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Addressing the seismic vulnerability of infrastructures is critical, especially for those built before the introduction of the current seismic regulations. One of the primary challenges lies in retrofitting these buildings without interrupting their functionality. In this context, the use of exoskeletons for seismic retrofitting represents an effective solution. This approach increases the seismic resistance and ensures the continuous operation of the building during retrofitting. This advantage is especially crucial for critical infrastructures, such as airports. Nevertheless, traditional seismic assessment methods based on pushover analyses might not accurately predict the seismic capacity of complex infrastructures dominated by local vibration modes. To bridge this gap, the study proposes refining the multimodal pushover analysis tailored for seismic vulnerability assessments of large infrastructures with exoskeletons characterized by low modal participation ratios. The Foggia Airport case study exemplifies these points and highlights the practical applications of the discussed advancements. The authors compared two force distributions for push-over analysis, addressing the fine-tuning of exoskeletons to maximize their seismic resistance. [ABSTRACT FROM AUTHOR]

Confined brick masonry structures have garnered considerable attention as an effective solution for earthquake-prone regions due to their robust construction, efficient wall-to-column connections, and optimised utilisation of material strength. Within the realm of building design and construction, openings play a pivotal role, serving as essential elements for facilitating natural light and fresh air into the structure. However, the presence of openings within confined brick masonry walls causes a significant reduction in their seismic resistance. Hence, striking the right balance between these openings and structural strength is crucial. For this purpose, it is necessary to investigate the influence of size, shape, and position of the openings in confined brick masonry walls on their seismic performance. In this work, a comprehensive finite element macro-model is adopted that treats the wall and tie members as a unified system. A concrete damage plasticity approach is employed to predict damage progression in confined brick masonry walls. Using a pushover analysis in finite element framework, the ultimate strength, stiffness, and energy absorption capacity of confined brick masonry with different types of openings is assessed. Furthermore, a parametric study is conducted incorporating various scenarios, such as aspect ratios of confined brick masonry walls, diverse shapes of opening and variations in the positions of windows, doors, and combinations of both openings. Based on the results, simplified equations are developed to facilitate analytical estimation of ultimate strength, along with recommendations for optimising opening shape, size, and placement to enhance the design of confined brick masonry walls with openings. The study highlights that larger openings in confined brick masonry walls diminish ultimate strength, stiffness, and energy dissipation due to reduced load distribution and increased stress concentrations. Openings smaller than 10% of the masonry area maintain load paths, but larger openings require additional support. Rectangular openings with greater height than width exhibit superior performance. Furthermore, the positioning of windows significantly influences wall strength, with placements farther from the loading point proving favorable. Door placement also impacts ultimate strength, with central placement compromising stiffness. Combining window openings with a centrally located door maintains consistent ultimate strength but affects stiffness. Overall, this research contributes to a better understanding of the seismic behaviour of confined brick masonry structures with openings, offering valuable insights for engineers and architects working in regions susceptible to seismic activity. [ABSTRACT FROM AUTHOR]

Traditional ancient Tibetan buildings (TATBs) date back hundreds of years. The seismic performance of TATBs constructed with stones and mud was analyzed by utilizing structural subscale features (materials, walls, and structures). The key to load-bearing in TATBs is the three-leaf stone wall. Based on the mechanical properties of materials, compression tests and quasistatic static tests of walls, this paper confirms that the seismic resistance capacity of the three-leaf stone wall of TATBs is unable to meet Chinese standards. The aims of this study are to present the dynamic behavior of TATBs by shaking table tests. According to the experimental data, the transcendence intensity magnification calculation method is modified to calculate the seismic vulnerability of TATBs. The results show that when the peak acceleration of ground motion is 1.042 m/s2, 1.598 m/s2 and 2.881 m/s2, TATBs undergo slight damage, moderate damage, and severe damage, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the seismic resistance of unreinforced masonry (URM) cylindrical columns is investigated with an equivalent static analysis procedure. To this end, an existing numerical model developed for the stability analysis of masonry elements with rectangular cross-section is utilized and modified for the cylindrical columns. In the numerical model which takes into account the cracking of the sections and the second-order effects, the columns are divided ideally into sufficiently high number of elements, each having uniform curvature. The columns are modeled as prismatic cantilevers undergoing their own weights, eccentric vertical loads and distributed and concentrated static horizontal loads equivalent to the inertia actions. By considering two examples of columns, firstly a reference column and secondly a column from a real building, lateral seismic coefficient versus top drift level curves are obtained. On the basis of these curves, lateral load behavior of the columns is interpreted and maximum seismic load values which can be resisted by each column are determined. Implementing parametric analyses on the reference column, sensitivity of the seismic resistance to parameters such as column slenderness, magnitude and eccentricity of vertical top load, and the flexibility parameter is determined. The influence of some structural imperfections such as the deviation from vertical on the seismic resistance is also discussed in the paper. [ABSTRACT FROM AUTHOR]

Soil liquefaction significantly contributes to inducing catastrophic damage to the infrastructures. Different ground improvement methods were used widely to improve the seismic resistance of liquefiable deposits to mitigate liquefaction. Use of granular column technique is a popular and well-recognized improvement technique due to its drainage, shear reinforcement, and densification characteristics. However, studies relating to seismic resistance of stone column-reinforced ground against multiple shaking events were limited. Recent seismic events also have shown the possibility of liquefaction and reliquefaction due to multiple seismic events. Considering this, the performance assessment of the granular column technique in liquefiable soil under repeated shaking events is addressed in this study. The possibility of re-using construction and demolition waste concrete aggregates as an alternative to natural aggregates is also attempted to propose sustainability in ground improvement. For experimental testing, a saturated ground having 40% density was prepared and subjected to sequential incremental acceleration loading conditions, i.e., 0.1 g, 0.2 g, 0.3 g, and 0.4 g at 5 Hz loading frequency for 40 s shaking duration using a 1 g Uni-axial shake table. The efficiency of selected ground improvement was evaluated and compared with untreated ground. The experimental results showed that ground reinforced with granular columns performs better up to 0.2 g shaking events in minimizing pore water pressure and settlement. Possibility of column clogging, and inadequate area replacement ratio (5%) affects the performance of column during repeated shaking. Also, irrespective of improvement in in-situ ground density; continuous generation of pore water pressure due to absence of drainage posing reliquefaction potential in untreated ground under repeated shaking events. [ABSTRACT FROM AUTHOR]

