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The aim of this study was to develop an innovative deep learning based intelligent software (DamageNet) and its mobile applications to classify seismic damage of Reinforced Concrete (RC) elements. Images of 2455 damaged elements that have been exposed to different destructive earthquakes were collected from the "datacenterhub" database. The DamageNet algorithm has been compared with the pretrained convolutional neural networks (CNN) algorithms (VGG16, ResNet-50, MobileNetV2 and EfficientNet) according to performance metrics. With the other models, a maximum test success of 89% was achieved, while with DamageNet a test success of 92% was achieved in damage classification. The mobile application developed based on the DamageNet model was tested in the field after the earthquakes (Mw:7.7 and Mw:7.6) in Kahramanmaraş/Turkey and classification success of 88% was obtained. [ABSTRACT FROM AUTHOR]

The damage assessment of numerous buildings after the earthquake is still a challenge by traditional methods as it requires a significant amount of time and resources for carrying out building-by-building seismic damage assessment. This study presents the machine learning (ML)-based damage assessment of buildings after an earthquake. The applicability of the machine learning model will be limited considering only structural properties or ground motion characteristics. Thus, in this study, the applicability of different machine learning techniques is explored using real-world earthquake damage datasets considering both the structural properties and ground motion characteristics. Initially, the entire dataset is used to train the ML models to classify the building's damage into five categories ranging from null to slight damage to collapse. Later, the dataset is divided into three traffic light damage tags: green, yellow, and red. The performance of the ML model to classify the building's damage into three damage tags is found better than that of classifying it into five damage categories. This research aims to be beneficial in planning and decision-making for emergency response and recovery following an earthquake. [ABSTRACT FROM AUTHOR]

Confined masonry (CM) buildings experienced some major damages in past earthquakes. Numerous studies have investigated various strengthening techniques to improve the seismic performance of CM walls. A state of the art for strengthening CM structures using externally bonded reinforced cementitious composites, subjected to inplane loads is presented. A database of previous test results was used to evaluate the effectiveness of the strengthening applications. The capacity prediction of strengthened CM walls was performed using available analytical models. A modification of the existing model is proposed by studying the correlation between the experimental parameters and the effective stress. [ABSTRACT FROM AUTHOR]

Seismic damage to components and structures may cause extensive degradation of the seismic capacities of the damaged buildings. The analysis of the residual hysteretic behavior of post-earthquake damaged components and structures is a critical step in the assessment of their residual seismic capacities. Whereas, the difficulty in quantifying the damage distribution of materials in post-earthquake damaged components leads to the challenge of quantitative analysis of their residual behavior (i.e. residual stiffness, strength, energy dissipation). In this study, a visual data-informed fiber beam-column model was developed to analyze the residual hysteretic behavior of post-earthquake damaged RC columns under cyclic loads. To begin with, the method for quantifying the damage strain fields of the columns according to their inspected visual data was proposed. Then, the stress-strain relations of the materials considering the effect of damage strain fields were constructed, and the visual data-informed fiber beam-column model was proposed for the analysis of the residual hysteretic behavior of post-earthquake damaged RC columns subjected to cyclic lateral loads. At last, the proposed model was validated by comparing model results with existing test data. The comparison shows that the proposed visual data-informed fiber beam-column model can accurately analyze the concrete crushing surfaces, the residual load-displacement responses, and the energy dissipation capacities of post-earthquake damaged RC columns, facilitating the evaluation of the residual seismic capacities of post-earthquake damaged RC columns. [ABSTRACT FROM AUTHOR]

With a view to providing general Storey Loss Functions (SLFs) for existing reinforced concrete (RC) residential buildings in Italy, this paper layouts the procedure and the development of SLFs for different residential building typologies, using post-earthquake observational damage data of the 2009 L'Aquila earthquake. To do so, the addressed building typologies and the cost ratios, with respect to the total construction cost, for structural and non-structural elements were defined according to the Italian price bulletin of building typologies, using the current average construction cost per square meter. Fragility models available in the literature, which had been specifically calibrated for structural and non-structural elements commonly found in Italian and Mediterranean RC buildings, were employed and the assumed repair costs were the ones incurred for repairing the buildings damaged during the 2009 L'Aquila earthquake. The proposed SLFs were then employed to perform loss assessment on a representative portfolio of Italian existing masonry-infilled RC residential buildings, showing the consistency of the results with respect to available research studies. The outcomes therefore denote how the proposed SLFs can be a useful tool as an alternative to the simplified conservative loss assessment guidelines currently employed in Italy, with a view to planning risk mitigation measurements both at a regional and single-building level. [ABSTRACT FROM AUTHOR]

Full-scale experimental tests are still needed to enhance knowledge on the seismic response of existing reinforced concrete buildings and to calibrate numerical models aimed at predicting damage. This study deals with pseudo-dynamic (PSD) tests and numerical modeling of full-scale multi-story infilled RC frames with different infill-to-frame connections. Nonlinear numerical models are calibrated using the experimental results at frame level and validated against the results of time-histories in terms of displacement demand, hysteretic response, and attained damage. This model is extended at building level and used to predicted damage to infills. The comparison with damage observed during post-earthquake inspections is reported and discussed. [ABSTRACT FROM AUTHOR]

