Incremental Dynamic Analysis Curves Research Articles

Seismic Damage Probability Assessment of Existing Reinforced Concrete School Buildings in Afghanistan

Existing Reinforced Concrete School buildings with low earthquake resistance may suffer structural failure or severe damage in a catastrophic seismic event. Ascertaining earthquake resistance in existing school buildings is vital to confirming the safety of students, teachers, and all school members. Reinforced concrete (RC) has been used significantly for numerous years as the primary material due to its easy access and low cost-effectiveness in construction. The current research focused on analyzing the existing RC school buildings designed and constructed in various regions of Afghanistan over the last three decades. Seismic fragility curves, which are generated from incremental dynamic analysis (IDA), have been used to evaluate the damage probability of RC school buildings against earthquake ground motions. In this investigation, 34 RC school buildings were selected from an extensive database and subsequently classified as either A-type or B-type based on specific criteria, including design details and construction year. Following this classification, an assessment of the seismic damage probability for these buildings was conducted using probabilistic models based on IDA curves. The results indicate that A-type school buildings with newer construction are less prone to damage compared to B-type school buildings, showing improved resilience. Especially the B-type buildings in seismic Zone-I are found to be highly vulnerable under the maximum considered earthquake scenarios.

Time-dependent seismic fragility analysis of reinforced concrete columns subjected to chloride-induced corrosion

This paper presents a stochastic methodology to perform time-dependent seismic fragility analysis for reinforced concrete (RC) columns subjected to chloride attacks. Numerical modelling methods considering the increasing variability of reinforcement mechanical properties were proposed based on the stochastic constitutive model for corroded steel bars. Depending on the finite element model validated by test data for uncorroded and corroded RC columns, two novel stochastic cases and a traditional deterministic case were introduced and then applied to pushover analysis, incremental dynamic analysis and seismic fragility analysis. The results of damage limit states (DLSs) determined by stochastic pushover curves indicated that the seismic capacity/DLSs for columns along the service life were time-dependent and followed lognormal distributions. The incremental dynamic analysis curves and seismic fragility curves implied that chloride-induced corrosion typically led to a substantial increase in the failure probability of columns. In comparison with the correlated stochastic method, considerable underestimations of component level fragility across different damage limit states were obtained using the deterministic approach, which highlighted the importance of accounting for the variability of mechanical properties of corroded steel bars in the time-dependent seismic fragility analysis.

Seismic response and capacity of inelastic acceleration‐sensitive nonstructural elements subjected to building floor motions

AbstractThe paper investigates the seismic response of nonstructural elements (NEs), focusing on acceleration‐sensitive components housed in buildings, modelled as inelastic Ibarra–Medina–Krawinkler (SDOF) systems. Incremental dynamic analysis (IDA) is carried out considering (a) representative suites of building floor motions (real loading histories recorded within reinforced concrete (RC) buildings and table testing protocol inputs) and (b) a wide range of NE models (with elastic frequencies ranging within 1–9 Hz). The Ibarra‐Medina‐Krawinkler (IMK) model was implemented in OpenSees, defining the key modeling parameters according to the formulations provided by Lignos and Krawinkler. Both IDA curves and component (acceleration) amplification factor (CAF) are characterized, also considering statistical measures. The seismic capacity of the investigated NEs is estimated through fragility curves, accounting for five incremental damage states (DSs). The fragility parameters are correlated with the frequency of the NE models, and (statistical‐based) closed‐form capacity criteria are provided. The study provides a robust technical and scientific methodological framework for assessing the seismic capacity of NEs that can be modeled by inelastic SDOF systems. The findings have a potential major impact on both research and practice, enriching scientific knowledge and providing useful applicative tools. In particular, quantitative response and capacity measures are supplied, and the developed capacity criteria can be particularly useful for expeditious but reliable design and assessment, as well as for comparison purposes.

