Evaluation Of Seismic Response Research Articles

Influence of the vertical seismic component on the response of continuous RC bridges

This paper investigates the influence of vertical seismic accelerations on the seismic response of RC bridges through numerical simulations using an enhanced non-linear numerical model. Results confirm that the incorporation of vertical accelerations, either through actual records or scaled horizontal records, can considerably modify the seismic response and the collapse mechanism. In the case of actual vertical records, the vertical component significantly contributes to premature structural deterioration, intensifying demand and accelerating failure mechanisms. On the other hand, the study underscores the inadequacy of using scaled horizontal records to represent vertical accelerations, as suggested by some seismic codes, as it not only distorts seismic response evaluation but also alters failure modes. The analysis of vertical vibration reveals higher displacements, increasing flexural demand on the deck, and leading to a progressive loss of vertical support at the central column. The research establishes the need to accurately account for vertical seismic accelerations in bridge design evaluations, as their impact on structural response and failure mechanisms cannot be underestimated. The work highlights the importance of a highly detailed 3D numerical model in assessing traditional parameters and capturing complex collapse mechanisms arising from material and geometric nonlinearities.

Comparative analysis of seismic response and vulnerability of laminated bamboo frame structure under near-field and far-field earthquake actions

The study offers an evaluation of seismic response and vulnerability for a five-story laminated bamboo frame structure, assessing the effectiveness of seismic intensity measures across various damage thresholds and the modeling uncertainties involved. A structural finite element model was developed in OpenSees software, utilizing the Pinching4 model to accurately represent the non-linear characteristics of T-shaped steel connections in beam-column joints. Two collections of earthquake records, one consisting of pulse-like near-field and the other of far-field events, were utilized to examine the structure's nonlinear behavior. Additionally, vulnerability curves for various damage states were generated using the multiple stripe analysis technique, applied to both ground motion datasets. The applicability of 24 seismic intensity measures was also analyzed across various damage limit states. The modeling uncertainty under different seismic actions was further estimated using a first-order second-moment method. Ultimately, the annual collapse probability of the structure are elucidated. Research indicates that due to the influence of joint stiffness, the overall structure demonstrates dynamic characteristics that are predominantly of the first mode shape. The spectral acceleration associated with the fundamental period achieves a reduced logarithmic standard deviation in the vulnerability analysis across various limit states. Other IMs considering higher mode effects or softening period actions no longer predominate. In most cases, the modeling uncertainty under far-field seismic action is higher than that under near-field, especially at the severe damage limit states by using an efficient intensity measure. The laminated bamboo frame structure faces a much higher collapse risk in near-field than in far-field conditions.

Cyclic pushover analysis for seismic response evaluation of a full-scale 10-story steel building tested on the E-Defense shake-table

In February 2023, shaking table tests on a full-scale 10-story steel building was conducted at the E-Defense facility to advance seismic structural techniques and validate numerical analysis models. This study presents a reliable and straightforward structural analysis method, cyclic pushover analysis (CPA), coupled with a simplified numerical simulation approach to capture global and local nonlinear seismic responses of the E-Defense 10-story test structure. CPA applies a cyclic displacement protocol with an appropriate lateral load distribution to a representative height of the structure, providing cyclic hysteresis curves and accounting for cumulative damage, unlike conventional pushover analysis. This results in a more precise evaluation of the structure's stiffness, strength, and displacement demands. The CPA and nonlinear modeling methods were verified using experimental data to ensure accurate system-level predictions. The numerical model of the test structure was built in OpenSees, integrating nonlinear rotational spring models capable of addressing stiffness/strength degradation of structural members and composite slab effects. The CPA displacement protocol was implemented based on the test records on the building roof. Three methods for calculating lateral force distributions in CPA were compared against experimental results. The outcomes indicate that the proposed CPA can accurately reproduce the same global and local responses observed during large ground motions. Additionally, the effect of individual structural components on the 10-story specimen and the damage mechanisms of the system are evaluated in detail based on the models with and without considering the slab effects.

