scholarly journals Elastic Critical Moment for the Lateral–Torsional Buckling (LTB) Analysis of Structural Glass Beams with Discrete Mechanical Lateral Restraints

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2492 ◽  
Author(s):  
Dario Santo ◽  
Silvana Mattei ◽  
Chiara Bedon
Keyword(s):  
Finite Element ◽  
Practical Interest ◽  
Accurate Estimation ◽  
Structural Glass ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Additional Advantage ◽  
Design Recommendations ◽  
Critical Moment ◽  
Analytical Approaches

Structural glass beams and fins are largely used in buildings, in the form of primary load-bearing members and bracing systems for roof or facade panels. Several loading and boundary conditions can be efficiently solved by means of bonded composites that involve the use of laminated glass sections. Additionally, the so-obtained glass members are often characterized by high slenderness. To this aim, several literature studies were dedicated to the lateral–torsional buckling (LTB) behavior of laterally unrestrained (LU) glass elements, with the support of full-scale experiments, analytical models, or finite element (FE) numerical investigations. Standardized design recommendations for LU glass members in LTB are available for designers. However, several design issues still require “ad hoc” (and often expensive) calculation studies. In most of the cases, for example, the mechanical interaction between the structural components to verify involves various typologies of joints, including continuous sealant connections, mechanical point fixings, or hybrid solutions. As a result, an accurate estimation of the theoretical LTB critical moment for such a kind of laterally restrained (LR) element represents a first key issue toward the definition and calibration of generalized design recommendations. Careful consideration should be spent for the description of the intrinsic features of materials in use, as well as for a combination of geometrical and mechanical aspects (i.e., geometry, number, position of restraints, etc.). In this paper, the attention is focused on the calculation of the elastic critical buckling moment of LR glass beams in LTB. Existing analytical approaches of the literature (mostly developed for steel constructional members) are briefly recalled. An additional advantage for extended parametric calculations is then taken from finite element (FE) numerical analyses, which are performed via the LTBeam or the ABAQUS software codes. The actual role and the effect of discrete mechanical restraints are, thus, explored for selected configurations of practical interest. Finally, the reliability of simplified calculation approaches is assessed.

Lateral torsional buckling of steel twin plate girder systems with torsional braces only

2016 ◽  
Vol 43 (2) ◽  
pp. 182-192 ◽  
Author(s):  
Chris Mantha ◽  
Xi Chen ◽  
Yi Liu
Keyword(s):  
Finite Element ◽  
Design Procedure ◽  
Element Model ◽  
Torsional Stiffness ◽  
Effective Length ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Finite Element Study ◽  
Element Study ◽  
Plate Girder

This paper presents results of both an experimental and a finite element study on the lateral torsional buckling behaviour and strength of twin plate girder systems with only discrete torsional braces. Two scaled twin-beam specimens with different arrangements of lateral and torsional braces were tested and results were used to validate the finite element model. The finite element study considered the effect of individual brace member stiffness and the number of braces. Results showed that for twin plate girders braced with only torsional braces, the critical buckling moment has the most significant increase when the number of interior braces increases from two to three. For a given girder section, the increase in the critical moment capacity by increasing the cross-frame member size is minimal. The lateral torsional buckling moment equation as well as the brace force design procedure contained in the Canadian Highway Bridge Design Code were examined. A relationship between the ratio of provided-to-required torsional stiffness and the effective length factor was discussed.