Mortar-less construction with interlocking bricks has many advantages, such as improved construction efficiency and relatively low requirements on labour skills. Nevertheless, the seismic performance of interlocking brick structures is not well understood yet. In this paper, laboratory tests and numerical modelling are carried out to investigate the seismic behaviour of interlocking brick walls. Laboratory shaking table tests are performed on a scaled reinforced mortar-less interlocking brick wall. The response and damage modes under in-plane seismic loading are investigated. A detailed numerical model is then generated and validated with the laboratory testing data. Unlike the conventional masonry wall that diagonal shear damage governs the failure, the interlocking brick wall exhibits rocking responses, whose damage is mainly at the two bottom corners of the wall. Full-scale interlocking brick walls are then modelled and compared with conventional concrete masonry unit (CMU) walls bonded by mortar. Comparisons are made between the seismic resistances and damage modes of the two walls. The influences of ground motion intensities, vertical components of seismic excitations and different seismic time histories on the seismic behaviour of the interlocking brick wall are examined. It is found that the interlocking brick wall has a higher seismic resistance capacity than the conventional CMU wall. Inter-brick friction is the main energy dissipation mechanism in the interlocking brick wall. Because of the rocking response, vertical component of the ground motion significantly influences the damage of interlocking brick wall. The interlocking brick wall is insensitive to velocity pulses of ground motions due to its relatively high natural frequency. [ABSTRACT FROM AUTHOR]

The efficiency of strengthening of unreinforced hollow clay block masonry buildings with fibre reinforced mortar coatings has been investigated. A full scale three-storey building model and a series of accompanying walls have been built and tested. Reference unstrengthened, and strengthened specimens of each type have been tested by subjecting them to cyclic shear at constant compressive load. First, the three-storey model was tested in its original state until the maximum resistance was attained and major, but still repairable damage, developed in the walls. Then, the damaged model was strengthened with fabric reinforced cementitious mortar coating and re-tested up to near collapse limit state. Typical storey mechanism was observed in original and strengthened state, with the majority of damage concentrated in the walls of the bottom storey. Diagonally oriented shear cracks prevailed in the elements in the direction of loading. The behaviour of single walls in cyclic shear tests was similar to that observed in the piers of the building models. The analysis of test results indicated that the resistance and displacement capacity of unreinforced masonry structures of the particular type tested can be significantly improved if delamination and separation of coating is prevented. Finally, a calculation model for the assessment of seismic resistance of reference and strengthened building model is presented and the comparison between calculated and experimental results discussed. [ABSTRACT FROM AUTHOR]

The development of seismic fragility functions for buildings generally relies on simplified modelling methods and the use of indirect engineering demand parameters (EDPs) for the determination of collapse or other damage states. The collapse response of real buildings, particularly those that have not been specifically designed for seismic resistance, can often be driven by local failures that may not be captured in simplified models. Furthermore, the use of EDP thresholds to indicate damage states may not be consistent with multiple possible failure modes, which may be triggered by different characteristics of the ground shaking or variations in model parameters. This paper demonstrates the use of non-linear finite element models including explicit progressive collapse simulation for the development of fragility functions. It presents an overview of the method developed and its application to an unreinforced masonry (URM) building typology in the Groningen region of the Netherlands, where induced seismicity risk is currently being evaluated. Multiple index buildings were selected to represent the variations in geometry, material properties, and connection types found within the typology. For each index building, Latin Hypercube sampling was used to generate batches of several hundred realisations of an LS-DYNA time-history analysis, each selecting from a set of 100 hazard-consistent ground motions, and varying material properties and other uncertain variables according to pre-assigned probability distributions. Automation was used in model generation, running analyses and in post-processing to allow the required computation with minimal analyst intervention. The main output from each analysis was a normalised debris cover estimate, which describes the extent of damage observed in the model and is correlated with life safety risk. Regression analyses were carried out directly on threshold levels of debris cover identified building collapse. Fragility functions were developed for the URM terraced house typology by combining results from the individual index buildings together. [ABSTRACT FROM AUTHOR]

To mitigate liquefaction and its associated soil deformations, ground improvement techniques were adopted in field to reinforce saturated sand deposits. Sand Compaction Pile (SCP) is one such popular proven treatment to improve liquefaction resistance of sandy deposits. Installation of sand compaction piles improves soil density and rigidity which further enhance seismic resistance against liquefaction and this was well evident from past field observations. However, studies involving SCP performance during repeated shaking events were not available/limited. In this study, using 1-g uniaxial shaking table, a series of shaking experiments were performed on SCP treated and untreated sand deposits having 40% and 60% relative density subjected to repeated incremental acceleration loading conditions (i.e., 0.1–0.4 g at 5 Hz frequency). Parameters such as improvement in soil resistance and relative density, generation and dissipation of excess pore water pressures, maximum observed foundation settlement and soil displacement and variation in cyclic stress ratio were evaluated and compared. Seismic response of liquefiable sand deposits was found to be improved significantly due to SCP installation together with occurrence of continuous soil densification under repeated loading. The experimental observations suggested that SCP can perform better even at repeated shaking events. [ABSTRACT FROM AUTHOR]

Rammed-earth dwellings are widely used in rural areas worldwide; with poor mechanical properties and weak seismic resistance, these structures are vulnerable to earthquakes. This study presents a method for reinforcing existing rammed-earth buildings by strengthening the walls with externally bonded fibers. Shaking table tests were conducted to study the seismic performance of two rammed-earth model structures-with and without reinforcement. We observed the crack patterns, failure modes, changes in dynamic properties, in-plane deformation, wall response, and roof-wall interaction in the models. The results confirm that the seismic resistance of rammed-earth structures reinforced using the proposed method was substantially improved. [ABSTRACT FROM AUTHOR]

Prestressed steel strips were used to provide quick retrofit for seriously damaged structures after earthquake, for the purpose of improving the seismic resistance capacity of seismic-damaged reinforced concrete frames in case of aftershock and providing possible conditions for comprehensive post-earthquake strengthening. In this paper, the retrofitting effect of retrofitted damaged structure was validated by means of pseudo-static test on 1/2 scaled undamaged RC frame with single span and three stories and retrofitted seismic-damaged structure using prestressed steel trips. The comparison of seismic performance including bearing capacity, stiffness, ductility and energy dissipation capacity was discussed to verify the retrofitting effect. According to the results, it was found that post-earthquake reinforced concrete frame retrofitted by prestressed steel strips could develop similar seismic performance as original frame and reduce the potential in structural failure when subjected again to an earthquake. The results also indicated that prestressed steel strips could be taken as a quick retrofit technology, providing effective and quick strengthening of damaged structure and it could help avoid unexpected loss of life and economy after earthquake. [ABSTRACT FROM AUTHOR]

