This study focuses on investigating the seismic behaviors of non-seismic joints, intermediate design joints, and the strengthening of non-seismic joints in frame buildings. For this purpose, a six-story frame building was designed according to the research objectives. The first frame assumed that the building was constructed with non-seismic joints lacking transverse reinforcement in the joint panel. According to ACI 318-19, the second building utilized the reinforcement detailing requirements for an intermediate moment frame. The third frame was strengthened utilizing carbon fiber reinforced polymer (CFRP) materials, with one layer covering the beam-column joint at a distance of 0.5 meters. The fourth model used two layers of CFRP to cover the beam-column joint of the non-seismic frame building. The final model, constructed similarly to the third model, used a CFRP length of 1.25 meters at the beam-column joint. The objective of reinforcing the frame structure in the beam-column joint area was to ensure safe seismic performance as specified in ACI 374.2R-13. Finite element analysis of the frame buildings was performed to evaluate their seismic behaviors using full-scale models. As previously indicated, following the experimental and numerical verification of the joint, the same element, material properties, and procedures were adopted to model the frame building using ABAQUS. El Centro earthquake loading was applied to the frame buildings. All frame buildings had the same number of longitudinal reinforcements and dimensional size to compare their seismic behaviors. The research variables were the types of joints used in the frame buildings. Numerical investigations revealed that strengthening the beam-column joint reduces the occurrence of soft story failure mechanisms related to joint strength. The joints play a pivotal role in affecting the seismic behavior of reinforced concrete frame buildings. Strengthening and seismic joints limit lateral displacement and roof displacement, reducing the lateral drift ratio demand and ensuring the frame building meets life safety and immediate occupancy performance levels. In contrast, inadequate structural detailing, such as a lack of transverse reinforcement in joints, causes steel yielding and concrete cracking, leading to the collapse of the frame building.