Amplitude and duration hazard-consistent ground-motion selection for seismic risk assessment in Mexico City

The emphasis of seismic design regulations on applying nonlinear dynamic analyses (NDAs) promotes using accelerograms that characterize site-specific ground motions. Commonly, amplitude levels of such accelerograms are defined by a target spectrum that could be based on a uniform hazard spectrum (UHS), which is determined by a probabilistic seismic hazard analysis (PSHA) and represents a response spectrum with ordinates having an equal probability of being exceeded within a given return period, Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document}. Conversely, the definition of ground-motion duration levels is not yet properly defined in current regulations to select accelerograms. Thus, adhering to data handling as that for amplitude ground-motion parameters, this study motivates executing PSHAs to define hazard-consistent levels for the ground-motion duration. That is, accelerograms can be selected to match both amplitude and duration ground-motion levels associated with Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document}. Further, fragility functions conditional on Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document} that cover typical performance objectives can be developed using sets of hazard-consistent accelerograms to implement, e.g., multiple stripe analyses (MSAs). To demonstrate the importance of choosing fully hazard-consistent accelerograms to perform NDAs, this study includes the displacement- and energy-based seismic-response evaluation of a steel frame building located at different soil-profile sites in Mexico City. Sets of fully hazard-consistent accelerograms and solely amplitude-based hazard-consistent accelerograms were artificially generated per site for values of Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document} up to 5000 years. Results indicate that the probability of failure can be underestimated if the ground-motion duration is unvaried in MSAs, e.g., structural damage caused by 50-year return-period or higher events can be more noticeable when fully hazard-consistent accelerograms take place.

The Seismic Response Evaluation of an Existing Multi-span Reinforced Concrete Highway Bridge in the Presence of Linear and Nonlinear Viscous Dampers

AbstractIt’s crucial to keep bridges safe and operational all the time. Before or after an earthquake, they may require immediate seismic retrofitting. In this situation, adopting both isolation systems and viscous dampers could be used as a solution. Therefore, the seismic performance of a RC bridge with linear and nonlinear viscous dampers at both pier tops and abutments is investigated. The selected bridge model is the Incesu Bridge in Artvin province in north–eastern Turkiye. In the bridge model, elastomer bearings (EBs) and viscous dampers (VDs) are added to the abutments and the tops of the piers (i.e., the bridge deck connection points). The results revealed that the maximum bending moment of two piers could be significantly reduced compared with the case where the pier’s tops are fixed to its deck. However, a large level of a viscous damper coefficient added to a bridge could cause structural damage to its deck under a strong design earthquake.

Evaluation of the Nonlinear Seismic Responses of High-Rise Reinforced Concrete Buildings with Different Foundations and Structural Plans—Considering Soil-Structure Interactions

Evaluation of the Nonlinear Seismic Responses of High-Rise Reinforced Concrete Buildings with Different Foundations and Structural Plans—Considering Soil-Structure Interactions

Evaluation of Seismic Response on Small-Scale Reinforced Concrete Frame Using Small-Scale Low-Cost Equipment’s

Evaluation of Seismic Response on Small-Scale Reinforced Concrete Frame Using Small-Scale Low-Cost Equipment’s

Numerical evaluation of seismic response of corroded bridges

Traditional seismic analyses of concrete bridges mainly focus on new bridges, ignoring the effect of durability on the performance, which causes limitations. Research on the seismic performance of corroded bridge piers considering the modal period of the piers is of utmost importance. The corrosion process of steel bars under chloride-ion erosion is simulated based on Faraday’s law, and the time-varying law of the performance degradation of reinforced concrete materials is calculated. Subsequently, a finite-element model of the bridge structure is established using the OpenSees platform. Two seismic waves are selected to analyze the time history within the established finite element model. Considering the influence of the pier modal period, the seismic capacity, and dynamic characteristics of a bridge exposed to a chloride-ion environment are evaluated. This study serves as a robust source of technical support for the comprehensive study of vulnerability analysis, encompassing the assessment of the risks associated with chloride-ion-induced corrosion degradation and seismic hazards.

