GNSS dynamic monitoring and time-frequency feature analysis in structural seismic response assessment

Shaking table test on seismic response of a planar irregular structure with differential settlements of foundation

Time-frequency fusion features-based incremental network for smartphone measured structural seismic response classification

New regulatory requirements in Japan have strengthened the mitigation of damage caused by natural hazards, such as earthquakes, and the operational guide for safety improvement evaluation recommends the use of a probabilistic risk assessment (PRA) as the evaluation method in Japan. In the PRA of an earthquake, also known as the seismic PRA, one of the most important issues is the realistic assessment of the structural seismic response and the conditional damage probability (fragility) assessment using a realistic response assessment of nuclear buildings and equipment. Accordingly, we conducted this study both on the analysis methods used for realistic seismic response and assessment methods of seismic fragility to ensure the seismic safety of nuclear buildings and equipment. In this study, we use a three-dimensional (3D) structural model of a reactor building to conduct a nonlinear seismic response analysis for input ground motions beyond a design basis. In addition, we identify the failure mode of the structural components of the reactor building associated with the equipment and assess the seismic fragility based on the 3D behavior of the reactor building. The local response and detailed damage progress of the reactor building obtained through seismic response analysis are reported, along with the results of the seismic fragility assessment.

EESD special issue: AI and data‐driven methods in earthquake engineering – (Part 1)

ABSTRACTA comprehensive methodology for the validation of simulated ground motions is presented. The suggested methodology can be geared toward any ground-motion simulation method and seismic response assessment, in a target engineering application. The methodology is founded on the comparison between conforming groups of ground-motion waveforms from recordings and simulations and their effect on a representative collection of structures that represent the engineering application. The comparison considers the statistics of earthquake scenarios at the level of the event and site parameters, the resulting waveform characteristics, and the subsequent structural responses. Regression models are developed at three levels (between structural responses and waveform characteristics, structural responses and event and site parameters, and waveform characteristics and event and site parameters). Similarities between the models from groups of recorded and simulated ground motions guide the validation process. The validation methodology is applied to CyberShake (v.15.12) simulations and for the estimation of the column drift ratio of a bridge structure. It is shown that CyberShake (v.15.12) can be used to assess the median seismic response of the used bridge. Some discrepancies between simulations and recordings are observed, which could be attributed to the basin and site-response models used for simulations. Further implementation and refinement of the suggested methodology are recommended to make broader conclusions.

Seismic Response of Base-Isolated Structures with LRB and FPS under near Fault Ground Motions

Seismic response of RC moment frame structures (particularly, in low-rise buildings) is affected by the inelastic hysteretic response and energy dissipation of beam-column joints. In current earthquake design codes, however, the earthquake response of the structures is evaluated without direct consideration of the energy dissipation of beam-column joints. In the present study, non-linear time history analysis using the energy-based hysteresis model was carried out to investigate the effect of the energy dissipation performances of the beam-column joints on the seismic response of the structures. To demonstrate the applicability of the proposed analysis method, it was applied to existing dynamic test results of RC moment frame structures. On the basis of the proposed method, non-linear time history analysis for six different typed low-rise RC moment frame structures under 14 earthquake records was performed. Design parameters were the energy dissipation ratios of beam-column joints (from pinching behavior to elasto-perfectly plastic behavior), moment frame stories (3, 5, and 9 stories), and moment frame configuration (two and four spans). The analysis results showed that the low energy dissipation of beam-column joints increased the ductility requirement of the low-rise RC moment frame structures.

A design procedure for dual eccentrically braced systems: Numerical investigation

Bond slip in RC beam–column joints may affect the seismic response or performance assessment of structures considerably. Explicit macroscopic models that satisfy the joint kinematics can be incorporated within a frame model to numerically account for the effect of bond slip. Seismic performance assessment of buildings generally rules out the explicit modeling owing to the associated computational cost. Simplified implicit models are instead preferred owing to the ease of implementation in a commercial finite element (FE) provided the model parameters are calibrated experimentally. Extrapolation of the calibration is generally not valid in other cases with different geometry, sizes and even loading protocols. Most commercial software do not offer the features to explicitly modeling the bond slip. Numerical modeling of bond slip is proposed in this paper that can be conveniently implemented in a commercial software such as Seismostruct. Unlike the prior art, the slip parameter can be extracted using a semiempirical approach preceded by the generation of a numerical database. The proposed framework is also validated against the experimental results of one exterior and one interior beam–column joints. Sample illustration on an example building designed against the same seismic hazard level but following the recommendations per IS 13920, ACI 318 and EC8 is considered for monotonic (without bond slip) and cyclic (with bond slip) pushover analyses. Consideration of bond slip initiates early yielding and results in reduction of secant stiffness at the onset of yielding. The extent of influence depends on the compliance of design standards. For example, relatively higher percentage of reinforcement when designed per IS 13920 (as compared to ACI 318 and EC8) leads to a somewhat lower slip parameter resulting in lesser yield displacement and reduction of secant stiffness at the onset of yielding.

Site effect on seismic response of buried nuclear power plant structure

Structural seismic safety assessment is a critical task in maintaining the resilience of existing civil and infrastructures. This task commonly requires accurate predictions of structural responses under stochastic intensive ground accelerations via time‐costly numerical simulations. While numerous studies have attempted to use machine learning (ML) techniques as surrogate models to alleviate this computing burden, a large number of numerical simulations are still required for training ML models. Therefore, this study proposes a prior knowledge‐infused neural network (PKNN) for achieving efficient structural seismic response predictions and seismic safety assessment at a low computation cost. In this approach, first, the prior knowledge inherently within a theoretical dynamic model of a structure is infused into a neural network. Then, by utilizing the few‐shot incremental learning technique, this network would be further fine‐tuned by only a few numerical simulations. The resulting PKNN would be able to accurately predict the seismic response of a structure and facilitate seismic safety assessment. In this study, the PKNN's accuracy and computational efficiency are validated on a typical frame structure. The results revealed that the proposed PKNN could be used for accurately predicting the structural seismic responses and assessing the structural safety under a low computational cost.

Seismic Response and Vulnerability Assessment of Representative Low, Medium and High-rise Buildings in Patna, India

Ground Motion Selection and Modification: An Overview of Recent Progress for Building Structures and the Implications for Lifeline Structures

Seismic reliability assessment of RC structures including soil–structure interaction using wavelet weighted least squares support vector machine

A comprehensive study on seismic dynamic responses of stochastic structures using sparse grid-based polynomial chaos expansion