Abstract
Based on the low cyclic loading test results of vertical stiffener joints between concrete-filled double steel tubular (CFDST) columns and steel beams, the shear transfer mechanism and shear resistance were analyzed in this paper. A conceptual model formulated was presented in terms of equilibrium and stress-strain relationships. The results calculated by the theoretical model and the available experimental data were compared, and then one new concept of shear storage coefficient was proposed for the determination of the shear storage capacity of the joint, which quantitatively explained the ductility failure progression of the joint specimens in the seismic performance test. It was concluded that the vertical stiffener joint had sufficient shear resistance, which met the seismic design principle of strong shear and weak bending. Results show that the ribbed joints have greater shear resistance than unribbed ones; lengthening the overhang of the vertical stiffener can both increase shear resistance and shear storage capacity of the joint; axial compression ratio can reduce the shear storage capacity. The paper also suggests that the joint design should ensure enough safety storage of shear resistance to improve the seismic performance.
Highlights
With the development of concrete-filled steel tubular (CFST) column, concrete-filled double steel tubular (CFDST) column emerged in the form of circular internally and square externally, fully filled with concrete
When shear strength calculation was not estimated accurately, the structure would lead to the lack of shear capacity even the shear failure [19,20,21,22,23], so shear storage capacity was analyzed in this paper based on the low cyclic loading test results of vertical stiffener joints between CFDST columns and steel beams
Vertical stiffener joints were tested by quasistatic cyclic loading at the both ends of the steel beam [6], i.e., the fixed vertical force N was applied on the column top, and two 500 kN MTS servo actuators were placed at east and west beam ends to achieve the reciprocating load by pushing and pulling at the same time. e joint specimens were intended to simulate the connection between an interior column and the two adjacent steel beams in a frame structure
Summary
With the development of concrete-filled steel tubular (CFST) column, concrete-filled double steel tubular (CFDST) column emerged in the form of circular internally and square externally, fully filled with concrete. E superposition method was applied to estimate the beam-column joint shear strength [13,14,15,16,17,18], and the applicability and accuracy of the strength superposition method for the estimation of joint shear strength were verified explicitly These studies have been limited in scope to ordinary CFST or composite concrete structures. When shear strength calculation was not estimated accurately, the structure would lead to the lack of shear capacity even the shear failure [19,20,21,22,23], so shear storage capacity was analyzed in this paper based on the low cyclic loading test results of vertical stiffener joints between CFDST columns and steel beams. In order to better evaluate the seismic design principles of strong joints, the joint’s safety reserve of shear capacity was quantitatively explained to ensure proper failure progression and ductility, which can provide reference for engineering design of CFDST structure
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