Comparative Analysis and Evaluation of Seismic Response in Structures: Perspectives from Non-Linear Dynamic Analysis to Pushover Analysis

This study presents a detailed comparative analysis of different methods for evaluating seismic response in structures, focusing on maximum displacements and collapse assessment. The results obtained through modal spectral analysis, non-linear dynamic analysis, and the incremental pushover analysis applied to a specific structure are compared. It has been found that the choice of time step and the consideration of ductility are critical for obtaining accurate predictions. The results of the non-linear dynamic analysis of the building’s response indicate that an earthquake equivalent to the one that affected the city of Lorca (southeast Iberian Peninsula) in 2011 would have a devastating impact on the studied structure, highlighting the importance of the finite element method modelling in predicting the formation of plastic hinges and assessing structural safety. These findings highlight the importance of utilising multiple analysis approaches and detailed modelling to fully understand the seismic behaviour of structures and ensure adequate resistance and stability to extreme events.

Shaking table tests of power distribution cabinets: Physical damage, post-earthquake functionality and seismic response evaluation

Power distribution cabinets (PDCs) are widely used in several critical facilities to ensure the power supply and distribution. Although these cabinets may suffer seismic damage during earthquakes, and result in cascading functionality, economic and life losses, they have received little attention in terms of seismic performance. Therefore, there is an increasing need to understand the performance of such equipment during earthquakes. This study conducted shaking table tests on three PDCs to investigate the seismic performance and dynamic responses. Both physical damage and post-earthquake functionality evaluation were conducted during shaking table tests. The seismic responses of tested cabinets including natural frequency, stress, acceleration, and deformation responses were presented in detail. Seismic qualification levels of tested cabinets based on existing rules were also introduced. This paper not only enlarges the experimental database of the seismic performance of PDCs, but also provides basic data and rules for performance-based seismic evaluation of such nonstructural components.

Reconstruction of a subsoil model for local seismic response evaluation through experimental and numerical methods: The case of the Wellington CBD, New Zealand

Defining a reliable subsoil model is one of the most crucial points in the evaluation of the local seismic response, especially when the study area presents a complex geological setting. Performing a large number of investigations during and subsequently a seismic crisis (following a strong earthquake) is useful for collecting valuable data. By applying a multidisciplinary approach, these data can be used for constraining and test the model, as well as for directly evaluating the effects of strong earthquakes on the environment and the distribution of structural damages in heavily populated areas. In the present study, through a new multidisciplinary experimental–numerical approach, we investigated the role of local site conditions on the damage observed in the Central Business District (CBD) of Wellington (New Zealand) after the 2016 M7.8 Kaikōura event.Numerical 1D/2D site response analyses were carried out to explore the hypothesis of damage exacerbation due to basin effects. Our numerical models were then validated by comparing the corresponding numerical amplification functions with those derived from the application of the standard spectral ratio technique to a large accelerogram dataset. This dataset was obtained by GeoNet stations deployed in the study area, including those operative during the 2016 M7.8 Kaikōura event. Differences in ground motion for near- and far-field events were highlighted.Our results show that the site response in the Wellington CBD was controlled by complex 2D/3D valley effects (mainly edge effects), which were related to the local buried geomorphology. Overall, these findings suggest that the type and location of an earthquake influence the maximum distance at which 2D effects (generated at the basin edge) are still detectable. Comparing our dataset with those from other published studies would be useful for clarifying the factors leading to an exacerbation of the seismic response in alluvial basins. This study has also possible implications for seismic hazard mitigation in cities built on such basins. We conclude that robust numerical 2D models can provide and capture notable characteristics of the ground motion associated with basin effects. These characteristics are fundamental for understanding basin effects and should be considered when formulating building regulations.

Energy-based evaluation of seismic liquefaction response of sand in level and sloping ground

Energy-based evaluation of seismic liquefaction response of sand in level and sloping ground

Evaluation of seismic response of server cabinets through shaking table tests

Telecommunication system is one of the critical lifeline systems for national life and post-earthquake emergency response. Telecommunication equipment is the necessary components to preserve communication functionality of telecommunication system. The severe damage and functionality loss of data center buildings resulting from damage to telecommunication equipment are frequently reported following earthquakes. Thus, there is an increasing need to understand the performance of telecommunication equipment during earthquakes.Seismic investigation of three server cabinets in internet data center buildings are presented in this study. The seismic damage and dynamic characteristics of server cabinets were evaluated and explained in terms of the natural frequency, stress, acceleration, dynamic amplification factor, and deformation by triaxial shaking table tests. The input acceleration time histories were generated based on the required response spectra in YD 5083 code and AC 156 code, with seismic intensities ranging from 0.1 g to 1.2 g. Based on the test results, the effects of different mass distributions inside the cabinets and earthquake inputs were investigated. The seismic damage limit states of server cabinets were identified based on observed damage phenomenon. The corresponding seismic fragility models of server cabinets were developed based on shaking table test data. The results show that the Power Distribution Units inside the cabinets still worked normally and the output voltage was normal for all loading cases although the frame of cabinets suffered severe seismic damage. The normal functionality of server cabinets including more electronic devices and equipment should be carefully checked by shaking table tests.

