Seismic Damage Assessment Research Articles

Seismic behavior and damage assessment of mid-rise cold-formed steel-framed buildings with normal and reinforced beam-column joints

Seismic behavior and damage assessment of mid-rise cold-formed steel-framed buildings with normal and reinforced beam-column joints

A new seismic damage assessment method for single-layer steel latticed shells considering multi-modal contribution

In this paper, a new seismic damage assessment method considering multi-modal contribution is proposed to evaluate the seismic damage of single-layer steel latticed shells more accurately and efficiently. In the proposed method, the contribution of each modal damage to the structural overall seismic damage is calculated based on a specially constructed equivalent static system derived in this paper, in which the structural multi-modal damage effects can be considered. Then, the measure technics of the structural seismic damage degree is proposed in this paper according to the equivalent static displacements, and then the recommended damage index equation is derived. Considering different actual engineering requirements, the damage assessment procedures for design and appraisal are given in this paper, respectively. Since the damage assessment process is based on the static analysis results of equivalent model, the proposed method retains the conceptual simplicity and computational attractiveness. For detailed comparative evaluation, several numerical examples carried out on a Kiewitt-6 single-layer latticed shell and a practical engineering structure, named Shanghai International Convention Centre, are conducted in this paper. In numerical examples, the influence of the damage assessment direction on the assessment results, the trend characteristic of damage index curves and its comparison with structural response are all discussed in detail. For practicality, combined with the numerical analysis results, seismic damage grades of single-layer latticed shells and the recommended values of characteristic points are discussed and obtained. Furthermore, seismic damage assessment results generated by the proposed method and the other three methods are compared, which confirms the necessity of considering multi-modal contribution and the satisfying accuracy and applicability provided by the proposed method in single-layer steel latticed shell seismic damage assessment.

Research on the disaster prevention mechanism of mega-sub controlled structural system by vulnerability analysis

The mega-sub controlled structural system (MSCSS) is a new structural system that combines structural response control theory with the construction principle of mega frame structure (MFS), and has significant response control effects. It is of practical significance to study the method which accurately evaluate the seismic vulnerability of structures. In this paper, Multiple Stripes Analysis (MSA) and Incremental Dynamic Analysis (IDA) are used to evaluate the vulnerability of MSCSS structure. The comparison between these two methods certify the accuracy of MSCSS vulnerability evaluation along with the impact of the number of stripes used in MSA method. In addition, through the comparative analysis of structural vulnerability analysis results, it is found that under limit state LS4, the failure probability of MSCSS is 30% lower than that of MFS, and the exceeding probability of megastructure is 50% lower than that of substructure, indicating that MSCSS structure has advanced disaster prevention design concept. Afterward, by introducing the seismic damage index used for regional structural seismic damage assessment into the vulnerability assessment, an intuitive seismic risk assessment method for buildings is anticipated by combining the seismic damage index and the beta distribution function, which can provide a reference for the risk assessment of super high-rise buildings.

Statistical numerical method for determining seismic performance and fragility of shallow-buried underground structure

Currently, research on the underground structures seismic fragility is still in its infancy state. In this study, we carried out numerical simulation on soil-underground structure system (SUSI) by taking the Daikai metro station damaged in the Kobe earthquake as analysis object. Considering input ground motion characteristics, based on incremental dynamic analysis (IDA method), a statistical numerical modeling method was established to classify underground structure seismic damage status and its seismic performance level. The analysis results showed that the input ground motions had a significant effect on the IDA curves. The rationality and randomness of the selected ground motions were important influencing factors to ensure the underground structures seismic fragility curves. In relation to the damage that occurred to the Daikai station in 1995, the peak ground acceleration (PGA) and peak relative lateral displacement (PRLD) of the site were suitable for estimating the seismic performance of the shallow buried structure constructed. Finally, the seismic fragility curves were compared with the existing research results, and a seismic damage assessment was carried out, which verified the effectiveness of the statistical numerical modeling method developed in this study.

