Earthquake-resistant Structures Research Articles

Uncertainty reduction in MASW inversion and ground response analysis using a-priori information

Multi-channel analysis of surface waves (MASW) method is commonly used for estimating the shear wave velocity (Vs) profile of soil and subsequent ground response analysis (GRA). However, the uncertainties from inversion non-uniqueness in MASW testing and the absence of soil type information in GRA can undermine their accuracy and affect seismic designs. Incorporating a-priori information from geotechnical investigations can be a potential solution, but its effectiveness in MASW testing is not well understood. This study aims to quantify the uncertainty reduction achieved by incorporating a-priori information in MASW testing and GRA. Extensive numerical simulations of MASW and GRA for nine idealized soil profiles were carried out. Subsequently, the findings were validated by carrying out field testing with and without a-priori information. The a-priori information included number and thickness of soil layers, soil type and index properties. The findings demonstrate that incorporating a-priori information significantly reduces inversion uncertainty in MASW and GRA, enhancing the reliability and accuracy of the analyses. This work provides a quantitative assessment of uncertainty reduction using a-priori information for different possible site and earthquake scenarios. The findings have important implications for design of earthquake-resistant structures and for improving the safety of people and infrastructure in earthquake-prone areas.

Implementation of PMDL and DRM in OpenSees for Soil-Structure Interaction Analysis

It is widely acknowledged that the effects of soil-structure interaction (SSI) can have substantial implications during periods of intense seismic activity; therefore, accurate quantification of these effects is of paramount importance in the design of earthquake-resistant structures. The analysis of SSI is typically conducted using either direct or substructure methods. Both of these approaches involve the use of numerical models with truncated or reduced-order computational domains. To ensure effective truncation, it is crucial to employ boundary representations that are capable of perfectly absorbing outgoing waves and allowing for the consistent application of input motions. At present, such capabilities are not widely available to researchers and practicing engineers. In order to address this issue, this study implemented the Domain Reduction Method (DRM) and Perfectly Matched Discrete Layers (PMDLs) in OpenSees. The accuracy and stability of these implementations were verified through the use of vertical and inclined incident SV waves in a two-dimensional problem. In terms of computational efficiency, PMDLs require a shorter analysis time (e.g., with PMDLs, the analysis concluded in 35 min as compared to 250 min with extended domain method) and less computational power (one processor for PMDLs against 20 processors for the extended domain method) thus offering a balance between accuracy and efficiency. Furthermore, illustrative examples of the aforementioned implemented features are presented, namely the response analysis of single-cell and double-cell tunnels exposed to plane waves inclined at an angle.

Revisiting the 1934 Mw 8.2 Bihar–Nepal earthquake—Simulation of broadband ground motions

SUMMARY The 1934 Mw 8.2 Bihar–Nepal earthquake was one of the devastating earthquakes, which made seismologists realize the importance of proper seismic hazard analysis and design aspects in India. The event occurred way before proper seismic networks were implemented and hence there are no recorded ground motions available for this event. This study, thus aims to generate possible ground motions for the 1934 Mw 8.2 Bihar–Nepal event. The complex geographical features, ambiguous source information and lack of ground motion data make the simulation and validation of ground motions very difficult. In this regard, the broad-band (BB) ground motions are simulated and validated for the most recent well-documented Himalayan event, that is, the 2015 Mw 7.9 Nepal earthquake in order to calibrate the model and simulation methodology. For this purpose, the computational model is presented for a region of 1000 km × 670 km (longitude 80–89 °E and latitude 23–30 °N) in the Indo-Gangetic Basin to simulate the low-frequency (LF) ground motions using spectral element method. These deterministically simulated LF ground motions are combined with stochastically simulated high-frequency (HF) ground motions based on an improved seismological model . The seismic moment and dimensions of the rupture plane are used to generate ten samples for the finite fault source model having different slip distribution along the rupture plane as a random field. The BB ground motions (0.01–25 Hz) are obtained by merging LF and HF ground motions in the time domain by matching them at a frequency of ∼0.3 Hz. Such BB results are simulated at a grid of stations and at locations where modified Mercalli intensity (MMI) values are available. The estimated MMI values and the observed MMI values are compared to emphasize the efficacy of the model. The maximum PGA estimated from the simulated ground motions in horizontal and vertical directions are observed to be 0.48 g and 0.4 g. Further, 5 per cent damped response spectra and spectral amplification are analysed concerning the sediment depth of the Indo-Gangetic Basin. The results from the study can serve as inputs for dynamic analysis and the design of earthquake-resistant structures across different locations in the Indo-Gangetic Basin.