Probabilistic Seismic Performance Assessment of Tall RC Special Moment-resisting Frame Buildings Equipped with Buckling-restrained Braces under Near-field Excitations

Many tall buildings have already been constructed near faults throughout the world, several of which have sustained casualties and economic losses during strong ground motions. This study investigates the effect of near-fault excitations on the vulnerability of tall, reinforced concrete (RC) special moment-resisting frame (SMRF) buildings equipped with buckling-restrained braces (BRBs) using seismic fragility curves. After attaining the structure’s response modification factor (R), three-dimensional (3D) models of 15-, 25- and 35-story frames were developed by the OpenSees software according to the Iranian code provisions. Thus, the seismic response of the elements was obtained. Subsequently, incremental dynamic analysis (IDA) was conducted by selecting a suitable number of compatible accelerograms in two near-field and far-field groups. Considering the maximum story drift as the demand parameter and selecting the interstory drift ratios (IDR) for the slight, moderate, extensive, and complete collapse seismic performance levels proposed by Hazus, IDA curves were plotted. Then, the seismic fragility curves were produced using the structural reliability relations. The median fragility at complete collapse damage level reduced from 0.73g, 0.62g, and 0.61g to 0.68g, 0.59, and 0.57g for the 15-, 25, and 35-story near-field and far-field earthquake models, respectively. This was attributed to increasing vulnerability and seismic fragility of the structures as a result of both height increase and distance reduction from fault. Based on the results, the most vulnerable structure, i.e., the 35-story near-fault model, experienced a 40, 17, 18, and 6% increase in median fragility at slight, moderate, extensive, and complete collapse damage levels, respectively.

Multi‐indicator evaluation method of important members of truss string structures

SummaryDuring the past decade, the progressive collapse of structures has received growing attention, and the study of member importance is a key step for investigating the progressive collapse resistance. However, traditional methods for evaluating the member importance usually employ a single indicator, and when multiple indicators are involved, different indicators may generate different member rankings. Moreover, the truss string structure is a multiple super‐stationary structure with many members, and the current studies mainly focus on cable failure, which does not mean that other members are not important. In this study, the initial selection of important members is first performed based on concept evaluation, and then, the alternate path method is used to analyze the progressive collapse resistance of truss string structures; the slope degradation coefficient γ of incremental dynamic analysis curve, load capacity degradation coefficient β, and nested load capacity degradation coefficient β′ are introduced; and the sensitivity coefficient SIj and fragility coefficient VIi are defined with axial force as the structural response. Based on the above five indicators, two cases are conducted to evaluate the member importance. The analysis results show that the cable and the bottom chord member at the support are evaluated as the first‐level important members. Through the analysis of different indicators, it is found that the regularity of the coefficient of each member is inconsistent for different indicators. The results could be one‐sided if the important members were evaluated by a single indicator only. In addition, the second‐level important members of truss string structures are evaluated by multi‐indicator analysis. Finally, the nominal progressive collapse resistance of truss string structures is given based on the importance coefficient of the first‐ and second‐level important members.

An efficient and accurate fragility approach for seismic performance assessment of structures

AbstractIn seismic risk assessment of bridges, developing fragility function is a fundamental step to characterize the structural vulnerability, which is usually derived based on the relationship between the engineering demand parameter (EDP) and intensity measure (IM). The EDP‐IM relationships are generally developed through three approaches, namely Cloud analysis (Cloud), incremental dynamic analysis (IDA), and multiple strip analysis (MSA). It is known that the Cloud method is computationally efficient while the IDA and MSA can provide the accurate fragility estimates. Thus, the present paper proposes an efficient and accurate fragility (EAF) approach which has similar computational demand as Cloud but keeps the same level of accuracy as IDA or MSA. In this proposed EAF procedure, the nonlinear time‐history responses at the intensifying duration of ground motions were used to develop the EDP‐IM curves. And these EDP‐IM curves are accurate enough to replace the IDA curves in developing fragility curves. To illustrate the efficiency and accuracy of the proposed EAF method, two typical bridges (a two‐span single‐frame bridge and a single‐pylon cable‐stayed bridge) were selected and modeled in OpenSees and employed as case studies. By comparing the fragility estimates of these bridges to IDA and MSA, it is demonstrated that the proposed EAF approach leads to reliable fragility results, while has similar computational time as Cloud.

