Experimental Study of Scale Effects on the Compressive Behavior of Short Concrete-Filled Steel Tube Columns

Composite Effect of Stub Square Steel Tubed Columns Under Axial Compression

“…The selection of 5 mm represents a typical corner radius of cold-formed square tube being welded at the middle of the plate, as also referenced in (Liu et al [3], Qi et al [17]). In the tests done by Sakino et al [10][11] and Yamamoto et al [13], the square tubes were welded at the sharp corners. In this study, the corner radius of specimens was about 2mm based on the measurement of the tube.…”

“…kt can be taken as 0.8 based on the experimental results. The effective lateral confining pressure ' r f can be calculated by ' r t e t r l f k f k k f   A total of 124 experimental axial strength values for tubed columns were collected from (Liu et al [3], Han et al [8], Sakino et al [10][11], Zhang et al [12], Yamamoto et al [13], and Qi et al [17]). The considered test parameters for the experimental results include width to tube thickness ratio D/t (20-162), concrete strength (28.5-132 MPa), and longitudinal reinforce ratio (0-6.5%).…”

“…The test results of Zhang et al [12] showed that the axial compressive strength of square tubed columns was greater than that of square CFT columns when the width to thickness ratio (D/t) of tube was 70 and that the trend reversed when width-to-thickness ratio D/t < 47. Yamamoto et al [13] demonstrated that the failure mode was not correlated with the cross section dimension, while the confinement effect was related to the cross section dimension and concrete strength. Kwon et al [14][15] presented an analytical prediction and experimental research for the long term behavior of both circular and square tubed columns and CFT columns.…”

“…The system parameters affecting the confinement effect are rather complicated. From the above literature review [7,[10][11][12][13][14][15][16][17], the available research results were focused on tubed plain concrete columns with small dimensions and width-to-thickness ratios (D/t < 100). Experimental and theoretical study on large width-to-thickness ratios (D/t > 100) tubed reinforce concrete columns are still short.…”

Size Effect on Confining Force of Circular Concrete Filled in Steel Tube under Axial Compression

“…Saknio [5] conducted 23 CFT short columns with different section sizes and wall thicknesses under axial compression, and all section diameters were smaller than 450mm, then the size effect correction coefficient ru = 1.67D -0.112 was fitted based on the test data of Blanks [1] , in which D was the outer diameter of the specimen; the correction coefficient was used in the part of uniaxial compression strength in the formula of bearing capacity of CFT. Yamamoto [6] carried on experimental study on size effect on circular and square CFT columns complied with the principle of similarity, with the diameter-thick ratio of 31.8 for circular CFT column and 44.4 for square CFT columns, and the section size was below 300mm; the results showed that size effect on compressive strength of circular CFT column was not obvious, while size effect on the square column was significant; the given calculation formula of bearing capacity adopted the same correction coefficient of size effect provided by Sakino [5] . Chen [7] took the CFT column of arch bridge with diameter of 1200mm and steel tube thickness of 24mm as the prototype, to carry on scale experiment of CFT columns in the proportion of 1:2.4 (diameter was 500mm) and 1:4.8 (diameter was 250mm) under axial compression; the test results showed that there was not big difference on the ratio of test bearing capacity to the code value between large size specimen and the small size one.…”