Noncompact and slender circular CFT members: Experimental database, analysis, and design

Lai, Zhichao

doi:10.1016/j.jcsr.2014.11.005

Cited by 85 publications

(21 citation statements)

References 21 publications

(28 reference statements)

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“…As discussed by the authors in Lai et al (2014b) and Lai and Varma (2015), the AISC 360-10 design equations (Equations 1 and 2) are extremely conservative in estimating the strengths of noncompact and slender CFT beam-columns. There are two primary reasons for this over-conservatism.…”

Section: Whenmentioning

confidence: 99%

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P-M Interaction Equations for Design of CFT Beam-Columns

Lai¹,

Varma²,

Griffis³

2015

Structures Congress 2015

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Concrete-filled steel tube (CFT) beam-columns are categorized as compact, noncompact or slender depending on the tube slenderness ratio (width-to-thickness b/t or D/t ratio, λ) and the slenderness limits (λ p , λ r , and λ limit ) specified by the AISC 360-10. The behavior and strength of CFT beam-columns depend on the tube slenderness ratio (λ), material strength ratio (F y /f' c ), axial load ratio (α) and member length-to-depth ratio (L/B or L/D). In previous articles, the authors have presented results of numerical investigations evaluating the effects of these four parameters, and developed P-M interaction equations for designing noncompact and slender CFT beamcolumns. This paper evaluates the applicability of the developed design equations for: (i) designing compact CFT beam-columns, and (ii) estimating the available strengths of CFT members in frames designed using the direct analysis method. The applicability for designing compact CFT beam-columns is evaluated by comparing the P-M interaction curves resulting from the developed equations with those calculated using the plastic stress distribution method specified by AISC 360-10. The applicability for the direct analysis method is evaluated by comparing the available strengths estimated using the developed equations with demands calculated by conducting second-order elastic analysis using MASTAN2 (V3.3).

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Section: Whenmentioning

confidence: 99%

“…The authors have presented the development of these slenderness limits in detail elsewhere in Lai et al (2014b) and Lai and Varma (2015). As shown in Table 1, the slenderness limits (λ p , λ r , and λ limit ) vary depending on the loading (axial compression or flexure) acting on the CFT member.…”

Section: Introductionmentioning

confidence: 99%

P-M Interaction Equations for Design of CFT Beam-Columns

Lai¹,

Varma²,

Griffis³

2015

Structures Congress 2015

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“…These studies have been summarized independently by several researchers in [1] [9] [10] [11] [12]. These experimental tests indicate that the behavior and strength of conventionalstrength CFT members depend on parameters such as the concrete compressive strength (f' c ), steel yield stress (F y ), tube width-to-thickness ratio (b/t) or diameter-to-thickness ratio (D/t), and member length (L).…”

Section: Introductionmentioning

confidence: 99%

“…The authors have presented the basis (development and verification) of these design provisions elsewhere in [1] [3] [12].…”

Section: Introductionmentioning

confidence: 99%

Analysis and behavior of high-strength rectangular CFT columns

Lai¹,

Varma²

2018

Proceedings 12th International Conference on Advances in Steel-Concrete Composite Structures - ASCCS 2018

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The current AISC Specification (AISC 360-16) specifies the material strength limits for concrete-filled steel tube (CFT) columns. According to AISC 360-16, the steel yield stress (F y ) for CFT columns should not exceed 525 MPa, and the concrete compressive strength (f' c ) should not exceed 70 MPa. CFT columns are classified as high strength if either F y or f' c exceeds these specified limits, and are classified as conventional strength if both F y and f' c are less than or equal to the limits. Due to lack of adequate research and comprehensive design equations, AISC 360-16 does not endorse the use of high-strength materials for CFT columns. This paper makes a contribution towards addressing this gap using a two-step approach. The first step consists of compiling an experimental database of high-strength rectangular CFT column tests in the literature and evaluating the possibility of extending the current AISC 360-16 design equations to high-strength rectangular CFT columns. The second step consists of developing and benchmarking detailed 3D nonlinear finite element models for predicting the behavior of high-strength CFT columns from the database. The benchmarked models are being used to perform comprehensive parametric studies to address gaps in the database and propose design equations for high-strength rectangular CFT members, which will be part of a future paper.

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“…Experiments on high-strength CFST slender columns have been undertaken by researchers in the past [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. However, experimental studies of circular high-strength CFSST columns are very limited [23].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear analysis of circular high strength concrete-filled stainless steel tubular slender beam-columns

Patel

Liang

Hadi

2017

Engineering Structures

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Nonlinear analysis of circular high strength concrete-filled stainless steel tubular slender beam-columns AbstractConcrete-filled stainless steel tubular (CFSST) slender columns are increasingly used in composite structures owing to their distinguished features, such as aesthetic appearance, high corrosion resistance, high durability and ease of maintenance. Currently, however, there is a lack of an accurate and efficient numerical model that can be utilized to determine the performance of circular CFSST slender columns. This paper describes a nonlinear fiber-based model proposed for computing the deflection and axial load-moment strength interaction responses of eccentrically loaded circular high-strength CFSST slender columns. The fiber-based model incorporates the accurate three-stage stress-strain relations of stainless steels, accounting for different strain hardening characteristics in tension and compression. The material and geometric nonlinearities as well as concrete confinement are included in the computational procedures. Existing experimental results on axially loaded CFSST slender columns are utilized to verify the proposed fiber-based model. A parametric study is conducted to examine the performance of high-strength slender CFSST beam-columns with various geometric and material parameters. It is shown that the fiber-based analysis technique developed can accurately capture the experimentally observed performance of circular high-strength CFSST slender columns. The results obtained indicate that increasing the eccentricity ratio, column slenderness ratio and diameter-to-thickness ratio remarkably decreases the initial flexural stiffness and ultimate axial strength of CFSST columns, but considerably increases their displacement ductility. Moreover, an increase in concrete compressive strength increases the flexural stiffness and ultimate axial strength of CFSST columns; however, it decreases their ductility. Furthermore, the ultimate axial strength of CFST slender columns is found to increase by using stainless steel tubes with higher proof stresses. decreases their ductility. Furthermore, the ultimate axial strength of CFST slender columns is found to increase by using stainless steel tubes with higher proof stresses.

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Noncompact and slender circular CFT members: Experimental database, analysis, and design

Cited by 85 publications

References 21 publications

P-M Interaction Equations for Design of CFT Beam-Columns

P-M Interaction Equations for Design of CFT Beam-Columns

Analysis and behavior of high-strength rectangular CFT columns

Nonlinear analysis of circular high strength concrete-filled stainless steel tubular slender beam-columns

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