The welding quality of beam-column joints of steel structures is one of the most important factors affecting seismic behavior of steel structures. In order to investigate the influence of initial defects on the seismic performance of H-shaped beam-column joints, the extended finite element method was used. A crack was set at the lower flange weld of H-shaped beam-column joints, and the influence of defect position and defect depth on the seismic performance was examined. The loading methods with different amplitudes were adopted. The research findings indicate that the initial defect exerts a significant influence on the seismic performance of the joint. The bearing capacity and energy dissipation capacity of the joints were decreased, and the degree of reduction accelerates with the increase of defect depth. However, the loading amplitude has a relatively minor effect on the seismic performance of the joint, with a maximum difference of 6.97% and an average difference of 0.31% in ultimate bending moment. Similarly, the influence of the initial defect location is limited, with a maximum difference of 11.9% and an average difference of 3.6%.

Near-fault ground motions are often influenced by forward rupture directivity effects, which may generate distinctive long-period velocity pulses and substantially increase seismic demands compared to far-field records. However, conventional design spectra prescribed in seismic codes generally fail to incorporate these near-fault characteristics, potentially resulting in unconservative structural designs. This study examines the spectral amplification associated with near-fault effects and introduces a coefficient-based modification approach derived through regression analysis. A total of 20 ground motion records from the 6 February 2023 Mw 7.7 Pazarcik earthquake were employed - 10 near-fault and 10 far-field - and to account for the bidirectional nature of seismic excitation, both the East-West (EW) and North-South (NS) components were analyzed separately, yielding 40 datasets. Five-percent-damped elastic acceleration response spectra were computed using the Newmark-Beta method across a broad period range, after which average spectra for the near-fault and far-field groups were compared and spectral ratios were calculated to quantify amplification due to fault proximity. The period range was classified into short (T

The ability to accurately estimate structural responses is essential for ensuring safety and enabling early damage detection in complex engineering systems. However, obtaining full-field structural state data is often hindered by the physical limitations of sensor installation in extreme operational environments and the scarcity of failure data required for data-driven approaches. To address these challenges, this paper proposes a physics-based virtual sensing technique that reconstructs the full-field strain distribution using a sparse array of strain sensors. The proposed method utilizes the mode superposition principle, approximating the global structural response as a linear combination of modal weights derived from limited sensor data. A key feature of this approach is the construction of a hybrid basis set that integrates dominant low-order eigenmodes with quasi-static correction vectors, ensuring that both dynamic characteristics and static aeroelastic deformations are accurately captured with high computational efficiency. The method is applied to a blended wing body (BWB) aircraft structure, and its performance is verified through numerical simulations under various cruise conditions with elliptical lift distributions. The analysis results show that the proposed technique effectively estimates the strain field over the entire structure. Relative errors are mostly within 10% compared to the finite element analysis reference value. In addition, the error is less than 4% in the major deformation area, showing high precision. These findings confirm the potential of the proposed virtual sensing framework as a robust and efficient solution for real-time structural health monitoring in aerospace applications.

As the state-of-the-art in seismic resilience evolves from basic life-safety toward damage mitigation and continuous functionality, piloti-type reinforced concrete (RC) buildings remain a critical vulnerability due to their inherent vertical irregularities. While extensive literature addresses general soft-story retrofits, few studies detail the specific plastic hinge evolution and directional isolator–column interactions required to optimize isolation strategies. To bridge this gap, this study evaluates a representative piloti-type RC prototype (Ministry of Land, Infrastructure and Transport, R.O.K.), explicitly selected because its mid-rise height, asymmetric wall layout, and column dimensions accurately represent the broader stock of vulnerable piloti structures. To ensure strict methodological reproducibility, including ASCE-41 plastic-hinge definitions, material nonlinearity parameters, and effective section properties, all modeling choices are comprehensively detailed in SAP2000. Also, distinct from dynamic earthquake simulations, this study employs displacement-controlled quasi-static analyses to systematically map capacity and collapse progression without ground motion variability. Comparative analyses in both principal directions for non-isolated and base-isolated (lead-rubber bearing) configurations reveal that the non-isolated frame develops collapse-level softstory hinges at low displacements. On the other hand, the base-isolated model completes the prescribed displacement history without collapse by dissipating input energy through isolator hysteresis, dramatically reducing superstructure hinge demand and standardizing the inter-story drift profile. Differentiating this work from prior research, the results highlight that directional stiffness disparities and column sizing dictate energy absorption pathways as larger column sections and higher-stiffness axes significantly enhance isolator efficiency. The findings in this study provide novel, reproducible insights into typical piloti-type RC structural interactions, offering practical guidance for performancebased design in high-density urban seismic regions.