Postelastic static behavior of certain beams with composed crosssection made of thin-walled steel profiles

Abstract

The paperwork presents the behavior of a pair of composed cross-section beams made “C†class thin-walled profiles, subjected to gravitational loads. The profiles are made of 3.5mm thick, cold-rolled plates of FeE 320G steel.
The specimens were tested on the existent stand from the laboratory of the Structural Mechanics Department of the Faculty of Civil Engineering and Architecture of Iaşi. The beams of 5,0 m length were mounted at 1,0m distance. The load input from the hydraulic jacks has been transmitted by the means of some steel profiles.
The system response was obtained by the measurement of the deflections of every beam at the midspan and quarter of span and the strain measurements at midspans. Inductive transducers were used to measure the transverse deflections and the strains were measured with the resistive electrical transducers placed at the bottom flanges of the beam. The loading has been carried out by the means of
hydraulic jacks up to a level of 10000daN per beam, when local buckling occurred.
The tests leaded to the following conclusions:
The necessity to eliminate the profile deformations due to the manufacturing, packaging and transportation processes, etc. because the buckling phenomena can be initiated at lower values than the than the design loads;

The structural elements (KB) must be provided with additional elements in order to assure the overall stability to bending and torsion effects;

The computational checking of the structural elements (beams, columns) must be also performed to avoid the stability loss by bending-torsion.