India’s building stock remains highly vulnerable to seismic hazards, with conventional retrofitting strategies often limited in their applicability under varying earthquake intensities. This study investigates the effectiveness of the Yielding Brace System as a novel lateral load–resisting mechanism for improving the seismic resilience of mid-rise reinforced concrete buildings. A six-storey special moment-resisting frame was analysed in bare and Yielding Brace System (YBS)-integrated configurations using a comprehensive multi-analysis framework, including nonlinear static pushover analysis, nonlinear time history analysis, incremental dynamic analysis, and probabilistic fragility assessment. Results demonstrate that the incorporation of YBS significantly reduces inter-storey drift demands by 30–53% and increases normalized base shear capacity from 0.30 in the bare frame to 0.75 in the YBS frame. Ductility improved from 3.20 to 3.98, while residual drift ratios consistently remained below the FEMA P-58/ASCE 41 threshold of 0.5%. Fragility analysis revealed that the bare frame reached a 50% probability of collapse at 5.1 m/s², whereas the YBS-equipped frame required 15 m/s², highlighting a threefold enhancement in collapse safety margin. By reducing collapse probability and ensuring functional recovery after earthquakes, Yielding Brace System advances resilient infrastructure development and aligns with global sustainability objectives under UN SDG 9 (Infrastructure), SDG 11 (Sustainable Cities), and SDG 13 (Climate Action).

ABSTRACT Multi-story ancient wooden buildings — repositories of humanity’s architectural heritage — are highly vulnerable to seismic events owing to their complex configurations, material properties, and accumulated historical service effects. However, existing evaluation frameworks often fail to account for their unique structural characteristics and localized damage mechanisms. structural impacts. This study proposes four evaluation methodologies based on distinct engineering demand parameters (EDPs) and applies incremental dynamic analysis (IDA) to analyze their applicability through a case study of the Yingxian wooden pagoda. First, multi-level EDPs with four measures and six limit states are introduced. Second, IDA is employed to evaluate the exceedance probabilities across different limit states for each method, and the collapse margin ratio is adopted to quantify collapse resistance redundancy. The results reveal that the displacement-based global indices M1 and M2 can effectively detect weak stories and global stiffness degradation. Furthermore, the localized index M3 can capture joint degradation, while the component-level index M4 reflects structural redundancy. These multilevel EDPs enable a balanced assessment of cumulative damage and instantaneous failure mechanisms by integrating global-, local-, and component-level indicators, thereby supporting tailored evaluation strategies. This study advances the understanding of seismic response mechanisms in historic wooden buildings and promotes adaptive conservation strategies.

This study presents a displacement-based seismic fragility assessment of a high-rise reinforced cement concrete (RCC) building designed in compliance with Indian seismic codes. The selected structure, a G+19 ordinary moment-resisting frame (OMRF), is modelled in ETABS with realistic material properties, geometric irregularities, and design loads as per IS 875 and IS 1893 provisions. Seismic performance evaluation is conducted through Incremental Dynamic Analysis (IDA) using a suite of ground motion records from FEMA P695, scaled progressively to capture structural response from elastic behaviour to collapse. Peak Ground Acceleration (PGA) and spectral displacement serve as intensity measures, while inter-storey drift ratio is adopted as the primary damage parameter. Fragility curves are developed for key performance levels based on maximum allowable drift limits. The results reveal significant sensitivity of the high-rise frame to torsional irregularities, with drift concentration occurring predominantly in the mid-height storeys. Probabilistic fragility functions indicate that the probability of exceeding life safety limits increases sharply beyond a PGA of 0.25g. Comparison with previous studies confirms that displacement-based assessment provides a more accurate representation of seismic vulnerability than force-based methods, particularly for irregular high-rise configurations. The findings emphasize the necessity for enhanced design considerations, including stiffness regularity and supplemental damping systems, to improve resilience in Indian high-rise RCC buildings. This research contributes a performance-based seismic assessment framework adaptable for both new designs and retrofitting strategies in similar structural systems.

