In-plane cyclic tests of double-skin composite walls with concrete-filled steel tube boundary elements

This paper focused on a new type of double-skin composite wall in which concrete-filled steel tubes are used as boundary elements, and steel-bar space trusses are used to stabilize the faceplates. The new composite wall is architecturally attractive and has some perceived advantages in strength and construction. However, limited knowledge exists regarding its behavior under the combined cyclic in-plane lateral load and axial compression. This paper reports the test results of five experimental specimens subjected to the intended combined loading. Among the tested specimens, four developed the preferred flexure-dominated limit state, while one developed the undesired shear-dominated limit state. The specimens with the flexure-dominated limit states exhibited ductile behavior up to the drift of 0.036 rad with minor strength degradations. It was found that local buckles in the faceplates of the composite wall did not compromise wall lateral resistance. The effect of using supplementary steel headed studs to stabilize faceplates is also addressed in the paper. Aside from the experimental work, a simplified model was established to compute the wall plastic moment and lateral resistance of the wall with the flexure-dominated limit state. Predictions from the model were found to agree well with the test results, suggesting the model can be used for future design and analysis of the composite wall.