Investigation of the seismic behavior of reinforced concrete buildings eith trm-strenghtened beam–column joints consiering soil-structure interaction

In this study, an experimental investigation was conducted on the strengthening of reinforced concrete (RC) beam–column joints, which play a critical role in the seismic performance of RC structures, using Textile-Reinforced Mortar (TRM). In the first phase of the study, eight 1/2-scale beam–column joint specimens, including those strengthened with TRM in various configurations, were produced and tested under cyclic loading. Additionally, the test conditions, cross-sectional dimensions, reinforcement layouts, material properties, and strengthening details were modeled in the ABAQUS finite element software, and nonlinear numerical analyses were performed accordingly. In the second phase of the study, RC frame systems with varying numbers of stories were modeled using SAP2000 software. These models were divided into two groups: unstrengthened (reference) and TRM-strengthened joints. Nonlinear static analyses were carried out to numerically assess the extent to which the developed strengthening technique improved the seismic performance of the structures. At this stage, the effects of soil–structure interaction on the performance of the strengthening technique were also investigated. In the numerical analysis phase, three different soil classes were considered. Thus, using the data obtained from the experimental study conducted in the first phase—which provided behavioral parameters not available in the SAP2000 library—the load–displacement behavior of TRM-strengthened beam–column joints was defined as a new plastic hinge model, and soil–structure interaction analyses were performed. The results of the experimental and analytical studies demonstrated that the TRM beam–column joint strengthening technique exhibited behavior consistent with the design requirements of the Turkish Seismic Code (TBEC 2018), thereby verifying the effectiveness of the proposed method. It was observed that, with the developed strengthening method, the yield strength, load-carrying capacity, initial stiffness, ductility ratio, and cumulative energy dissipation capacity of the strengthened reinforced concrete elements increased by approximately 54%, 38%, 7%, 46%, and 835%, respectively.