Abstract:
Cold-formed steel is widely used for routine structural steel design including portal frames
composed of open and/or closed sections. Nowadays, cold rolled steel channel and Z
sections are now used in structure as a structural member with the hot rolled steel by
welding connection. The connection between hot rolled and cold rolled steel is very
important in the structure. Structural behavior of steel structures generally depends on the
rigidity of the connections and their force transfer mechanism.
In the present study, an experimental investigation has been conducted on double shear
welded connections made of ASTM A653 Gr.50 and ASTM A36 grades of cold-formed
steel. Primarily a set of coupons extracted from the cold form steel of different thicknesses
and steel grades are tested under uniaxial tension to understand their actual strength and
modulus of elasticity. In addition, a total of 4 numbers of weld coupons are fabricated to
determine different weld specifications used in this study. Finally, 24 test specimens of
double shear welded connections are formed by overlapping two cold-formed steel plates
of similar thickness with the two hot rolled steel plates and forming a double shear welded
connection at the joint. The influence of weld strength, plate strength, and plate thickness
on joint behavior is evaluated meticulously by employing standard data acquisition system.
These weld connections are tested on tensile loading until failure.
The response of the double shear welded connections for varying material properties is
examined in terms of load-elongation plot, connection strength, failure mode, stiffness, and
ductility. It is observed, that with the increase of plate thickness failure mode changes from
net-section fracture to weld throat failure. Usually increasing weld strength, steel grade,
and plate thickness shows a rise in joint capacity and stiffness. Current American design
provisions are evaluated for these ASTM A653 Gr.50 and ASTM A36 grade samples.
Research into the Heat Affected Zone (HAZ) strength resulting from joint welding reveals
a reduction in joint capacity of 6 to 19% due to the Heat Affected Zone (HAZ) effect.