Seismic performance and design of an innovative structure with controlled rocking shear wall using ring springs

The application of ring springs in civil engineering, aimed at improving the seismic behavior of structures, has been largely overlooked despite their many advantages. These springs are highly durable, heat-resistant, low-maintenance, and self-centering, meaning that they withstand large deformations while always returning to their original state. Structures equipped with properly designed ring springs survive earthquakes without suffering major damage or plastic deformation, making them an excellent investment in terms of both economic efficiency and sustainable resource use. This paper explores a new use for ring springs in earthquake-resistant structures, with a focus on their implementation into controlled rocking shear walls. A parametric study utilizing the Non-Linear Time History Analysis method was conducted on a simplified model to investigate the rocking behavior and derive a design methodology based on the obtained results. A comparative study was conducted on elastic, non-linear, and rocking shear walls to demonstrate the feasibility and design principles of the rocking systems. Furthermore, the results of the comparative studies provided evidence supporting the efficacy of incorporating ring spring dampers into the rocking systems. The controlled rocking shear wall demonstrated elastic behavior during seismic loading, indicating that the addition of ring spring dampers was effective in enhancing its performance. On the other hand, the conventionally designed numerical model exhibited nonlinear behavior at its base. The developed design procedure ultimately enables the practical application of controlled rocking shear walls using ring spring dampers in earthquake engineering.

Determination of individual disaster resilience levels of hospital staff: A case study of Kartal Dr. Lütfi Kirdar City Hospital

Istanbul is one of Turkey's most important financial and industrial centers, and it is located in a region with a high potential for seismicity. Due to its historical architecture and high level of urbanization, the city has a large population and is particularly vulnerable due to the building stock that will be affected by earthquakes. In the event of a possible earthquake in Istanbul, it is crucial that the hospital staff have high levels of disaster resilience/resilience. This is particularly important given the seismically isolated and earthquake-resistant structure of Istanbul Kartal Dr. Lütfi Kırdar City Hospital and its capacity to serve those injured by the earthquake. This study examines the resilience levels of hospital staff at Kartal Dr. Lütfi Kırdar City Hospital in the face of earthquake disasters and the various factors that affect these resilience levels. The data for this study were collected using a 13-question personal information form and the ‘Individual Disaster Resilience Assessment (IDRA)’ scale developed by DiTirro (2018). Descriptive statistics, Pearson Chi-square tests, Independent Samples T-tests, and One-Way ANOVA were used to analyze the data. The research found that the hospital staff's IDRA scores averaged 3.27. It was concluded that the mean resilience score of the participants was above the medium level. The research findings show that receiving disaster training or being prepared for disasters in advance significantly influences individual resistance/resilience. In this context, it is essential to determine the earthquake resistance levels of all healthcare workers in Istanbul, especially those at the city hospital where the study was conducted. Necessary training should be provided, and simulation-based disaster drills should be planned and integrated into in-service training programs. Additionally, projects should be developed to ensure that healthcare workers can reach their hospitals safely during disaster situations.

Bayesian optimization-based Model-Agnostic Meta-Learning: Application to predict maximum cyclic moment resistance of steel bolted T-stub connections

Accurately assessing the maximum moment resistance of steel bolted T-stub connections under cyclic loading is crucial for designing earthquake-resistant structures with such connections. Traditional methods based on design standards like ASCE 41-17 often lack precision. Recently, supervised machine learning techniques, particularly Artificial Neural Network (ANN), have been explored. However, conventional ANNs require substantial data for generalization, which is limited for steel bolted T-stub connections. To address these challenges, this study explores the feasibility of using the Model-Agnostic Meta-Learning (MAML) to predict the maximum cyclic moment resistance of steel bolted T-stub connections. MAML adapts task-specific model parameters rapidly and transfers knowledge across tasks to fine-tune global model parameters, potentially enhancing prediction accuracy with limited data. The MAML model is first optimized using Bayesian optimization with a Gaussian Process model to identify ideal hyperparameters. The optimized MAML model is then compared with two ANN models (one with optimized hyperparameters, another matching MAML's neural network architecture) and ASCE 41-17 method. Results demonstrate the optimized MAML model's superior generalization capabilities, offering a promising approach for steel bolted T-stub connections.

