| PaperNO | Paper / Abstract |
|
SE3-001
10:50
|
11:10
|
COMPACTNESS REQUIREMENT FOR SEISMIC DESIGN OF DEEP STEEL WIDE FLANGE COLUMNS
Recent full-scale testing of steel wide-flange columns under axial compression and cyclic lateral drifts for special moment frame (SMF) applications showed that deep, slender columns could experience significant strength degradation due to plastic hinge formation with local buckling and axial shortening. Although cross sections of these columns met the highly ductile requirements specified in the AISC Seismic Provisions, test results showed that the interaction between web and flange local buckling played a major role for the observed degradation. These observations were also confirmed by extensive numerical simulations. To mitigate these effects, an approach that limits significant axial shortening from occurring is proposed, and alternative limiting width-to-thickness ratios for both special and intermediate moment frames (IMF) are developed.
Chia-Ming Uang, Gulen Ozkula
axial shortening, buckling, plastic hinge, seismic compactness, steel moment frames, wide-flange columns
|
|
SE3-012
11:10
|
11:30
|
Seismic Behavior of HSS Columns under Lateral Loading
The favorable properties of hollow structural sections have led to a growing interest in the US and continued interest elsewhere toward the use of HSS as columns in high seismic regions. Square and rectangular HSS steel columns provide excellent resistance to both local and global instabilities and similar behavior for loading in both orthogonal directions. However, lack of knowledge about their cyclic behavior, especially when high axial load is present, has hindered their widespread adoption for seismic applications. To address this shortcoming, computational simulations using thoroughly validated models are used to investigate the seismic behavior of HSS columns subject to various levels of constant axial load combined with cyclically applied lateral loading. The studied HSS columns are selected to cover various local and global slenderness ratios. Simulation results show that the dominant failure mode of the studied columns is local buckling, highlighting the importance of the local slenderness ratios on the seismic behavior of HSS columns. The computational results are used to assess current seismic design provisions’ highly-ductile limits for HSS columns.
Sherif El-Tawil, Omar A. Sediek, Tung-Yu Wu, Jason McCormick
axial capacity, finite element modeling, Hollow structural sections, steel columns
|
|
SE7-001
11:30
|
11:50
|
JSCE SPECIFICATONS ON EVALUATINON OF DUCTILE CRACK INITIATION DUE TO ELCF IN STEEL BRIDGE STRUCTURES
A fracture process composed of ductile crack initiation followed by stable crack growth and finally explosive failure in a ductile mode was observed in the damage of steel members, such as steel beam-to-column connection, steel bridge pier corner, steel brace and so on. It is because of the past mega earthquakes that the failure mode induced by extremely low cycle fatigue (ELCF) is deemed to be another big problem in thick-walled structures, together with failure mode induced by local buckling occurring in thin-walled structures. The focus of this paper is to introduce details of JSCE specifications on evaluation of ductile crack initiation in steel members with unstiffened sections, and further investigate the evaluation method of the ductile crack initiation of steel bridge piers with stiffened cross section.
Hanbin Ge, Wataru Fujie, Miki Taguchi
ductile failure, extremely low cycle fatigue, steel bridge structure
|
|
SE3-014
11:50
|
12:05
|
A SEVEN-STORY STEEL BRACED FRAME UNDER FAR-FIELD AND NEAR-FAULT EARTHQUAKES: LOADING PROTOCOL AND SEISMIC TEST OF HIGH-STRENGTH STEEL H-SHAPED COLUMNS
This paper presents the design and analysis of a seven-story steel braced frame using high-strength steel columns. Specimens that represent the full-scale, first-story columns of a seven-story steel braced frame were tested under near-fault and far-field loading protocols, developed in this work. Recent studies showed that the cyclic loading protocol of the beam-to-column moment connections, specified by AISC Seismic Provisions (2016), might be too stringent to the building column. Moreover, the seismic hazard of buildings under near-fault earthquakes in Taiwan is not clear. The prototype building is a seven-story apartment building, assumed to be located near Xinhua fault in Tainan, Taiwan. The building was designed for a special moment-resisting frame (SMRF) together with a buckling-restrained braced frame (BRBF), which uses SM570MC high-strength steel (nominal yield strength of 420 MPa) for columns and SN490B steel for beams and braces. Eleven far-field and eleven near-fault ground motions were scaled to match the seismic design spectra (DBE and MCE levels), based on the Taiwan specification (2011). Nonlinear time history analyses were conducted on the prototype to develop loading protocols that represent the seismic demand of the first-story columns subjected to near-fault and far-field earthquakes. Four full-scale specimens, which represent the exterior columns of the seven-story frame, were tested with varied axial force and lateral drift based on the proposed loading protocol. The test results showed significant effects of the near-fault loading protocols on the seismic performance of the high-strength steel columns.
Te-Hung Lin, Guan-Wei Chen, Chung-Che Chou
Full-Scale Test, High-strength steel, Hollow Box Column, H-Shaped Column, Near-Fault and Far-Field Loading Protocols, Nonlinear Time History Analysis
|
|
SE3-019
12:05
|
12:20
|
US-TAIWAN COLLABORATIVE RESEARCH ON STEEL COLUMNS: CYCLIC TESTING OF TWO-STORY SUBASSEMBLAGES
The objective of this research is to study the seismic performance of first-story steel columns under axial load and cyclic lateral load. Recent studies showed that the seismic performance of steel columns is affected by the boundary conditions at both ends of the member. To reflect realistic boundary conditions, four half-scale, two-story steel subassemblage frames with beams and columns are designed for testing to evaluate the cyclic behavior of columns. The prototype design is based on a seven-story apartment building located near Xinhua fault in Tainan, Taiwan. The building is a dual system with a special moment-resisting frame (SMRF) and a buckling-restrained braced frame (BRBF), which utilizes SM570MC high-strength steel (nominal yield strength of 420 MPa) for the columns and SN490B steel (nominal yield strength of 325 MPa) for the beams and BRBs. One subassemblage specimen represents a bottom portion of the seven-story prototype; the other three specimens have different column sizes with different compactness ratios. Testing of the first subassemblage is scheduled to be conducted at NCREE during the 20th Anniversary of Chi-Chi Earthquake Conference. This paper summarizes the design of the prototype frame, the analytical study of the subassemblage frame, and the test plan. After this test program, a one-story subassemblage braced frame and a seven-story braced frame are planned for future study.
Chia-Ming Uang, Sherif El-Tawil, Jason P. McCormick, Gilberto Mosqueda, Te-Hung Lin, Hou-Chun Xiong, Yun-Chuan Lai, Chung-Che Chou
H-Shaped Column, Two-Story Subassemblage Frame Test, Welded-Box Column
|