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 weldedjoints of steel truss for encased composite steel–concrete beams. The results ofexperimental tests are presented and interpreted. The steel truss is made of a steelplate acting as the bottom chord, made of S355 structural steel, coupled with steelrebars which form the upper chord, and steel inclined web rebars (V-reverse) weldedto the two chord elements, both of them made of steel B450C. Butt welded joints ofweb bar to bottom steel plate and fillet welding joints of inclined web bars to topchord bars were tested, as they are different from the ones which are normally useddue to the coupling of different steel types and complex geometry. For the predictionof strength of fillet welding joints, two analytical expressions are derived: the first isbased on a local failure criterion and the second on a limit domain of the weldingsection. Comparison with experimental data proves the equivalence and reliabilityof the proposed indications. Guidelines for choosing the effective dimensions ofthe fillet weld able to ensure a required strength are provided. For validation of thesuggested guidelines, a high precision digital scanner is used to determine thegeometrical characteristics of the fillet weld.