Smartphones as Sensor Alternatives in Shake Table Tests: Experimental and Numerical Insights

Steel structures are widely adopted in seismic design due to their superior strength, ductility, and energy dissipation capacity. This study presents a comprehensive experimental and numerical investigation into the seismic performance of three steel building models incorporating different concentric bracing configurations—diagonal, X-shaped, and inverted V—with circular cross-sections. Shake table tests were conducted on twelve structural variants, including both braced and unbraced systems, under three ground motion records of varying intensities. Parallel finite element analyses were carried out using SAP2000, with calibrated stiffness parameters to reflect realistic dynamic behavior. A novel aspect of this study lies in evaluating the feasibility of utilizing smartphone accelerometers as low-cost alternatives to conventional sensors in structural health monitoring. Acceleration and displacement responses captured by smartphones showed strong correlation with those obtained from high-resolution accelerometers and numerical simulations, particularly within the optimal frequency band. Results reveal that diagonal bracing consistently provides the highest lateral stiffness and lowest story drift across all models and seismic intensities. Smartphone-based measurements yielded reliable dynamic properties, such as natural periods and peak accelerations, with deviations within acceptable engineering limits. The findings support the use of smartphone sensors for rapid post-earthquake assessments in regular structures and demonstrate that bracing type and cross-section significantly influence seismic performance. This study affirms the potential of integrating accessible technology with traditional methods to enhance resilience evaluation in earthquake-prone regions.