The bearing connections of hollow-core slab (HCS) floors require the use of steel reinforcement to prevent slab displacements under lateral loads. Inadequate connection detailing could result in compromising the structural integrity of buildings that utilizes HCS floors. Traditionally, size 10M steel bars have been implemented in several regions in Canada as connections of HCS floors to supporting members. However, North American design codes and guidelines do not offer sufficient provisions to predict the capacity of these connections, and the literature has not yet addressed their behaviour. Hence, this thesis presents the test results of twenty full-scale reinforcing bar connections of HCS to steel beam and masonry wall supports under in-plane forces to investigate their modes of failure and carrying load capacities. The connections were constructed using 203-mm thick HCS, cut to 1,220-mm square segments. Eleven HCS specimens were supported on steel beam, while nine specimens were supported on masonry walls. Test parameters included the type of HCS bearing (end or side bearing), in-plane load direction (pulling or pushing against the support) and orientation (parallel or normal to the axis of the support). Test results revealed that the connection detailing used in HCS floors over steel beams is adequate to ensure the structural integrity of HCS floors as it satisfies code requirements under tension (pulling) forces. Reducing the free length of the connection bar and decreasing the bar bends resulted in greater stiffness and ductility, yet the bars had relatively lower strength under compression. On the other hand, the connection bars in specimens supported on masonry did not meet the specified strength under tension for buildings more than three floors. The specimens suffered bar pull-out, excessive slab displacements and loss of bearing before attaining the peak load. Bonding the connection bar to the masonry wall prevented the bar pull-out but did not provide the required strength in tension.