Evaluation Of Seismic Response Research Articles

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.

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.

Seismic response evaluation of spring-based piston braced frames by employing closed-loop dynamic (CLD) testing

This paper employs the Closed-Loop Dynamic (CLD) testing method for evaluating the seismic response of Spring-Based Piston Braced Frames (SBPBF) by utilizing a combination of experimental and numerical approaches. The CLD testing procedure is an iterative process, which is initiated by conducting cyclic tests on a reduced-scale bracing element and followed by computational simulations of a full-scale braced frame. To this end, a hysteresis model is developed, based on testing the Spring-Based Piston Bracing (SBPB) element, which is incorporated into a simulated multi-story SBPBF. The time-dependent deformations of SBPBs under earthquake loadings are scaled down using similitude law, serving as a loading protocol for further testing and refining the hysteresis model. The developed model is then calibrated, scaled up, and integrated into the computational model to generate more precise deformation histories of the SBPB. The refined model is validated through aniterative process that combines experimental and numerical results. An illustrative example is presented to demonstrate the feasibility of the CLD testing method for SBPB archetypes. The efficiency of this approach is demonstrated by the remarkable match between the experimental and computational results. Additionally, a comparative numerical assessment is conducted on braced frames equipped with non-compressed and pre-compressed SBPBs, revealing their superior performance compared to the Buckling-Restrained Braced Frames (BRBFs).

Research on seismic analysis methods of large and complex underground pipe structures in hard rock sites

In order to study the seismic design methods of large and complex underground pipe structures (LCUP) in hard rock sites, firstly, the structural characteristics of LCUP and the calculation principles of four typical seismic analysis methods were carefully sorted out. Secondly, based on different seismic analysis methods, the deformation and internal force response of three representative pipes were studied in detail, and the calculation accuracy and error causes of each seismic analysis method were analyzed. Finally, the advantages, disadvantages and applicability of the seismic analysis methods on typical pipes were systematically explained, and the technical route for seismic design of LCUP was proposed. The results showed that both the reaction displacement method and the reaction acceleration method can effectively analyze the seismic performance of standard section structures. The three-dimensional time-history analysis method was comprehensive and highly accurate for seismic analysis of complex spatial cross-node structures. The rigid connections of different pipes leaded to serious discontinuities in stiffness at the intersection, and the deformation and bending moment distributions were highly concentrated at the height away from the intersection. The influence range of the intersection was about three times the width of the intersection, and LCUP was classified according to this influence range. For standard section structures, seismic analysis should be carried out using the reaction acceleration method or reaction displacement method, while for spatial cross-node structures, three-dimensional time-history analysis should be used for seismic analysis. This scientific seismic design method achieved multiple optimal balances of seismic safety, analysis accuracy, efficiency and economy in the seismic analysis of large and complex underground structures. A theoretical basis and useful reference for the scientific design, accurate prediction and seismic safety evaluation of seismic response of LCUP were provided in this paper.

Evaluation of Seismic Response of Irregular Buildings: A Review

The modern design and construction of buildings have led to the adoption of irregular shapes buildings which can attract large seismic forces and induce stress concentrations in the building itself. To investigate this fact a large number of research studies have been carried out. This study presents a review summary of seismic performance of irregular buildings considering vertical irregularity subjected to earthquake loadings. The seismic performance can be found by using linear and nonlinear time history analysis. Different types of irregular buildings are analyzed to review the seismic performance of the structure. It was found that the buildings with the soft story having variation in the storey stiffness yield large inter-storey drift values showing more damage as compared to types of building irregularities.

Evaluation of Seismic Response of Composite Buildings under Near-Field Earthquakes

This paper represents the effectiveness of the bracing system concerning the seismic performance of steel-concrete composite buildings by comparing 5-storey composite buildings with and without bracings subject to extreme earthquake loads. The nonlinear time history analysis (NTHA) is carried out on the specific building models considered for this study. The seismic response is obtained in terms of different seismic response parameters which are further compared to determine the effect of the bracing system. The results obtained by applying real earthquake records of different near-field & far-field earthquakes were compared for three earthquake response parameters which include base shear, inter-storey drifts, and storey displacements. The bracing system is very effective in resisting the seismic force when subjected to extreme earthquakes as it increases the overall stiffness of the building. The bracing system improves the overall performance of the composite building by reducing the inter-storey drifts and maximum storey displacement under extreme earthquakes.

