Steel Bracing of RC Frames for Seismic Retrofitting

Badoux, Marc; Jirsa, James O.

doi:10.1061/(asce)0733-9445(1990)116:1(55)

Cited by 127 publications

(50 citation statements)

References 1 publication

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“…Several analytical and experimental studies have been conducted on the use of steel bracing as a seismic retrofit technique for RC frame buildings (Badoux and Jirsa 1990), (Yamamoto and Umemura 1992). However, its implementation in bridges has been limited to steel diaphragms and steel bridges (Itani 1996).…”

Section: Steel Bracingmentioning

confidence: 99%

Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes

Dusicka¹,

Bazaez²,

Knoles³

2015

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Research was conducted to investigate the effect of subduction zone earthquakes on structural damage. The study suggests that large magnitude ground motions of long duration have the potential of significantly increasing the number of inelastic excursions and consequently incur more extensive structural damage as compared to ground motions with similar elastic spectral demands but of shorter duration. This increase in demand plays a crucial role in the Pacific Northwest where a mega subduction zone earthquake is impending. Typical reinforced concrete bridge bents constructed in the 1950 to mid-1970 in the State of Oregon were designed and built with minimum seismic considerations. This resulted in inadequate detailing within plastic hinge zones, leaving numerous RC bents highly susceptible to damage following an earthquake. In this study, the cyclic performance of an asbuilt RC square column and a reinforced concrete bridge bent retrofitted using buckling restrained braces (BRBs) was experimentally evaluated using quasi-static cyclic loading protocols aiming to reflect subduction zone earthquake demands up to displacement ductility. The buckling restrained braces were designed as replaceable elements in order to take the earthquake-induced energy and dissipate it through nonlinear hysteretic behavior. Two BRB designs were considered in the study in an effort to assess the influence of BRB stiffness on the overall structural performance. The results of these large-scale experiments successfully demonstrated the effectiveness of utilizing buckling restrained braces for achieving high displacement ductility of the retrofitted structure, while also controlling the damage of the existing vulnerable reinforced concrete bent up to the design performance levels. The potential of improving the overall seismic behavior and the design performance levels with BRBs offers structural design professionals a viable method for performance driven retrofit of reinforced concrete bents. 17. Key Words Subduction zone earthquakes, reinforced concrete bridge bents, plastic hinge zone, performance levels, bridge seismic retrofit, quasi-static loading protocol, buckling restrained braces.18. Distribution Statement: Copies available from NTIS, and online at

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Section: Steel Bracingmentioning

confidence: 99%

Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes

Dusicka¹,

Bazaez²,

Knoles³

2015

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“…For example, reinforce concrete frames have been strengthened using steel braces (Badoux and Jirsa 1990), in which, the steel braces can be fixed to concrete beam/column ends using concrete anchors such as post-installed adhesive anchors or through bolts. The anchor bolts in such connections on the side faces of a concrete frame are subjected to cyclic shear during an earthquake, and the anchors have limited edge distance in the loading direction.…”

Section: Introductionmentioning

confidence: 99%

Shear Behavior of Single Cast-in Anchors in Plastic Hinge Zones

Petersen¹,

Lin

Zhao

2018

Int J Concr Struct Mater

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This paper presents two shear tests of -in. diameter cast-in anchors embedded in the plastic hinge zone of reinforced concrete columns. Design codes, such as ACI 318-14, require special reinforcement for concrete anchors in concrete that could be substantially damaged during an earthquake. The test anchors in this study were equipped with the anchor reinforcement recommended and verified in the literature. The column specimens were subjected to quasi-static cyclic loading before the test anchors were loaded in shear. Steel fracture was achieved in both test anchors despite cracks and concrete spalling occurred to the concrete within the plastic hinge zones. Meanwhile, the measured anchor capacities were smaller than the code-specified capacity, especially for the anchors subjected to cyclic shear. Concrete cover spalling was found critical to the observed capacity reduction, which caused combined bending and shear action in the anchor bolts. Measures should be developed to mitigate such adverse impact. In addition, further studies are needed for post-installed anchors before practical applications.

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“…A number of reports over the past two decades have shown that the most efficient strengthening method to resist the lateral earthquake loads for RC buildings is to use steel bracing, and retrofitted steel bracing can strengthen earthquake-damaged buildings and increase the seismic capacity of existing RC buildings [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on Non-Compression X-Bracing Systems Using Carbon Fiber Composite Cable for Seismic Strengthening of RC Buildings

Lee

2015

Polymers

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Cross-bracing (X-bracing) is one of the most popular methods of seismic retrofitting, and has been shown to significantly increase the structural stiffness and strength of buildings. Conventional steel X-bracing methods typically exhibit brittle failure at the connection between the brace and the building, or buckling failure of the braces. This study investigated the structural properties of a new type of non-compression X-bracing system using carbon fiber composite cable (CFCC). This non-compression X-bracing system uses CFCC bracing and bolt connections between structural members and the terminal fixer of the CFCC, instead of conventional steel bracing. The aim is to overcome the brittle and buckling failures that can occur at the connection and bracings with conventional steel X-bracing methods. We carried out cyclic loading tests, and the maximum load carrying capacity and deformation were investigated, as well as hysteresis in the lateral load-drift relations. The test results revealed that the CFCC X-bracing system installed in reinforced concrete frames enhanced the strength markedly, and buckling failure of the bracing was not observed.

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Steel Bracing of RC Frames for Seismic Retrofitting

Cited by 127 publications

References 1 publication

Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes

Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes

Shear Behavior of Single Cast-in Anchors in Plastic Hinge Zones

An Experimental Study on Non-Compression X-Bracing Systems Using Carbon Fiber Composite Cable for Seismic Strengthening of RC Buildings

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