Cross-section design of nuclear power plant buildings satisfying target floor response spectrum

Physics-guided neural network for structural seismic response reconstruction based on floor response spectra

For the study, we have considered ten test models, out of which one model is not having shear wall. This model is called bare frame. From the bare frame model other nine test models with shear wall is compared in order to define the optimum location of shear wall for L shaped building. Dynamic Analysis is done for the comparative study of the models. We have used standard software package of CSI ETABS ver. 16.0.0 for the modeling and analysis of the structure. Under dynamic analysis, we have limited ourselves to RSA & THA Both of these analyses are done under elastic limit. For Response Spectrum Method, we have considered the graph for Seismic Zone V with medium soil for a damping ration of 5% and importance factor as ‘1’. The RS Analysis has been carried out according to IS 1893 (Part-1):2016 by using CSI ETABS ver. 16.0.0. For Time History Analysis, we have used the time history data of Array Recording Station, El Centro, USA. The data is under the software package. We have determined the suitable configuration of shear wall in building, on various ground of comparison which is defined in the thesis.

A key choice should be made between Equivalent Static Method (ESM) and Response Spectrum Method (RSM) during the seismic design of buildings. The current paper tests and compares the performance of these two procedures to reinforced concrete dual-system structures of different heights. The cases of 4-story, 8-story, and 16-story regular buildings were modelled with the use of software ETABS v21.0.0 in accordance with the Nepal National Building Code (NBC 105:2020). The important parameters in seismic response comparison such as base shear, roof displacement and maximum inter-story drift were compared. The findings show that an important trend exists, which is, the deviation between the methods grows as the height of the building increases. For base shear, ESM for the 4-story building predicted values 9.9 % and 12.5 % higher in X and Y-direction respectively. However, for the 8-story and 16-story buildings, ESM was found to underestimate the seismic load by approximately 25.1% and 25.4% in the X-direction, and by 24.7% and 25.6% in the Y-direction, respectively, when compared to RSM. Regarding roof displacement in the X-direction, RSM consistently predicted larger values, with the absolute difference growing from 1.39 mm to 14 mm and finally to 31 mm in the 4,8 and 16 story buildings respectively. Similarly, for maximum story drift the absolute difference widened from 0.0191 % to 0.0779 % and finally to 0.1106 % in the 4,8 and 16 story buildings respectively. The paper concludes that the ESM might prove to be adequate in the case of low-rise buildings but cannot be effective in the design of midrise to high rise buildings where the Response Spectrum Method is preferred.

This study validates a frequency-domain method to derive incident wavefields from strong motion records for 1D site response analysis. Using site-specific adjustment coefficients ζ , seismic waves are modified for single- and multi-layer soils. The Adjusted Wave Input Method (AWIM) significantly outperforms the traditional Wave Input Method (WIM), achieving > 95 % accuracy in velocity/displacement predictions when benchmarked against the Vibration Input Method (VIM). Application to the 2011 Tohoku Earthquake records at three KiK-net sites (low/medium/high stiffness) confirms AWIM’s robustness: surface response spectra align closely with field data. This method improves the accuracy of the wave input method, especially for soft soil.

Earthquake-induced damage to reinforced concrete buildings remains a major concern in seismic regions, necessitating the adoption of advanced vibration control techniques beyond conventional strength-based design. Among these techniques, base isolation and seismic dampers represent two fundamentally different approaches to mitigating seismic demand. This study presents a comprehensive comparative case analysis of base isolation systems and column-installed seismic dampers to evaluate their effectiveness in improving structural seismic performance. A multi-storey reinforced concrete frame is analytically modelled and subjected to seismic loading using response spectrum and time-history analysis methods. Key response parameters including fundamental time period, base shear, storey displacement, inter-storey drift, floor acceleration, and energy dissipation are systematically examined. The results demonstrate that base isolation significantly lengthens the structural time period and achieves substantial reduction in base shear and floor accelerations, making it particularly suitable for acceleration-sensitive structures. In contrast, seismic dampers installed in columns exhibit superior control over inter-storey drift and internal force demand by dissipating seismic energy through hysteretic behavior. The comparative assessment highlights that while both systems considerably enhance seismic resilience, their effectiveness is strongly influenced by building height, functional requirements, soil conditions, and retrofitting feasibility. The study provides practical insights and design-oriented guidance for selecting appropriate seismic protection strategies in performance-based earthquake-resistant design.

This study proposes a novel artificial neural network-based methodology for classifying the incident wave direction during ship navigation using the heave–roll–pitch motion response spectra as input. The proposed model demonstrated a balanced performance with an overall accuracy of approximately 0.888, effectively classifying the wave direction into three major categories: head-sea, beam-sea, and following-sea. The methodology utilizes Response Amplitude Operators derived from linear potential flow theory to generate motion response spectra, which are then used to classify the incident wave direction. The model effectively learns the frequency-distribution characteristics of the response spectrum, enabling wave direction classification without the need for complex inverse analysis procedures. This approach is significant in that it allows wave direction recognition solely based on measurable ship motion responses, without the need for additional external sensors or mathematical modeling. This data-driven approach has strong potential for integration into autonomous ship situational awareness modules and real-time wave monitoring technologies. However, the study simplified the directional domain into three representative groups, and the model was validated primarily using a numerically generated dataset, indicating the need for future improvements. Future research will expand the dataset to include a broader range of sea states, improve directional resolution, and explore continuous wave direction prediction. Additionally, further validation using field-measured data will be conducted to assess the real-time applicability of the proposed model.