Shear-deformable hybrid finite-element formulation for lateral-torsional buckling analysis of composite thin-walled members

2020 ◽  
Author(s):  
Emre Erkmen ◽  
Vida Niki ◽  
Ashkan Afnani
Keyword(s):  
Finite Element ◽  
Beam Theory ◽  
Buckling Analysis ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Hybrid Finite Element ◽  
Thin Walled ◽  
Shear Deformable

A shear deformable hybrid finite element formulation is developed for the lateral-torsional buckling analysis of fiber-reinforced composite thin-walled members with open cross-section. The method is developed by using the Hellinger-Reissner functional. Comparison to the displacement-based formulations the current hybrid formulation has the advantage of incorporating the shear deformation effects easily by using the strain energy of the shear stress field without modifying the basic kinematic assumptions of the thin-walled beam theory. Numerical results are validated through comparisons with results based on other formulations presented in the literature. Examples illustrate the effects of shear deformations and stacking sequence of the composite layers in predicting bucking loads.

scholarly journals The Collapse Analysis of the Lateral-Torsional Buckling of I-Shaped Stepped Steel Beams

2020 ◽  
Vol 6 (3) ◽  
pp. 295
Author(s):  
Kelsen Trista Kweenisky ◽  
Naomi Pratiwi ◽  
Paulus Karta Wijaya
Keyword(s):  
Plate Thickness ◽  
Maximum Amplitude ◽  
Cover Plate ◽  
Steel Beams ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Beam Shape ◽  
Critical Moment ◽  
Stepped Beam ◽  
Collapse Analysis

The use of a non-prismatic member such as a stepped beam as a design method has the ability to function as a tool for steel beams optimization. A cover plate is partially welded on the upper and lower flange of the member at the maximum bending moment location to increase its flexural strength and, under critical load, flexural members bend about its strong axis, displace to the lateral direction, and twist coincidentally through a phenomenon known as the Lateral-Torsional Buckling (LTB). There is, however, no equations in the AISC 360-16 specification to calculate the critical moment of a stepped beam (Mst). Therefore, this research focuses on developing Mst for a simply supported stepped beam which deforms on its shear center under static-transverse loading through the use of a collapse analysis and the behavior of the beam. The results showed the welded cover plates consequently increased the LTB resistance of the prismatic I-shaped steel beam from 9.8% to 202% while the critical moment increased more significantly with an increment in the ratio of the cover plate length to the unbraced length (α). The cover plate thickness was observed to have dominantly affected only a large α ratio while the post-buckling characteristic of large α showed a sudden collapse phenomenon. Furthermore, the LTB modification factor was generated in this study due to the initial geometrical imperfection from the first mode of Eigen shape with maximum amplitude Lb/2000 (Cb1) and stepped beam shape (Cst) which were required to estimate the critical moment of a stepped beam based on the AISC equation for a prismatic beam.

scholarly journals Dimensionless Analytical Solution and New Design Formula for Lateral-Torsional Buckling of I-Beams under Linear Distributed Moment via Linear Stability Theory

2017 ◽  
Vol 2017 ◽  
pp. 1-23 ◽  
Author(s):  
Wen-Fu Zhang ◽  
Ying-Chun Liu ◽  
Ke-Shan Chen ◽  
Yun Deng
Keyword(s):  
Analytical Solution ◽  
Linear Stability ◽  
Stability Theory ◽  
Numerical Solutions ◽  
Beam Theory ◽  
Linear Stability Theory ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Design Formula ◽  
Critical Moment

Even for the doubly symmetric I-beams under linear distributed moment, the design formulas given by codes of different countries are quite different. This paper will derive a dimensionless analytical solution via linear stability theory and propose a new design formula of the critical moment of the lateral-torsional buckling (LTB) of the simply supported I-beams under linear distributed moment. Firstly, the assumptions of linear stability theory are reviewed, the dispute concerning the LTB energy equation is introduced, and then the thinking of Plate-Beam Theory, which can be used to fully resolve the challenge presented by Ojalvo, is presented briefly; secondly, by introducing the new dimensionless coefficient of lateral deflection, the new dimensionless critical moment and Wagner’s coefficient are derived naturally from the total potential energy. With these independent parameters, the new dimensionless analytical buckling equation is obtained; thirdly, the convergence performance of the dimensionless analytical solution is discussed by numerical solutions and its correctness is verified by the numerical results given by ANSYS; finally, a new trilinear mathematical model is proposed as the benchmark of formulating the design formula and, with the help of 1stOpt software, the four coefficients used in the proposed dimensionless design formula are determined.

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