Experimental study on seismic behavior of innovative multi-cellular CFT-walls with tie-bolts

Abstract

The hysteretic behavior of an innovative multi-cellular concrete-filled steel tube walls (CFT-walls) with tie-bolts was studied. Seven full-scale tests were conducted under constant axial loads and cyclic lateral loads. The tie-bolts were arranged to fix connectors, attach the wall studs as well as enhance the confinement between steel sheets and infill concrete. The axial compression ratio was taken be the limit which may encounter in real projects. Before the treatment of the test results, the P − ∆ effect was excluded from the lateral force–drift curves as it is considered independently in the current design codes. All the specimens presented similar spindle-shaped lateral force versus displacement hysteretic curves and failed in the severe plastic local buckling–tension cycles of the steel sheets and the crushing of concrete. No discernible pinching effect and out-of-plane buckling were observed and the specimens showed favorable hysteresis behavior, deformation capacity, and energy dissipation during the tests. The tie-bolts arranged at middle tubes and the width-to-thickness ratios of the faceplates had no discernible effect on the behavior in the investigated range. The point when the force reached two-thirds of the maximum lateral force was defined as the yield point of the member. Based on test results, two idealized backbone curves were proposed. Moreover, the hysteretic curves of all the specimens were calculated using the fiber element method and showed good agreement with the experimental results.