The code-based response modification factors are mainly developed based on engineering judgments and experiences from past earthquakes, and hence, they may not lead to reliable solutions considering different performance targets and hazard levels. On the other hand, the uncertainties associated with these proposed values are more significant for new lateral load-carrying systems, such as tunnel-form buildings, due to insufficient information about their performance against seismic events. To address these challenges, this study aims to propose a multi-level approach for the estimation of response modification factors for tunnel-form building structures by taking into account the site seismicity and the damage level defined as the target performance. Using the proposed approach, the modification factors corresponding to different ranges of earthquake intensity and damage levels are obtained for 2-, 5-, 7-, and 10-storey tunnel-form buildings. The results are then used to verify the efficiency of the response modification factors proposed by design codes for the preliminary design (code-based factors) of such systems. It is shown that, in general, by adopting a response modification factor between 4 and 6, the tunnel-form structural systems exhibit excellent seismic performance and can satisfy the requirements of the Immediate Occupancy (IO) performance level even under the Maximum Considered Earthquake (MCE). The outcomes of this study could be useful for performance-based design of tunnel-form building structures aligned with the new generation of seismic design codes. [ABSTRACT FROM AUTHOR]

Traditional post-earthquake safety assessment of damaged buildings is always time-consuming and qualitative. This paper proposes a novel quantitative method for evaluating seismic damaged buildings based on 65 RC buildings from the Wenchuan and Lushan earthquakes. The results show that: the uncertainty of the model regression coefficient leads to obvious variability in damage index of the structure (Dz); the residuals do not show obvious trend with the variables; the Pearson correlation coefficient between the calculated and judgment values of test samples is 0.96. Results indicate that the proposed model is feasible for evaluating the safety of damaged buildings on site. [ABSTRACT FROM AUTHOR]

For shield tunnels, seismic isolation layer is an effective countermeasure to reduce structural damage during earthquakes. In this paper, the physico-mechanical properties of asphalt-cement (A-C) materials applied to backfill grouting of shield tunnels were investigated by laboratory tests. Then, fragility curves were developed by analytical approach for shield tunnels before and after setting three typical A-C isolation layers (i.e. A-C Iso-layer1, 2, and 3), which were used to express the seismic vulnerability of tunnel lining and evaluate the seismic-reduction effectiveness under earthquakes. The results reveal that A-C isolation layers are effective in seismic-reduction under excitation of low input intensity (less than 0.5 g), while its effect is not significant at high-input intensity. The fragility curves for tunnel lining after setting A-C isolation layers show less vulnerability than not setting one at all seismic intensity levels. From the perspective of damage probability, the seismic-reduction effectiveness decreases with the increasing shear modulus of A-C isolation layer. The probability of minor damage of examined tunnel lining setting up with A-C Iso-layer1 decreased from 23% to 15% at most. [ABSTRACT FROM AUTHOR]

Past major earthquakes have witnessed extensive pile-supported transmission tower-line systems (PSTLs) failing, which highlights the great susceptibility of PSTLs to damage from earthquakes. However, a comprehensive literature review in seismic analysis of PSTLs reveals that two critical aspects, i.e. soil–structure interaction (SSI) and depth-varying spatial ground motions (DVSGMs), have been completely overlooked in numerous previous studies. To be specific, pile-supported transmission towers are generally assumed to be fixed to the ground surface and are excited using uniform ground motion inputs. Such analytical schemes may result in severe misestimates of seismic response predictions of PSTLs. Within this context, the main objective of the present study is to accurately assess the seismic performance of PSTLs by considering SSI and using DVSGMs as inputs. For this purpose, an existing prototype PSTL is firstly selected and the corresponding three-dimensional finite element model is created in ABAQUS software, in which SSI is simulated by the Beam on Nonlinear Winkler Foundation (BNWF) model. Then, the three-dimensional DVSGMs are stochastically synthesized based on the computed ground motion transfer functions (GMTFs) of local sites. Next, seismic performance of the PSTL with SSI, including dynamic responses, ultimate bearing capacity, and failure mechanism, is assessed using the generated DVSGMs as seismic inputs. Finally, a parametric study is conducted to comprehensively examine and discuss the influences of SSI, seismic excitation types, coherence loss, and local site conditions on seismic performance of the PSTL. Numerical results show that seismic performance of PSTLs can be affected significantly by the above mentioned influencing factors. This research is expected to offer a meaningful reference to seismic performance assessments of PSTLs. [ABSTRACT FROM AUTHOR]

