An analytical procedure for dynamic stability of CFST column accounting for the creep of concrete core is proposed. The long-term effect of creep of concrete core is formulated based on the creep model by the ACI 209 committee and the age-adjusted effective modulus method (AEMM). The equations of boundary frequencies accounting for the effects of concrete creep are derived by the Bolotin’s theory and solved as a quadratic eigenvalue problem. The effectiveness of the proposed method and the characteristics of time-varying distribution of instability regions are numerically surveyed. It is shown that the CFST column becomes dynamically unstable even when the sum of the sustained static load and the amplitude of the dynamic excitation is much lower than the static instability load. It is also found that due to the time effects of concrete creep under the sustained static load, the same excitation, that cannot induce dynamic instability in the early stage of sustained loading, can induce the dynamic instability in a few days later. The critical amplitude and frequency of the dynamic excitation can ecrease by 6% and 3% in 5 days, and 11% and 6% in 100 days.
Steel hollow sections are very efficient in resisting compression forces, and filling these sections with concrete greatly enhances the load-carrying capacity . The concrete-filled steel tubular (CFST) structure possesses many mechanic benefits, such as high strength andfire resistances, favorable ductility and large energy absorption capacities, so the CFST members are widely used in modern structures . Moreover, with the advancement in the strength resistance and construction techniques of CFST column, slender CFST columns are frequently adopted to support the roofs of industrial plants, the decks ofrailways and the floors of multistory buildings . It is known when a slender column is subject to an axial compression, it could fail owing to lateral instability . The instability of slender CFST columns under axial static compression has been experimentally and numerically studied by many researchers . These studies have shown that slender CFST columns are prone to global buckling under static loading.
Publisher : ELSEVIER
By : Y.Q. Huang, J.Y. Fu, A.R. Liu, Y.L. Pi, D. Wu, W. Gao
File Information: English Language/ 9 Page / size: 0.98 MB
سال : ۱۳۹۷
ناشر : ELSEVIER
کاری از : Y.Q. هوانگ، J.Y. فو، A.R. لیو، ی.ل. Pi، D. Wu، W. Gao
اطلاعات فایل : زبان انگلیسی / 9 صفحه / حجم : MB 0.98