An explainable prediction framework for engineering problems: case studies in reinforced concrete members modeling

PurposeEngineering design and operational decisions depend largely on deep understanding of applications that requires assumptions for simplification of the problems in order to find proper solutions. Cutting-edge machine learning algorithms can be used as one of the emerging tools to simplify this process. In this paper, we propose a novel scalable and interpretable machine learning framework to automate this process and fill the current gap.Design/methodology/approachThe essential principles of the proposed pipeline are mainly (1) scalability, (2) interpretibility and (3) robust probabilistic performance across engineering problems. The lack of interpretibility of complex machine learning models prevents their use in various problems including engineering computation assessments. Many consumers of machine learning models would not trust the results if they cannot understand the method. Thus, the SHapley Additive exPlanations (SHAP) approach is employed to interpret the developed machine learning models.FindingsThe proposed framework can be applied to a variety of engineering problems including seismic damage assessment of structures. The performance of the proposed framework is investigated using two case studies of failure identification in reinforcement concrete (RC) columns and shear walls. In addition, the reproducibility, reliability and generalizability of the results were validated and the results of the framework were compared to the benchmark studies. The results of the proposed framework outperformed the benchmark results with high statistical significance.Originality/valueAlthough, the current study reveals that the geometric input features and reinforcement indices are the most important variables in failure modes detection, better model can be achieved with employing more robust strategies to establish proper database to decrease the errors in some of the failure modes identification.

Seismic damage assessment of unanchored nonstructural components taking into account the building response

The paper presents an extended seismic damage assessment of unanchored nonstructural components by means of rigid block analysis. Both (real) ground and floor motions are considered as loading histories, together with accelerogram inputs developed according to the latest protocols for shake table testing of (acceleration-sensitive) nonstructural components (AC156 and FEMA 461). A performance-based methodology is developed for the damage analysis of the components, also taking into account magnification and filtering actions of reinforced concrete buildings. Fragility curves are evaluated, and the influence of the key parameters on the seismic performance of rocking components is characterized. Floor motions are found to be more severe than (strong) ground motions, except for large blocks under moderate to overturning rocking amplitude (considering ground acceleration-based intensity measures). Strong floor motions are significantly more severe than (strong) ground motions, and they are associated with a relatively reduced record-to-record uncertainty. AC156 protocol produces inputs overall compatible with floor motions, whereas FEMA 461 protocol inputs are more severe and fit better strong floor motions. The severity of the record sets is found to be correlated with the frequency content of the loading histories. The study provided new knowledge and technical insights regarding the seismic damage assessment of unanchored (building) components.

Effect of Near-Fault Pulsed Ground Motions on Seismic Response and Seismic Performance to Tunnel Structures

Seismic analysis of tunnels close to or crossing seismogenic faults is a complex problem, which is often neglected at the design stage for the lack of specific codes or guidelines and also because underground structures are considered less vulnerable than that of the corresponding above-ground facilities. Near-fault ground motions are generally assumed to providing more powerful energy to tunnel structures. Therefore, a recently developed velocity pulse equivalent model is proposed to synthesize the artificial near-fault pulsed ground motion for the seismic response behavior of the tunnel structure. A newly proposed nonlinear dynamic time history methodology, the incremental dynamic analysis method, is introduced into the analysis of seismic performance and fragility for tunnel structures. This study takes the Zheduoshan tunnel as a case study to illustrate the effects of velocity pulse on the seismic response behavior and seismic performance. The applicability of different seismic intensity measures is preliminarily discussed, and the vulnerability of the tunnel structure at different characteristic locations is analyzed. Afterward, the seismic vulnerability probabilities of the tunnel structure under the action of the near-fault pulsed ground motions and the far-field ground motions are presented, and then, the failure probabilities of the tunnel structure under the three-level support requirements are obtained. Research results provide an objective assessment of the velocity pulse effects and acts as a reference for the likely seismic damage assessment of tunnel structures.