When the high-speed railway (HSR) bridge is subjected to earthquakes, some components in the HSR bridge are damaged, and these components' damages will be reflected in the deterioration of the rail unevenness. In this study, a framework to address the lateral seismic rail unevenness corresponding to the damages of different components in the HSR track-bridge subjecting to earthquakes is developed. In the first place, a benchmark HSR track-bridge system is selected to conduct the nonlinear dynamic analysis, and the distribution law of the seismic residual drifts in the HSR track-bridge system subjecting to different earthquake intensity levels is proposed. Next, a refined mapping model is developed to assess the additional rail unevenness corresponding to the damages of different components in the system. The seismic rail unevenness sample is established by combining the initial and additional rail unevenness. Finally, the assessment method for the power spectrum density (PSD) of the seismic rail unevenness is introduced, and the PSD assessments of rail unevenness corresponding to the seismic damages of different components in the HSR track-bridge system are developed. The proposed methodology provides an innovative approach to assessing the seismic damage status of the HSR track-bridge subjecting to random earthquakes. [ABSTRACT FROM AUTHOR]

On 30.10.2020, a Mw = 6.6 magnitude earthquake occurred at the offshore Aegean Sea, hitting the western coast of Turkey and Samos Island of Greece, causing loss of lives and properties. In the scope of this study, a site investigation was conducted at the earthquake-hit area of İzmir (Turkey), where 17 buildings (7 partially, 10 totally) were collapsed and many of them were heavily damaged. The impact of the Aegean Sea Earthquake on structures in the İzmir region, as observed during this site investigation is presented in this paper. The seismic vulnerabilities of structures, by referring to the observed typical damages caused by the earthquake, are discussed and preliminary analyses were also conducted in two reinforced concrete buildings to investigate the causes of seismic damages. The damage mechanisms are explained to highlight the causes and defects that led to failure of structures and recommendations are made for preventing such failures and life losses in the future. In additional to the structural damages, widespread non-structural damages which can make buildings non-functional are investigated. This paper also outlines seismological aspects of the region and characteristics of the recorded strong ground motion. [ABSTRACT FROM AUTHOR]

Recently, it was reported that seismically detailed beam-column joint suffered from joint damage during earthquake. Performance of geopolymer as repair material for seismically detailed beam-column joint following removal and replacement technique under cyclic loading is yet to be explored. Experimental program was carried out to examine suitability of geopolymer mortar (GM) and steel fiber reinforced geopolymer mortar (GMSF) to rehabilitate seismically detailed beam-column joint under cyclic loading. It was observed that GM failed to restore cyclic performance of rehabilitated specimens, whereas specimens rehabilitated with GMSF showed better performance in terms of stiffness degradation, ductility, energy dissipation, and damage index. [ABSTRACT FROM AUTHOR]

This study aimed to provide an experimental evaluation method for train's moving safety on a post-earthquake bridge. First, an improved real-time hybrid simulation (RTHS) framework was constructed, based on utilizing the moving load superposition algorithm to solve the train-track-bridge interaction (TTBI) problem. An RTHS test was then conducted for the TTBI problem. The train model was tested using a shake table and was dynamically linked to the numerical substructure. A post-earthquake seven-span high-speed railway simply supported bridge was studied, in which earthquake-induced damage, such as stiffness reductions, residual displacements of piers, girder gap expansions, and pier settlements were all tested. [ABSTRACT FROM AUTHOR]

It is an important study direction in the field of seismic engineering to accurately evaluate the damage degree of RC pier columns under seismic action in saline soil environment. Based on this, eight RC pier columns were designed and manufactured. Based on the residual drift of the specimen, a seismic damage assessment method suitable for saline soil environment was propsed. The corrosion rate, axial compression ratio and residual drift were considered in this model. The results showed that the model is simple and accurate. It can provide reference for post-earthquake damage assessment of RC columns in saline soil environment. [ABSTRACT FROM AUTHOR]

Earthquake damage to freestanding nonstructural components has occurred in past earthquakes. Ceramic vase is one of the most vulnerable freestanding nonstructural components in museums, residential, and historical buildings. To investigate the seismic performance of a freestanding vase, shaking table tests were conducted, where four motions, consisting of two historic and two artificial ones, were selected and generated. The kinetic friction coefficient was acquired with a slow-pull test, which was used to define the possible response modes. The rocking and sliding responses of the vase were observed by accelerometers and high-speed camera. Results showed that the response mode of the vase was highly dependent on the input peak acceleration, i.e., the higher the peak acceleration, the larger the peak and residual displacements and rocking angles. In addition, the dynamic response varies with the excitation of different input motions, indicating that the frequency contents of the input motion also affect the rocking intensity. Generally, the experimental kinetic friction coefficient from the shaking table test matched the one from the slow-pull test closely, demonstrating that the two approaches were reasonable and accurate enoughand can be accepted. Using the philosophy of the second generation of performance-based earthquake engineering, damage modes, performance levels, and fragility curves were defined and generated on account of crack intensity, repair actions, and rocking angles, respectively. These efforts are also beneficial for the seismic evaluation of the freestanding objects in building structures. [ABSTRACT FROM AUTHOR]

