Experimental assessment of I-shaped steel beams with longitudinal stiffeners under lateral-torsional buckling

This study focused on the experimental assessment of the behavior of I-shaped steel beams with longitudinal stiffeners under the action of lateral-torsional buckling. Thirty-three IPE-140 steel beams with and without longitudinal stiffeners were tested under simple-support conditions with a laterally unbraced length ranging from 0.69 to 6.0 m. The stiffeners spacing was 0.42 m, which represented three times the depth of the section. The structural behavior of the beams is discussed in terms of their flexural capacity, the lateral displacement of the compression flange and the failure twist angle. The results showed that the use of longitudinal stiffeners increased the flexural capacity up to 82%, decreased the lateral displacement of the compression flange and the failure twist angle up to 72 and 90% respectively, with respect to the specimens without stiffeners.

Download Full-text

Effect of longitudinal stiffeners’ spacing in lateral-torsional buckling

10.7764/rdlc.19.3.190-199 ◽

2020 ◽

Vol 19 (3) ◽

pp. 190-199

Author(s):

Néstor I. Prado ◽

◽

julian Carrillo ◽

Sergio M. Pineda

Keyword(s):

Lateral Displacement ◽

Elastic Buckling ◽

Flexural Capacity ◽

Lateral Torsional Buckling ◽

Torsional Buckling ◽

Experimental Assessment ◽

Longitudinal Stiffeners ◽

Simple Support ◽

Failure Angle ◽

Support Conditions

This study focused on the experimental assessment of the effect of the spacing between longitudinal stiffeners welded to I-shaped beams under the action of lateral-torsional buckling. In this procedure, 192 aluminum beams on a 1:9 scale were tested under simple-support conditions with a laterally unbraced length ranging from 0.55 m through 1.95 m. Moreover, the stiffeners’ spacing was also ranged from 3 to 9 times the depth of section. The structural behavior of the beams is discussed in terms of their flexural capacity, spacing between longitudinal stiffeners, lateral displacement of compression flange and failure angle twist. Results show that the spacing of longitudinal stiffeners influences the flexural capacity of I-shaped beams, so that, when the spacing of longitudinal stiffeners decreases, flexural capacity tends to increase, especially in the elastic buckling zone.

Download Full-text

Lateral Torsional Buckling of Steel Beams Elastically Restrained at the Support Nodes

Applied Sciences ◽

10.3390/app9091944 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1944

Author(s):

Rafał Piotrowski ◽

Andrzej Szychowski

Keyword(s):

Twist Angle ◽

Major Axis ◽

Steel Beams ◽

Lateral Torsional Buckling ◽

Torsional Buckling ◽

Critical Moment ◽

Simple Physical Interpretation ◽

Approximation Formulas ◽

Lateral Rotation ◽

Elastically Restrained

The study shows the results of theoretical investigations into lateral torsional buckling of bisymmetric I-beams elastically restrained against warping and against rotation in the plane of lateral torsional buckling (i.e., against lateral rotation) at the support nodes. The analysis accounted for the whole variation range of node stiffnesses, from complete warping freedom to full restraint, and from complete lateral rotation freedom to full restraint. It was assumed the beams are simply supported against bending about the major axis of the section. To determine the critical moment, the energy method was used. Both the twist angle function and the lateral deflection function of the beam were described using power polynomials with simple physical interpretation. Computer programmes were developed to make numerical and symbolic “computations”. General approximation formulas for the critical moment for lateral torsional buckling were derived. The formulas covered the basic and most frequently found loading diagrams. Detailed computations were performed for different values of the index of fixity against warping and against rotation in the plane of lateral torsional buckling. The critical moments determined using the programmes devised and approximation formulas were compared with the values obtained with LTBeam software (FEM). A very good congruence of results was found.

Download Full-text

Elastic lateral-torsional buckling of general cold-formed steel beams under uniform moment

Thin-Walled Structures ◽

10.1016/j.tws.2017.07.010 ◽

2017 ◽

Vol 119 ◽

pp. 586-592 ◽

Cited By ~ 4

Author(s):

R.S. Glauz

Keyword(s):

Steel Beams ◽

Lateral Torsional Buckling ◽

Torsional Buckling ◽

Cold Formed Steel

Download Full-text

A comparative study of beam design curves against lateral torsional buckling using AISC, EC and SP

Structural Mechanics of Engineering Constructions and Buildings ◽

10.22363/1815-5235-2019-15-1-25-32 ◽

2019 ◽

Vol 15 (1) ◽

pp. 25-32 ◽

Cited By ~ 2

Author(s):

Vera V Galishnikova ◽

Tesfaldet H Gebre

Keyword(s):

Steel Structures ◽

Reduction Factor ◽

Steel Beams ◽

Steel Beam ◽

Lateral Torsional Buckling ◽

Torsional Buckling ◽

Vertical Loading ◽

Beam Design ◽

Overall Stability

Introduction. Structural stability is an essential part of design process for steel structures and checking the overall stability is very important for the determination of the optimum steel beams section. Lateral torsional buckling (LTB) normally associated with beams subject to vertical loading, buckling out of the plane of the applied loads and it is a primary consideration in the design of steel structures, consequently it may reduce the load currying capacity. Methods. There are several national codes to verify the steel beam against LTB. All specifications have different approach for the treatment of LTB and this paper is concentrated on three different methods: America Institute of Steel Construction (AISC), Eurocode (EC) and Russian Code (SP). The attention is focused to the methods of developing LTB curves and their characteristics. Results. AISC specification identifies three regimes of buckling depending on the unbraced length of the member ( Lb ). However, EC and SP utilize a reduction factor (χ LT ) to treat lateral torsional buckling problem. In general, flexural capacities according to AISC are higher than those of EC and SP for non-compact sections.

Download Full-text