Local effective length factor in the equivalent slenderness ratio

1995 ◽  
Vol 22 (6) ◽  
pp. 1164-1170 ◽  
Author(s):  
Murray C. Temple ◽  
Ghada Elmahdy
Keyword(s):  
Key Words ◽  
Slenderness Ratio ◽  
Effective Length ◽  
Component Part ◽  
Square Root ◽  
Ratio Equation ◽  
Effective Length Factor ◽  
Equivalent Slenderness Ratio ◽  
Compressive Resistance

The Canadian Standard S16.1 specifies an equivalent slenderness ratio to be used when determining the compressive resistance of a built-up member when buckling occurs about an axis perpendicular to the interconnectors. This equivalent slenderness ratio is the square root of the sum of the squares of the slenderness ratio of the built-up member acting as a unit and the maximum slenderness ratio of a component part between fasteners. The Standard specifies for this second component that an effective length factor be used, the magnitude of which depends on the type of connection. An effective length factor of 0.65 is specified when welds are used. This is of concern to the authors. It is pointed out that the derivation of this equation by Bleich, and by Timoshenko and Gere, does not contain an effective length factor in the second term. The effective length factor of 0.65 comes from a paper by Duan and Chen. Results of tests on five built-up members, channels arranged in the toe-to-toe configuration, indicate that the use of an effective length factor of 0.65 gives unconservative results, especially when the member is slender. It is recommended that a factor of 1.0 be used in the second term of the equivalent slenderness ratio equation. Key words: battens, built-up members, equivalent slenderness ratio, interconnectors, standards.

Equivalent slenderness ratio for built-up members

1993 ◽  
Vol 20 (4) ◽  
pp. 708-711 ◽  
Author(s):  
Murray C. Temple ◽  
Ghada Elmahdy
Keyword(s):  
Key Words ◽  
Carrying Capacity ◽  
Slenderness Ratio ◽  
Load Carrying Capacity ◽  
Lateral Deformation ◽  
Numerical Example ◽  
Ratio Equation ◽  
Load Carrying ◽  
The One ◽  
Equivalent Slenderness Ratio

Built-up struts that buckle about an axis perpendicular to the plane of the connectors should be treated as a "built-up" member as opposed to a "simple" member. This mode of buckling causes shear and moments in the connectors which deform the connectors. These deformations increase the lateral deformation of the member and hence affect the load-carrying capacity. To account for this effect the easiest method is to use an equivalent slenderness ratio such as the one included in the Canadian Standard. This note outlines the derivation of the equivalent slenderness ratio equation, discusses when it should and should not be used, and includes a numerical example. A rewording of the applicable clause in the Canadian Standard is suggested. Key words: battens, built-up members, connectors, slenderness ratio.

Influence of the assumed effective length factor on the load carrying capacity of steel angles in compression

1995 ◽  
Vol 22 (6) ◽  
pp. 1171-1177
Author(s):  
Murray C. Temple ◽  
Davide M. Petretta ◽  
Catherine Morand
Keyword(s):  
Principal Axis ◽  
Design Procedure ◽  
Effective Length ◽  
Experimental Program ◽  
Load Carrying Capacity ◽  
Effective Length Factor ◽  
Compression Members ◽  
Load Carrying ◽  
Steel Angles ◽  
Compressive Resistance

Single angle compression members are usually attached by one leg only. In Canada it is common practice when designing such members to neglect the end eccentricities, to assume the angle buckles about the minor principal axis, and to assume an effective length factor of 1.0. Clause 13.3.1 of S16.1 is then used to calculate the compressive resistance. An experimental program was undertaken to determine the effect that the assumed effective length factor has on the compressive resistance of such angles. Eighteen specimens were tested in which the angles were slender or of intermediate length. The effective length factor was assumed to be 1.0, 0.9, or 0.5. It was determined that when there is substantial restraint at the ends of the angles the assumed effective length factor has a very significant effect on the compressive resistance of an angle attached by one leg. Key words: angles, axis of bending, buckling, design procedure, effective length factor.

scholarly journals Balanced and unbalanced welds for angle compression members

1994 ◽  
Vol 21 (3) ◽  
pp. 396-403 ◽  
Author(s):  
Murray C. Temple ◽  
Sherief S. S. Sakla
Keyword(s):  
Key Words ◽  
Carrying Capacity ◽  
Compressive Load ◽  
Tensile Load ◽  
Effective Length ◽  
Load Carrying Capacity ◽  
Compression Members ◽  
Load Carrying ◽  
Compressive Loads ◽  
Compressive Resistance

Angles used as web members in trusses are often welded to the chords with unbalanced welds. This is necessary because of space limitations. It is not known what effect such a weld has on the compressive load carrying capacity of an angle. The standards and specification examined allow an unbalanced weld for an angle. The justification for using such a weld is based on research conducted on angles in tension. For these members, it was concluded that an unbalanced weld does not affect the tensile load carrying capacity of the angle. Research results for angles with different weld patterns subjected to compressive loads are not available in the literature. Eighteen tests were conducted on angle compression members with various weld patterns. It was determined that an unbalanced weld is detrimental to the load carrying capacity of an intermediate length angle but is beneficial for a slender angle. Key words: angles, column (structural), compressive resistance, effective length, standards, welds.

