Seismic performance of active tendon-controlled structures with embedded foundations

This study investigates the optimal tuning of a Proportional–Integral–Derivative (PID) controller to mitigate structural responses o active tendon-controlled (ATC) structures including soil-structure interaction (SSI) under near- fault ground motions. Five ATC structures with varying numbers of tendons depending on the embedment ratio are analyzed in the time domain. Metaheuristic algorithms such as Harmony Search (HS), Flower Pollination Algorithm (FPA) and Teaching Learning based Optimization (TLBO) inspired by nature are used in the optimization process to obtain the optimal parameters of the PID controller. Furthermore, two different assumptions about the ground wave velocity (v s =100 m/s and v s =200 m/s) are considered to derive the soil properties that influence the optimal parameters. The novelty of this study lies in the simultaneous evaluation of seismic performance of ATC structures while considering embedment ratio of structures, the positioning of the active tendons on the stories, and soil conditions through metaheuristic optimization. It is observed that the reductions in structural responses show similarities in structural models with embedment stories (regardless of the embedment ratio) when the control parameters are adjusted accordingly. In the absence of embedment stories, the structural response mitigation performance of ATC structure becomes more negative for low shear wave velocity. The maximum displacement of the structural model with a tendon only on the 1st floor is approximately 50% higher than that of the model with tendons on every story under the same conditions, such as the same control force limit, but the tendon installation and the total cost of ACT structure are about one-tenth. These results demonstrate that the optimum parameters of the PID controller, achieved through metaheuristic algorithms combined with strategic tendon placement and careful assessment of soil properties and embedment ratio, can provide both effective seismic risk mitigation and significant cost savings.