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Steel and Composite Structures
  Volume 32, Number 2, July25 2019 , pages 199-212
DOI: https://doi.org/10.12989/scs.2019.32.2.199
 


Seismic behavior of Q690 circular HCFTST columns under constant axial loading and reversed cyclic lateral loading
Jiantao Wang and Qing Sun

 
Abstract
    This paper presents an investigation on seismic behavior of out-of-code Q690 circular high-strength concrete-filled thin-walled steel tubular (HCFTST) columns made up of high-strength (HS) steel tubes (yield strength fy ≥ 690 MPa). Eight Q690 circular HCFTST columns with various diameter-to-thickness (D/t) ratios, concrete cylinder compressive strengths) fc and axial compression ratios (n) were tested under the constant axial loading and reversed cyclic lateral loading. The obtained lateral load-displacement hysteretic curves, energy dissipation, skeleton curves and ductility, and stiffness degradation were analyzed in detail to reflect the influences of tested parameters. Subsequently, a simplified shear strength model was derived and validated by the test results. Finally, a finite element analysis (FEA) model incorporating a stress triaxiality dependent fracture criterion was established to simulate the seismic behavior. The systematic investigation indicates the following: compared to the D/t ratio and axial compression ratio, improving the concrete compressive strength (e.g., the HS thin-walled steel tube filled with HS concrete) had a slight influence on the ductility but an obvious enhancement of energy dissipation and peak load; the simplified shear strength model based on truss mechanism accurately predicted the shear-resisting capacity; and the established FEA model incorporating steel fracture criterion simulated well the seismic behavior (e.g., hysteretic curve, local buckling and fracture), which can be applied to the seismic analysis and design of Q690 circular HCFTST columns.
 
Key Words
    Q690 circular HCFTST columns; seismic behavior; deteriorating behavior; simplified shear strength model; stress triaxiality dependent fracture criterion
 
Address
Department of Civil Engineering, Xi'an Jiaotong University, Xianning West Road No. 28, Xi'an, P.R. China.
 

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