The out-of-plane mechanism (rocking) of walls often causes fatalities and collapses of historic buildings during earthquakes. This paper addresses the problem of assessing the seismic resistance of walls subjected to out-of-plane bending, before and after reinforcement. A new retrofitting method, consisting in the use of high-strength steel cables fully embedded in the mortar bed joints was studied. An experimental investigation using full-scale brickwork specimens was therefore conducted in an attempt to assess the walls' structural response when these are subject to out-of-plane loads. Test results demonstrated that it is possible to increase the out-of-plane capacity with the proposed method. A simplified macro-element procedure is also presented along with recommendations for the calculation of the walls' capacity before and after the application of the steel cable reinforcement. Predictions of the magnitude of horizontal force required to cause out-of-plane failure using the proposed procedure and quasi-static analysis procedures are compared with the results of laboratory experiments. [ABSTRACT FROM AUTHOR]

The paper presents a simplified static force-based procedure for seismic retrofit design of RC frames using internal eccentric steel braces (ESBs), connected to long beam at distance of L/8 from beam ends, to enhance seismic resistance of the frame. The technique uses the linear static procedure given in ASCE 7-16 for calculation of appropriate design base shear for frame analysis, and the AISC 360-16 seismic provisions for preliminary design of steel braces. Response modification factor R was derived based on simplified kinematics of rigid frame response and flexure hinging of link beam, to reduce the elastic base shear force for lateral load analysis of frame and design of steel braces. This shifts plastic hinges from columns, and reduces joint shear deformation, by means of capacity protected braces and beam shear. The procedure was used for the preliminary design of ESB retrofitting technique for a two-story RC frame, employing hollow box steel sections. Quasi-static cyclic tests were performed on both as-built and ESB retrofitted portal frame panels under multiple-levels of lateral displacements demands. The tests performed on frames were analysed to understand the damage mechanism and retrieve the essential seismic response properties: force–displacement capacity curves, hysteretic cyclic response and hysteretic damping, and to establish performance-based story drift limits. The experimental data was used to calibrate finite element based nonlinear numerical models in SeismoStruct. Nonlinear static pushover analysis of considered two-story ESB retrofitted frame was carried to quantify structure ductility and response modification factors. The preliminary design was verified through nonlinear time history analysis (NLTHA) for both design base earthquakes and maximum considered earthquakes. Proposed seismic design of ESB retrofit for multi-stories RC frames having three to six stories has been presented and verified through NLTHA. It indicates the promising behaviour of ESB retrofit technique as well as the efficiency of the proposed simplified design procedure. [ABSTRACT FROM AUTHOR]

By integrating the vulnerability index of buildings, earthquake disaster matrix, and historical earthquake disaster data, the vulnerability of typical buildings and compounds in rural areas of China are analyzed. The disaster matrix of buildings in historical earthquakes was obtained by analyzing historical earthquake disaster data. By integrating the historical disaster matrix and vulnerability analysis of typical structures in rural areas, a seismic disaster matrix was established to assess the seismic performance of regional compounds. Combined with the historical earthquake disaster matrix and vulnerability index, the lognormal distribution function was used to analyze the vulnerability index of regional structures and compounds to obtain the disaster matrix of structures under different seismic intensities. Considering the structures and compounds in the rural areas in the Tianjin district as an example, the seismic vulnerability of typical structures was investigated. The regional structure disaster matrix of the study region was established and the vulnerability indices of different types of structures and compounds were obtained to clarify the regional disaster prevention ability. [ABSTRACT FROM AUTHOR]

Insufficient information about the seismic performance of tunnel-form buildings and limited relevant design codes and standards are the main barriers towards application of these systems in seismically active areas. Vertical and horizontal irregularity of typical tunnel-form buildings is another cumbersome challenge restricting the application of these systems. To address these issues, this study aims to evaluate the seismic behaviour of tunnel-form buildings with horizontal irregularity and develop appropriate design methodologies. Based on the results of 3, 5, 7 and 10-storey buildings, new response modification factors are proposed as a function of seismic demand and expected performance level. Fragility curves are also derived for various levels of intensity, and simple equations are introduced to estimate uncoupled frequency ratios. The results, in general, demonstrate the flexible torsional behaviour of irregular tunnel-form structures and their adequate seismic resistance capacity. The buildings studied herein, managed to satisfy the immediate occupancy performance requirements under design-basis earthquake, which implies that the plan regularity requirement for tunnel-form buildings in seismic codes may be too conservative. Moreover, it is concluded that using response modification factor equal to 5 can generally result in sufficient stability and adequate performance level under both design basis and maximum considered earthquake scenarios. [ABSTRACT FROM AUTHOR]

Due to their expected high seismic resistance, a significant number of tunnel formwork buildings have been built over the past few decades, especially in regions of high seismic hazard. However, only few real data analyses have been reported and are available so far. Different techniques, including real data analysis, numerical simulations, and their combination, are employed to investigate and compare their potentials for estimating different aspects of a tunnel formwork building. This study is based on data from a 16-story residential building in Istanbul, Turkey. The real data analysis of the building’s dynamic characteristics is based on both the vibrational (spectral analysis) and waveform (deconvolution interferometry) approaches, which yield information on the soil–structure system and the fixed-base building. For this purpose, dense ambient vibration/generated source measurements and earthquake recordings of both temporary and permanent networks are used. Furthermore, finite element analysis (FEA) of the building is carried out. The order of the first bending and torsional modes is reversed in the results of the numerical simulations compared to those from the real data. This can be attributed to the simplifications and assumptions made in the numerical simulations of tunnel formwork structures. It emphasizes the importance of analyzing real data for better constraining numerical simulations. Finally, the response of the building (synthetic seismograms) to a real data input is calculated using FEA. Deconvolved wavefields of synthetic and the real data are estimated. Despite the changed order of the modes, the deconvolved wavefields for both cases match very well. [ABSTRACT FROM AUTHOR]

This paper presents numerical simulations within the frame of the project SERA—AIMS (Seismic Testing of Adjacent Interacting Masonry Structures). The study includes blind pre-diction and post-diction stages. The former was developed before performing the shaking table tests at the laboratory facilities of LNEC (Lisbon), while the latter was carried out once the test results were known. For both, three-dimensional finite element models were prepared following a macro-modelling approach. The structure consisted of a half-scaled masonry aggregate composed by two units with different floor levels. Material properties used for the pre-diction model were based on preliminary tests previously provided to the participants. The masonry constitutive model used for the pre-diction study reproduced classical stress–strain envelope, whereas a more refined model was adopted for the post-diction. After eigenvalue analysis, incremental nonlinear time history analysis was performed under a unique sequence based on the given load protocol to account for damage accumulation. In the post-diction, the numerical model was calibrated on the data recorded during the shaking table tests and nonlinear dynamic analysis repeated under the recorded accelerogram sequence. The interaction between the two units was simulated through interface elements. Moreover, the timber floors were accounted following different strategies: not modelling or considering nonlinear wall-to-floor connections. Advantages and disadvantages are then analysed, comparing the pre-diction and post-diction results with the experimental data. Numerical results differ from the experimental outcomes regarding displacements and interface pounding, although a clear improvement is visible in the post-diction model. [ABSTRACT FROM AUTHOR]