Analysis of Multistorey RCC Building with Differents Types of Bracing by using STAAD Pro.

The primary objective of this research is to evaluate structural stability using appropriate techniques, including standard configurations and the correct cross-sections for columns and beams. This involves developing preferred requirements for various support conditions, load types, and load combinations. It is noted that many buildings in India have been damaged or demolished by earthquakes, resulting in the loss of precious lives. The ability of structures to withstand major earthquakes is significantly improved by understanding how buildings respond to seismic activity and leveraging the expertise of engineers. This study examines the effects of different bracing systems (X- bracing bracing, inverted v bracing, k bracing) on the seismic performance of a building located in seismic Zone IV in India using STAAD Pro software. The analysis reveals that all bracing systems significantly control the lateral displacement of the frame. Designing an earthquake-resistant structure presents numerous challenges, especially in earthquake-prone areas. This research highlights the critical role of bracing systems in improving the seismic resilience of high-rise buildings in India.

Design of Earthquake Resistant structure based on Shinbashira Concept

Design of Earthquake Resistant structure based on Shinbashira Concept

Seismic response of combined piled raft foundation using advanced liquefaction model

The design of earthquake resistant structures founded on combined piled raft foundation (CPRF) mainly depends on raft-pile-soil interaction (RPSI). This interaction become more complex for these heavy structures, if founded on the liquefiable soil. The CPRF is considered to be useful foundation in practice to support such heavy structure; in which both raft and pile increase the bearing capacity of the soil. Where raft reduces the liquefaction induced settlement and piles help to transfer the load of the structure to the non-liquefiable soil layer. The aim of this paper is to carry out the 3D nonlinear finite difference analysis of CPRF considering the RPSI. A recently developed constitutive model i.e. CycLiq for the liquefaction modelling of the soil is utilized to represent the behaviour of sand in inelastic range which consider the cyclic behaviour and large post-liquefaction shear deformation of sand. The validation of the model is carried out with the centrifuge data. The effect of CPRF over the raft and pile group is carried out for harmonic excitation with varying frequency and earthquake motion with varying PGA. The study provides important observations and insights that were not previously evident. The findings emphasize the need to consider frequency effects, geometrical nonlinearity, and material nonlinearity in the design of NPP structures. Additionally, the study introduces the application of the CycLiq liquefaction model and the development of a user-defined material for FLAC3D. Further, the outcome shows the useful conclusion on the importance of CPRF foundation over the conventional foundation i.e. raft and pile group in the liquefiable soil. It is found that excitation frequency, ground motion PGA, porosity of sand and pile spacing of CPRF have great effects on the response.

Analysis of Base Shear and Story Drift in the Low-Rise RC Sructure

<p class="Abstract">Earthquakes frequently occur in Indonesia because it is an earthquake-prone area. Due to lateral load from an earthquake can cause a weakly constructed building to collapse. Designers often only consider tall buildings in designing earthquake-resistant building structures but ignore earthquake-resistant designing for low-rise buildings. This study focuses on the analysis of earthquake resistant structures with a case study of low-rise buildings in the form of a 3-story reinforced concrete (RC) building in the South Jakarta area. The objective of the study is to analyze the base shear and story drift of the structure due to lateral or earthquake loads. The structure is a reinforced concrete with the concrete compressive strength of <em> </em>= 30 MPa and longitudinal reinforcement of = 420 MPa and stirrups of = 280 MPa. This study uses equivalent static analysis manually and using ETABS 20.1.0 application. The results showed that three story buildings analyzed using equivalent static analysis method and using ETABS 20.1.0 application had almost the same results on horizontal forces with manual result of 1680.97 kN and ETABS of 1648.46 kN. The elastic story deflection and inelastic story drift in this study are still within safe limits because it is below the drift limit.</p>