In this paper, a post-earthquake damage assessment method for 11 different structural systems is proposed. The method is mainly based on residual inter-story drift ratios of all structural elements in the building, an important response parameter due to its simplicity of measure after the earthquake. nearly 2000 test specimens representing structural elements characterized by different structural systems (walls, frames, etc.) and materials (masonry, reinforced concrete, and steel) which were tested under quasi-static cyclic loading provided more than 100,000 data points that were used to correlate the residual drift ratio and damage states in structural elements. The damage severity of each structural element was then determined based on the weighted average of each damage state's exceedance probabilities given a residual drift ratio. The method also considers the damage propagation among different structural elements by considering the weighted average overall damage scores in structural elements concerning their load-bearing contribution. The pre-earthquake condition of the building and the level of experienced earthquake intensity is the other input parameters for the proposed method, which finally leads to the building's overall damage score. To verify the accuracy of the proposed method's results, an example building hit by the Ezgeleh earthquake is evaluated, and the results are compared with those of other post-earthquake damage assessment methods. [ABSTRACT FROM AUTHOR]

Seismic retrofitting of exiting building structures is a technical and social issue aimed as earthquake risk mitigation. In this study, a new technique for seismic retrofitting via the attachment of an external steel frame with length-adjustment control box (ESFLC) was developed to strengthen medium-to-low-rise reinforced concrete (RC) buildings. The developed method, categorized as a strength design approach, can be used to perform seismic strengthening construction while residents continue to live within the building, exhibiting excellent constructability because a control box is applied as a length-adjustment device to cope with errors in the field associated with assembly works between the existing structure and reinforcing frame. Two full-size two-story RC frame specimens were designed based on an existing Korean RC building without seismic details; one control specimen and one specimen strengthened with the ESFLC system were used. Pseudodynamic tests were carried out to verify the effects of seismic retrofitting in terms of the maximum response strength, response displacement, and degree of earthquake damage compared with a control RC frame. Nonlinear dynamic analysis was also conducted based on the material properties of the test specimens, including mathematical models that represent the nonlinear hysteresis of the used structural members, to compare the results of the pseudodynamic tests. Test results revealed that the proposed ESFLC strengthening method, externally attached to the existing RC frame, effectively increased the lateral ultimate strength, resulting in reduced response displacement of RC structures under large-scale earthquake conditions. The nonlinear dynamic analysis and test results were in reasonable agreement. [ABSTRACT FROM AUTHOR]

The paper discusses the performance of prefabricated reinforced concrete (RC) buildings, known as large-panel buildings (LPE), that were affected by the November 26, 2019 Durrës, Albania earthquake (M 6.4). This was a common typology for multi-family housing in urban areas of Albania and neighbouring countries, e.g. ex-Yugoslavia, Romania, and Bulgaria, in the period from 1960 to 1990. The paper outlines the key structural and seismic features of LPE buildings in Albania and presents observations from a field survey of selected buildings at eight different localities within the earthquake-affected area. A new post-earthquake damage classification for LPE buildings has been proposed. [ABSTRACT FROM AUTHOR]

This study presents an overview of seismic hazards in Bhutan and the vulnerability of Bhutanese vernacular constructions derived from damage caused by two earthquakes that occurred in 2009 and 2011. Interpretations of damage and seismically vulnerable features of such constructions are provided from field observations. The taxonomy and vulnerability of all existing Bhutanese buildings are presented using a newly developed classification system. Empirical seismic fragility functions for vernacular stone masonry buildings are constructed using the damage data of 2009 and 2011 earthquakes. The sum of observations highlights that Bhutanese masonry buildings are highly vulnerable even in moderate far-field earthquakes. [ABSTRACT FROM AUTHOR]

In this study a seismic risk analysis of masonry buildings based on damage data of L'Aquila 2009 earthquake is presented. Typological loss curves and Expected Annualized Losses (EAL) values are presented, starting from the data collected into AeDES forms available in the Da.D.O. database. A completion is proposed for improving the sample statistical significance, and correctly including undamaged and not surveyed buildings that suffered low shaking values. Finally, the loss curves proposed permits to economically assess the effectiveness of some local and very frequent interventions (such as chains/ring beams), and their consequent impact in seismic risk mitigation. [ABSTRACT FROM AUTHOR]

The paper investigates the potential of adopting the spectral acceleration Sa(T) as an efficient measure for the estimation of the seismic performance of bare and infilled R/C buildings within the context of Performance-Based Earthquake Engineering. A large number of planar R/C buildings with different masonry infills' distributions are analyzed using nonlinear time-history analyses. The correlation between several damage measures and the Sa(T) for a wide range of periods is investigated. The results point out the conditions under which the Sa(T) can be used as an efficient parameter that describes adequately the damage response of bare and infilled R/C frames. [ABSTRACT FROM AUTHOR]

In recent earthquakes in Japan, it was difficult for some reinforced concrete buildings to maintain their functionality after earthquakes due to damage to nonstructural RC walls. Currently, society expects quick recovery, if not uninterrupted functionality, of buildings after earthquakes. In this paper, four hybrid rocking wall specimens, along with rocking wall and RC wall were tested to quantify the damage level and limit states based on the 2015 AIJ guidelines. The behaviour of hybrid rocking walls was modelled with amulti-spring model. As aresult, limit states of analyzed walls were successfully classified in agood agreement with experimental results. [ABSTRACT FROM AUTHOR]