In the paper the seismic response of different variants of the three-story reinforced concrete frame structure SPEAR is compared. The basic structure is representative of building practice before the adoption of seismic codes. This structure has been compared with four modified variants, which were designed partly or completely in accordance with the Eurocode family of standards. For seismic assessment the practice-oriented nonlinear N2 method was used. The results demonstrate the low seismic resistance of buildings designed for gravity loads only. On the other hand, the advantages of new standards are clearly apparent. By taking into account the requirements of Eurocode 8 it is possible to ensure adequate strength, stiffness and ductility. By means of capacity design it is possible to ensure a global plastic mechanism. All these characteristics contribute to the high seismic resistance of structures designed according to Eurocode 8 and to their satisfactory behaviour during earthquakes. [ABSTRACT FROM AUTHOR]

Within seismology, geology, civil and structural engineering, deep learning (DL), especially via generative adversarial networks (GANs), represents an innovative, engaging, and advantageous way to generate reliable synthetic data that represent actual samples' characteristics, providing a handy data augmentation tool. Indeed, in many practical applications, obtaining a significant number of high-quality information is demanding. Data augmentation is generally based on artificial intelligence (AI) and machine learning data-driven models. The DL GAN-based data augmentation approach for generating synthetic seismic signals revolutionized the current data augmentation paradigm. This study delivers a critical state-of-art review, explaining recent research into AI-based GAN synthetic generation of ground motion signals or seismic events, and also with a comprehensive insight into seismic-related geophysical studies. This study may be relevant, especially for the earth and planetary science, geology and seismology, oil and gas exploration, and on the other hand for assessing the seismic response of buildings and infrastructures, seismic detection tasks, and general structural and civil engineering applications. Furthermore, highlighting the strengths and limitations of the current studies on adversarial learning applied to seismology may help to guide research efforts in the next future toward the most promising directions. [ABSTRACT FROM AUTHOR]

Improving the seismic resistance of traditional buildings is essential for preserving cultural heritage and increasing their safety. This is especially important for old masonry buildings in Lisbon ('Pombalino', 'Gaioleiro' and 'Placa'), which are still used for housing and services. Taking this into account, this paper is focused on the seismic assessment of these three types of buildings. The buildings were modelled based on the equivalent frame model approach, their dynamic characteristics were determined and non-linear static (pushover) analyses were performed. Furthermore, for the seismic demand of Lisbon, the seismic performance of such building classes was defined and compared. Finally, with the aim of supporting seismic risk and loss estimation studies, a probabilistic assessment was carried out and the fragility curves for each building type derived. [ABSTRACT FROM AUTHOR]

Most of the buildings in Turkey constructed before 1999 Kocaeli and Duzce Earthquakes do not have sufficient seismic resistance due to construction errors and do not satisfy the recent Turkish Building Earthquake Code (2018) or its preceding versions. In Istanbul, the building stock consists of 1,116,300 buildings. Clearly, seismic safety assessment of this amount of buildings is not practically possible by code-based detailed assessment approaches, which generally assess the seismic performance of buildings in terms of pass or fail, rather than rank and classify/prioritize these buildings considering their seismic safety. Moreover, the probability of a catastrophic earthquake that could hit Istanbul is high. Therefore, to minimize casualties and economic losses, it is important to determine the most vulnerable existing buildings effectively in terms of cost and duration. Accordingly, Istanbul Metropolitan Municipality has started to evaluate the seismic safety of existing reinforced concrete buildings using the PERA2019 method considering the actual structural data collected on site. The buildings are then divided into 5 seismic risk classes from low-risk to very high-risk according to the computed seismic safety ratio. In this study, the reliability of the PERA2019 is evaluated by considering the predicted risk classes of another large group of actual buildings that have been subjected to actual earthquakes and experienced earthquake-induced damages in different extents. The comparative evaluation of actual seismic damages and predictions of PERA2019 showed clearly that the methodology has a sound ability to estimate the structural seismic performance of the investigated buildings. [ABSTRACT FROM AUTHOR]

Building with rammed earth has become increasingly popular in recent years because it is highly sustainable and has little environmental impact. More than half of the world's population lives in earthen houses, many of which are located in earthquake-prone areas such as Croatia. However, their seismic performance still needs to be researched, especially considering local construction techniques. One of the first steps in this process is the experimental testing of such walls. Four models of rammed earth walls were constructed using traditional local building techniques and experimentally tested under in-plane cyclic loading to investigate their seismic behaviour. The model walls were built using locally available soil material. The new particle size distribution envelope for determining the suitability of soil material for rammed earth construction was proposed for the first time. The building material was chosen according to the envelope. Moreover, walls were made using two different material compositions—i.e., natural soil from eastern Croatia and "man-made" soil with the addition of fine gravel. The main objective, the seismic performance of the RE walls, was evaluated in terms of their bearing capacity, behaviour after yielding, failure mode, stiffness degradation, initial elastic stiffness, and energy dissipation capacity. [ABSTRACT FROM AUTHOR]

The present paper employed the Applied Element Method (AEM) to investigate the damage patterns in high-strength concrete (HSC) frames under extreme loads. Unlike existing computational techniques, AEM offers a distinct advantage in accurately identifying structural damage in all stages of loading conditions. The research focuses on analysing the impact of displacement-controlled in-plane cyclic loads on single- and multi-storey reinforced concrete frames with and without infill walls. AEM analysis coincided with experimental results, theoretical predictions, and FEMA 356 code provisions, affirming a reliable examination of cyclic damage patterns. The study reveals distinct damage patterns, shedding light on infilled frames' superior in-plane lateral load resistance compared to bare frames. Interestingly, multi-storey frames with soft-storey configurations exhibited higher resistance to lateral loads than those with infilled walls due to premature collapse of HSC columns. The study highlights the crucial role of robust, strong infill walls in reinforcing slender HSC frames. The results provide valuable insights for designing resilient structures under extreme operating conditions, thus contributing to advancing structural engineering practices. [ABSTRACT FROM AUTHOR]

