Size Effect on Nominal Strength of Lightweight and Normal Concrete-Filled Steel Tube Columns under Axial Compression: Mesoscale Simulations

Meso‐scale modeling of size effect on pure torsional failure of concrete‐filled steel tubular columns

“…A 3D microscopic numerical model of standard cubic concrete test block was established. Through repeated trial calculation of mechanical parameters in the ITZ, when each mechanical parameter is the same as in Table 2, the simulated value of concrete compressive strength (54.28 MPa) is consistent with the experimental value (55 MPa), indicating the parameters were reasonable 6,21 . In addition, in order to explore the influence of grid sensitivity on the simulation results, the specimen CH45 10 was selected to conduct pure torsion simulation under different mesh sizes (2, 4, and 5 mm), and the comparison between simulation results and experimental results is shown in Figure 3.…”

“…Through repeated trial calculation of mechanical parameters in the ITZ, when each mechanical parameter is the same as in Table 2, the simulated value of concrete compressive strength (54.28 MPa) is consistent with the experimental value (55 MPa), indicating the parameters were reasonable. 6,21 In addition, in order to explore the influence of grid sensitivity on the simulation results, the specimen CH45 10 was selected to conduct pure torsion simulation under different mesh sizes (2, 4, and 5 mm), and the comparison between simulation results and experimental results is shown in Figure 3. It can be seen that the difference of failure diagram of core concrete column and torsion moment-rotation angle relation under different grid size is small, proving that the grid sensitivity is eliminated.…”

“…The comparison between the calculated values and the simulation values as well as the test values 1,8,9,14,16,17,46,48,49,50 is shown in results, the specimens have different section sizes (B = 114, 130, 140, 160, 200, and 400 mm), steel ratios (0.05-0.2), steel strength (345-450 MPa), concrete strength (30-90 MPa), and slenderness ratios (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). It can be seen that under different section sizes, steel ratios, steel yield strength, concrete strength, and slenderness ratios, the errors between the modified formula and the experimental values are <21%, indicating that the modified formula is suitable for the calculation of the torsional capacity of the square columns.…”

“…At present, the SEL of concrete material has been basically perfected, 25 and the fracture mechanics SEL proposed by Bažant 44 was widely accepted, which applied in many studies. 6,21,31 The SEL for torsion proposed by Bažant 44 was modified by Jin et al, 24 and a new SEL was proposed as…”

“…These engineering structures may be subjected to earthquake, 3,4 impact, 5 and so forth during their service period. The CFST columns not only bear axial compression, 6 but also may suffer torsion load, 7–9 such as the transmitting poles of electricity, the columns (particularly at corners) of the high‐rise building under earthquake. The presence of torsional load makes the failure of the structure unpredictable and may lead to catastrophic collapse of the structure.…”