An-Chien Wu

Experimental Investigation of Chevron Concentrically Braced Frames with Yielding Beams

AbstractSteel concentrically braced frames designed prior to the implementation of capacity design principles in seismic design provisions may exhibit poor inelastic response under seismic excitation. These older, nonductile concentrically braced frames (NCBFs) used several configurations, with the chevron configuration being one of the most common. The response of chevron-configured NCBFs is unknown, as relatively large axial and flexural demands are imposed on the beam after brace buckling. Current code requirements for special concentrically braced frames (SCBFs) promote full yielding of the braces while the beam remains elastic, but NCBFs develop a mechanism in which the beam yields, deforms plastically, and limits tensile elongation of the brace. However, if ductile, this plastic mechanism may meet current performance limits and not require retrofitting. To examine this issue, four tests of two-story NCBFs were conducted at the National Center for Research on Earthquake Engineering in Taipei, Taiwan....

Seismic Design and Hybrid Tests of a Full-Scale Three-Story Concentrically Braced Frame Using In-Plane Buckling Braces

This research investigates the brace-to-gusset connection designs to allow the braces buckle in the plane (IP) of the frame. In order to study the performance of the IP buckling brace connections with different design details, five 3,026 mm–long A36 H 175 × 175 × 7.5 × 11 mm braces were tested using cyclically increasing axial displacements. All specimens failed at an average axial strain less than 0.025 due to the brace fracture at the mid-length where severe local buckling had occurred. Pseudo-dynamic tests on a three-story special concentrically braced frame (SCBF) using the proposed brace end connection details for six A36 H 150 × 150 × 7 × 10 mm braces were conducted using the PGA = 597 cm/s2 LA03 record to confirm with the component tests. The knife plates and IP buckling braces sustained a peak 0.049 rad interstory drift under the design base earthquake without fracture. The highly nonlinear responses were satisfactorily predicted by OpenSees. Recommendations on the seismic design of the IP buckling brace connections are provided.

Pseudo-dynamic Performance Evaluation of Full Scale Seismic Steel Braced Frame Braced frame Braced frame Braced frame Braced frame s Using Buckling-Restrained and In-Plane Buckling Braces

A series of hybrid and cyclic loading tests were conducted on a 3-story single-bay full-scale frame specimen in the Taiwan National Center for Research on Earthquake Engineering (NCREE) in 2010. There were total three hybrid tests conducted on this frame specimen. Two different lateral force resistant systems including buckling-restrained brace d frame (BRBF) and special concentrically braced frame (SCBF) were tested separately. The newly developed thin and welded end-slot buckling-restrained brace s (BRBs) were adopted for the first two BRBF hybrid tests. The in-plane (IP) buckling braces were installed in the SCBF for the last hybrid test. The BRBF or the SCBF was designed to sustain a design basis earthquake in Los Angeles and ground motion LA03 was used as the input ground motion for these tests. The inter-story drift reached near 3 % and 4 % radians in the BRBF and SCBF hybrid tests, respectively. The maximum base shear also reached more than 2,000 kN in these tests. Test results indicate that both frame systems performed satisfactorily. This chapter presents the seismic performance of the BRBF and SCBF hybrid tests.

Pseudo-dynamic Performance Evaluation of Full Scale Seismic Steel Braced Frames Using Buckling-Restrained and In-Plane Buckling Braces

A series of hybrid and cyclic loading tests were conducted on a 3-story single-bay full-scale frame specimen in the Taiwan National Center for Research on Earthquake Engineering (NCREE) in 2010. There were total three hybrid tests conducted on this frame specimen. Two different lateral force resistant systems including buckling-restrained brace d frame (BRBF) and special concentrically braced frame (SCBF) were tested separately. The newly developed thin and welded end-slot buckling-restrained brace s (BRBs) were adopted for the first two BRBF hybrid tests. The in-plane (IP) buckling braces were installed in the SCBF for the last hybrid test. The BRBF or the SCBF was designed to sustain a design basis earthquake in Los Angeles and ground motion LA03 was used as the input ground motion for these tests. The inter-story drift reached near 3 % and 4 % radians in the BRBF and SCBF hybrid tests, respectively. The maximum base shear also reached more than 2,000 kN in these tests. Test results indicate that both frame systems performed satisfactorily. This chapter presents the seismic performance of the BRBF and SCBF hybrid tests.

Pseudo-dynamic Performance Evaluation of Full Scale Seismic Steel Braced FrameBraced frameBraced frameBraced frameBraced frames Using Buckling-Restrained and In-Plane Buckling Braces

A series of hybrid and cyclic loading tests were conducted on a 3-story single-bay full-scale frame specimen in the Taiwan National Center for Research on Earthquake Engineering (NCREE) in 2010. There were total three hybrid tests conducted on this frame specimen. Two different lateral force resistant systems including buckling-restrained brace d frame (BRBF) and special concentrically braced frame (SCBF) were tested separately. The newly developed thin and welded end-slot buckling-restrained brace s (BRBs) were adopted for the first two BRBF hybrid tests. The in-plane (IP) buckling braces were installed in the SCBF for the last hybrid test. The BRBF or the SCBF was designed to sustain a design basis earthquake in Los Angeles and ground motion LA03 was used as the input ground motion for these tests. The inter-story drift reached near 3 % and 4 % radians in the BRBF and SCBF hybrid tests, respectively. The maximum base shear also reached more than 2,000 kN in these tests. Test results indicate that both frame systems performed satisfactorily. This chapter presents the seismic performance of the BRBF and SCBF hybrid tests.