An effective assessment of the seismic risk of building stock is important for informing stakeholders and developing strategies to improve community seismic resilience. To address this need, a parametric pushover curve model for seismic performance assessment of building stock is introduced. The model employs twelve parameters for estimating the trilinear pushover curve. The models of these parameters are developed specifically for reinforced concrete and masonry buildings in Slovenia by focusing on the low level of knowledge about the building. Consequently, it can be used for preliminary studies of seismic performance assessment of building stock to raise awareness about seismic risk. To evaluate its efficacy, the model was applied to assess the seismic performance of the University of Ljubljana's building stock. Because of uncertainties arising from the lack of knowledge about the buildings and the associated assumptions, the results were interpreted relative to those obtained for a new building stock scenario. The case study revealed that the seismic capacity in terms of the limit state peak ground acceleration of the building stock is only half of what would be expected in the new building stock scenario, highlighting a significant seismic risk. These findings emphasise the need for systematic efforts to enhance the seismic safety of the building stock under consideration. Further research is recommended to explore the model's accuracy concerning the level of knowledge about the building, which will contribute to a better understanding of its applicability. [ABSTRACT FROM AUTHOR]

In engineering practice, creating window openings in partition infill walls is a common requirement for infilled frames. However, the intervention of infill walls may interrupt the desired cyclic behavior of the infilled frame, and worst yet, the inevitable window opening might further aggravate such negative interaction. To protect the openings from the detrimental multiple diagonal struts mechanism of the traditional infill wall with a window opening under lateral loadings, this research presents a novel infill wall system with a window opening for semi-rigid steel frames. Three half-scaled specimens are subjected to quasi-static cycle tests: a bare steel frame, a steel frame infilled with a traditional infill wall with a window opening, and a precast infill wall with a window opening and sliding joints in a steel frame. Experimental results show that the proposed infill system with a window opening can release adverse crack development or opening deformation of the window opening by mitigating the detrimental multiple diagonal struts effect in conventional infill walls with window openings under lateral loadings. In this way, the developed infilled frame exhibits similar cyclic behavior to the designed bare steel frame with higher energy dissipation capacity. Furthermore, parametric analysis results reveal that the friction factor of the sliding joints has a significant effect on enhancing the bearing capacity of the proposed infill system, while the change of opening sizes and locations of the window opening has negligible impact on the cyclic behavior of the developed infill system. [ABSTRACT FROM AUTHOR]

To comprehend the empirical seismic vulnerability capability of various typical structures in towns and suburbs, this study considers, as the research background, the structural damage data observation from the Mw 7.1 Yushu earthquake that occurred on 2010 April 14th in China. The proposed research activity sorts out the actual investigation data (7156 buildings) of five types of typical structures in towns and villages and establishes the vulnerability and seismic fragility evaluation model of a group of buildings considering multidimensional parameters by using the Chinese macroseismic intensity standard. Using spatial modal, numerical calculation, and regression analysis methods, an updated lognormal distribution vulnerability and resilience assessment model based on multidimensional quantitative parameters is performed. Based on the principle of the conditional probability and damage quantification model, an innovative model (domain, point cloud, curve, surface, matrix, and function) is established for regional vulnerability and seismic resilience assessment of typical group buildings. A logarithmic relationship model considering both the updated Chinese macroseismic intensity and three-dimensional composite peak ground acceleration as intensity measures is proposed, and an empirical vulnerability assessment model for typical rural buildings is established. The traditional average earthquake loss index calculation model is updated, and an innovative regional domain vulnerability assessment model is conducted. Taking the samples of various typical structures surveyed in the Yushu earthquake, regional group structure vulnerability domain comparison models of various structures are performed. Ultimately, depending on the typical damage characteristics of structures, the actual damage features and mechanisms of various structures are analysed. [ABSTRACT FROM AUTHOR]

Ordinary (customary) light gauge steel framing is a convenient construction technology; however, given the studs low axial capacity, it has been considered mainly for low-rise buildings in low seismicity regions. This paper investigates the boundaries of application of this type of steel framing (in moderate and high seismicity areas) by designing the structures of three representative 5, 7 and 10-storey buildings in order to examine their feasibility. The necessity of using built-up columns consisting of two or more sections is investigated. The axial capacity of studs is estimated by code-type analyses. The critical buckling stress is determined with well-known closed-form expressions; as they do not contemplate the flexibility of the screwed connections (in built-up sections), the obtained results are complemented with those of the finite strip method and generalized beam theory formulations. [ABSTRACT FROM AUTHOR]

Barcelona is in an area of low- to medium-seismicity and its earthquake vulnerability and risk has been assessed in different studies over the last 20 years. Most of these works have developed vulnerability models for the representative building classes of the city, trying to capture their main characteristics, and have been mostly represented through fragility curves. However, due to the lack of data for historical earthquake losses in the city, it has not been possible to validate, nor calibrate, any of these vulnerability models. In the absence of earthquake loss data, the objective of this paper is to compare the earthquake risk results of Barcelona, using common hazard and exposure datasets and different sets of vulnerability functions from previous studies to see how they rank compared with other locations with similar studies but more complete historical loss data. The results show large differences between the analysed vulnerability datasets, with some results that in our view tend to overestimate earthquake risk in Barcelona, and also allow identifying critical aspects that require future research. [ABSTRACT FROM AUTHOR]

Assessing the actual seismic economic losses of regional building portfolios is essential to quantify the seismic resilience of urban and rural areas. Various building clusters indicate different damage levels under real earthquakes of different intensities, which directly leads to apparent anomalies in the actual economic losses of various building portfolios. This paper proposes an economic loss assessment model for large-scale regional building portfolios, considering the damage probability matrices. The traditional empirical vulnerability quantification method is optimized and updated by combining the analysis methods of probability risk, reliability, macroseismic intensity, and instrument intensity. Five typical building sample sets (total survey area: 56,937.1893 × 104 m2) of 57 typical cataclysmic earthquakes that occurred in Yunnan Province, China, from 1993 to 2022 are collected and processed, and an updated fragility dataset is established. The calculation model considering empirical structural vulnerability and economic loss quantitative parameters is innovatively developed. Combined with the quantitative approaches of the multidimensional nonlinear fitting model and the established regional empirical structural vulnerability database, the seismic loss evaluation model of large-scale regional structures is established. Ultimately, the earthquake loss point cloud and matrix of typical building portfolios in the large-scale zone are developed using cloud analysis and the proposed seismic loss evaluation model. [ABSTRACT FROM AUTHOR]

