TEST AND FINITE ELEMENT ANALYSIS OF HIGH-STRENGTH CONCRETE FILLED STEEL BOX COLUMNS UNDER COMBINED HIGH-AXIAL LOAD AND CYCLIC-LATERAL LOAD
Chung-Che Chou12 and Sung-Cheng Wu1
1 Department of Civil Engineering, National Taiwan University (NTU), Taipei, Taiwan
2 National Center for Research on Earthquake Engineering (NCREE), Taipei, Taiwan
This work presents an experimental study of the seismic performance of rectangular high-strength Concrete Filled Box Columns (CFBCs) under combined cyclic and axial loads. All specimens are made of high-strength SM 570M steel with the yield strength of 520~580 MPa and concrete compressive strength, , exceeding 80 MPa. Three parameters that affect the inelastic performance of the columns are planned, including the column width-to-thickness (b/t) ratio (11, 18 and 30), the magnitude of axial load and the addition of concrete infill. The column specimens that are 280 to 420 mm in width and 2000 mm in height are tested under combined axial load (4,058~10,090 kN) and cyclic-lateral load. Experimental results indicate that the displacement ductility decreases significantly with the increase of either the axial load level or b/t ratio of the steel column. The addition of the concrete infill inside a hollow column does not improve the displacement ductility of CFBCs under high axial load. Although the CFBC specimen satisfies the b/t limit of a highly ductile member of AISC Seismic Provisions (2016), the specimen under a high-axial load (40%Pn) fails at 4% drift, indicating that the b/t requirement may not be appropriate for CFBCs under the high-axial load. The finite element analysis program ABAQUS is also used to predict the cyclic behavior of the high-strength CFBC under high axial load.
High-strength steel and concrete; Concrete filled box column; High-axial load; Cyclic-lateral load