scholarly journals Buckling of built-up compression members in the plane of the connectors

1993 ◽  
Vol 20 (6) ◽  
pp. 895-909 ◽  
Author(s):  
Murray C. Temple ◽  
Ghada Elmahdy
Keyword(s):  
Finite Element Analysis ◽  
Slenderness Ratio ◽  
Element Analysis ◽  
The North ◽  
Compression Members ◽  
Compressive Loads ◽  
European Standards ◽  
Equivalent Slenderness Ratio ◽  
Compressive Resistance

An examination of the requirements for the design of built-up compression members in the North American and European standards and specifications reveals a great variation in the allowable maximum slenderness ratio for an individual main member, and also in the determination of an equivalent slenderness ratio. The requirements of the Canadian standard with regard to the determination of the maximum allowable slenderness ratio of a main member between points of connection can be a bit confusing.This research involved a study of model built-up members that buckled about an axis perpendicular to the plane of the connectors. Twenty-four tests were conducted on model built-up members. The theoretical analysis consisted of a finite element analysis of the model built-up struts. In addition, an equivalent slenderness ratio was calculated by several methods. These equivalent slenderness ratios were then used in conjunction with the requirements of the Canadian standard to calculate a compressive resistance, which was compared with the experimental failure load.From this research on built-up members that buckle about an axis perpendicular to the plane of the connectors it was found that at least two connectors should be used, that the slenderness ratio of the main member between points of connection has a significant effect on the compressive resistance, and that Timoshenko's equivalent slenderness ratio when used in conjunction with the Canadian standard gives results that are in the best agreement with the experimental results. Key words: battens, built-up members, compressive loads, connectors, equivalent slenderness ratio.

Slenderness ratio of main members between interconnectors of built-up compression members

1996 ◽  
Vol 23 (6) ◽  
pp. 1295-1304 ◽  
Author(s):  
Murray C. Temple ◽  
Ghada M. Elmahdy
Keyword(s):  
Slenderness Ratio ◽  
Steel Structures ◽  
Imperfection Sensitivity ◽  
Design Standards ◽  
Limit States ◽  
Compression Members ◽  
Equivalent Slenderness Ratio ◽  
The Individual ◽  
Compressive Resistance ◽  
Steel Design

Many steel design standards, including CAN/CSA-S16.1-M89 "Limit states design of steel structures," specify maximum slenderness ratios for the individual main members between the interconnectors of built-up compression members. Previous research on which these requirements are based is reviewed. It is shown that the imperfection sensitivity due to coupled instabilities is measured from bifurcation critical loads. However, steel standards are based on a compressive resistance determined for a member with an initial out-of-straightness and a suitable residual stress pattern. It is shown that the use of an equivalent slenderness ratio equation is sufficient to predict the compressive resistance of these built-up members. Further restrictions on the slenderness ratio of built-up members between interconnectors are not warranted. Thus, the elimination of these requirements from S16.1-94 is justified. Key words: built-up members, codes, compressive resistance, coupled instabilities, equivalent slenderness ratio, interconnectors.

Factored axial compressive resistance of schifflerized angles

1991 ◽  
Vol 18 (6) ◽  
pp. 926-932 ◽  
Author(s):  
Seshu Madhava Rao Adluri ◽  
Murty K. S. Madugula
Keyword(s):  
Key Words ◽  
Design Method ◽  
Design Criteria ◽  
Design Practice ◽  
Buckling Mode ◽  
Flexural Buckling ◽  
Mode Of Failure ◽  
Current Design ◽  
Similarities And Differences ◽  
Compressive Resistance

The concept of schifflerization of 90° equal-leg angle is presented and its application in triangular-base latticed steel towers is explained. The similarities and differences between schifflerized angles and regular 90° angles are discussed. The current design practice for schifflerized angles is reviewed and its limitation is highlighted. A design method which includes the effect of the torsional-flexural buckling mode of failure is proposed. For ready use of designers, the factored axial compressive resistances of schifflerized angles are tabulated for both the present and proposed design methods. Key words: buckling, compressive resistance, design criteria, schifflerized angles, stability, standards, steel, struts, towers, guyed towers.

scholarly journals Inelastic Effective Length Factor of Nonsway Reinforced Concrete Columns

2009 ◽  
Vol 135 (9) ◽  
pp. 1034-1039 ◽  
Author(s):  
A. Bendito ◽  
M. L. Romero ◽  
J. L. Bonet ◽  
P. F. Miguel ◽  
M. A. Fernandez
Keyword(s):  
Reinforced Concrete ◽  
Concrete Columns ◽  
Effective Length ◽  
Reinforced Concrete Columns ◽  
Effective Length Factor
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