In previous studies, the dynamic characteristics of a base-isolated structure on non-liquefied soil foundation have been investigated by some model tests. However, soil liquefaction can change the seismic responses of the base-isolated structure. In particular, due to the soil-structure interaction, the seismic-isolation layer of the structure is also bound to change the seismic responses of the pile foundation under the isolation layer, and then this also affect inversely the isolation performance of the isolated layer. However, this scientific problem has not been effectively studied. To investigate the seismic responses of a complex soil-pile-isolated structure interaction (SPISI) system after the soil foundation liquefied, a new shaking-table model test was designed. The test results were analyzed and compared with a series of previous model tests on isolated structures with different non-liquefied soil foundations. As results, after the soil foundation liquefied, severe swing responses of the isolated structure and pile cap were observed. Then, the seismic responses of the pile were also changed evidently by the SPISI and severely aggravated by the strong swing responses of the isolated structure. Meanwhile, the foundation liquefaction also significantly weakened the isolation performance of the lead-rubber bearing and even amplified the horizontal acceleration response of the isolated structure. Because of the above SPISI effects, the dynamic characteristics and response laws of the isolated structure on a liquefied soil foundation are not consistent with those of base-isolated structures on non-liquefied soil foundations. On the contrary, they are similar to those of a non-isolated structure on the general soil foundation. [ABSTRACT FROM AUTHOR]

The Eurocode 8—Part 4 approaches, per their December 2022 update, are presented for the design of acceleration-sensitive industrial ancillary components. The seismic performance of such nested and/or supported ancillary elements, namely mechanical and electrical equipment, machinery, vessels, etc. is critical for the safety and operability of an industrial facility in the aftermath of an earthquake. Of primary importance are the structural characteristics of the supporting structure and the supported component, pertaining to resonance, strength, and ductility, and whether these are known (and to what degree) during initial design and/or subsequent modifications and upgrades. Depending on the availability and reliability of information on the overall system, the Eurocode methods comprise (a) a detailed component/structure-specific design accounting for all pertinent component and building characteristics, equivalent to typical building design per Eurocode 8—Part 1–2, (b) a conservative approach where a blanket safety factor is applied when little or no such data is available, and (c) a ductile design founded on the novel concept of inserting a fuse of verified ductility and strength in the load path between the supporting structure and the ancillary element. All three methods are evaluated and compared on the basis of a case-study industrial structure, showing how an engineer can achieve economy without compromising safety under different levels of uncertainty. [ABSTRACT FROM AUTHOR]

Nepal is located in a highly active tectonic region of the Himalayan belt, one of the most severe earthquake prone areas of the world. Nepal is lying between the Indian and the Eurasian plate, which are moving continuously, resulting in frequent devastating earthquakes. Moreover, different authors state that the accumulated slip deficit (central seismic gap) is likely to produce large earthquakes in the future. Cultural heritage buildings and monuments are, therefore, at risk, and the eventual cultural loss in the consequence of an earthquake is incalculable. Post-seismic surveys of past earthquakes have shown the potential damage that unreinforced masonry structures, particularly Pagoda temples, may suffer in future earthquakes. Most of the Nepalese Pagoda temples, erected during XIV century, are considered non-engineered constructions that follow very simple rules and construction detailing in respect to seismic resistance requirements and, in some cases, without any concern for seismic action. Presently, conservation and restoration of Nepalese temples is one of the major concerns, since they are considered world heritage with universal value. The present paper is devoted to outline particular building characteristics of the UNESCO classified Nepalese Pagoda temples and the common structural fragilities, which may affect their seismic performance. Moreover, based on a parametric sensitivity analysis, structural weaknesses and fragilities of Pagoda temples were identified associated to the local and traditional construction techniques, detailing and common damages. [ABSTRACT FROM AUTHOR]

Fragility curves are constructed for a portfolio of prototype regular RC frame and wall-frame buildings designed and detailed to EC2 and EC8. The aim is to use EC8's own seismic performance assessment methods and criteria for existing buildings to evaluate how EC8 achieves its performance goals for new RC buildings. The overall conclusion is that these goals are met in a very consistent and uniform way across all types of buildings considered and their geometric or design parameters, except for RC walls of Ductility Class Medium, which may fail early in shear despite their design against it according to EC8. In fact, these walls do not perform much better than those of braced systems designed to EC2 alone. Therefore, wall shear seems to be an aspect in EC8 worth looking at again. Another finding is that the slenderness limits and the lateral bracing requirements of EC2 for 2nd-order effects under factored gravity loads place severe restrictions on the size of columns and walls, which, although ignored in ordinary seismic design practice, materially impact the outcome of the design and, to a smaller extent, the seismic fragilities of the building's members. Mixing in the same building columns with significantly different stiffness most often penalizes the more flexible ones and not the stiff, despite their smaller deformation capacities. Another finding is that the reduction in fragility from higher design peak ground accelerations is disproportionately low. Even buildings designed for gravity loads only, but in full accordance to EC2, possess substantial seismic resistance. [ABSTRACT FROM AUTHOR]

The heritage value of the mixed wood-masonry 18th century Pombalino buildings of downtown Lisbon is recognized both nationally and internationally. These buildings have a three-dimensional timber structure composed of wooden floors, stairs and walls intended to provide better seismic resistance and are enclosed by masonry walls. These interior wooden walls are called 'frontal' walls and their behaviour under cyclic loading has scarcely been studied. This report describes an experimental programme to determine the hysteretic behaviour of these 'frontal' walls, using static cyclic shear testing with imposed displacements. Two tests were conducted on two identical real-size walls. A new hysteretic model for the cyclic behaviour of these 'frontal' walls in Pombalino buildings is presented and calibrated based on the experimental results. The hysteresis model was developed based on a minimum number of path following rules that can reproduce the response of the wall tested under general monotonic or cyclic loading. The model is constructed using a series of exponential functions and linear functions. The nine parameters in this model capture the nonlinear hysteretic response of the wall. The hysteretic behaviour of such walls subjected to cyclic loading exhibit high nonlinear force-displacement responses and high ductility. [ABSTRACT FROM AUTHOR]

In this lecture the particularities of the seismic re-design of Monuments are discussed, related to their structural repair or strengthening. A Monument, besides its possible practical use and its economical value, requires a lot of other Values to be respected during its aseismic retrofitting, such as its aesthetic Form, the authenticity of its materials, etc. In order to respect these Values, the Engineer tends to minimize structural intervention-thus, violating social values such as the preservation of the Monument for future generations, the protection of human lifes, etc. An optimization is needed, and the lecture attempts to describe the necessary procedures to this end. On the other hand, emphasis is given to the particular difficulties in the determination of the resistance of masonry, as well as in the selection of suitable methods of Analysis, taking into account the specificity of each Monument. To this end, the lecture includes comments on monumentic Values and performance requirements, and emphasizes the need for an institutionalization of levels of importance, levels of visitability and of acceptable damage-levels for all monuments of each Country, as a basic input of aseismic design of monuments. Subsequently, criteria are given for the selection of methods of Analysis, and detailed comments are included about experimental investigations and strengths' determination. The final optimization procedure is then described, regarding the optimum seismic resistance level to be lent to a specific Monument. [ABSTRACT FROM AUTHOR]