Metamodel-based state-dependent fragility modeling for Markovian sequential seismic damage assessment

Accurate characterization of seismic damage accumulation is crucial to reliable seismic risk assessment. Emerging research efforts have been devoted to state-dependent fragility modeling considering the impact of sequential earthquake excitations so as to better inform the management of structure and infrastructure assets. However, the current state-dependent fragility models largely rely on simple functional forms conditioned on only a scalar ground motion intensity measure (IM); fragility models are separately developed for different state-transition scenarios, without any joint modeling mechanism to preserve the multivariate nature among the different damage states; and the lack of parameterization further hinders these models from offering pertinent fragility estimates for structural portfolios with uncertain structural parameters. By leveraging advanced ground motion selection and machine learning techniques, this study proposes a novel metamodel-based state-dependent fragility modeling approach that offers superior parameterization and damage classification capability and can be seamlessly integrated into the Markovian sequential seismic damage assessment (SSDA) framework. The proposed fragility modeling approach features a systematic sequential dynamic analysis procedure that leverages efficient experimental design and hazard-consistent ground motion selection to sufficiently cover the feature space, and an artificial neural network (ANN) classification model conditioned on one-hot encoded initial damage states along with other earthquake and structure-related predictors. Based on generic inelastic single-degree-of-freedom (SDOF) systems with varying structural configurations, damage state classification performance of the proposed fragility model is thoroughly evaluated, and its applicability within the Markovian SSDA framework is elaborated and discussed.

Seismic performance and damage evaluation of spiral ribbed thin-walled concrete filled and encased steel tube composite columns

As a new type of composite components, thin-walled concrete-filled steel tubes (CFSTs) have some advantages in terms of economy and processing. After the steel tube wall thins, the local buckling performance decreases and the stiffness decreases, which is not conducive to the structural safety. In this paper, combining the advantages of traditional spiral hoops and a stiffener, a new constraint in the form of a screw stiffener was proposed. On this basis, the composite member of thin-walled CFSTs with spiral ribs was put forward. The horizontal hysteretic test was carried out for the new composite column, and the failure mode, hysteretic characteristics, ductility, and energy dissipation capacity were obtained. The results showed that, compared with the traditional form, the seismic bearing capacity of the new composite column was increased by 11% and the ductility was increased by 45%. The deformation capacity was significantly improved. Based on experimental research, the seismic bearing capacity calculation and seismic damage assessment of the composite column were studied, and the practical calculation and the two-parameter damage assessment method considering the interaction between deformation and energy were proposed, which were in good agreement with the test results. This study can provide a technical basis for its engineering application. The composite column has good seismic performance, durability, and fire resistance, and thus has potential for application in practice.

Fragility curves for seismic damage assessment in regular and irregular MRFs using improved wavelet-based damage index

In the conventional performance‐based earthquake engineering framework, fragility curves are mapped to a function of story drift ratio or spectral acceleration corresponding to the first mode. Based on the fragility curves, the probability of structural healthy status can be estimated. Practically, it is difficult to measure story drift and expensive to develop an automative measuring system. Therefore, this paper strives to develop fragility curves by using wavelet-based refined damage-sensitive feature (rDSF), considering higher mode contributions. These fragility curves can be obtained from absolute acceleration responses recorded at each story of buildings. As irregularities have important and significant effects on behaviour and seismic performance of Moment Resisting Frames (MRFs) especially in the field of structural health monitoring, in the next step, we extend the fragility curves for irregular MRFs. To this end, an efficient and more precise rDSF using Morlet and cmorfb-fc wavelets are extended to map fragility curves. The correlation coefficient between rDSF and maximum story drift ratio is evaluated as a criterion to determine the effects of irregularity. The 6-story steel benchmark MRF was manufactured to consider a stiffness reduction irregularity caused by the deference in story height and ductility of beam-column members. To assemble rDSFs, acceleration responses recorded both from the regular and irregular MRFs were analyzed by using incremental dynamic analysis, subjected to different ground motion sets. Moreover, a system identification method is used to identify the natural frequencies of each MRF. Based on the acquired results, it can be concluded that the MRFs including higher first story and weak columns-strong beams changes with a higher probability of damages lead to damage occurrence at lower seismic intensities and also lower maximum story drift ratios as compared with those of reference MRF. Moreover, the results show that the fragility curves estimated by wavelets-based rDSF, especially by using cmorfb-fc wavelet-based rDSF, due to lower probability of damages (varied between 27% and 81% for different damage states) have more efficiency than the fragility curves derived from Morlet wavelet-based DSF, considering only the first mode, for all the MRFs of interest. Furthermore, global fragility curves lead to a total assessment of the MRFs, while for a more accurate damage diagnosis, the rDSF-base fragility curves computed for each story can be used.

