Experimental Investigation of the Deformation of Built-up Members of Cold-Formed Steel Profiles

Abstract

Built-up members of cold-formed steel (CFS) profiles were tested in 4-point bending. CFS profiles (generally thin-walled) deform considerably under load, and the deformed configuration is a result of the superposition of different buckling mode shapes. Local buckling propagates through the profile walls; during distortional buckling parts of the cross-section rotate around a web-flange juncture. Alongside the buckling effects, the overall deformation of the member is considerable. To study these slender and relatively long members, a sufficient number of measuring positions on the specimens is needed. Often, this is not feasible with the conventional measuring techniques. An optical measuring device was used to record the movement of a large number of points per specimen. The obtained results are placed in a 3D coordinate system and can be exported for further data processing. The goal of the measurement campaign was to calibrate a Finite Element model that will simulate the tests. The model will be used for the analysis of composed frame members of CFS profiles, whose design is not entirely covered by the European Standard [1]. After calibration, the FEA predicts the performance of these built-up members well.

Optical Measuring Technique for the Investigation of Built-Up Cold-Formed Steel Structural Members

“…The objective of this detailed analysis is to understand the behaviour of this type of structural member and place it in the framework of the European design codes, in particular [5] and [4]. These experiments were used to calibrate and verify shell Finite Element models of some of the tested specimens (see [7]). Table 1 presents a comparison of the rotations at the load application points obtained through experiments and through FEA.…”

Experimental study of cold-formed steel built-up columns

“…The authors showed that the ultimate capacities of the columns were intermediate between the predictions given by the DSM when considering the built-up cross-section as fully integral and the predictions assuming two independent profiles, suggesting that some level of composite action was present. Georgieva et al (2011Georgieva et al ( , 2012aGeorgieva et al ( , 2012bGeorgieva et al ( , 2012c carried out an extensive experimental and numerical investigation to study the buckling behaviour of double-Z built-up columns and assess the accuracy of the DSM predictions. The application of the DSM, based on finite element models to obtain the elastic global buckling stresses, was found to give conservative strength predictions.…”

Experimental Study and Direct Strength Method for Cold-Formed Steel Built-Up I-Sectional Columns under Axial Compression

“…A series of buckling tests and numerical analyses were performed by some researchers [12][13][14][15][16][17][18] including various types of CFS built-up cross-sections. e axially-compressed and eccentrically-compressed built-up box columns were studied by experiment and finite element analysis [12] considering the slenderness ratio and ratio of width to thickness of the section.…”

“…Li et al [13,14] investigated the ultimate strength of CFS box columns by test and numerical analysis and proposed the design method to predict the load capacities of the built-up box members. Georgieva et al [15][16][17][18] studied a series of CFS built-up columns formed with zee, sigma, and track sections. e comparison on ultimate strength between test results and results calculated by using presented DSM which considers the buckling interaction was completed.…”