Experimental and Numerical Investigation of Buildings with Novel Shear Link Coupling and Eccentric Bracing Systems under Wind- and Earthquake-Induced Structural Pounding

This report investigates retrofitting strategies to mitigate structural pounding effects in a 10-story administrative building located at Massenbergstraße 9-13, 44787 Bochum, Germany. The building, with a total floor area of approximately 14,000 m², consists of reinforced concrete columns, composite steel-concrete beams, and composite floor slabs, supported by a reinforced concrete mat on pile foundation. Due to its location in a dense urban area, the building is susceptible to pounding from adjacent structures during high windstorms, which are common in the region. While seismic activity in Bochum is low, wind-induced structural impacts pose a significant concern. This study explores two retrofitting strategies: a novel shear link coupling system that connects the target building with adjacent structures through steel shear links and rigid beams, and a conventional eccentric bracing system incorporating shear links to improve energy dissipation.

To evaluate the effectiveness of these strategies, a series of wind tunnel tests and shake table tests were conducted on reduced-scale multi-story single-bay models. The shake table tests applied simulated ground motions from historical European seismic events, while wind tunnel simulations recreated high-intensity storm scenarios recorded in North Rhine-Westphalia. Structural pounding was simulated by controlling the separation distance between adjacent models and using impact plates at critical locations. The experimental results demonstrated that the unretrofitted building experienced significant impact forces, excessive inter-story drift, and localized damage at pounding locations under wind- and earthquake-induced oscillations. The novel shear link coupling system significantly reduced pounding forces, inter-story drift, and peak acceleration response, surpassing the performance of the eccentric bracing system, which, while beneficial, exhibited lower energy dissipation capabilities.

A detailed finite element analysis was performed using Abaqus to extend these findings to the full-scale structure and its adjacent buildings. The numerical model incorporated nonlinear material behavior, contact-impact algorithms, and time-history analysis under both extreme wind loads and potential seismic scenarios. The complex model was solved using high-performance computing resources, enabling the simulation of large-scale pounding interactions under multi-hazard loading conditions. The results corroborated the experimental findings, showing that the shear link coupling system effectively mitigated pounding-induced forces, reducing peak impact loads, lateral displacements, and energy transfer compared to conventional eccentric bracing. The system also demonstrated superior performance under wind loads, minimizing repeated impact-induced damage.

Based on the experimental and numerical evidence, the shear link coupling system is recommended as the primary retrofitting strategy due to its superior ability to control pounding effects and enhance structural resilience in wind-prone environments. While the eccentric bracing system remains a viable alternative, it provides comparatively lower impact mitigation. Further optimization of shear link design is advised to balance energy dissipation and structural stiffness, ensuring long-term effectiveness. Additionally, implementing structural health monitoring post-retrofit is recommended to validate performance under real-world conditions. This case study highlights the potential of shear link coupling as an innovative solution for mitigating wind- and earthquake-induced structural pounding in densely built environments.