Seismic damage analysis of a brick masonry loess cave by a shaking table and FEM

In this paper, a typical brick masonry loess cave (BMLC) is selected, and finite element analysis software is used to establish a model and analyse its seismic performance. The model was verified by the test results of the BMLC on a 3D shaking table, and the damage quantification index was proposed. On this basis, seismic vulnerability analysis was carried out. A method based on nonlinear incremental dynamic analysis (IDA) was proposed to solve the rapid damage assessment of the traditional building of BMLC structures after earthquake action. The proposed method relies on an accurate numerical finite element model and pre-run multidimensional nonlinear IDA simulations with vibration data recorded during earthquakes. The IDA curves were built with different positions of the BMLC structure being considered. Moreover, meaningful local damage parameters were correlated with relevant seismic intensity measures. The results showed that the proposed method immediately and accurately estimated damage after seismic action if the IDA curve set had been previously constructed using a suitable model.

Evaluation of performance and storey drift ratio limits of high-rise structural systems with separated gravity and lateral load resisting systems using time history analysis and incremental dynamic analysis

To increase the efficiency of prefabricated construction of high-rise structure, a composite structural system with separated gravity and lateral load resisting systems (referred to as a ‘new separable system’) is proposed. Efficient numerical models of the composite frames, reinforced-concrete (RC) shear walls, RC coupling beams, and braces in the new separable system were developed using the finite-element program MSC.Marc. The fragility curves of these components were developed through parametric analysis and a literature review of previous research and database documents. Through time history analysis, the responses of roof displacement, storey drift, and residual drift were analysed and compared with those of the traditional composite frame–shear wall system. An incremental dynamic analysis (IDA) was performed to obtain the IDA curves of the new separable system and the traditional system, and the seismic fragility curves of the two systems were built. The seismic performance of the new separable system was compared with that of the traditional system in terms of the collapse probability, dynamic safety factor, and risk of seismic damage. The results indicated that for high-rise composite structural systems with separated gravity and lateral resisting systems under frequently occurring earthquakes, the reasonable range of the storey drift ratio limit in design is 1/800 to 1/1000, and a limit value of 1/1000 is recommended conservatively.

Artificial Neural Networks for seismic demand prediction of a single degree of freedom

This paper proposes using an artificial neural network (ANN) to estimate and predict the seismic demand of Single Degree of Freedom (SDOF) systems. Our methodology entails the production of a comprehensive dataset containing SDOF and earthquake characteristics. Nonlinear Time History Analysis (NL-THA) is performed on a randomly generated SDOF system using thirty-one artificial ground motions (GMs) matched to the EuroCode-8 (EC8) response spectrum to train the ANN model. To assess the performance of the ANN model, we compare the Incremental Dynamic Analysis (IDA) curves, the median IDA curve, and the 3D fragility surface in a case study. This analysis assists in determining the precision and dependability of the predicted maximum displacement of the SDOF system. The results showed a remarkable reduction in processing time without losing prediction accuracy. . It was concludedthat the ANN-based method can be used as an alternative for the current method for estimating the performance points and the fragility assessment of buildings.

Incremental Dynamic Analysis and Seismic Fragility Analysis of Reinforced Concrete Frame

Abstract Due to technological developments in last decade, new methods of seismic evaluation are in use like simulation based, algorithm based, probabilistic, software based etc. These developments have enabled researchers to move from linear to non-linear methods of analysis. Incremental dynamic analysis (IDA) is performance evaluation method where a suite of ground motions applied to structure are further scaled to particular levels of seismic intensity. Seismic fragility curves become significant in estimation of structures risk possibility from the point of view of potential earthquakes and helps in predicting the economic consequences for forthcoming earthquakes. The paper reflects IDA and seismic fragility analysis of ground storey + 7 floor (G + 7) reinforced concrete frame subjected to suite of eleven ground motions. Primary objective was to perform equivalent static and linear-dynamic analysis to meet the National and International codal requirements. Then, pushover analysis is carried out by introducing parametric auto hinges as per ASCE 41-13 tables. To carry out pushover analysis, both geometric and material non-linearity was introduced. Strong ground motions were selected as per suitable criteria of seismic intensity. IDA is then carried out as per SeismoStruct 2022 software and using IDA curves, the fragility analysis was carried out. The results of study found useful for researchers to predict the probability of damage of the structure under earthquakes.