Abstract. A frequency-domain model for floating wind turbine dynamics has been extended to model floating wind farms with couplings from shared mooring systems. The model, called RAFT, could previously calculate the mean offsets and wave-induced response spectra for single floating wind turbines. Now, the model supports multiple floating wind turbines, each with their own properties and responses, along with mooring lines that run directly between floating wind turbines in the array, meaning that shared mooring lines or fully suspended dynamic power cables can be included. This capability is achieved by setting up an array-level solution of the system mean offsets and assembling the full system matrices for solving the dynamic response. The quasi-static mooring model MoorPy is used to linearize the mooring system properties. To compute the floating wind turbine relative motions, phase offsets are applied to each turbine's response as a function of wave frequency based on the wavelength and relative positions in the array. These differential motions are then applied to mooring system tension Jacobians to compute the tension loads in the shared mooring lines. Overall, the capability provides a frequency-domain analog to the modeling capabilities of the floating support structure in FAST.Farm. Mean offsets and power spectral density plots of responses are compared between RAFT and FAST.Farm to verify the implementation. The results indicate good agreement within the expectations of a frequency-domain modeling approach and suggest correct implementation of the shared mooring aspects. Additionally, a unique comb-like frequency response in the shared mooring line tensions has been observed. This phenomenon has a clear physical basis and may be an important design consideration for future shared mooring systems.

This study investigates the seismic retrofit of historic single-nave churches through the optimization of roof diaphragms designed to enhance energy dissipation. The proposed strategy introduces a deformable box-type diaphragm above the existing roof, composed of timber panels and steel connectors with a cover of steel stripes, where energy dissipation is concentrated in the connections. The retrofit design is guided by the estimation of Equivalent Damping Ratio (EDR) instead of the usually adopted resistance criterion, considering an energy-based approach to improve global seismic performance while preserving architectural integrity. In this way, the retrofitted configuration of the roof can be considered a damper. Three numerical phases are presented to assess the effectiveness of the equivalent damping-based intervention. In the first one, the seismic response of the initial non-retrofitted configuration is implemented using a 3D linear finite element model subjected to a response spectrum. Subsequently, nonlinear equivalent models subjected to spectrum-compatible accelerograms are implemented, simulating the possible retrofitted configurations of the roofs to detect the optimum damping and finding the corresponding roof diaphragm configuration. In the third one, the response of the detected retrofitted configuration is also evaluated by nonlinear 3D model subjected to accelerograms. The three phases with the relative numerical approaches are here applied to a case study, located in a high seismic hazard area. The results demonstrate that the EDR-based methodology can optimize the retrofitted roof diaphragm configuration; the nave transverse response is improved in comparison with that designed with the traditional approach, considering only the over-strength of the interventions. Comparisons about the approaches based on the EDR and the strength criteria are presented in terms of lateral displacements, in-plane shear acting on the roof diaphragm, and in-plane stresses on the façade.

With the rapid advancement of offshore wind power, structural vibration induced by multi-source excitations in complex marine environments is a critical concern. This study developed a multi-degree-of-freedom (MDOF) dynamic model of an offshore wind turbine using a lumped mass approach, which was then reduced to a first-order linear system to improve frequency-domain analysis and optimization efficiency. Given the non-stationary, broadband nature of wind and wave loads, a band-pass filtering technique was applied to extract dominant frequency components, enabling linear modeling of excitations within primary modal ranges. The displacement response spectrum, derived via system transfer functions, served as the objective function for optimizing tuned mass damper (TMD) parameters. Both single TMD and multiple TMD (MTMD) strategies were designed and compared. A hierarchical particle swarm optimization (H-PSO) algorithm was proposed for MTMD tuning, using the optimized single TMD as an initial guess to enhance convergence and stability in high-dimensional spaces. The results showed that the frequency-domain optimization framework achieved a balance between accuracy and computational efficiency, significantly reducing structural responses in dominant modes and demonstrating strong potential for practical engineering applications.

Concrete gravity the massive structure that plays a significant role in the community. The Incremental Dynamic Analysis (IDA) was performed to develop the IDA curve for the concrete gravity dam, considering dam height and water level variations in response to single and repeated earthquake events. Using the Koyna dam's material properties, a nonlinear numerical analysis model is developed in AB QUS. Five ground motions were converted to the response spectrum and scaled according to the developed elastic response spectrum to match the characteristics of the ground motion to the soil type. IDA curves were generated to illustrate the damage states at various ground motion intensities. For the 50 m dam with full and half water height, the average maximum crest displacement is 8.91 mm, 25.13 mm and 9.71 mm, 34.71 mm respectively. For the 100 m dam with full and half water height, the average maximum crest displacement at the yielding and ultimate states is 24.44 mm, 46.09 mm and 41.65 mm, 72.99 mm respectively. It shows that the higher dam receives significantly greater damage during earthquakes. Subsequently, dams with lower water level experienced more serious damage as PGA increased. Furthermore, the dam received greater destruction due to repeated earthquakes than a single earthquake event.