Seismic damage assessment of a historic masonry building under simulated scenario earthquakes: A case study for Arge-Tabriz

Damage prediction of existing buildings against natural events is a challenge for engineers. Although several approaches have been proposed in the bibliography for damage assessment of steel and concrete structures, more studies are required to survey the damage state of masonry buildings.In this research, seismic damage of a historical masonry building, named Arge-Tabriz, has been assessed using region-specified simulated ground motion records. The main goal of the research is to predict the damage levels of Arge-Tabriz monument under probable earthquakes. Potential scenario earthquakes with different magnitudes are simulated to evaluate the seismic damage of the Arge-Tabriz building. For ground motion simulation of the scenario earthquakes, the stochastic finite-fault methodology, which employs a finite-fault approach comprised of point-source models, is used. The building is modeled using macro-modeling approach; and for the masonry material, concrete damaged plasticity constitutive model is utilized. After performing nonlinear dynamic analyses of the model in ABAQUS commercial software, the damage state of the building is assesses through failure area and failure volume methods, Park-Ang damage index, performance limits proposed by FEMA 356, and finally tensile damage variable DAMAGET as ABAQUS output variable. The accuracy of the employed numerical method is verified through comparison of the developed damage patterns with the existing damage patterns of the building. The results disclose that failure area and failure volume indices have the highest accuracy, while the drift limits of FEMA 356 have the lowest precision to predict the damage level of the building. The application of region-specific simulated scenario earthquakes reveals that the building has adequate strength to resist against weak seismic events and it experiences moderate damage, keeping up its whole stability under moderate potential events; while it is susceptible to collapse against severe earthquakes, and therefore, a rehabilitation scheme seems to be essential for preserving this valuable heritage.

Machine Learning-Based Approach for Seismic Damage Prediction Method of Building Structures Considering Soil-Structure Interaction

Conventional seismic performance evaluation methods for building structures with soil–structure interaction effects are inefficient for regional seismic damage assessment as a predisaster management system. Therefore, this study presented the framework to develop an artificial neural network-based model, which can rapidly predict seismic responses with soil–structure interaction effects and determine the seismic performance levels. To train, validate and test the model, 11 input parameters were selected as main parameters, and the seismic responses with the soil–structure interaction were generated using a multistep analysis process proposed in this study. The artificial neural network model generated reliable seismic responses with the soil–structure interaction effects, and it rapidly extended the seismic response database using a simple structure and soil information. This data generation method with high accuracy and speed can be utilized as a regional seismic assessment tool for safe and sustainable structures against natural disasters.

Examining the contribution of near real-time data for rapid seismic loss assessment of structures

This study proposes a probabilistic framework for near real-time seismic damage assessment that exploits heterogeneous sources of information about the seismic input and the structural response to the earthquake. A Bayesian network is built to describe the relationship between the various random variables that play a role in the seismic damage assessment, ranging from those describing the seismic source (magnitude and location) to those describing the structural performance (drifts and accelerations) as well as relevant damage and loss measures. The a priori estimate of the damage, based on information about the seismic source, is updated by performing Bayesian inference using the information from multiple data sources such as free-field seismic stations, global positioning system receivers and structure-mounted accelerometers. A bridge model is considered to illustrate the application of the framework, and the uncertainty reduction stemming from sensor data is demonstrated by comparing prior and posterior statistical distributions. Two measures are used to quantify the added value of information from the observations, based on the concepts of pre-posterior variance and relative entropy reduction. The results shed light on the effectiveness of the various sources of information for the evaluation of the response, damage and losses of the considered bridge and on the benefit of data fusion from all considered sources.

