Influence of ultra-high strength infill in slender concrete-filled steel tubular columns

Abstract

This paper describes 24 tests conducted on slender circular tubular columns filled with normal, high, and ultra-high strength concrete for plain, bar reinforced and steel fiber reinforced columns. These were reinforced and subjected to both concentric and eccentric axial load. It is a continuation of a previous research paper [1], which presented test results on eccentrically loaded plain concrete columns. The test parameters are nominal strength of concrete (30, 90 and 130 MPa), eccentricity e (0, 20 and 50 mm) and type of reinforcement. A comparison with the corresponding empty tubular columns is performed, as the aim of the paper is to analyze the influence of each type of infill and establish the best option for practical application. For the limited cases analyzed the results show that the addition of high or ultra-high strength infill is more useful for concentric loaded cases than for eccentric loaded ones, where it seems that the best design option is the utilization of bar reinforced concrete filling rather than steel fiber to reinforce CFST columns. The experimental ultimate load of each test was compared with the design loads from Eurocode 4, accurate for the eccentrically loaded tests.

Experimental Study on Ultrahigh Strength Concrete Filled Steel Tube Short Columns under Axial Load

“…The tests by Tan and Pu [9] show that compared with the ordinary CFST, the strength and plastic deformation of UHSC will be significantly improved due to the confinement effect of steel tube, the same as the bearing capacity of UHSCFST. The authors [10][11][12][13] also reached similar conclusions. However, Liew and Xiong [14,15] described that the UHSCFST has strong bearing capacity, but the load versus axial displacement curves tended to drop quickly after peak loads.…”

Ultra-high Strength Concrete on Eccentrically Loaded Slender Circular Concrete-filled Dual Steel Columns

“…In the case of CFST columns tested at ambient temperature, this effect was observed by Portolés et al [1] through an extensive test program on slender columns, being the effect of UHSC as infill particularly significant for axially loaded columns.…”

Behavior of steel fiber reinforced concrete-filled steel tube columns under axial compression

“…Tokgoz and Dundar [24] stated that when rectangular steel tube columns filled with steel fiber reinforced high strength concrete were subjected to eccentric load, the use of fiber reinforced concrete improved the ductility and the deformation capacity but had little effect on the ultimate strength. Portolés [25] reported experimental investigations on slender steel tube columns filled with normal, high and ultra-high strength concrete under eccentric load. The infill concrete included plain concrete, steel fiber reinforced concrete and bar reinforced concrete.…”