The southern Korean Peninsula faces complex seismic challenges due to the concentration of critical infrastructure and the region’s unique intraplate tectonic environment. In this study, over 300 strong-motion records from 10 moderate-magnitude earthquakes were analyzed using data from 10 representative seismic stations. Acceleration response spectra, normalized by peak ground acceleration, were generated and systematically compared with international and domestic seismic design standards, including USNRC Regulatory Guide 1.60 and KBC 2016. The observed spectra frequently exceeded existing code requirements in the mid-to-high-frequency range critical for local infrastructure, indicating potential vulnerabilities in applying generic global standards to Korean conditions. Analysis of vertical-to-horizontal spectral ratios further revealed pronounced frequency dependence and amplification effects, especially in sedimentary basin sites. These findings underscore the importance of accounting for site-specific geological and seismic characteristics in the seismic design of critical infrastructure in Korea. The results advocate for the development of regionally calibrated, risk-informed seismic design frameworks and provide essential empirical data to support safer, more resilient infrastructure amid moderate but potentially hazardous earthquake activity.

Abstract This paper presents a comprehensive experimental investigation into the shock characteristics associated with a low-thrust, low-shock separation mechanism incorporating Mild Detonating Cord (MDC) within a rubber bellow interface. Two test configurations were developed with varying explosive charge masses to study their influence on pressure generation and shock propagation. Linear accelerometers and high-speed pressure transducers were employed to capture transient dynamic responses at both piston and cylinder interfaces. The results demonstrate a significant reduction in peak pressure and shock levels, especially in the second test configuration, where the explosive mass was reduced to 60% of the initial configuration. The shock response spectrum (SRS) analysis confirms that the lower charge mass leads to proportionally reduced shock amplitudes across the frequency range of interest. Furthermore, comparative assessment of shock levels reveals a significant reduction of shock levels as compared to conventional separation mechanisms, such as a flexible linear-shaped explosive charge (FLSC) mass or a separation bolt actuated with a pyro cartridge. The experimental pressure values are shown to correlate well with theoretical predictions, validating the design approach. These findings provide critical insights into tailoring explosive-based separation mechanisms for sensitive payload environments, highlighting the importance of confined detonation and charge optimisation in mitigating pyroshock.

The stochastic finite-fault method based on dynamic corner frequency has been widely applied to simulate high-frequency ground motion of near-fault field. The model input parameters include source term, path term and site condition, many of which exhibit strong regional properties and are particularly sensitive to the site. Based on strong-motion stations drilling data and recordings within North China, some region-specific key parameters including local site amplification and high-frequency decay factor kappa are examined and analyzed. The local amplification function over versus frequency for class II and III site are computed using the quarter-wavelength approximation. The kappa in North China Plain and Mountain regions are calculated by employing the spectral decay method, respectively. In addition, the calibration of stress drop is achieved by adopting the trial-and-error method, which can be also applicable to the determination of other uncertain model parameters. After input parameters are determined and model bias is evaluated, we applied the region-specific parameters in North China to simulate and analyze time history, peak ground acceleration, Fourier amplitude spectrum, acceleration response spectrum, ShakeMap of PGA for the Dezhou earthquake. Overall, the simulated results coincide well with observed recordings. The validation of region-specific parameters demonstrates that they could be applied to the synthetic high-frequency ground motions in North China.

With the increasing population and unavailability of plain grounds in some regions, the need for high-rise buildings is increasing day by day. Buildings constructed on sloping terrain are more prone to earthquakes because of their uneven floor plans and elevations. This study examines the seismic behavior of high-rise buildings on both flat and sloping terrains, with a focus on comparing regular and irregular structural configurations. In this study a total of 25 G+15 RCC Step-back buildings with regular and irregular configurations such as Square shape, C-shape, U-shape, L-shape and Cross shape each of which are resting on grounds with sloping angles of 0º, 10º, 20º, 30º and 45º have been made using ETABS software as per IS 1893 (Part 1): 2016. The study employs the Response Spectrum Method to evaluate Storey Displacements, Storey Drifts, Base shears, and Time periods. It is observed that the storey displacement and storey drift decrease as we increase in sloping angle mainly due to curtailment of the columns, and the regular configurations of structures have better seismic performance than irregular configurations.

Evaluating the ratio of peak ground acceleration to peak ground velocity from the response spectrum

Regression-based evaluation of viscoelastic damping behavior in bridge vibrations using 3D response spectrum analysis

Digital seismic assessment for primary electrical distribution device using response spectrum technique

Generating elastic floor response spectra using ensemble learning methods with whale optimization algorithm

A simple approach for incorporating soil-structure interaction and site uncertainty into floor response spectra