Seismic Categories Research Articles

Assessment of the seismic capacity of existing RC buildings short columns or soft storey, in accordance with the Second-Degree Pre-earthquake Inspection

The seismic capacity assessment of two three-storey reinforced concrete buildings constructed prior to 1984 is being conducted in this paper. Specifically, the case of short columns or soft storey on the ground floor is investigated and a comparison is made regarding the seismic response obtained for each case. The approximate method of the Second-degree pre-earthquake inspection is applied for the case of known and unknown of reinforcement amounts. The obtained results are then compared to the corresponding of a Non-linear static analysis. The primary criterion for the comparison is the failure index of the buildings, as derived from each method. The buildings are categorized into seismic categories according to the Second-degree pre-earthquake inspection, which are compared with the seismic classifications determined by KANEPE. The results of the failure indices and seismic categories according to the Second-degree pre-earthquake inspection were in great convergence with the corresponding results of failure indices in terms of acceleration and the seismic classifications according to KANEPE obtained when the Non-linear static analysis is applied. This convergence is particularly pronounced when known amounts of reinforcement are considered for the vertical elements. Furthermore, the seismic vulnerability of buildings with soft storey or short columns was confirmed in both methods in a similar manner.

Unveiling the Geological Divide: Contrasts Between Intraplate and Plate Boundary Earthquakes.

This review compares the distinctions between interplate earthquakes, primarily situated at plate boundaries, and intraplate earthquakes occurring within the interior of tectonic plates. While plate tectonics effectively explains the mechanisms of interplate seismicity, intraplate earthquakes, notably observed in northeast Asia, pose a more intricate puzzle with no overarching model. This study tackles the fundamental question of whether these two seismic categories exhibit similarities, exploring their respective origins and variations. Despite the challenges associated with understanding intraplate earthquakes due to their infrequency compared to plate-boundary seismic events, this comparative analysis seeks to provide insights into the shared and unique aspects of these significant geological occurrences.

An update on the seismic categorization for seismic risk assessment of existing Canadian buildings

An investigation has been done to update key input parameters in the recent seismic-risk-screening tools developed by the National Research Council Canada for the six seismic categories. In this study, the seismic categorization system in the recent seismic-risk-screening tools of the National Research Council Canada is extended to include Canadian buildings abroad by including threshold peak ground acceleration values, a more global set of modified Mercalli intensity, peak ground acceleration, and spectral response acceleration and peak ground acceleration relationships. The relationships among spectral response acceleration, peak ground acceleration, and peak ground velocity values have been derived using least-squares regression analyses to obtain the threshold values of both peak values associated with various modified Mercalli intensity values for each seismic category. Based on the updated relationships, the seismic categorization system is applied to 679 locations in Canada and 226 locations outside Canada.

IDA analysis of regular and irregular seismically isolated structures in different stories and different seismic categories

The effect of superstructure stiffness, types of plan irregularities, and kinds of seismic categories on the behavior of isolated structures by nonlinear dynamic analysis has been investigated. Incremental nonlinear time history of base isolated structures with different types of irregularities, seismic categories, and at different elevation levels with different superstructure stiffness is the main purpose of this study. In this regard, 72 structures from 8 to 32 floors with regular and irregular spindle-shaped plans were analyzed in seismic design categories C and D (According to ASCE07). The buildings had basements, and the rest were on the ground. Furthermore, in isolated structures, the stiffness of the superstructure was considered once in normal condition (that satisfied the main criteria of drift control and strength design), and once 10 times on average (to achieve higher stiffness). The incremental dynamic analysis (IDA) results showed that in all the cases, along with a noticeable reduction in acceleration and relative lateral displacement of the floors, the response modification factor of the structures was higher than what was considered in the design. In all the studied structures, the plastic joints formed within the immediate occupancy (IO) range. In 10 times stiffened structures, the roof acceleration decreased in all isolated structures. Also, in isolated structures, plan and torsional irregularities did not remain especially in 10 times stiffened isolated structures.