A study of the relevance of seismic steel structures to urban carbon neutrality

Global warming has triggered dramatic climate change and natural disasters. Since the 21st century, the frequency of all kinds of extreme weather has increased significantly. This study, in accordance with the carbon peak targets and stage requirements, improve the building low carbon building standards system, accelerate the formulation, revision and collation of energy-saving design standards for public buildings energy-saving and carbon reduction standards. The application of earthquake-resistant steel structure of the building, the promotion of green low carbon building materials and green construction methods. Actively promote such buildings, the past sixty years each country's carbon emissions intensity have shown a general downward trend, especially South Korea, South Africa and Brazil and other countries due to economic development began to focus attention on environmental issues. In this study, we take Busan, Korea as an example, and use carbon neutral calculations to realize carbon neutrality by designing superstructures with a reduced degree of intensity, so that the reduction of carbon emissions mainly includes emission reductions brought about by a reduction in the amount of steel and cement used. It is hoped that this study will be taken into account, and that the early realization of peak carbon emissions in South Korea will be the current situation to be realized, and will be a challenge not only for developing countries, but also an important issue to be considered by all countries.

Methods of Assessing the Damage Capacity of Input Seismic Motions for Underground Structures

This paper investigates a method for improving the selection of seismic motions for designing earthquake-resistant underground structures. It is found that PGV alone is unreliable as a predictor of structural damage with increasing earthquake intensity. Therefore, based on characterizing seismic intensity by using PGV, another parameter, referred to here as “the severest parameter”, is introduced to distinguish potential damage capacity for different seismic motions. A numerical model of a soil–underground structure system was established using the finite element software OpenSees. A total of 120 real ground motions were selected for the model, considering the influences of eight different site groups on the underground station and the rupture distances of the input seismic motions. The results show that as seismic intensity increases, substantial variability in the response of underground structures emerges under the same amplitude of PGV, diminishing the effectiveness of the relationship between PGV and structural damage. When assessing the potential damage capacity of seismic motions with similar or close amplitudes of PGV, VSI is an appropriate severest parameter for Class III sites and ASI is suitable for Class II sites. When the correlation coefficient between the severest parameter and the structural response is greater than 0.8, it can be used to reliably assess seismic damage capacity based on the size of the severest parameter.

Experimental investigation on the effect of hoop spacing and crosstie configuration on the cyclic performance of reinforced concrete beams

According to ACI 318-19(SI), in the plastic hinge zone of RC beams, the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties. However, in RC construction practice, the longitudinal reinforcement of RC beams is densely arranged, making construction difficult. In this study, four large RC beam specimens were designed and fabricated to conduct experiments to verify the effect of hoop spacing and crosstie configuration on the cyclic performance of reinforced concrete beams. It is found that: (1) The crosstie configuration with seismic hook engaging the longitudinal reinforcement at the bottom is recommended and that during construction, within the range of twice the beam depth from the RC column outer face, the bottom and side formwork should be completed after the crossties are assembled, which should solve the problem of difficult construction. (2) The transverse reinforcement spacing between 4 and 6 times the smallest longitudinal reinforcement diameter of RC beams may have no significant effect on the cyclic performance of RC beams. (3) The requirement that in the plastic hinge zone of RC beams, every corner and alternate longitudinal bar on the perimeter must have lateral support provided by the corner of a tie or crosstie in ACI 318-19(SI) may not have a major impact on the cyclic performance of the RC beam. (4) The ultimate drift angle of each specimen in the negative direction was between 4.3% rad and 4.5% rad; thus, all the specimens satisfied the ACI requirement. However, the cyclic performance (plasticity rotation angle) of all specimens basically did not meet the requirement of 3.0% rad for earthquake-resistant structures.

