| doi:10.3850/978-981-08-6218-3_FRP-Fr037 |
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COMPRESSIVE PERFORMACES OF THE CONCRETE FILLED CIRCULAR CFRP-STEEL TUBES (1): FINITE ELEMENT SIMULATION AND LOAD BEARING CAPACITY
S. J. Xua, Q. L. Wangb and Y. B. Shaoc
School of Civil Engineering, Shenyang Jianzhu University, Shenyang, Liaoning.
adanielupup_47@126.com
bceqlwang@sjzu.edu.cn
School of Civil Engineering, Yantai University, Yantai, Shandong.
ccybshao@ytu.edu.cn
EXTENDED ABSTRACT
The stress-strain relationship of concrete confined by circular CFRP-steel tube under axial compressive load is presented. The load-strain curves and the deformed modes of the concrete filled circular CFRP-steel tubular stub columns under axial compressive load are obtained from finite element simulation. The numerical load-strain curves are a little conservative but agree reasonably well with experimental results. The failure modes of the concrete filled circular CFRP-steel tubular stub columns are similar to those of the corresponding concrete filled circular steel tubular stub columns, but the deformation is relatively smaller. The index and parametric equations of the load bearing capacity for the concrete filled circular CFRP-steel tubular stub columns are proposed and the calculated results from the equations agree well with the experimental results.
1. INTRODUCTION
In recent years, concrete filled tubular structures were used widely all around the world due to their excellent performances, and the corresponding study was also conducted deeply, in which the research work on concrete filled circular CFRP-steel tube (hereinafter referred to as C-CFRP-CFST) members attracts more and more concerns. In order to understand the compressive performances of the C-CFRP-CFST members theoretically further, in this paper, the load-strain curves and deformed modes of these composite stub columns under axial compressive load are simulated by using software ABAQUS, and the index and parametric equations of the load bearing capacity for the C-CFRP-CFST stub columns are proposed.
2. FINITE ELEMENT SIMULATION
The stress-strain relationships of steel, concrete and CFRP are defined respectively. The finite element model is made also. Overall 10 C-CFRP-CFST stub columns under axial compressive load are analysed by using ABAQUS software and part of the FE results together with experimental measured results are plotted in Figure 1. It can be found from Figure 2 that the FE results agree reasonably well with experimental results.
Figure 1: Comparison between predicted results and tested results of load-strain curves for part of the columns
C-CFRP-CFST stub column convexes at the mid-cross-section, however, its deformation is relatively smaller than that of concrete filled circular steel tube (hereinafter referred to as C-CFST) stub column due to the confinement of the un-fractured CFRP.
3. LOAD BEARING CAPACITY
The bearing capacity at the longitudinal strain εcfscy is defined as the load bearing capacity index of axial compressive strength (fcfscy). They are expressed as follows:
The load bearing capacity (Nu) of C-CFRP-CFST stub column under axial compression can be calculated by using the following equation, and It is found that the simplified equation can produce reasonably accurate estimations.
4. CONCLUSIONS
The load-strain curves of the C-CFRP-CFST stub columns under axial compression are analysed by using ABAQUS and the numerical results agree well with experimental results. The deformed mode of concrete filled circular CFRP-steel tubular stub columns under axial compression is relatively smaller than that of concrete filled circular steel tubular stub columns. The parametric equations of the load bearing capacity of the composite stub columns are presented and the calculated results agree well with experimental results.
5. ACKNOWLEDGEMENTS
The research reported in the paper is part of the Project NCET-08-0865 supported by New Century Excellent Talent of the Ministry of Education of China, and the Project 2007R31 supported by Colleges and Universities Excellent Talent of Liaoning Province, China. Their financial supports are highly appreciated.