Probabilistic Analysis of RC Buildings Based on Incremental Dynamic Analysis

Earthquake is a natural disaster that can induce immense damage to properties and human lives. Fragility curve, defined as the probability of reaching or exceeding a specific damage state under an earthquake excitation, provides a prediction of damage that may occur during an earthquake. Incremental Dynamic Analysis Curve (IDA curve) developed from Incremental Dynamic analysis can be considered as the initial step of fragility curve development. The present study summarises the development of IDA curve for a RC building considering maximum roof displacement and storey drift as Damage Measure (DM) and peak ground acceleration as Intensity Measure (IM). The fragility curves developed using incremental dynamic analysis provide an overview of the probability of exceedance of damage limits in an existing building when acted upon by different levels of earthquake excitations and the performance level can be improved by incorporating appropriate design changes.

Inovativna metoda za krivulje inkrementalne dinamičke analize djelomično izoliranih mostova

This paper proposes an innovative method for determining the approximate incremental dynamic analysis curves of semi-isolated bridges, including the derivation of statistical mathematical formulas. Ultimately, an innovative method is devised based on the primary and limit state tangential stiffness values of semi-isolated bridges. The bridges selected for this study are two reinforced concrete highway bridges in the United States, which have been optimally re-designed using lead rubber bearing isolators. The established procedure can be used in future studies to extract the probabilistic responses of semi-isolated bridges via a simplified and efficient method.

Kahramanmaraş—Gaziantep, Türkiye Mw 7.8 Earthquake on 6 February 2023: Strong Ground Motion and Building Response Estimations

The effects on structures of the earthquake with the magnitude of 7.8 on the Richter scale (moment magnitude scale) that took place in Pazarcık, Kahramanmaraş, Türkiye at 04:17 a.m. local time (01:17 UTC) on 6 February 2023, are investigated by processing suitable seismic records using the open-source software OpenSeismoMatlab. The earthquake had a maximum Mercalli intensity of XI (Extreme) and it was followed by a Mw 7.5 earthquake nine hours later, centered 95 km to the north–northeast from the first. Peak and cumulative seismic measures as well as elastic response spectra, constant ductility (or isoductile) response spectra, and incremental dynamic analysis curves were calculated for two representative earthquake records of the main event. Furthermore, the acceleration response spectra of a large set of records were compared to the acceleration design spectrum of the Turkish seismic code. Based on the study, it is concluded that the structures were overloaded far beyond their normal design levels. This, in combination with considerable vertical seismic components, was a contributing factor towards the collapse of many buildings in the region. Modifications of the Turkish seismic code are required so that higher spectral acceleration values can be prescribed, especially in earthquake-prone regions.

Performance of Medium-Rise Buildings with Reinforced Concrete Shear Walls Designed for High Seismic Hazard

This work has evaluated the collapse fragility of a typical Chilean building for residential use, structured based on shear-resistant RC walls and inverted beams arranged along its entire perimeter, using the incremental dynamic analysis (IDA) for the evaluation of its structural behavior, using for this the 2018 version of the SeismoStruct software. This method evaluates the global collapse capacity of the building from the graphical representation of its maximum inelastic response, obtained through a non-linear time-history analysis, against the scaled intensity of a set of seismic records obtained in the subduction zone, thus creating the IDA curves of the building. The processing of the seismic records is included within the applied methodology to make them compatible with the elastic spectrum of the Chilean design, achieving an adequate seismic input in the two main structural directions. In addition, an alternative IDA method based on the elongated period is applied to calculate the seismic intensity. The results of the IDA curve obtained with this procedure and the standard IDA analysis are analyzed and compared. The results show that the method relates very well to the structure's demand and capacity and confirms the non-monotonous behavior exposed by other authors. Regarding the alternative IDA procedure, the results indicate that the method is inadequate, failing to improve the results obtained by the standard method.