WITHDRAWAL – Administrative Duplicate Publication: Seismic Architecture: The Architecture of Earthquake Resistant Structures

WITHDRAWAL – Administrative Duplicate Publication: Seismic Architecture: The Architecture of Earthquake Resistant Structures

WITHDRAWAL – Administrative Duplicate Publication: Seismic Architecture: The Architecture of Earthquake Resistant Structures

WITHDRAWAL – Administrative Duplicate Publication: Seismic Architecture: The Architecture of Earthquake Resistant Structures

Multi-objective optimization of energy-dissipating steel plate fuse links using response surface method

Steel plates with openings are used to provide energy dissipation in earthquake-resistant structures. Shear-acting steel plates with butterfly-shaped or straight links are particularly used as easily replaceable fuses in low-damage design of structures. Sensitivity analyses have shown that the cyclic response of steel plate fuses varies depending on the shape of the fuse link. However, simultaneous response optimization approaches have not been applied in the past research on steel plate fuses. A multiple-response optimization study is needed to find optimal link shapes with improved cyclic response characteristics while simultaneously considering different optimization objectives. In this study, experimentally validated finite element simulations and response surface methodology are used to predict the cyclic load-displacement response of steel plate fuses. The behavior of steel plate shear links is evaluated in terms of initial stiffness, yield strength, ultimate stiffness, effective damping, peak strength, and ductility. Predictive equations are derived and verified for each response characteristic in terms of three influential factors, including the length to end-width ratio (L/b), end-width to thickness ratio (b/t), and mid-width to end-width ratio (a/b) of shear links. The predictive equations are then employed to perform multi-objective optimization studies using a desirability approach. Four different optimization objectives are considered, such as the maximization of effective damping and ductility. Optimal ranges are determined for each factor. The results show that the energy dissipation, strength, and ductility of the fuse can be simultaneously maximized if using relatively thick and moderately long links (with b/t smaller than 6.6, L/b between 2.7 and 6, and a/b between 0.33 and 0.96). Optimal fuses links are those with an intermediate a/b between 0.37 and 0.89 and a small to moderate b/t between 3.0 and 6.6.

Strength and Deformability of Structural Steel for Use in Construction

The purpose of the study is an experimental determination of the stress-related characteristics of the structural steel produced in the Republic of Kazakhstan for use in conventional and earthquake-resistive construction. Since 2015, the construction industry has been using European regulatory documents—Eurocodes—as a statutory framework. In particular, the Eurocode 1993 for steel structures and the Eurocode 1998 for the design of earthquake-resistant structures However, the study of stress-related properties of structural steel using experimental methods of ISO standards has not been performed. Therefore, in the construction industry of the Republic of Kazakhstan, steel-work structures have been used in fairly limited volume since 2015. The experimental studies were conducted on 7 types of structural steel with thicknesses of 8, 10, and 20 mm manufactured by Arcelor Mittal. The yield strength, ultimate tensile strength (breaking stress), and tensile strength at break were studied. The experimental studies were carried out on the basis of ISO standards. In each test run, 5 samples were used. In two series, 20 samples each were tested, which made it possible to estimate the yield strength and strength distribution functions. The correlation relationships between Brinell hardness and yield and strength limits have been studied. As a result of experimental studies, it was found that the strength and deformability parameters fully comply with the requirements of Eurocode 1993. Based on the application of the Student's test, it is revealed that the distribution functions of yield strength and resistance correspond to the normal law (Gaussian function). The calculation of a three-story, two-span residential building with box section columns for construction in an area with a seismicity of 8 points is performed by the finite element method. The work results will significantly increase the scope of Kazakhstani structural steel use in seismic and conventional areas of the Republic of Kazakhstan. Doi: 10.28991/CEJ-2024-010-03-09 Full Text: PDF