Empirical-based support vector machine method for seismic assessment and simulation of reinforced concrete columns using historical cyclic tests

Support vector machine models are generally considered as “black box” procedures, which sometimes render them unexplainable and prone to over-fitting or under-fitting in absence of sufficient data. In this study, an empirical-based support vector machine (EM-based SVM) method is proposed to model the complicated relationships among the basic characteristics of reinforced concrete columns and their corresponding critical performance metrics on hysteretic curves. Moreover, a database of historical pseudo-static cyclic tests is established for model training and test after rigorous screening of specimens. The developed model is then validated by comparing with the results of common SVM method and semi-empirical formulas, as well as pseudo-static and shake table tests. Finally, its applicability and effectiveness for seismic damage assessment and simulation are explored, which demonstrates its potential value in engineering applications.

Seismic responses and damage assessment of a mid-rise cold-formed steel building under far-fault and near-fault ground motions

The responses and damages of cold-formed steel (CFS) structures under near-fault ground motions are not clear currently, which are important for seismic design of CFS structures. This paper investigates the effects of near-fault ground motions on a 6-story CFS building. Three groups of records were chosen from the same events and different stations. The mean damage index of the first-story wall increases by 6.9∼18.7% and 34.3∼53.4% under the near-fault (no-pulse) and near-fault (pulse-like) records, respectively. The effects of near-fault earthquakes should be considered, and the Park-Ang seismic damage index is more appropriate for the seismic design of CFS buildings.

Seismic damage assessment of masonry buildings in Elazığ and Malatya following the 2020 Elazığ-Sivrice earthquake, Turkey

On January 24 at 8.55p.m, a major earthquake of moment magnitude Mw = 6.8 struck the Sivrice district of Elazig, located in the southwest of the Eastern Anatolia region of Turkey. A total of 7429 buildings were severely damaged or collapsed. Unreinforced masonry buildings still represent a significant part of the residential building stock in rural surroundings of the Eastern Anatolia region. Unfortunately, most of the masonry buildings near to epicenter were found to have collapsed or suffered severe damage. This study provides an evolution of seismological characteristics of the earthquake, including recorded accelerograms and acceleration response spectra. Case studies of damaged masonry buildings and failure or collapse mechanisms are also examined. It is concluded that almost all the damaged buildings had not been designed or constructed in accordance with contemporary Turkish earthquake codes.

Human-machine collaboration framework for structural health monitoring and resiliency

Post-earthquake damage assessment can be significantly expedited when machine learning (ML) algorithms supported by sensing technologies are used. ML has some limitations when it comes to seismic damage assessment. ML tools require data from each class while training but in the case of seismic structural health monitoring, vibration data are usually available from the undamaged structures. In this paper, a framework called the human-machine collaboration (H-MC) is proposed. The H-MC framework combines the ML tools and human (domain) expertise for damage assessment of real instrumented buildings with only data from undamaged cases. It uses novelty detection as the ML tool and structure-specific analytical model to enable rapid damage detection. Subsequently, the framework is applied to detect damage in real instrumented buildings. The results showed that the H-MC algorithm correctly detected the damaged cases. It also labeled all the undamaged events accurately eliminating false positive detection. Furthermore, it is revealed that the resiliency of a building can be improved when the H-MC method is implemented over traditional field inspection. The proposed framework can be a viable tool for rapid post-earthquake damage assessment which is essential for improving community resiliency.

