Experimental evaluation of the strength of the T-shape eccentrically-welded anchor rod connections to column bases in steel columns using digital image correlation method

In regular thick column base connections, because of severe pinching effect in the hysteresis diagram during loading and unloading, the stiffness and strength of the connection and the amount of energy consumption are reduced. In order to prevent pinching and improve the seismic performance of the column-base connections, it is suggested to connect the anchor rods vertically under the plates by wedeled connections without any eccentricity between anchor rods and the flange axis of the column. In the proposed column-base connections, because of the non-replaceability or repairability of the connection components, according to the design codes, all connection components, including the base plate, welded connections, anchor rods, and concrete, must remain elastic and the source of ductility should be inside the plastic hinge in the end section of the column. In this case, the anchor rods have the ability to carry tensile and compressive forces at any moment simultaneously. Because of the unknown behavior of welded connections under tensile loads, T-shaped connections were used to evaluate the strength and stiffness of special fillet welds, full penetration groove welds, cylindrical groove welds and conical groove welds. Digital images Correlation method was used to measure the strain field of welded connections and identify the type of failure of the anchor rods. As a result, the welded connections had the ability to withstand the maximum tensile capacity of the anchor rods and remained elastic. During the loading of the anchor rods, no failures occurred in the elastic region of the rods due to the reduction of resistance in the Heat Affected Zone (HAZ). As a result, there is no uncertainty in the behavior of welded connections under tensile load as a force-control component in the proposed connections. Fillet weld and full penetration groove welds were more superior in terms of cost than other welds.