A seismic loss-based design framework is proposed. It relies on the introduction of a multi-objective loss-performance matrix that attempts to set an innovative design approach directly associating loss measures to performance levels as a function of the design seismic intensity and the social importance of the building. This approach provides higher awareness about the economic consequences caused by structural and non-structural damage in the aftermath of an earthquake event. The design framework is applied to a case-study-reinforced concrete frame building designed as a traditional cast-in-situ moment resisting frame system, analyzing its performances within the new loss matrix. [ABSTRACT FROM AUTHOR]

After earthquakes, an accurate and efficient seismic-damage prediction is indispensable for emergency response. Existing methods face the dilemma between accuracy and efficiency. A real-time and accurate seismic-damage prediction method based on machine-learning algorithms and multiple intensity measures (IMs) is proposed here. 48 IMs are used for representing the ground-motion characteristics comprehensively, and the workload of the nonlinear time-history analysis (NLTHA) method is replaced by model training in the non-urgent stage to promote efficiency. Case studies with various buildings prove the accuracy and efficiency of the proposed method, and corresponding key IMs are identified by iterative optimization. [ABSTRACT FROM AUTHOR]

The present study proposes a statistical methodology to rate the habitability of different types of buildings after an earthquake. The first step was to rank variables that affect the vulnerability of a building and formulate a statistical study with a discrimination index that makes it possible to identify buildings as habitable or non-habitable. This ranking applied the criteria established in various international guidelines that are used to distinguish between habitable (undamaged/no structural damage) and non-habitable buildings (structural damage). The proposed methodology was applied to a database with information about buildings and damage grade experienced following the 2011 earthquake in Lorca. The approach presented could be extended to other regions where neccessary data are available. [ABSTRACT FROM AUTHOR]

The 2017 M5.4 Pohang, South Korea, earthquake damaged numerous buildings. Immediately after the main shock event, 1,880 professional engineers inspected the damaged buildings and assigned three damage grades ("Usable," "Restricted use," and "Unusable"). We investigate factors influencing the building damage. The built year, number of stories, and estimated peak ground acceleration are strongly related with the frequency of building damage. We also prove that the damage caused to the building is influenced by the basin geometry, based on site parameters such as N value, shear wave velocity, depth to rock, and site fundamental period. [ABSTRACT FROM AUTHOR]

This discussion presents review of the seismic hazard in Peshawar, performed by various national and international researchers and agencies in the past, which was critically compared with the proposed peak ground acceleration (PGA) of 0.06 g. The PGA = 0.06 g corresponds to seismic Zone 1, which is the lowest seismic hazard as per the Building Code of Pakistan. The building damages observed in Peshawar in the recent past earthquakes are revisited to judge the correctness of PGA = 0.06 g for Peshawar that pertain to its suitability for use in the seismic design of structures. The recent seismic hazard studies reported also by other researchers are presented. Seismic hazard studies of Peshawar report widely conflicting results. The placement of Peshawar in the lowest seismic hazard Zone 1 will have a number of socioeconomic implications. Therefore, a critical review of these studies was essential to recommend suitable design level ground motion for Peshawar. [ABSTRACT FROM AUTHOR]

We analyze the global and local uncertainties of ground motion-macroseismic intensity conversion equations and derive new probabilistic relationships between the macroseismic intensity and peak ground motion parameters (peak ground acceleration and peak ground velocity) for western China based on the assumption that the peak values of ground motion are randomly distributed for each MMI level, bounded by a normal distribution. For this purpose, a strong ground motion database consisting of 37 moderate- to large-magnitude earthquakes that occurred in western China between 1994 and 2017 is employed along with the corresponding modified Mercalli intensity (MMI) information inferred from isoseismal maps and earthquake damage reports. The mean value and standard deviation parameters in the probabilistic formulas are obtained from the result of the analysis of the local uncertainties of the data compiled for Western China. We propose a method for the rapid assessment of computer-generated intensity maps using the new probabilistic formulas. Our method composed of two steps. (1) According to a Bayesian formula, the possibility, expectation and standard deviation of the seismic intensity are calculated by the ground motion parameters recorded at a site station. (2) Furthermore, expectation and standard deviation maps of the seismic intensity throughout an area are obtained through spatial interpolation. Finally, an application is illustrated to validate this new methodology by presenting rapidly estimated (computed) intensity maps of the 8 December 2016 Hutubi (Ms 6.2) earthquake in western China. [ABSTRACT FROM AUTHOR]

Brittle punching failures can occur in slab–column connections due to earthquake-induced unbalanced moments. The performance of undamaged specimens and various repair/strengthening techniques have been studied in the past. This paper investigates a less studied scenario, in which a flat slab–column connection severely damaged by an earthquake is subjected to another earthquake without undergoing repair. The performance under this special loading protocol is analysed. It is shown that the drift capacity was not significantly impaired, but both the lateral and bending stiffness were reduced. Other relevant observations regarding the post-earthquake life of slab–column connections are brought to attention. [ABSTRACT FROM AUTHOR]

