Experimental Study And Analysis Of RPC-filled Steel Tube Under Axial Compression And Push Out Test

RPC-filled steel tubes(RFSTs) is a composite column in which the steel tube relieve the brittleness of RPC and ensure its high strength. This new composite column is potential in ultra-high building, large-span and heavy structures. Based on the research of CFT under axial compression and push-out test in history, a series of experiments about axial loading and bond-slip behavior of RFST is carried out in this paper. As the following is the main work of this paper:1. After summarizing the obtained achievements of CFT under axial compression and push out test, this paper suggest it’s necessary to acquire the mechanical behavior of the RFST by experiment.2. A push out test including 5 specimens is carried out successfully during which the mechanical behavior of the RFST is recorded. In the experiment, the curves of V-s, τ-s and position-strain are obtained and a calculation method of bond strength under a curing condition is suggested. After analyzing the interface in the RFST, this paper construct a general link between the microlocking with interface condition. Finally, based on several important experiments, the confinement quality in the macrolocking is proposed by which the classification criteria and mechanism of two type of V-s curve is investigated.3. An axial compression experiment of 31 RFST members is carried out during which the mechanical behavior of the RFST is recorded. In the experiment, the curves of cN-ε, N-ε and h vε-ε are acquired and analyzed. The effects of D/ t,load model and interface condition are analyzed.Based on the h vε-ε curve of all specimens, the envelope line of average steel strain is proposed. This paper also suggest a formula to calculate the uN of the RFST under axial compression according to classical experimental data.4. Based on the internal decomposition analysis, the redistribution of two materials during the axial compression and push out test is figured out. The effect caused by loading way and interface condition is also analyzed. The stress path of the steel is figured and a formula to calculate the uN of confined RPC filled tube is suggested. Obtained from the decomposition analysis, the confinement stress curve in the push out test is well explained macrolocking.