Experimental and Finite Element Study on the Seismic Performance of Reinforced New-Type Joints: Adding Beams to Existing Columns

Currently, the development of civil engineering industry is gradually slowing down, with the focus gradually shifting toward the reinforcement and renovation of existing buildings. Among these existing structures, reinforced concrete (RC) structure is a kind of structure with high proportion. Therefore, this paper conducts research on the seismic properties of RC buildings after adding new beams to existing columns. This paper first introduces the design situation of the specimen, followed by an experimental investigation of its mechanical properties using pseudo-static tests. Based on the failure patterns and hysteresis curves, the differences between the new-type specimen and RC specimen are analyzed. The findings indicate that, while ensuring load-bearing capacity, the new-type joints exhibit better seismic performance: the bearing capacity and maximum displacement are increased by at most 9.2% and 14.9% respectively, and the fuller hysteresis curve shows that the new-type specimen has better energy dissipation capacity. Finally, this paper extends the analysis of the design parameters of the specimens using finite element components. The modeling results reveal that the bearing capacity varies by less than 1% with different parameters such as connector thickness, concrete strength grade, and bolts quantity and strength, indicating that these parameters have a relatively small impact on the bearing capacity. While for the specimen dimensions and thickness and strength of wrapped steel of beam, the maximum increase in bearing capacity is 32.3% and 6.0%, respectively. Indicating that their impact is quite significant. The findings of this paper provide a reference for structural design and contribute to advancing the work of reinforcement and renovation of existing concrete structures.