Due to their potential to reduce greenhouse gas emissions, light-frame timber buildings (LFTBs) are widely used in seismically active regions. However, their construction in these areas remains limited, primarily due to the high costs associated with continuous anchor tie systems (ATSs), which are required to withstand significant seismic forces. To address this challenge, frictional seismic isolation offers an alternative by enhancing seismic protection. Although frictional base isolation is an effective mitigation strategy, its performance can be compromised by extreme ground motions that induce large lateral displacements, resulting in impacts between the sliders and the perimeter protection ring. The effects of these internal lateral impacts on base-isolated LFTBs remain largely unexplored. To fill this knowledge gap, this study evaluates the collapse capacity of a set of base-isolated LFTBs representative of Chilean real estate developments. Nonlinear numerical models were developed in the OpenSeesPy platform to capture the nonlinear behavior of the superstructure, including the impact effects within the frictional isolation system. Incremental dynamic analyses following the FEMA P695 methodology were performed using subduction ground motions. Collapse margin ratios (CMRs) and fragility curves were derived to quantify seismic performance. Results indicate that frictional base-isolated LFTBs can achieve acceptable collapse safety without ATS, even with compact-size bearings. Code-conforming archetypes achieved CMRs ranging from 1.24 to 1.55, indicating sufficient safety margins. These findings support the cost-effective implementation of frictional base isolation in mid-rise timber construction for high-seismic regions.

ABSTRACTThe traditional structural finite element seismic response analysis process is often complex and time consuming. This study introduces a novel prediction methodology utilizing machine learning (ML) models to facilitate the rapid analysis of the seismic fragility of high‐rise shear wall structures. Three high‐rise shear wall structural models with varying story heights were designed in compliance with current Chinese codes. Ground motion records were selected as inputs based on the target response spectrum, and a sample database for ML was constructed using the incremental dynamic analysis (IDA) method. Key ground motion intensity and structural parameters were chosen as the characteristic inputs, with the maximum interstory drift angle (θmax) and maximum floor acceleration serving as the output parameters. Structural responses were predicted using both the multilayer perceptron (MLP) and random forest (RF) methods. The MLP model was further analyzed using SHapley Additive exPlanations (SHAP) to explore the contributions of each characteristic parameter to the structural response. The seismic fragility of the high‐rise shear wall structures was subsequently assessed. Results indicate that the RF‐based method provides higher accuracy in seismic fragility analysis compared with the MLP algorithm. Notably, peak ground acceleration (PGA) emerged as the most significant parameter impacting structural response. The proposed methodology effectively enables rapid seismic fragility analysis of high‐rise shear wall structures.

This paper presents the results of numerical investigations on seismic modification factors (R) for algerian box girder bridges (BGBs) with both equal and unequal pier heights, using a proposed pushover technique that incorporates torsional vibration modes. In the first part, the BGB referenced in a project by the Algerian Highway National Agency is selected to evaluate the components of the R-factor in the transverse direction. Conventional pushover analysis (CPA), employing the elastic first mode, uniform, and upper-bound lateral load patterns, as well as the proposed pushover technique, is conducted. The results of CPA and the proposed pushover technique for the reference BGB are examined in terms of R-factor components, including overstrength (Ω) and global ductility (R-µ), and are compared with those obtained using the incremental dynamic analysis (IDA) technique. The findings indicate strong agreement between the proposed pushover technique and the IDA technique.

Seismic vulnerability analysis of local prestressed concrete frame with varying partial prestressing ratio based on incremental dynamic analysis

