The use of precast concrete is known to improve productivity, quality control, and cost efficiency in reinforced concrete structure. The Connection is the most important aspect of precast concrete structures. The connection transfers force between the precast components, determine strength, stiffness, and ductility of the whole structure. Providing joint in the beam-column connection region always cause difficulties during the erection stage. Relocation of the connection at a certain distance from the column to the beam span is an alternative solution that creates the beam-to-beam connection. It will be much easier to assemble the connection that consists of some joints. Research and application of the precast concrete beam-to-beam connection details have published since 1975. This paper reviews the state of the art of research and practical application of beam-to-beam connection system related to connection models, joint locations, and details. It concluded from the review that the developing research leads to improve the performance of earthquake resisting structures

The welding connection between reinforcing steel and steel plates are widely used as part of a building structure system, including the precast concrete connection system. This experimental study aimed to investigate the behavior of the tee joint welding between reinforcing steel and steel plates, using both the yield (YS) and tensile (TS) strengths as indicators. It was also directed towards understanding the strain hardening value (TS/YS), which is the ratio between these factors. The experiment was conducted by testing three types of welding connections, WC-1, WC-2, and WC-3, under tensile loads. The WC-1 and WC-2 are common models mostly used to join steel components in reinforced concrete structures, while WC-3 was the proposed connection model. The results showed TS/YS ratios of WC-1, WC-2, and WC-3 specimens were 1.19, 1.23, and 1.27, respectively. This means the value of the proposed specimen is higher than the required 1.25 by the ASTM A706M and was also recorded to have the best tensile strength.