Experimental investigation of exposed column base plate connections subjected to combined axial and bi-directional lateral loading

Abstract

Column base plate (CBP) connections are critical components in the overall design of a steel structure. CBP connections are responsible for transferring the forces exerted on base columns through a base plate and grout pad into the concrete foundation utilizing anchor rods. Exposedtype column bases are widely used in low-rise building construction all over the world, and considerable research efforts have been made to identify the parameters that affect their strength and serviceability. Current design codes and guidelines do not address the design of these exposed base plate connections under combined axial load and bi-axial bending. Although, the columns are designed and checked under combined axial load and bi-axial bending, when it comes to the base plate connection, only the axial load and major axis bending are considered. Practicing engineers often adopt complex finite element method or design them in two directions separately, which often results in overly conservative design. A more direct approach to designing CBP connections subjected to combined axial and lateral loading conditions would help ensure column base connections perform as intended under extreme loading. The inadequate design of a CBP connection will cause the failure of the connection before the column can reach its peak design values. This configuration is known as a "Strong Column / Weak Connection". This failure is initiated by the inelastic deformation of one or more of the following components: anchor rods, concrete, grout, weld, or base plate. The design of all these components will have a combined effect on the CBP connection's stiffness, strength, and deformation capacity. [...]