This paper presents a post-earthquake damage assessment of the 6.5 Mw earthquake in Pidie Jaya, Indonesia which occurred on December, 7th 2016. The earthquake killed 112 people and caused the collapse of about 3000 buildings. The assessment started on the day after the earthquake. The survey covered nine sub-districts of Pidie Jaya regency in the Province of Aceh, northern Sumatra. The post-event damage assessment was conducted by a team of researchers from Syiah Kuala University and local authorities. The damage survey assessed the damage levels of residential houses, school buildings and markets. The most common construction damages reported in this article are failures of reinforced concrete, confined masonry and timber structures. The ground motion field was modeled using Openquake application and the site response employed Vs30 values inferred from topography. This calculated ground motion was compared to data from post-earthquake field assessment reports. The highest percentage of heavy damage was recorded in the area of the fault rupture and along the shorelines area. The types of failure observed are summarized in the context of Indonesian construction practice, with particular reference to the seismic resilience of the Rumoh Aceh traditional wood construction. [ABSTRACT FROM AUTHOR]

With the soil constitutive model developed for the dynamic large deformation of soft soil, a finite element model was constructed to simulate the soil–underground structure static and dynamic coupling interaction system, in which the dynamic contact between soil and underground structure and the dynamic damage of reinforced concrete were considered. The seismic performance and damage mechanism of the large underground subway station in different soil foundations were investigated and evaluated in detail. It was proven that the interaction mechanism between the soil and underground structure would change with the type of soil foundation and the peak acceleration of input ground motion, which can be evaluated by the interaction coefficient between the soils and underground structure. At the same time, some regulations on the seismic performance of underground structure in China code are already unsuitable for evaluating the seismic performance of a large underground subway station in the soft soil foundation or subjected to a strong earthquake, which should be investigate by the specialized time–history analysis method instead. In this study, five seismic performance levels were firstly defined by the inter-storey drift angle of underground structure and corresponding earthquake damage states. [ABSTRACT FROM AUTHOR]

The damages done by earthquakes in the human history can't be denied in any sense as the phenomenon is responsible for bringing catastrophes both socially and economically. It is known that Pakistan is located in one of the seismically active regions of the world. The Quetta earthquake which occurred in 1935, the Ziarat earthquake of 2008, the Kashmir earthquake in 2005 and the Dallbaandin earthquake in 2011 bear the testimony of active seismicity in Pakistan. The Building code of Pakistan (BCP) 2007 has placed Peshawar in seismic zone 2B with a PGA range of 0.16–0.24. However, this is not in line with the historical data and available ground motion records. Therefore, in this research, a probabilistic seismic hazard assessment technique was used to estimate the strong ground motion parameters for a grid of 11 km by 11 km, covering all the active faults within and around the Peshawar region and having significant effect on the seismicity of Peshawar. Moreover, PGA along with spectral acceleration values are required by modern building codes (IBC 2009 and ASCE-7) for the estimation of seismic loads, is calculated. From seismic hazard analysis, it was found that Peshawar lies in seismic Zone 1 with a PGA value of 0.06. The estimated PGA value was also validated and in line with the PGA values obtained from the ground motion records of Peshawar Meteorological Department. [ABSTRACT FROM AUTHOR]

The gravity load designed (GLD) reinforced concrete (RC) framed structures have undergone severe damage during earthquake excitation due to their inherent weaknesses. This underlines the need for development of an effective retrofit strategy for seismic damage mitigation of the beam–column sub-assemblages which are the most critical components of existing GLD RC structures. In the present study, an innovative steel bracket and haunch hybrid retrofit system is developed for strengthening of earthquake damaged GLD structures. Also, experimental investigations are carried out on three types of GLD beam–column specimens, namely, (a) control undamaged specimen, (b) control specimen upgraded with single haunch and (c) damaged specimen repaired and retrofitted with the innovative steel bracket and haunch hybrid system, under reverse cyclic loading to evaluate the comparative seismic performance of hybrid retrofit system. An improvement in load carrying capacity of 1.82 and 1.61 times that of control specimen is observed in the repaired and retrofitted specimen in positive and negative cycles, respectively. Moreover, the specimen retrofitted with hybrid retrofit system sustained larger drifts compared with the control specimen and showcased improvement in the total cumulative energy to the tune of 4.48 times that of the control specimen. This demonstrates that the steel bracket and haunch hybrid retrofit system is an excellent candidate for seismic strengthening of earthquake damaged GLD beam–column sub-assemblages. Further, the hybrid retrofit system is found to be superior to single haunch retrofit strategy. [ABSTRACT FROM AUTHOR]

This paper presents a simplified mathematical formulation for a set of closed-form solutions to compute static and seismic active and passive earth pressure on a retaining wall with bilinear backface. The concept of the method of stress characteristics in the framework of hyperbolic partial differential equations has been employed for the intended purpose. The advantage of varying the wall geometry for obtaining an economical design is briefly discussed. This mathematically robust but elementary procedure may be useful as a predecessor for obtaining an efficient and economical design of a retaining wall to palliate the earthquake damage. [ABSTRACT FROM AUTHOR]

