Issue 46

W. Hao et alii, Frattura ed Integrità Strutturale, 46 (2018) 391-399; DOI: 10.3221/IGF-ESIS.46.36

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.

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

Specimen No.

Experiment Nu/kN

1 2 3 4 5 6 7 8 9

708 694 573 588 629 749 480 450 410 382 464 510

357 1.983 353 1.964 350 1.638 345 1.704 424 1.482 468 1.599 241 1.994 239 1.882 237 1.727 235 1.624 298 1.557 333 1.531

727 648 564 663 736 529 464 401 477 533

0.974 1.071 1.043 0.949 1.018 0.907 0.970 0.952 0.972 0.956 0.976 0.046

902 739 600 666 700 734 572 450 502 530

0.785 0.940 0.980 0.944 1.070 0.654 0.787 0.849 0.924 0.963

717 642 551 614 642 498 446 383 425 443

0.987 700 1.081 685 1.068 660 1.025 743 1.167 802 0.963 505 1.009 497 0.998 482 1.092 555 1.152 608

1.011 1.014 0.852 0.891 0.846 0.934 0.950 0.906 0.837 0.792 0.836 0.839 0.892 0.072

602 0.952

661 0.866

590 0.971 673

430 0.954

502 0.817

410 0.999 490

10 11 12

Mean value

/ /

/ /

1.724 0.186

/ /

/ /

0.881 / 0.111 /

1.043 0.069

/ /

Standard deviation

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 T

reduced integration). The RPC stress-strain relationship [13] is as follows: The compressive stress-strain relationship of RPC is shown in formula (1):

4    1.3 0.4x 0.1x x

5

x  

0

1

 

y

x



x

1

2     6( 1) x

(1)

x

i cp 







x

y



f

c

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 .

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