Seismic fragility and damage assessment of reinforced concrete bridge pier under long-duration, near-fault, and far-field ground motions

Observations from recent earthquakes around the world have revealed the destructive nature of near-fault ground motions that cause significant damage to structures. On the other hand, the effect of long-duration motions on seismic demands has attracted a lot of interest over the last decade. This study aims to numerically explore how long-duration (LD) motions and near-fault (NF) ground motions affect the seismic performance of a seismically designed bridge pier and compare the response with short duration far-field (FF) motions. A fiber based nonlinear finite element model of a bridge pier is used for evaluating the damage potential of different types of ground motions. The bridge is assumed to be a major route bridge located in Western Canada and is designed following the performance-based seismic design requirements of the Canadian Highway Bridge Design Code. A set of 20 long-duration motions, 20 spectrally equivalent near-fault and far-field motions are used to study the effect of ground motions on drift and damage measures of the bridge pier. The results indicate that since the current design guidelines consider neither the ground motion duration effect nor the pulse effect of near-fault motions, damage measures for performance-based design should be reviewed to take into account the duration effect as well as the velocity pulse associated with NF motions.

Case Study of a Heavily Damaged Building during the 2016 MW 7.8 Ecuador Earthquake: Directionality Effects in Seismic Actions and Damage Assessment

In this work, the directionality effects during the MW 7.8 earthquake, which occurred in Muisne (Ecuador) on 16 April 2016, were analyzed under two perspectives. The first one deals with the influence of these effects on seismic intensity measures (IMs), while the second refers to the assessment of the expected damage of a specific building located in Manta city, Ecuador, as a function of its azimuthal orientation. The records of strong motion in 21 accelerometric stations were used to analyze directionality in seismic actions. At the closest station to the epicenter (RRup = 20 km), the peak ground acceleration was 1380 cm/s2 (EW component of the APED station). A detailed study of the response spectra ratifies the importance of directionality and confirms the need to consider these effects in seismic hazard studies. Differences between IMs values that consider the directionality and those obtained from the as-recorded accelerograms are significant and they agree with studies carried out in other regions. Concerning the variation of the expected damage with respect to the building orientation, a reinforced concrete building, which was seriously affected by the earthquake, was taken as a case study. For this analysis, the accelerograms recorded at a nearby station and detailed structural documentation were used. The ETABS software was used for the structural analysis. Modal and pushover analyses were performed, obtaining capacity curves and capacity spectra in the two main axes of the building. Two advanced methods for damage assessment were used to obtain fragility and mean damage state curves. The performance points were obtained through the linear equivalent approximation. This allows estimation and analysis of the expected mean damage state and the probability of complete damage as functions of the building orientation. Results show that the actual probability of complete damage is close to 60%. This fact is mainly due to the greater severity of the seismic action in one of the two main axes of the building. The results are in accordance with the damage produced by the earthquake in the building and confirm the need to consider the directionality effects in damage and seismic risk assessments.

Seismic damage assessment of a supertall tubed mega frame structure based on a simplified finite element model

SummaryA tubed mega frame structure is composed of tubes located at the perimeter of the structure as mega columns and mega beams. This paper explores the applicability of this structural system to supertall buildings in high seismic intensity areas. First, a refined finite element (FE) model of a 585‐m tall tubed mega frame structure was built in ABAQUS, as well as a mega‐braced frame‐core structure on which the tubed mega frame structure is based. In order to improve the efficiency of nonlinear analyses, beam‐based simplified FE models of the two structures were developed in OpenSees and validated against the refined FE models. Then, incremental dynamic analyses of the tubed mega frame structure were conducted based on its simplified model. The damage of the tubes was quantified by a modified Park–Ang damage model. The analyses indicate that the seismic damage of the tubes in the tubed mega frame structure develops rapidly after yielding, because tubes at the perimeter of the structure suffer severe axial load under high‐intensity earthquakes. It is suggested that the axial load ratio of the tubed mega columns should be controlled to avoid brittle failure in the seismic design of supertall tubed mega frame structures.