Assessment of the impact of seismic retrofit on electrical switchboards based on shaking table tests

Electrical switchboards are essential in power plants for managing, distributing, and converting high-voltage electricity. However, seismic events can cause structural and functional damage, leading to severe secondary failures in critical infrastructure. Conventional reinforcement methods, such as anchoring and base strengthening, are widely used but often fail to prevent rocking and uplifting, resulting in localized deformations and impact damage. This study assesses the impact of seismic reinforcement on switchboards using shaking table tests. Initial tests revealed that standard anchoring methods were insufficient to prevent structural damage, causing significant stress and deformation around anchoring points. To address this, two alternative reinforcement strategies were examined: (1) increasing the number of connecting bolts between the switchboard and the base channel and (2) reinforcing the switchboard's bottom panel with a welded steel grid. Numerical simulations and additional tests validated their effectiveness. Results showed that increasing the connecting bolts significantly improved structural stiffness, reducing acceleration responses and deformation by up to 20%. However, welded grid reinforcement enhanced localized stiffness but failed to mitigate impact acceleration effectively. The findings emphasize anchoring reinforcement as a practical and cost-effective solution for improving seismic resilience in electrical switchboards, offering valuable insights for optimized seismic retrofitting in power plants.