European Seismic Performance Categories C1 and C2 for Post-Installed Anchors

European Seismic Performance Categories C1 and C2 for Post-Installed Anchors

Regarding Requirements to Load Combinations in Case of Evaluation of SSC Seismic Resistance by Indirect Methods

Extension of the list of load combinations that should be analyzed during the nuclear power plant (NPP) components seismic resistance justification is one of the important new regulatory requirements.
 The paper deals with the thermomechanical equipment for which seismic resistance assessment is performed using operating experience method, in particular the methodology of indirect assessment using the GIP (Generic Implementation Procedure) for the WWER reactors (GIP-WWER procedure).
 Review of GIP-WWER procedure has been performed. The paper presents the analysis of seismic screening evaluation work sheet based on the example of motor-operated valve. The disadvantages of the GIP-WWER procedure in terms of ensuring compliance with current regulatory requirements for combinations of operating and seismic loads have been identified and the ways of eliminating the revealed disadvantages have been offered.
 The supporting structures of the equipment in most cases are the metal structures. Impact of different NPP operating modes to the steel supporting structures of the equipment has been considered and the provisions of building codes governing the calculation of steel support structures have been analyzed. A minimum listing of operating and seismic loads combinations has been established, which should be considered in the justification of the seismic strength of steel support structures referred to the first and second seismic categories.
 The paper is a part of a series of publications devoted to consideration of regulatory requirements to combinations of operational and seismic loads in assessing the seismic resistance of NPP components.

Structural damage estimation in mid‐rise reinforced concrete structure based on time–frequency analysis of seismic accelerograms

The aim of this study is to evaluate the intensity and damage potential of seismic accelerograms on structures combining a fuzzy inference system with a set of new seismic intensity parameters. The proposed seismic parameters stem from the energy content of seismic signals. More specifically, a time-window is utilised to define the strong motion duration of seismic excitations and the ensemble empirical mode decomposition is employed for a time–frequency analysis of the selected strong motion area. The maximum inter-storey drift ratio is selected as the seismic structural damage index. Strong interdependence between the proposed seismic intensity parameters and the selected damage index is reported. The membership functions of the fuzzy system are tuned by means of a genetic algorithm. The effectiveness of the proposed fuzzy model is tested on a reinforced concrete frame structure. The methodology should be repeated for every new examined structure and it can be applied to other building types with minor changes. Numerical results indicate total mean square error <0.25 for the maximum inter-storey drift ratio estimation and 91% correct classification rate to seismic categories, revealing the effectiveness of the fuzzy model to estimate numerically the structural damage.

Safety Classifications for the Fusion DEMO Plant of Korea

Regulatory requirements and industrial codes and standards (C&S) are to be compulsory top-tier prerequisites for the design and construction of the fusion DEMO plant of Korea (DEMO Plant) as it will have safety-related functions to mitigate radiation hazards to the environment. However, these prerequisites will be developed in parallel with the design and construction of DEMO Plant due to the first-of-a-kind nature of the DEMO Plant. To overcome this dilemma, a tentative set of general design criteria and classification criteria that are to be applicable for the design studies of DEMO Plant is proposed, making use of the commonalities between the DEMO Plant and existing nuclear power plants (NPPs). To determine the tentative set, the radiation release to the environment and consequences of the postulated events in the DEMO Plant are analyzed with rough approximation assuming the inherent safety of a fusion DEMO reactor. The classification criteria of the tentative set include safety class, IEEE electrical classes, quality groups, and seismic categories for the structures, systems, and components of the DEMO Plant. As it will take considerable time and substantial amounts of investment to develop the regulatory requirements and C&S, the use of ASME Section III for the design study of DEMO Plant is also proposed to make the best use of the commonalities between the DEMO Plant and existing NPPs.

Seismic Performance of RC Structures Using an Improved Inelastic Analysis Method

Inelastic analysis procedures may be useful as a first approximation for the seismic response of a structure. The Capacity Diagram Method procedure, which is based on R--T (Reduction-ductility-Period) relationships, is investigated to compare with the modified CDM procedure. The CDM procedure is applied to the example model, which is moment resistant RC frame. Two seismic hazard categories having exceedance probabilities of 2% in 50 years and 10% in 50 years earthquake ground motions have been selected for evaluating the performance of the example model. The performance objective of the example model is represented by the combination of a structural performance level and an earthquake hazard level.