In this study, detailed finite element analysis was conducted to examine the seismic performance of square and circular hollow steel braces under axial cyclic loading. Finite element models of braces were constructed using ABAQUS finite element analysis (FEA) software and validated with experimental results from previous papers to expand the specimen’s matrix. The influences of cross-section shape, slenderness ratio, and width/diameter-to-thickness ratio on hysteretic behavior and compressive-tensile strength degradation were studied. Simulation results of parametric studies show that both square and circular hollow braces have a better cyclic performance with smaller slenderness and width/diameter-to-thickness ratios, and their compressive-tensile resistances ratio significantly decreases from cycle to cycle after the occurrence of the global buckling of braces.

In this paper, the shaking table tests and finite element analyses were conducted on the traditional thermal power plant main building and the thermal power plant main building with BRBs, respectively. The differences in torsional resistance between the two structural systems were studied, and the suppression effect on the displacement field distortion of the plane consisting of crane and tracks through adding BRBs in the thermal power plant main building was discussed. The study shows that after adopting a buckling-restrained brace in a thermal power plant main building, the damage and torsional response of the structure under an earthquake can be reduced, the occurrence of inelastic torsion can be effectively blocked, and the translation-torsion coupling effect can be reduced. At the same time, it can reduce the distortion amplitude of the displacement field of the plane consisting of crane and tracks and play a key role in improving the reliability of roof truss, crane, coal bucket, and low-ductility connectors, and it also facilitates the realization of performance-based seismic design.

Short-time Fourier transformation (STFT) has been widely recognized as an intuitive time-frequency analysis method. However, its application in building structures is constrained by its low accuracy of low-frequency recognition in short data. Accordingly, an all-phase chirp-z transformation (AP-CZT) proposed for frequency recognition in building structures. Specifically, the autoregressive (AR) model, which has a proposed order determination algorithm, is used to solve the problem of data length limitation in the all-phase data process. Subsequently, an algorithm based on absolute inverse proportional function (AIP) is developed for post-refinement frequency correction. To verify its actual application, the ap-CZT method is used to analyze simulating finite element model and white noise feedback data from the actual shake table. The ap-CZT method is proven to be capable of correctly finding high-order frequencies. Moreover, it can accurately identify signal frequencies in short data. Therefore, the ap-CZT method can be applied as a frequency identification method in STFT in the field of building structures.

Base isolation technology, as a mature seismic mitigation method, demonstrates potential for enhancing seismic margins in nuclear power plant structures. This study investigates the seismic performance of isolated and non-isolated models for a diesel generator building in a nuclear power plant through shaking table tests. A 1/8-scale structural model was designed and tested under operational safety ground motion (SL-1), ultimate safety ground motion (SL-2), and beyond design benchmark ground motion (BDBE) seismic excitations. A finite element model considering different tensile and compressive stiffnesses of isolation bearings was established to simulate structural dynamic responses under test conditions. The results demonstrate that the test model design is effective, with the maximum isolation rate was close to 50%. The maximum displacement of the isolation layer meets the collision prevention ditch limit. Numerical simulations showed good agreement with experimental results in acceleration time histories, displacement time histories and bearing hysteresis curves. Additionally, the seismic isolation structure has a certain overturning effect in the test. To further optimize the base isolation scheme, numerical analyses incorporating dampers into the isolation layer were conducted, which demonstrated improvements in mitigating the rocking effect of the superstructure.