Nonlinear analysis of circular double-skin concrete-filled steel tubular columns under axial compression

Advances in Civil Engineering

Zhao

2018

e design of composite joints for connecting concrete-filled double-skin tubular (CFDST) columns to steel beams supporting reinforced concrete (RC) slabs is presented in this paper. Five half-scale specimens were designed, including four composite joints with RC slab and one bare steel beam joint, and were tested under a constant axially compressive force and lateral cyclic loading at the top end of the column to evaluate their seismic behavior. e main experimental parameters were the construction of the joint and the type of the column. e seismic behaviors, including the failure modes, hysteresis curves, ductility, strength and stiffness degradation, and energy dissipation, were investigated. e failure modes of the composite joints depended on the joint construction and on the stiffness ratio of beams to columns. Joints of stiffening type had significantly higher load-bearing and deformation capacities than joints of nonstiffening type. Compared with the bare steel beam joint, the bearing capacities of the composite joints with RC slabs were markedly increased. e composite action was remarkable under sagging moments, resulting in larger deformation on the bottom flanges of the beams. Overall, most specimens exhibited full hysteresis loops, and the equivalent viscous damping coefficients were 0.282∼0.311. e interstory drift ratios satisfied the requirements specified by technical regulations. Composite connections of this type exhibit excellent ductility and favorable energy dissipation and can be effectively utilized in superhigh-rise buildings erected in earthquake zones.

Section: Introductionmentioning

confidence: 99%

Cyclic Testing of Concrete‐Filled Double‐Skin Steel Tubular Column to Steel Beam Joint with RC Slab

Advances in Civil Engineering

Zhao

2018

Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

“…CFDST columns consist of concentric inner and outer steel tubes with infill concrete between them. The steel tubes are hollow structural sections, it may be supplied with carbon steel material, these sections can be circular (CHS) [3][4][5][6][7][8][9], square (SHS) [10] and rectangle (RHS) [11,12].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Rectangular Concrete-Filled Double Skin Tubular Short Column With External Stainless Steel Tubes

Yossef¹,

Kharoob²

2019

Concrete-filled double skin steel tubular (CFDST) columns could be utilized in structures such as bridges, high-rise buildings, viaducts and electricity transmission towers due to its great structural performance. Alternatively, lean duplex stainless steel has recently gained significant interest for its high structural performance, similar corrosion resistance and lower cost compared to the austenitic steel grade. Hence, this paper presents nonlinear numerical simulations of rectangular outer lean duplex stainless steel (EN 1.4162) CFDST short columns under compression, based on the finite element (FE) method, The FE model and its validation were initially presented. Then, the effect of the key parameters that influence the behavior of these types of columns was introduced. Based on that model, the behavior and design of rectangular outer lean duplex stainless steel (EN 1.4162) CFDST short columns under compression were discussed. All classes of the outer rectangular hollow section according to the depth-to-thickness (D/t) ratios were considered. The results showed that the axial ultimate strength of rectangular CFDST short columns increased linearly by increasing the concrete compressive strength, while it does not influence when changing the hollow ratios. Finally, the axial capacities were compared with the available design methods, and recommendations were conducted for the design strength of this type of column. The presented design model, for calculation of the ultimate axial strength of rectangular CFDST short columns with external lean duplex stainless steel outer tubes, gave suitable conservative results if compared with the other literature model.

“…A CFDST column is composed of double concentric steel tubes with the internal space fully or partly filled with concrete. Comparing with the conventional CFST column, the bending stiffness, ductility, and seismic performance of the CFDST column are significantly increased because of the inner steel tube [1][2][3][4]. CFDST columns may also be effective for dealing with the requirement for large-profile columns in some engineering projects.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of Concrete‐Filled Double‐Skin Steel Tubular Column for Steel Beam Joints

Zhao

Advances in Materials Science and Engineering

2018

This paper presents a new type of joint for connecting steel beams with a concrete-filled double-skin steel tubular (CFDST) column. Four half-scale specimens of the joint with different specifications were constructed and tested under a constant axially compressive force with vertical low-reversal loads applied to the beam ends to examine their failure modes and hysteretic behaviors. The beam hinging mechanism of the joint was observed in the radian area of the horizontal end plates. The proposed connection was found to exhibit good energy dissipation capabilities with its limit rotation in the failure state reaching 0.05 rad, thus satisfying the FEMA-350 ductility requirement of ≥0.03 rad for seismic resistance. A finite element analysis (FEA) model of the joint was also established and validated by comparing its predictions with experimental results. The FEA model was used to investigate the effects of different parameters such as the stiffened height of the web anchorage plate, axial load level, steel and concrete strengths, steel ratio on the moment-rotation relationship, and initial stiffness of the connection. This paper presents some important design considerations of the connection, as well as aspects requiring further study.