The efficiency of improving the seismic resistance of old masonry buildings by means of seismic isolation and confining the structure with CFRP laminate strips has been investigated. Five models of a simple two-story brick masonry building with wooden floors without wall ties have been tested on the shaking table. The control model has been built directly on the foundation slab. The second model has been separated from it by a damp-proof course in the form of a PVC sheet placed in the bed-joint between the second and the third course, whereas the third model has been isolated by rubber isolators placed between the foundation slab and structural walls. Models four and five have been confined with CFRP laminate strips, simulating the wall ties placed horizontally and vertically at floor levels and corners of the building, respectively. One of the CFRP strengthened models has been placed on seismic isolators. Tests have shown that a simple PVC sheet damp-proof course cannot be considered as seismic isolator unless adequately designed. Tests have also shown that the isolators alone did not prevent the separation of the walls. However, both models confined with CFRP strips exhibited significantly improved seismic behavior. The models did not collapse even when subjected to significantly stronger shaking table motion than that resisted by the control model without wall ties. [ABSTRACT FROM AUTHOR]

Nonlinear static pushover analysis has been widely used for the seismic assessment of building structures. It can predict not only the base shear and deformation capacity of buildings but also the acceleration response of each floor. The floor acceleration is a significant design parameter for nonstructural components. The National Center for Research on Earthquake Engineering proposed a nonlinear analysis procedure, the Taiwan Earthquake Assessment for Structures by Pushover Analysis (TEASPA). This study predicts the capacity curve and acceleration response of each floor of a 10-story RC building using TEASPA. A shaking table test is conducted on the 10-story RC building in E-Defense in 2015. The predicted results are verified by the experimental data of the 10-story RC building. It is found that TEASPA can effectively and conservatively predict the story shear and deformation capacity of each floor of the tested building. The predicted deformation shape agrees well with the test results. In addition, this study proposes a procedure to estimate the acceleration demand values for each floor in accordance with the comparison of the test observations. [ABSTRACT FROM AUTHOR]

From November to December 2015, shaking table experiments were conducted on a ten-story reinforced-concrete building to acquire useful data for developing advanced technology for seismic structures and to investigate numerical analysis models. Two structural system types, which are a free-standing base-sliding and conventional seismic structure system, were used in this experiment; the second system was the same building as the first, but with a fixed base. The specimen building was subjected to Kobe earthquake motions with amplitudes of 10%, 25%, 50%, 100%, and 60%. The experimental results of the free-standing base-sliding and conventional seismic structures were compared, and regression analysis was conducted on the relationship between the seismic performance of each structure and seismic intensity. During the Kobe earthquake with 100% amplitude, the peak maximum inter-story drift ratio of the free-standing base-sliding was smaller than that of the conventional seismic structure. The acceleration response distributions for the free-standing base-sliding and conventional seismic structure system experiments with smaller amplitudes were similar to the distribution provided by the Architectural Institute of Japan. The shear force coefficient at the base-sliding surface did not fluctuate significantly, despite the increase in sliding velocity. According to the regression analysis results, the global rotation stiffness ratio and equivalent story stiffness ratio of each story may be related to the cumulative value of the peak velocity of the shaking table; further, the peak maximum inter-story drift ratio may be linearly related to the seismic intensity. [ABSTRACT FROM AUTHOR]

The capabilities of certain standard macro numerical models were evaluated by simulating a shaking table experiment that was performed on a full-scale ten-storey fixed-base building with a frame and dual structural system in two perpendicular directions (denoted as the frame and wall directions) at the largest shaking table in the E-Defense centre in Japan. The lumped plasticity model for columns and beams, the multiple-vertical-line-element model for walls and the scissors model for beam-column joints were evaluated. The results indicated that the experiment was simulated reasonably well. The most significant discrepancy was observed between the maximum drifts along the wall direction in the strongest cycle of the strongest test (calculated drift of 1.9% versus measured drift of 1.5%). In other cycles and tests, these differences were smaller. The calculated and measured maximum accelerations along the wall direction in the strongest test were 13.8 m/s2 and 13.5 m/s2, respectively. The discrepancy between the analysis and experiment results was smaller along the frame direction. The maximum calculated and measured drifts were 2.9% and 3.1%, respectively. The maximum calculated and measured accelerations were 15.8 m/s2 and 19.0 m/s2, respectively. In general, the standard input parameters were used in the evaluated models. However, some parameters required modifications, particularly when modelling weakly reinforced beam-column joints with substandard reinforcement that were considerably damaged. Their yielding rotation and near-collapse strength were, on average, reduced to 55% and 30% of the standard value, respectively. One of the most important parameters influencing the response was the effective width of the slabs, which was increased to the total span length for the highly loaded beams. The ratios of the strength, stiffness and amount of dissipated energy in the joints, beams and columns also significantly influenced the response. The adequate ratio of the dissipated energy was obtained by reducing the standard unloading stiffness in the beams and columns. The initial stiffness considerably influenced the response, particularly under weaker excitations. This stiffness was reduced threefold to account for various factors that typically reduce its value, which, among others, includes the influence of preceding tests on the same building with sliding foundations, as well as the assembly, transportation and handling of the specimen. [ABSTRACT FROM AUTHOR]

A base-rocking dual-core braced-frame (BRDC) system equipped with vertical buckling-restrained fuses (BRF) was developed to prevent the soft-story failure mechanism. The proposed system comprises two elastic cores connected by BRF between the floor levels. BRFs are used as replaceable fuses in this system to dissipate the input energy and reduce the seismic responses. The seismic performance of the proposed system was evaluated using a new time history analysis method called endurance time. The method was numerically applied in three structures with different heights, specifically 12, 15, and 18 stories. The truncated design spectra method was used to design the cores. The results show that the proposed system resolves both the problem of column uplifting and the large cross-section needed for post-tensioned cables in the rocking systems. [ABSTRACT FROM AUTHOR]

In order to contribute to the lack of statistical anomaly detection and sensitivity visualization of the response parameters from international seismic codes, this study presents a comparative analysis between multiple Chilean codes for the seismic design of reinforced concrete buildings. The seismic response and its similar implications to the US codes are studied from a model of a reinforced concrete building in the city of Viña del Mar, Chile. The first study case is the NCh433 Of.96 Mod.2009, the second case is the NCh433 Of.96 Mod.2009 + D.S. 117 and 118, and the third case is the NCh433 Of.96 Mod.2009 + D.S. 60 and 61. The results show that the seismic response does not present great differences, but they show noticeable dependencies between multiple parameters within the three study cases. The third case presents the most oversized values of the response parameters, which require a design against a higher base shear. An analysis of the bio-seismic profile is included, which is a procedure commonly used for buildings in Chile, and its indexes are analyzed with statistical models that provide an easy overview of the data structure. Additionally, a pier wall with an opening, and a pier with a T-shaped wall are selected, which present an increase in the amount of reinforcing steel from the first code case to the third, and then to the second code case. [ABSTRACT FROM AUTHOR]

