In this modern era, where construction time is extremely valuable, prefabrication systems have gained considerable attention in the construction industry due to their time efficiency and quality control. One of the ubiquitous vertical connections in precast concrete walls is the loop bar joint, recognized for its simplicity in construction and installation processes. While extensive research is dedicated to the exploration of innovative joint configurations in precast wall systems to bolster their seismic resistance, there remains a relative dearth of exploration into the behavior of the existing joints. This investigation focuses on the direct shear behavior of diverse loop bar connection configurations through a push-off test. A comprehensive analysis was conducted on a total of 12 panels, assembled into six vertical joint specimens featuring distinct joint configurations. These specimens were categorized into two groups: loop bar joints with and without shear keys. The loops, constructed with either 6-mm RB or 5-mm wire rope, varied in number from 1 to 2 bars. The primary objective was to examine the effect of shear keys on shear resisting and deformation of the joints, and the influence of shear keys. From the results, the introduction of shear keys emerges as a pivotal factor influencing the shear strength of shear connections. It was found that the cracking load and ultimate load in every specimen with an embedded shear key increased significantly. While the traditional joints without shear keys incorporating 5-mm wire rope exhibited the lowest shear capacity. Furthermore, an escalation in the number of 6-mm RB loop bars, from 1 to 2 loops, resulted in an increased in the shear strength of the vertical plane joints. Notably, the incorporation of shear key also resulted in a change in the shear response mechanism.