Aftershock fragility assessment of steel gabled frames consisting of web-tapered members

Due to the widespread construction of steel gabled frame systems throughout the world, many of them are located in regions with high seismicity and experience sequential strong events in the future. Previous studies have clearly shown that the damage caused by the mainshock modifies the overall strength and stiffness and consequently dynamic response to the aftershock. However, the current structural design process only considers the main seismic event, and the post-mainshock scenarios and their effects are generally ignored. In order to address this issue, in the present study, the mainshock incremental dynamic analysis (IDA) was first conducted on four SGFs. Then mainshock damage states based on the transient absolute maximum drift angle were considered, and aftershock incremental dynamic analysis analysis was performed on the mainshock-damaged structures. Aftershock fragility curves using probabilistic seismic demand models for transient absolute maximum drift angle and median IDA curves for residual absolute maximum drift angle were developed to compare intact and pre-damaged SGFs. The results showed that aftershocks significantly increase the vulnerability of short-period SGFs when higher damages are induced during mainshock, where the aftershock collapse capacity is reduced by up to 13% for the largest mainshock damage state. It was also found that in terms of aftershock collapse capacity associated with the residual absolute maximum drift angle, long-period SGFs require major realignment while short-period SGFs cannot be repaired.

Assessing Seismic Fragility of Low-Rise RC Buildings by means of Incremental Dynamic Analysis (IDA)

The modern era witnessed an urbanization and economic growth concentrated in urban areas. Despite an increase in welfare, this receives a greater threat when an earthquake occurs. This research aims to assess the structural risk of low to medium-rise reinforced concrete building structures, commonly built in developing countries. This research was carried out by performing an incremental dynamic analysis (IDA) od an existing building model. In this analysis, the structural model was given a set of dynamic earthquake loads which were increased in magnitude according to certain scale rules until the structure experienced nonlinear behavior and reached a near collapse condition. Five artificial accelerogram recordings were applied on the structure after matching with the spectral response of the target location of the structure. From the analysis, the IDA curves were obtained which describes the global dynamic behavior of the structure, namely displacement due to earthquake lateral loads. Then the damage limits were determined on the IDA curve based on the HAZUS criteria. Then the seismic risk was expressed by constructing a seismic fragility curve. This curve states the probability of exceeding certain damage limits due to variation in earthquake intensity during the service life of the structure.

Seismic Fragility Assessment of Irregular High Rise Buildings using Incremental Dynamic Analysis

The construction of high rise buildings is common in city areas. These buildings may be irregular because of aesthetics or other requirements. As Nepal lies in a seismically active region these irregular high rise buildings may not perform well during earthquakes. Two existing irregular high rise buildings are taken as case study buildings that had pre-existing torsion. Shear walls are added to the building at the required location to minimize torsion in the buildings. The objective of the study is to determine the performance of building with and without torsional irregularity. The seismic performance of all the buildings is carried out by taking seven pairs of ground motions using nonlinear time history analysis. These ground motions are scaled to the required intensity to develop incremental dynamic analysis (IDA) curve. These IDA curves are used to develop fragility curves to access the performance in the buildings. The result from the analysis showed that performance in one building improved by 35% and in another by 70% at the peak ground acceleration (PGA) of 0.35g.