With the continuous improvement of the prefabricated modular technology system, the prefabricated subway station structures are widely used in underground engineering projects. However, prefabricated subway stations in soft soil can suffer significant adverse effects under seismic action. In order to study the seismic performance of a prefabricated subway station, this work is based on an actual project of a subway station in soft soil. And the nonlinear static and dynamic coupling two-dimensional finite element models of cast-in-place structures (CIPs), assembly splicing structures (ASSs), and assembly monolithic structures (AMSs) are established, respectively. The soil-structure interaction is considered, and different peak ground accelerations (PGA) are selected for incremental dynamic analysis. The displacement response, internal force characteristics, and structural damage distribution for three structural forms are compared. The research results show that the inter-story displacement of the AMS is slightly greater than that of the CIP, while the inter-story displacement of the ASS is the largest. The CIP has the highest internal force in the middle column, the ASS has the lowest internal force in the middle column, and the AMS is between the two. The damage to the CIP is concentrated at the bottom of the middle column and sidewall. The AMS compression damage moves upward, but the tensile damage mode is similar to the CIP. The ASS can effectively reduce damage to the middle column and achieve redistribution of internal force. Further analysis shows that the joint splicing interface between cast-in-place and prefabricated components is the key to controlling the overall deformation and seismic performance of the structure. The research results can provide a theoretical basis for the seismic design optimization of subway stations in earthquake-prone areas.

ABSTRACTThis paper presents the application of the performance‐based plastic design (PBPD) method for designing a reinforced concrete (RC) dual special moment frame (SMF)‐structural wall system. An RC dual SMF‐structural wall system found in two 10‐story archetype buildings (buildings A and B) is examined and modeled. The buildings are assumed to be an office building built in Jakarta, Indonesia. The baseline buildings are designed based on the current codes prior to being redesigned using the PBPD method. The baseline and PBPD structures are subjected to extensive applications of nonlinear static (pushover) and dynamic (incremental dynamic involving 14 pairs of ground motion records) analyses. The plastic hinge distribution of PBPD structures based on both nonlinear static (pushover) and incremental dynamic analyses closely matches the plastic hinge distribution on the preselected yield mechanism assumed during preliminary design. In addition, the distribution of energy dissipation between frame‐wall is only slightly different from that determined in the preliminary design. The probability of collapse is evaluated using the methodology outlined in FEMA P‐695, where it is expressed as the adjusted collapse margin ratio (ACMR). The well‐designed building shall have ACMR higher than or equal to ACMR10%, which reflects that the maximum probability of collapse of a structure is not more than 10% when it is subjected to maximum considered earthquake (MCE) ground motions. The ACMR10% is 1.96, while the ACMRs for PBPD buildings A and B, respectively, are 2.48 and 2.31. On the other hand, the ACMRs for baseline buildings A and B are 1.60 and 1.29, respectively. Therefore, the PBPD method is appropriate for designing a 10‐story RC dual SMF‐structural wall system.

ABSTRACT This research investigates the seismic behavior of single-story reinforced concrete (RC) moment-resisting frame buildings with strength irregularity in plan due to variability in concrete compressive strength. The study aims to evaluate the influence of this kind of irregularity on the seismic performance of code-compliant RC structures. Field data on concrete strengths from RC buildings constructed in Tabriz, Iran, is utilized to define statistical parameters and create potential strength irregularity scenarios. The effects of strength deterioration and stiffness degradation are explicitly studied. Incremental dynamic analysis is employed to capture the non-linear response accurately. Fragility curves are developed to assess the probability of exceeding different damage states. This study highlights the critical role of incorporating cyclic deterioration for accurate seismic performance predictions, especially at higher damage levels. Failing to account for cyclic deterioration can lead to overestimations of the spectral acceleration (up to 36%) at collapse. While strength irregularity has minimal influence on behavior at moderate drift levels, its impact becomes significant in the larger non-linear deformation range, with a potential reduction in the seismic collapse capacity up to 14% compared to the reference regular structure. The findings suggest that a higher number of low-strength load-bearing members exacerbate reductions in collapse capacity. Additionally, higher standard deviations in concrete compressive strength amplify torsion in structures with strength irregularities, observed at both design-basis earthquake (DBE) and maximum considered earthquake (MCE) levels.

