Experimental test results vs. analytical prediction of welded joint strength in hybrid steel trussed concrete beams (HSTCBs)

The aim of the paper is to provide practical guidelines for the design of welded joints of steel truss for encased composite steel–concrete beams. The results of experimental tests are presented and interpreted. The steel truss is made of a steel plate acting as the bottom chord, made of S355 structural steel, coupled with steel rebars which form the upper chord, and steel inclined web rebars (V-reverse) welded to the two chord elements, both of them made of steel B450C. Butt welded joints of web bar to bottom steel plate and fillet welding joints of inclined web bars to top chord bars were tested, as they are different from the ones which are normally used due to the coupling of different steel types and complex geometry. For the prediction of strength of fillet welding joints, two analytical expressions are derived: the first is based on a local failure criterion and the second on a limit domain of the welding section. Comparison with experimental data proves the equivalence and reliability of the proposed indications. Guidelines for choosing the effective dimensions of the fillet weld able to ensure a required strength are provided. For validation of the suggested guidelines, a high precision digital scanner is used to determine the geometrical characteristics of the fillet weld.