Seismic Isolation Materials for Bored Rock Tunnels: A Parametric Analysis

Most recent tunnel designs rely on more thorough analyses of the intricate rock interactions. The three principal techniques for excavating rock tunneling are drill-and-blast for complete or partial cross-sections, TBM only for circular cross-sections with full faces, and road header for small portions. Tunnel-boring machines (TBM) are being utilized to excavate an increasing number of tunnels. Newer studies have demonstrated that subterranean structures such as tunnels produce a variety of consequences during and after ground shaking, challenging the long-held belief that they are among the most earthquake-resistant structures. Consequently, engineering assessment has become crucial for these unique structures from both the geotechnical and structural engineering standpoints. The designer should evaluate the underground structure’s safety to ensure it can sustain various applied loads, considering both seismic loads and temporary and permanent static loads. This paper investigates how adding elastic, soft material between a circular tunnel and the surrounding rock affects seismic response. To conduct the study, Midas/GTS-NX was used to model the TBM tunnel and the nearby rock using the finite element (F.E.) method to simulate the soil–tunnel interactions. A time–history analysis of the El Centro (1940) earthquake was used to calculated the stresses accumulated in the tunnels during seismic episodes. Peak ground accelerations of 0.10–0.30 g, relative to the tunnel axis, were used for excitation. The analysis utilized a time step of 0.02 s, and the duration of the seismic event was set at 10 s. Numerical models were developed to represent tunnels passing through rock, with the traditional grout pea gravel vs. isolation layer. A parametric study determined how isolation material characteristics like shear modulus, Poisson’s ratio, and unit weight affect tunnel-induced stresses. In the meantime, this paper details the effects of various seismic isolation materials, such as geofoam, foam concrete, and silicon-based isolation material, to improve protection against seismic shaking. The analysis’s findings are discussed, and how seismic isolation affects these important structures’ performance and safety requirements is explained.

Seismic design of reinforced concrete buildings equipped with viscous dampers using simplified performance-based approach

Passive control systems, such as Fluid Viscous Dampers (FVDs), have gained significant consideration in the design of earthquake-resistant structures. However, simple analysis and design methods are scarce for more practical and feasible implementation. This study provides a simplified procedure for performance-based seismic design of Reinforced Concrete (RC) special moment resisting frame using nonlinear FVDs. It adopts an extended performance-based design approach, focusing on maximum displacement along with floor acceleration to control the overall behavior of the structure. The fundamental principle of the method is to achieve the fully stressed (effect of FVDs on response indices) design approach to place dampers, which is attained by placing dampers among the storeys where drifts exceed the pre-decided performance limits. Further, a uniform damage distribution concept is followed to maximize the dampers' capacity. This study examines a rectangular-shaped RC SMRF with dampers to get the required performance when subjected to design basis and maximum considered earthquake levels. To check the efficacy, the proposed method is contrasted with a practical design method and a standard placement method employed in previous studies for RC structures with dampers. The analysis shows that the structure meets the performance targets of the design basis and the maximum considered level of earthquake hazards using the proposed step-by-step procedure. The comparison with the other two methods confirmed that the structure with dampers improved seismic behavior with the suggested process. Structural engineers can refer to the proposed method for the design of RC buildings with FVDs.

OpenSeismoMatlab: New Features, Verification and Charting Future Endeavors

To facilitate the precise design of earthquake-resistant structures, it is imperative to accurately evaluate the impact of seismic events on these constructions and predict their responses. OpenSeismoMatlab, a robust, free ground motion data processing software, plays a pivotal role in this endeavor. It empowers users to compute a wide array of outcomes using input acceleration time histories, encompassing time histories themselves, as well as linear and nonlinear spectra. These capabilities are instrumental in supporting structural design initiatives. This study provides a comprehensive exposition of the latest version (v 5.05) of OpenSeismoMatlab. It delves into intricate facets of the software, encompassing a detailed exploration of the input and output variables integral to each operational category. Comprehensive calculation flowcharts are presented to elucidate the software’s organizational structure and operational sequences. Furthermore, a meticulous verification assessment is conducted to validate OpenSeismoMatlab’s performance. This verification entails a rigorous examination of specific cases drawn from existing literature, wherein the software’s outcomes are rigorously compared against corresponding results from prior studies. The examination not only underscores the reliability of OpenSeismoMatlab but also emphasizes its ability to generate outcomes that closely align with findings documented in the established body of literature. Concluding the study, the paper outlines potential directions for future research, shedding light on avenues where further development and exploration can enhance the utility and scope of OpenSeismoMatlab in advancing seismic engineering and structural design practices.