Performance Evaluation of RC Frame - Wall Structures Using Incremental Dynamic Analysis

A structure whose resistance to lateral loading is provided by a combination of shear walls and rigid frames, may be categorized as a frame-wall structure. The behaviour of RC structures under the effect of earthquake loading has always been a subject of investigation. Structural seismic design has been undergoing a major revaluation in recent time, with importance shifting from strength to performance. Nonlinear Time-History Analysis (NLTHA) constitutes the accurate way for simulating response of structures subjected to seismic excitation. Incremental Dynamic Analysis (IDA), involves performing nonlinear dynamic analysis of the structure under a set of ground motion records, each scaled monotonically to several intensity levels. In the present paper, RC moment resisting frame-wall structure with 18, 22 and 26 storeys are analysed for seismic zone IV, resting on hard soil and designed as per IS code provisions. Geometrical configuration of the buildings are considered as per IS 16700:2017. Analysis and design of frames are carried out using ETABS-2016. The performance evaluation of above frames is done using NLTHA and IDA using SeismoStruct software for set of 11 recorded ground motions of past Indian earthquake varying in range of magnitude from 5.6 to 7.8. For this parametric study, the performance criteria as per FEMA 356 for the limit states of Immediate Occupancy (IO), Life Safety (LS) and Collapse Prevention (CP) are considered. Results obtained from NLTHA are shown in terms of Interstorey Drift Ratio (IDR) profile. The results of NLTHA showed satisfactory performance when evaluated by a set of recorded ground motions of past Indian earthquakes. Individual and summarized IDA curves for 16%, 50% and 84% IDA of IDR | Sa illustrates that RC Frame-walls crosses the IO performance level and are well below the CP level for all cases which shows acceptable performance.

Modelling and evaluation of brittle shear effects on the seismic performance and loss assessment of RC buildings

This paper focuses on the seismic vulnerability assessment of old RC buildings prone to brittle shear effects, i.e., with extremely low transversal reinforcement ratios in columns. Within this context, two limitations are identified: 1) the inadequacy of the available analytical shear models in literature since most of them are based on experimental results performed on specimens with transversal reinforcement ratios higher than those found in old buildings and 2) the lack of simplified numerical modelling approaches to simulate shear failure prior to flexural yielding of the element’s longitudinal reinforcement. To overcome these limitations, a simple modelling approach is proposed, and its impact is evaluated through seismic and loss assessment of a RC structure typical of the Lisbon building stock. For comparison purposes, the building is modelled using two different numerical models: one that only captures the nonlinear flexural behaviour of the structural elements, and another that considers both flexural non-linear behaviour and brittle shear failure through the incorporation of uncoupled shear springs that limit the maximum strength that the RC columns can withstand. The seismic performance evaluation is carried out through nonlinear static and Incremental Dynamic Analysis (IDA). Collapse assessment is evaluated considering two different collapse criteria, namely global failure (GF) based on the identification of flattening of the IDA curves and first component failure (FCF) which is conducted based on post-processing analysis of shear forces and inter-storey drifts. The results show that the proposed modelling approach combined with the GF collapse criterion leads to estimates of expected annual losses (EAL) compatible with those reported in other studies found in the literature. Additionally, it is observed that the adoption of a first component failure criterion based on shear force control conducts to consistent estimates of EAL.

Seismic Performance Analysis of RC Frames with ECC Short Columns Based on the IDA Method

Engineered cementitious composite (ECC) is a high-performance composite material with greater shear deformation and shear strength than normal concrete, which has been proposed for use as a shear component in structures. This study modeled three frames, a pure reinforced concrete (RC) frame, an RC frame with concrete short columns and an RC frame with ECC short columns, using the incremental dynamic analysis (IDA) method to evaluate the contribution of ECC to the structural performance. A modified IMK model was applied to model the entire history of the mechanical behaviors of the short columns. The IDA curves, interfloor displacement angle distribution and limit state of the vertex displacement of the frames were analyzed to investigate the seismic responses of the frames. The model analysis results showed that an RC frame with short columns would form a weak layer on the floor where the short columns were located, which greatly weakened the seismic performance of the structure. ECC was certified to be effective in improving the shear formation of the short columns in the frames. The frame with ECC short columns improved the seismic performance of the structure to a certain extent relative to the frame with RC short columns. The deformation capacity of the frame with ECC short columns was close to that of the pure RC frame at the collapse level.