Experimental study of failures in steel tubular bridge structures due to cyclic loading

![CDATA[Circular hollow sections (CHS) are widely used in most types of structures such as bridges, communication towers and offshore platforms that are subjected to different types of loading. The main girder for truss arch bridges and cabled stayed bridges can be made of CHS and concrete-filled circular hollow sections (CFCHSs) in large span bridges. Extensive experimental determinations of stress concentration factors (SCFs) on empty tube to tube T-joints have been previously investigated. These investigations resulted in the development of design guidelines for fatigue of CHS uniplanar T-joints such as CIDECT Design Guide No. 8. On the other hand, little research has been carried out on the determination of the SCFs of T-joints with concrete-filled chords. As a result, there is no design guide for T-joints with concrete-filled chords. An experimental investigation was performed at Western Sydney University (WSU), Kingswood Campus. The strain gauging process was used to install strip and single strain gauges onto two T-joint specimens with concrete-filled chords for the measurement of strains. The strain gauging enabled the measurement of strains in concrete-filled T-joints and determined the SCFs of two concrete-filled T-joints specimens under axial tension, axial compression and in-plane bending. The stress distributions around the weld joints for empty T-joints have been previously researched. Calculations of the SCFs for these empty T-joints under axial load and in-plane bending can be determined based on the CIDECT Design Guide No.8. The calculated SCFs values for empty joints are compared to the SCFs of the concrete-filled chord T-joints obtained from the results of the experiment. The purpose of this comparison is to find out if it is beneficial to use concrete- filled T-joints for fatigue design.]]