In this study, debonded high-strength rebar (DHSR) is used to reinforce a concrete encased-and-filled steel tubular (CEFST) column, reducing residual deformation through high elastic self-centering (SC). The experimental results confirm that the CEFST column with DHSR has a strong SC capacity. Owing to the simple and low-cost technology, the advantages of the standard CEFST columns, the resilient CEFST column is an ideal option for constructing bridge columns. A bridge archetype with four spans and two-column bents is designed to compare seismic responses and post-earthquake reparability. The steel-bond slip due to debonding is described using the softening of Young's modulus of DHSR, which is used to simulate the seismic behaviors of the CEFST columns with DHSR. The applicability is verified by comparing the hysteretic behaviors between the experimental and predicted results. An incremental dynamic analysis of bridge archetypes is performed, based on 20 ground motions to accumulate a database for fragility analysis. The results show that the yield and failed lateral drifts of the CEFST bridge column with DHSR are larger than that of other types of CEFST bridge columns. The seismic and fragility analyses of the residual lateral drift results indicate that DHSR can greatly improve seismic safety and post-earthquake reparability. Further refinement of the predictions of the residual lateral drift based on the JRA and FEMA codes is required. [ABSTRACT FROM AUTHOR]

The concept of macroseismic intensity arose with the purpose of measuring the strength of an earthquake by the effects it causes on buildings, people, and domestic furnishings. From this perspective, buildings can be considered seismic sensors that record the shaking. Early scales were conceived at a time when buildings were mainly in masonry and therefore they could be used as markers of the intensity in case of earthquakes. Indeed, since they were fairly homogeneous, their level of damage could be considered as an indicator of the shaking level. In recent decades, the evolution of construction techniques have made the MCS scale unsuitable for damage assessment of buildings of various resistance. To overcome this problem the EMS-98 scale was designed. Because the MCS scale is still used in Italy, even in the presence of many reinforced concrete buildings, the purpose of this work is to show that the EMS-98 is the most suitable tool for assessing intensity as it is more consistent with the built environment. Theoretical and real intensity assessments, by both MCS and EMS-98, have been determined and compared, showing that nowadays intensity is a function of the vulnerability. MCS and EMS-98 would be comparable only when the building stock is composed of very vulnerable edifices (generally class A). Finally, thanks to the similarity of the two scales for old and vulnerable buildings, EMS-98 appears fully adequate to investigate historical earthquakes and represents a powerful tool to ensure continuity among earthquakes of different epochs. [ABSTRACT FROM AUTHOR]

The post-earthquake repairability of building structures is attracting attention as much as its safety properties. Concrete-filled steel tube (CFT) columns are widely used for high-rise buildings in earthquake areas due to their excellent seismic performance. In this paper, through experimental and numerical analysis, the seismic behavior and deformation performance of steel-reinforced CFT (RCFT) and X steel-reinforced CFT (XRCFT) columns using ultra-high-strength steel rebar are studied, and the influence of built-in steel bars on the seismic performance of traditional CFT columns is studied. A simple cumulative numerical analysis model is proposed to predict the seismic capacity curve of these built-in reinforced CFT columns. Experimental results verify that the use of ultra-high-strength steel bars greatly improves the resistance of the traditional CFT columns under an earthquake load. Their energy absorption properties are reduced, however, the buckling of the steel tubes was delayed and the peak deformation and the ductility of the columns all increase significantly. The model proposed is proven to reasonably predict the seismic capacity curves of RCFT and XRCFT columns. Compared with other cases, the ultra-high-strength steel bars can present a better-enhancing effect on the seismic performance of the long-span CFT columns dominated mainly by bending deformation. [ABSTRACT FROM AUTHOR]

To evaluate quantitatively the performance of earthquake-damaged structures, the damage distribution model (DDM) for damaged RC components based on fiber-based damage index (FDI) is developed. Firstly, 25 RC columns under cyclic loadings from the Pacific Earthquake Engineering Research Center Structural Performance Database (PEERSPD) are selected as the database to develop DDM. The material damage, including concrete material damage and steel bars material damage, is represented by FDI computed based on the stress–strain history of the material. The threshold of concrete regarding tensile failure and compressive failure are determined. Compared with the Park–Ang damage index, FDI is associated with the observed damage and can more accurately determine the damage displacement corresponding to four damage states. Furthermore, the damaged section is divided into five regions and five DDMs regarding four damage states corresponding to various quantiles are determined. The proposed DDM-50th is realized on six column specimens and is verified by the comparison of the responses between the damaged column model established based on DDM-50th with the experimental results. Furthermore, the properties of the skeleton curve of the damaged column established based on five DDMs are compared with experiment results. The DDM-84th is recommended to evaluate the post-earthquake performance of the RC structure. Moreover, the DDM-50th and DDM-90th are proposed to respectively evaluate the upper limit and lower limit post-earthquake performance of RC structure to obtain comprehensive results. In contrast, DDM-10th and DDM-16th, which are prone to dangerous results, are not recommended to evaluate the performance of RC structures. [ABSTRACT FROM AUTHOR]

The modern engineering approach to design of structures exposed to rare but intense earthquakes allows for their inelastic response. Models and tools to rapidly but accurately assess the extent of the inelastic response of the structure and control its performance are, therefore, essential. We develop a closed-form μ - R ∗ - S d , y relation between the ductility μ and the strength reduction factor R*, as well as its approximate inverse R*- μ -Sd,y relation, both functions of the SDOF oscillator yield displacement Sd,y, not its vibration period T. The fundamental vibration period of the structure varies during the iterative design process focused on modifying its strength. However, the yield displacement of the structure is practically invariant with respect to the strength of the structure, as it depends primarily on its geometry and material properties. We use these relations to formulate a constant yield displacement seismic design procedure and exemplify it. Noting the structure of the developed relations, we use dimensional analysis to formulate a version of the ductility-strength and strength-ductility relations that are dimensionless and independent of the seismic hazard intensity. These novel, dimensionless master relations are the μ -R*-H/B- κ ductility-strength and the R*- μ -H/B- κ strength-ductility relations. [ABSTRACT FROM AUTHOR]