Evaluation of seismic responses from well-associated gas producing sands using integrated approaches for optimal field production in Zamzama gas field, Pakistan

The producing fields often observe early decline due to many misapprehended factors concerning structural interpretation, facies identification, and proper estimation of geological properties. The accuracy of the estimation of these characteristics is critical for enhanced recovery. An integrated approach based on well identified potential lithofacies distribution in relation to seismic trace responses and accurate fluid estimation is vital. In the present study, gas-bearing sands are appraised for their reservoir characteristics within a complex anticline structure. The faulted anticline's hanging wall provided suitable locations for optimum gas entrapment; however, its connection with the footwall through lateral ramps allows the aquifer's early encroachment into the reservoir. For enhanced recovery, the combination of well-derived petrophysical parameters with seismic extracted responses provided insight into the producing facies with quantitative fluids identification using fluid replacement modeling (FRM) and their amplitude variation with offset (AVO) responses. The reliable AVO responses of substituted fluids comprising 85% gas with 15% brine are observed for identified potential sands, classifying sands as class-II. Similarly, the intercept (A), gradient (B), and product (A*B) of angle dependent seismic traces were mapped within the Pab Formation and showed amplitude anomalies for porous channelized gas-bearing sands. Finally, crossplotting intercept-gradient volumes differentiated the gas-bearing sands and precisely demarcated the identified gas sands throughout the field, with confirmation at producing well locations. Hence, the integrated assessment of the outcomes resulting from structural interpretation, petrophysical evaluation, and seismic trace valuation can be readily employed for distinguishing the producing sand facies in complex structures and demarcating risk-efficient zones.

Seismic isolated bridge performance evaluation and design proposal using artificial neural network

AbstractSeismic isolators such as rubber bearings and other dampers are critical components of seismic design. The hysteresis behavior of such bearings is complicated, and engineers are using a bilinear model or equivalent linearization method in design practice. The response evaluation and initial design parameter assumptions are highly dependent on engineers' expertise and need repeated analysis. Therefore, this study proposed a machine learning‐based approach to conduct bridge seismic isolation performance evaluation and design parameters proposal without repeating the nonlinear simulations. The training data were generated by conducting a nonlinear time history analysis of the bridge structure model with input design earthquakes. Four trained three‐layer neural network models could perform bridge seismic response evaluation, predict the structure's seismic response, and suggest design proposal using some input parameters.

Identification of Torsionally Stiff and Flexible Asymmetric Systems, and Their Comparative Seismic Response Evaluation for Low-Rise Frames

ABSTRACT Torsional status indicators of asymmetrical plan systems are evaluated. The ratio of two modal participation factors in a translational direction (lower to higher mode) is proved as a more accurate indicator than the ratio of translation and rotation dominant modal periods. Seismic responses of low-rise asymmetric-plan frames are then assessed through linear elastic and nonlinear response analysis of representative systems under bi-axial ground motion pairs. The results revealed that those systems that are initially identified as torsionally stiff exhibit a torsionally stiff nonlinear response, whereas those initially categorized as torsionally balanced or flexible evolve to a stiffer torsional performance.

