ä max /ä y ) r f tensile reinforcement ratio (%) r s shear reinforcement ratio (%)

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“…Therefore the BRB does not lose its overall stability, and has stable hysteretic behavior under cyclic loads. Just with such structural performances, BRBs are widely used not only as a centrally compressed bracing in framing structures but also as energy dissipating dampers in building and bridge engineering structures [1,2]. The external restraining system of BRBs is subjected to bend and shear actions produced by the lateral deformation of the core, and its strength and rigidity depends on the load-carrying capacity of BRBs.…”

Section: Introductionmentioning

confidence: 99%

11.27: Elastic buckling load and load resistance of core‐separated assembled BRB confined by two concrete‐infilled tubes

Zhu

Guo

2017

ce papers

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This paper presents a novel type of the core-separated assembled BRB (CSA-BRB). It consists of two single BRBs confined by concrete-infilled tubes that are connected longitudinally by two continuous webs. This directly results in a sectional cavity of the CSA-BRB by spacing two independent BRBs, and significantly enhances its cross-sectional flexural stiffness and loadcarrying capacity. The two independent steel cores of the CSA-BRB are strengthened and connected at its end with a core stiffener to form a robust H-shaped sectional core, as a whole. The core stiffener is inserted into the restraining member by a distance, further remarkably improving the core strength and stiffness at un-restrained core projections of the CSA-BRB. The CSA-BRB is simulated approximately by "an equivalent framed model" and accordingly its elastic buckling load was obtained by using an equilibrium method. A number of numerical examples of CSA-BRBs were designed and investigated by using a large deflection elastic-plastic beam element model to predict the influence of the restraining ratios on their load-carrying capacities. An overall geometric imperfection with the amplitude of l/1000 at mid-span of the CSA-BRB is also involved in the analysis. The results obtained reveal that the CSA-BRBs could achieve required load-carrying capacity without overall failure, considering the strain hardening (for example 0.02E) of the core after its initial yielding, as well as the ultimate axial compressive strain of 2% applied to the core if the restraining ratio of CSA-BRBs is greater than around 3.0.

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Seismic behavior of bidirectional-resistant ductile end diaphragms with buckling restrained braces in straight steel bridges

Cited by 51 publications

References 14 publications

Skewed Slab-on-Girder Steel Bridge Superstructures with Bidirectional-Ductile End Diaphragms

Skewed Slab-on-Girder Steel Bridge Superstructures with Bidirectional-Ductile End Diaphragms

Non-compression X-bracing system using CF anchors for seismic strengthening of RC structures

11.27: Elastic buckling load and load resistance of core‐separated assembled BRB confined by two concrete‐infilled tubes

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