The current research trends focus on the popularization and application of recycled aggregate concrete (RAC) structures in civil engineering. So far, the damage evolution mechanism of RAC structures has been investigated and reviewed by few engineering researchers and practitioners. In this study, a classification criterion for earthquake damage for the RAC frame structure is put forward. The damage index-based limit state criterion is proposed, and the corresponding seismic performance level is established. The refined models based on the stiffness degradation and the cumulative dissipated energy, and the modified Park and Ang model are developed and compared with the experimental results. [ABSTRACT FROM AUTHOR]

A ground motion intensity measure (IM) well correlated with structural demand plays an important role in predicting the damage potential of earthquake records. This study presents a new approach to develop a compound IM through canonical correlation analysis (CCA). This method utilizes the ability of CCA to search for two linear combinations to maximize the correlation between the corresponding random vectors. To illustrate, the nonlinear responses of single-degree-of-freedom (SDOF) systems due to 98 real ground motion records are used. In a log-log scale, a compound IM in terms of a linear combination of six non-structure-specific IMs is developed with a maximum dependence on the linearly combined structural demand of both peak displacement and dissipated energy. Through a comprehensive discussion, the feasibility and performance of the presented approach is investigated for SDOF systems over the entire period range. It is found that the developed compound IM shows significantly high-level correlation with structural demand, and the corresponding correlation coefficients are greater than 0.95 at most periods. This validates the effectiveness of the presented method in improving prediction accuracy for earthquake damage potential through considering multiple IMs. [ABSTRACT FROM AUTHOR]

Evaluating losses consequent to damages induced by earthquakes has become one main paradigm in seismic performance assessment. Within this context, this paper explores a simplified seismic loss assessment methodology for steel structures that utilises displacement-based assessment in place of non-linear dynamic analyses. To this end, two case studies have been considered: (i) an archetype existing single-storey non-residential building, (ii) a prototype new multi-story residential building. Comparing results obtained using the fully probabilistic and the simplified displacement-based assessment methodologies allows the benefits of the simplified method to be highlighted. Possible difficulties encountered in applying the simplified method are also identified. [ABSTRACT FROM AUTHOR]

In the framework of the evaluation of the consequences of an earthquake, the paper provides a procedure for the economic loss assessment in unreinforced masonry (URM) buildings, proposing an analytical approach based on a cost function directly dependent on the damage level associated to different structural elements and identified by specific engineering demand parameters. The procedure follows a component-based approach, to be implemented within modern probabilistic seismic risk analyses, and it includes both the in-plane and out-of-plane damage modes that can be activated in a URM structure. It is applied to a three-storey building, examined varying some configurations of structural details, aimed to simulate two different in-plane collapse mechanisms (with damage concentrated mostly on piers or also in spandrels), or to allow, in one case, also the activation of local out-of-plane mechanisms. [ABSTRACT FROM AUTHOR]

To help facilitate performance-based earthquake engineering (PBEE) in Italy, this study examines an existing reinforced concrete frame building damaged during the 2009 L'Aquila earthquake and compares direct monetary loss estimates computed via a simplified Displacement-Based Assessment (DDBA) method with those obtained using the refined PEER-PBEE approach. The considered case study is representative of a category of buildings that has undergone some level of seismic design, typical of post-70s construction in Italy, where previous buildings were largely designed for gravity loads only. The research finds that the expected annual loss predicted using the two approaches are comparable and thus DDBD could aid loss-assessment and hence reparability evaluations. Different retrofit options are examined and it is concluded that the DDBA approach could provide useful indications of the impact that retrofit can have on expected annual losses. [ABSTRACT FROM AUTHOR]

Seismic fragility functions are essential for performance-based seismic design of structures. Global demand parameters, such as peak roof displacement or maximum drift over the height of the building, are commonly used to estimate seismic fragility. However, in case of buildings with vertical irregularities, the global demand parameters may not suffice since maximum demand in such building is mostly concentrated at the level of irregularity. The current study focuses on one of the most common forms of vertically irregular reinforced concrete (RC) buildings, known as open ground story buildings, where irregularity lies at the ground story. Nonlinear dynamic analyses of RC frames subjected to a number of ground motions, each scaled-up for different PGA, are carried out to estimate the component level and global drift demands, also known as engineering demand parameters (EDPs). Seismic fragilities developed for the frames based on both the component and global EDPs are presented. Finally, the importance of component-based fragilities for estimation of seismic fragility of irregular frames is emphasized. The component level EDP-based fragility is found to be effective in predicting the actual damage scenarios in such buildings observed during past earthquakes. [ABSTRACT FROM AUTHOR]

This paper puts forward a new methodology for time-variant seismic risk analysis of transportation networks. Risk here denotes the probability of exceeding the sum of direct loss due to repair costs of bridges in the network and indirect loss due to the reduced capacity for traffic flow. The proposed methodology employs reliability methods and a host of probabilistic models for earthquake events, damage, repair cost, downtime, and travel time, while accounting for time-varying phenomena of aging and discounting. A comprehensive application on the transportation network of Isfahan, Iran, is presented that features 64 bridges subject to seismicity from seven sources. [ABSTRACT FROM AUTHOR]