Seismic response evaluation of waffle slab with and without bracing system using time history analysis

In the analysis and design of structures, seismic ground motion is a significant factor. Seismic criteria consideration is necessary for serviceability and feasibility of existing as well as new structures. Time History analysis is the one in which base is subjected to a specific ground motion and dynamic response of structure is analysed at each increment of time. The bracing system increases the structure’s resistance to lateral loads by transferring load from the frame to the braces. This study uses the ETABS software to do a time history analysis on a G+4 RCC building with a waffle slab and an X-type bracing system. For designing purposes, the IS 456-2000 code is thought about. According to IS 875-part 1, live loads are measured, and IS 1893-2016 earthquake analysis is carried out. For this structure, a number of factors are analysed, including storey drift, base shear, storey stiffness, and storey displacement, among others.

Seismic response and damage evaluation for anchored and unanchored cylindrical above ground steel tanks

This paper aims to first present a review of studies on numerical modeling and seismic response analysis of above ground steel liquid storage tanks. On that basis, a procedure for estimating dynamic parameters associated with simplified models for anchored and unanchored conditions together with calculation methods of seismic responses and damage states of tanks are presented. In which, the nonlinear behavior of the bottom plate in the case of unanchored conditions caused by sliding and uplift phenomena is properly modeled based on the nonlinear static pushover analysis on a 3D finite element model. Finally, an example of the numerical modeling and seismic response analysis of a water tank is presented. The seismic responses and damage of both anchored and unanchored conditions are compared and evaluated in detail.

DYNAMIC PROPERTIES OF SAND FOR EARTHQUAKE RESPONSE ANALYSIS IN THE BAY OF CAMPECHE

The Bay of Campeche is located in a region of moderate to high seismic activity related to the active triple junction between the North American, Caribbean, and Cocos plate boundaries. Therefore, the fixed offshore platforms and subsea structures in the Bay of Campeche must be designed against earthquake loading. A database was developed of classification and index properties tests, in situ measurements of shear wave velocity (Vs) using downhole P-S suspension seismic velocity logging, in situ piezocone penetration tests, resonant column tests to characterize the shear modulus and material damping ratio at small shear strains (10−5 % to about 0.1 %), and strain-controlled cyclic direct simple shear tests to evaluate the decrease of shear modulus and the increase of material damping ratio at large shear strains (0.1 % to about 10 %) performed on sand from the Bay of Campeche, including sands with no carbonate content to 100 % carbonate content, retrieved from the seafloor to a penetration depth of 120 m below seafloor. The database was tailored specifically to develop empirical correlations for the Bay of Campeche sand to determine Vs when in situ measurements of Vs are not available and to develop numerical modeling to predict the variation of the normalized shear modulus (G/Gmax) and material damping ratio (D) as a function of shear strains (g) when dynamic test results are unavailable for all the sand layers. The equations developed to calculate Vs and the curves of G/Gmax-g and D-g of Bay of Campeche sands are recommended for preliminary or perhaps even final seismic site response evaluations.

DYNAMIC PROPERTIES OF CLAY FOR EARTHQUAKE RESPONSE ANALYSIS IN THE BAY OF CAMPECHE

The Bay of Campeche is located in a region of moderate to high seismic activity related to the active triple junction between the North American, Caribbean, and Cocos plate boundaries. Therefore, the fixed offshore platforms and subsea structures in the Bay of Campeche must be designed against earthquake loading. A database was developed of classification and index properties tests, in situ measurements of shear wave velocity using downhole P-S suspension seismic velocity logging, in situ piezocone penetration tests, resonant column tests to characterize the shear modulus and material damping ratio at small shear strains (10−5 % to about 0.1 %), and strain-controlled cyclic direct simple shear tests to evaluate the decrease of shear modulus and the increase of material damping ratio at large shear strains (0.1 % to about 10 %) performed on clays from the Bay of Campeche, including clays with no carbonate content to 100 % carbonate content, retrieved from the seafloor to a penetration depth of 120 m below seafloor. The database was tailored specifically to develop empirical correlations for the Bay of Campeche clay to determine Vs when in situ measurements of Vs are not available and to develop numerical modeling to predict the variation of the normalized shear modulus (G/Gmax) and material damping ratio as a function of shear strains (g) when dynamic test results are unavailable for all the clay layers. The equations developed to calculate Vs and the curves of G/Gmax-g and D-g of Bay of Campeche clays are recommended for preliminary or perhaps even final seismic site response evaluations.