Seismic Response Evaluation of PSCI Girder Bridges Considering Stiffness Variation in Elastic Bearings

Seismic Response Evaluation of PSCI Girder Bridges Considering Stiffness Variation in Elastic Bearings

Evaluation of soil structure interaction effects on structural performance of historical masonry buildings considering earthquake input models

Consideration of the soil domain is significant in the evaluation of seismic response. Since, the wave propagation, soil amplifications, and deformability of subsoil significantly affect the seismic response of structures. For this reason, the effect of soil-structure interaction and soil condition should be considered in the evaluation of the seismic response of structures. This paper presents a seismic performance evaluation of a historical masonry building considering different soil conditions and earthquake input models. The building investigated in this study dates back to the 1870 s. The seismic performance of the building was evaluated with a new guideline specifically published for the assessment of historical structures. At the end of the analyses, natural frequencies, mode shapes, maximum displacements, and principal stresses were obtained and presented in detail. In terms of drift ratio control, the building showed only limited damage during the applied earthquake record. Also, in general, the requirement for the stresses was satisfied. This means that the building behaved in a linear response. While the natural frequency values decreased from the hard soil condition to the soft soil condition, the drift ratios increased for each earthquake input model. The maximum differences between natural frequencies obtained from massless-soil and massed-soil SSI systems increased from the hard soil to soft soil conditions. It was concluded that the soil models with mass or without mass did not affect the frequencies too much in the hard soil condition, but it was quite effective in medium and soft soil conditions. It was clearly seen that there were differences between the results obtained from earthquake input models based on different soil conditions. In this context, it should be noted that the soil-structure interaction of historical masonry structures sensitive to seismic effects should be considered depending on different earthquake input models. As a matter of fact, it was thought that it is necessary to contribute to the studies available in the literature in this field.

Evaluation of ground motion parameters and seismic response of reinforced concrete buildings from the Mw 6.9, 2011 Sikkim earthquake

The continuous collision of the Eurasian plate and the Indian plate has resulted in several earthquakes in the Himalayan region. The 6.9 Mw 2011 Sikkim earthquake, which caused immense damage to the built environment in Sikkim, was triggered by an intraplate source on the overriding Eurasian plate. Strong ground motions from the earthquake were recorded at stations established by IIT Roorkee as part of the PESMOS program. In this paper, near-field and far-field ground motions from this earthquake were analyzed to evaluate their key characteristics and examine their time-frequency features by employing Fast Fourier Transforms (FFTs) and Continuous Wavelet Transforms (CWTs). A comparison between the ground motion parameters of near-field and far-field seismic waves highlights the distinct characteristics of near-field ground motions. Additionally, the impact of near-field and far-field ground motions on the seismic response of a code-compliant RC building is investigated. The results from the non-linear time history analyses indicate that the roof displacements, drift ratio and strain induced in the frame elements are less than the code-prescribed maximum limits. Further, the demand and capacity levels for the RC frame elements were evaluated to compute the performance ratios. The results indicate that the extensive damage to reinforced concrete buildings in the 2011 Sikkim quake was primarily due to the non-engineered nature of the structures and also due to the non-compliance of the built structures to the seismic design code provisions.

Seismic response and fragility evaluation of circular tunnels in the Himalayan region: Implications for post-seismic performance of transportation infrastructure projects in Jammu and Kashmir

The expanding infrastructural projects together with the prior historical records of significant earthquakes including the deadliest 2005 Kashmir earthquake in the Himalayan region, urge to assess the seismic vulnerability and risk of Jammu and Kashmir. This paper attempts to assess the seismic vulnerability of circular tunnels using the fragility function for various seismic environments. To accomplish this, the seismic performance of tunnels is quantified for each hazard zone with a diverse typology and seismic scenario. Microzonation results aided in defining the four hazard zones based on seismic severity. Zone A, B, C, and D are seismic zones with severe, high, moderate ad low Seismic Hazard Indexing (SHI). Tunnel performance is evaluated for each hazard zone, and empirical correlations for damage indices are defined. For Zone A, the fragility curves presented for minor, moderate, and extensive damage states for both shallow and deep tunnels appear to be extremely catastrophic. For various slippage conditions, the variation of flexibility and racking ratios for tunnels with shallow and deep overburden depths is significant. The proposed fragility curves are used to evaluate the seismic risk of a roadway network that includes A, B, and C routes that pass through Jammu. The risk matrices and probability function revealed that all tunnels on Route A are extremely vulnerable to damage. Extensive portal collapse and tunnel lining failure will render this route inoperable during the post-seismic phase. The developed empirical correlations, fragility curves, and risk matrices will serve as a ready-to-use tool for tunnel design engineers working on any Himalayan infrastructure project.