Structural Performance of Inclined Shear Key in Steel- Concrete Composite Construction

Abstract

The use of steel-concrete composite structures is growing in popularity within the construction sector. In steel-concrete composite structure full composite action between steel and concrete is developed using shear connector. Shear connector transfer the transverse shear developed at the interface of steel and concrete. Headed shear stud is the most common type of shear connector which is conventionally welded perpendicularly to the flange surface of the steel beam with zero inclination. Some of the shear connectors unconsciously get welded at an inclined angle during this process. Design equations are not available for inclined shear key in the current design codes like Eurocode 4, CSA S4-14, BNBC- 2020, AASHTO LRFD. Here an attempt has been made to investigate the structural performance of inclined shear key in steel-concrete composite construction. A numerical finite element model of push out test of steel-concrete composite structure as per Eurocode is developed using FEA software ANSYS. The developed FE push-out test model for a 19 mm perpendicularly placed headed shear stud is validated and its results are compared with the previous experimental test. The ultimate shear resistance of a perpendicularly welded headed shear stud obtained from FE analysis is found to be very close to that calculated using the BNBC-2020 & AASHTO LRFD recommended design equations. The ultimate shear resistance of 15, 30 & 45-degree inclined headed shear stud is found to be increased by 15 %, 17.33 % & 24 % respectively for the inclination of headed shear stud along the direction of loading and decreased by 56 %, 42.57 % & 46.93 % respectively for inclination opposite to the direction of loading. For inclination along the direction of loading, 15-degree & 30-degree inclined Headed shear stud exhibits ductile behaviour with maximum slip value 10.79 mm & 7.97 mm respectively but for 45-degree inclination headed shear stud is found to be brittle with maximum slip value 3.95 mm. Headed shear studs are vi found to be brittle for all the angles of inclination opposite to the direction of loading having maximum slip less than 6 mm, which is the Eurocode 4 recommended minimum threshold for ductile behaviour. Hence, headed shear stud shall be welded to the flange surface very carefully in steel-concrete composite construction. Only if the direction of loading is known, inclined shear keys may be a better choice for enhanced composite action of steel concrete composite structures.