Issue 46

W. Hao et alii, Frattura ed Integrità Strutturale, 46 (2018) 391-399; DOI: 10.3221/IGF-ESIS.46.36 396 The bearing capacity of RPC filled square steel tubular column is an important indicator of engineering design, so an appropriate calculation formula for bearing capacity is very essential. According to the calculation formulas recommended in five commonly used bearing capacity calculation specifications (or codes) for ordinary concrete-filled steel tubes, namely AISC2005 [8], DBJ13-51-2003 [9], GJB4142-2000 [10], CECS28-2012 [11] and GB50936-2014 [12], this paper calculates the eccentric compression capacities of the RPC filled square steel tubular specimens, with the results shown in Tab. 6. It can be seen that, the ratio of bearing capacity Nu/N between the experiment result and CECS28-2012 calculated results have a standard deviation of 0.069, a coefficient of variation of 0.066, and a mean value of 1.043. Compared with the others specifications (or codes), the CECS28-2012 calculated results are quite close to the experiment results and also relatively conservative. Therefore, the formula provided in CECS28-2012 is recommended for calculation of the bearing capacity of RPC filled square steel tubular column in engineering practice. Specimen No. Experiment Nu/kN AISC2005 DBJ13-51-2003 GJB4142-2000 CECS28-2012 GB50936-2014 N/kN Nu/N N/kN Nu/N N/kN Nu/N N/kN Nu/N N/kN Nu/N 1 708 357 1.983 727 0.974 902 0.785 717 0.987 700 1.011 2 694 353 1.964 648 1.071 739 0.940 642 1.081 685 1.014 3 573 350 1.638 602 0.952 661 0.866 590 0.971 673 0.852 4 588 345 1.704 564 1.043 600 0.980 551 1.068 660 0.891 5 629 424 1.482 663 0.949 666 0.944 614 1.025 743 0.846 6 749 468 1.599 736 1.018 700 1.070 642 1.167 802 0.934 7 480 241 1.994 529 0.907 734 0.654 498 0.963 505 0.950 8 450 239 1.882 464 0.970 572 0.787 446 1.009 497 0.906 9 410 237 1.727 430 0.954 502 0.817 410 0.999 490 0.837 10 382 235 1.624 401 0.952 450 0.849 383 0.998 482 0.792 11 464 298 1.557 477 0.972 502 0.924 425 1.092 555 0.836 12 510 333 1.531 533 0.956 530 0.963 443 1.152 608 0.839 Mean value / / 1.724 / 0.976 / 0.881 / 1.043 / 0.892 Standard deviation / / 0.186 / 0.046 / 0.111 / 0.069 / 0.072 Coefficient of variation / / 0.108 / 0.047 / 0.126 / 0.066 / 0.081 Table 6: Bearing capacity of the specimens. F INITE ELEMENT ANALYSIS Finite element model of columns his paper simulates the eccentrically loaded RPC filled square steel tubular column using the finite element software Abaqus. The RPC filled square steel tubular column model consists of three parts, namely RPC, an outer steel tube and a loading cover. Both the RPC and the loading cover are modelled with C3D8R brick elements (8-node 3D brick elements with reduced integration); and the steel tube is modelled with S4R shell element (4-node shell elements with reduced integration). The RPC stress-strain relationship [13] is as follows: The compressive stress-strain relationship of RPC is shown in formula (1): 4 5 2 1.3 0.4x 0.1x 0 1 1 6( 1) i cp c x x y x x x x x y f                  (1) where: ε cp is the compressive strain when RPC reaches the peak compressive strength, which is set to be 4400×10 -6 ; f c is the peak compressive strength of RPC, which is set to be 93.49N/mm 2 . T