On 24 August 2016, Mw 6.8 earthquake occurred near Chauk, Central Myanmar. This earthquake caused a significant amount of damage over a very large number of historical monuments. After providing a general summary of the regional tectonic settings and seismicity, the observed ground motion has been discussed, and performance of structures in the epicentral area is addressed, focusing on the damage observed in both historical and recent constructions. The observed damage patterns and their extent are analyzed and interpreted in light of observed damage that was found. Lastly, seismic fragility curves of local buildings have been derived. [ABSTRACT FROM AUTHOR]

Cultural heritage structures are an integral facet of the irreplaceable cultural heritage of a nation and have been constructed several hundreds and even thousands of years ago. In this paper, based on a field reconnaissance of the highly damaged areas of Kathmandu Valley and Sindhupalchowk district, damage to cultural heritage structures due to the 2015 Nepal Gorkha earthquake and its impact on Nepal are reported. Damages to engineered and non-engineered buildings are also discussed. The damage patterns observed and discussed will be useful for the prevention of damage to cultural heritage structures and other buildings in seismically active countries. [ABSTRACT FROM AUTHOR]

In endurance time method, seismic performance of structures under artificial intensifying accelerograms is investigated. In this method, the time duration of excitation (target time) will be assigned on the basis of linear response spectra. Damage spectra, which are the variation of a damage index versus the system period, can be used effectively to modify the target time of the excitations. In this research, various damage indices for a number of steel moment frames are estimated using the endurance time method with two types of target time, and the results are compared with those corresponding to the scaled real earthquakes. It is observed that damage estimation of the frames via the endurance time method with initial target time is not always acceptable and can be considerably improved by applying the modified target time, obtained on the basis of damage spectra. [ABSTRACT FROM AUTHOR]

This study deals with attenuation relation for Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and spectral acceleration of Iran’s major seismic zones (the Central Iran and Zagros zones) considering ground amplification of site classes. The main development of attenuation relationship in terms of site classes has already been published by the authors. This study discusses site amplification in spectral acceleration compared to the seismic design codes of Iran (Standard 2800, 2014) and FEMA368 limits of amplification. Moreover, the relationships between the PGA or PGV and average shear wave velocity at 30-m depth (AVs30) are presented. This helps to predict appropriate PGA or PGV for each site corresponding to its AVs30. [ABSTRACT FROM AUTHOR]

On February 6, 2015, a local magnitude (ML) 6.6 earthquake struck southern Taiwan, devastating the Tainan area. A field investigation was conducted by a survey team from the National Center for Research on Earthquake Engineering immediately after the earthquake. This paper summarizes the observed geotechnical damage features caused by the earthquake, including liquefaction, slope sliding, levee failure, and dam performance. Several liquefaction sites were observed despite the intensity of ground shaking being moderate (peak ground acceleration, ~0.2 g). Most of these sites were originally old ponds that were backfilled during different periods in the last three to eight decades. Two significant types of damage to the levee of the Tseng-wen River were observed. At the Jianshan site, a typical type of levee damage was observed, in which the level crest subsided and the side slope developed several cracks. At the Rixin site, a flow-type of failure caused tremendous loss of levee (~400 m in total) at three adjacent locations. The levee embankments had “flowed” up to 60 m into the river. [ABSTRACT FROM AUTHOR]

Probabilistic loss modeling can be used to develop risk reduction measures, such as the identification of regions more prone to human and economic losses, or to develop financial mechanisms to transfer the earthquake risk from local governments to the private sector. This study addresses several critical issues in probabilistic loss modeling, and provides recommendations depending on the intended final use of the risk results. Modeling issues related to convergence in probabilistic event-based analysis; consideration of epistemic uncertainties within a logic tree; generation of different types of loss exceedance curves; and derivation of risk maps are thoroughly investigated. The Metropolitan Area of Lisbon is used to explore these issues, and it is demonstrated that different assumptions in the loss modeling process can lead to considerably different risk results. Furthermore, the findings and recommendations of this study are also relevant for institutions that promote the assessment of earthquake hazard and risk, such as the Global Earthquake Model Foundation. [ABSTRACT FROM AUTHOR]

Emergency centers, communication systems, and hospitals are essential infrastructures for emergency rescue and subsequent reconstruction activities. An investigation into the Nepal 2015 earthquake sequences found that the visited government offices were functioning normally 40 days after the main shock; that the local media failed to coordinate with the entire society at the beginning, but mobile phone-based communication recovered quickly; and that the hospitals in high-intensity areas were badly damaged as a result of improper design and adverse site configuration. Recommendations are proposed to enhance the aseismic capacity of structural and non-structural components using earthquake early warning and base isolation. [ABSTRACT FROM AUTHOR]

This paper presents a study on the techno-economic efficiency of seismic strengthening techniques for old residential buildings, with application to construction typologies in Lisbon (stone masonry and “Placa” buildings). A comprehensive review on strengthening techniques and implications for the seismic behavior is made. Different strengthening schemes are implicitly simulated within equivalent frame models of the representative buildings. Then, pushover analysis is applied in order to compare the seismic performance of the buildings, before and after strengthening. A cost-benefit analysis of the strengthening solutions is finally performed, comparing the economic benefit gained by reducing the seismic damage, against the intervention cost. [ABSTRACT FROM AUTHOR]