Flexural behavior of composite beams with concrete filled steel tube flanges and honeycombed steel webs

Honeycombed beams are widely used because they are conducive to the layout of pipelines and circuits, and the traditional honeycombed beams are generally H-shaped steel beams and concrete-encased upper flange composite beams. In this paper, a composite beam with concrete-filled steel tube as both upper and lower flanges and steel plate with circular openings as web is proposed. The effective constraint of steel tube on concrete strengthens the deformation ability of concrete. In order to study the flexural behavior of composite beams with concrete filled steel tube flanges and honeycombed steel webs (SHC), 25 simply-supported SHC beams were designed to carry out the four-point bending load simulation analysis. By reasonable modeling method. The main parameters of SHC concluding the compression strength of concrete ( f ck ), yield strength of steel ( f yfk ), height-to-span ratio ( H/L ), ratio of space to height of web ( s/h w ), thickness of steel tube flange ( t 1 ), thickness of web ( t 2 ) and ratio of hole to height of web ( a/h w ) were discussed, and the whole loading process of the beam was analyzed. The results showed that the SHC specimens could be divided into elastic stage, elastic-plastic stage and plastic stage under four-point bending load. Steel tube in the tensile zone yielded firstly before specimens failed, and the failure mode of the specimens was that the concrete at the loading point was crushed. Though the steel tube in lower flange at the support, loading point and mid-span yielded, the web did not buckle. SHC could meet the requirements of Chinese code in the normal use stage, and the cross-section deformation basically conformed to the plane assumption. Finally, based on the unified strength theory, a prediction formula of ultimate bending moment is established, which is in good agreement with experiment and can lay the foundation for the popularization and application of this kind of beams.