Lateral torsional buckling of open cross-sections with lateral and torsional restraints
Concrete floor, if connected to beams by shear studs, effectively restrains lateral-torsional buckling of these beams. Trapezoidal sheeting or sandwich panels typically connected by self-drilling screws do not have sufficient strength and stiffness to restrain lateral-torsional buckling completely. But they may help up to some point. How this lateral-torsional restraint is applied is described in this article.
In this thorough study by authors from ETH, Zürich, the results of three software of linear buckling analysis are compared: LTBeam, Abaqus, and IDEA StatiCa Member. The differences are discussed and explained. Furthermore, the results of geometrically and materially nonlinear analysis with imperfections of two software are compared: Abaqus and IDEA StatiCa Member. LTBeam does not have this functionality.
Two cross-sections are investigated:
- IPE 240
- CFC265x65
Three types of restraints at the top flange are investigated:
- Lateral (shear) restraint
- Torsional restraint
- Combination of lateral and torsional restraint
Two types of loading are considered:
- Uniformly distributed load
- Force at mid-span
Two types of boundary conditions:
- Fixed
- Pinned
Conclusions
- Linear Buckling Analysis (LBA) simulations show good agreement for low values of restraints for all three software; however, at higher values of restraints, LTBeam diverges. This is caused by a large simplification: the cross-section of LTBeam that uses 1-D element cannot deform. IDEA StatiCa Member with Abaqus shows good agreement in critical buckling factor.
- Geometrically and Materially Non-linear Analysis with Imperfections (GMNIA) again shows good agreement between IDEA StatiCa Member and Abaqus (maximum difference of 5%).
The full report is attached.
Author: Andreas Müller M.Sc.
Responsible investigator: Prof. Dr. techn. Andreas Taras
ETH Zurich, Institute of Structural Engineering (IBK)