To accurately assess the seismic damage of high-rise structures under long-period ground motions (LPGMs), a 36-story SRC frame-RC core tube high-rise structure was designed. Twelve groups of LPGMs and twelve groups of ordinary ground motions (OGMs) were selected and bidirectionally input into the structure. The spectral acceleration S90c considering the effect of higher-order modes was adopted as the intensity measure (IM) of ground motions, and the maximum inter-story drift angle θmax under bidirectional ground motions was taken as the engineering demand parameter (EDP). Structural Incremental Dynamic Analysis (IDA) was conducted, the structural vulnerability was investigated, and seismic vulnerability curves, damage state probability curves, vulnerability index curves, as well as the probabilities of exceeding performance levels and vulnerability index of the structure during 8-degree frequent, design, and rare earthquakes were obtained, respectively. The results indicate that structural damage is significantly aggravated under LPGMs, and the exceeding probabilities for all performance levels are greater than those under OGMs, failing to meet the seismic fortification target specified in the code. When encountering an 8-degree frequent earthquake, the structure is in a moderate or severe damage state under LPGMs and is basically intact or in a slight damage state under OGMs. When encountering an 8-degree design earthquake, the structure is in a severe damage or near-collapse state under LPGMs and is in a moderate damage state under OGMs. When encountering an 8-degree rare earthquake, the structure is in a near-collapse state under LPGMs and in a severe damage state under OGMs.

Double-layer diagrid structures, as a novel structural system, have been shown to be more suitable than conventional diagrid structures in meeting lateral stiffness and strength requirements. However, current research on their seismic performance remains limited, particularly in comparison to conventional diagrid structures. This study aims to evaluate the seismic fragility and energy dissipation performance of double-layer diagrid structures. First, finite element models of both double-layer and conventional diagrid structures were developed under equal steel consumption constraints and in accordance with Chinese seismic design codes. Then, the seismic energy dissipation characteristics of the two structural systems were analyzed through incremental dynamic analysis (IDA). In addition, based on the IDA results, seismic fragility curves were constructed for multiple damage states, and the effect of the inner tube’s diagonal angle on structural fragility was investigated. The results demonstrate that the double-layer diagrid structure exhibits lower failure probabilities and more efficient energy dissipation across all considered damage states. Moreover, as the diagonal angle of the inner tube’s members decreases from 90° to 62°, the failure probability is further reduced.

ABSTRACTHigh‐rise buildings are particularly susceptible to structural damage during long‐period ground motions because of resonance effects. This study employs seismic fragility analysis through incremental dynamic analysis (IDA) to evaluate the extent of damage in such structures under long‐period excitations. A notable contribution of this research is the incorporation of probabilistic vulnerability assessment across multiple damage states, offering a comprehensive insight into the seismic performance of reinforced concrete (RC) frame‐core buildings with hybrid coupled shear walls. Three structural models, 15‐, 25‐, and 35‐story buildings with identical architectural configurations, were analyzed using Perform‐3D software. The findings reveal a marked increase in seismic vulnerability under long‐period ground motions. As structural damage progresses from slight to moderate, extensive, and ultimately complete, the difference in fragility between long‐ and short‐period excitations becomes increasingly evident. Notably, at the complete damage state, the median seismic fragility capacity under long‐period excitations decreases by approximately 60%, underscoring the significant adverse effect of such excitations on the seismic performance of high‐rise buildings.

Scaling wind loads for incremental dynamic analysis applications

Abstrak Struktur jembatan beton bertulang eksisting yang direncanakan berdasarkan peraturan lama umumnya belum mempertimbangkan konsep perencanaan tahan gempa dan belum mengaplikasikan detailing seismik yang memadai. Hal ini menjadi perhatian bagi jembatan eksisting dengan kolom pendek yang memiliki aspek rasio (a/h) di bawah 2.5 dan berpotensi mengalami mekanisme keruntuhan geser atau geser-lentur. Mekanisme keruntuhan tersebut mengakibatkan performa struktur jembatan akibat gempa memiliki tingkat ketidakpastian yang tinggi. Analisis kerentanan seismik pada struktur jembatan eksisting dapat dilakukan dengan mengembangkan kurva kerentanan menggunakan incremental dynamic non-linear time history analysis yang mampu menghasilkan nilai probabilitas kerusakan pada berbagai intensitas gempa. Penelitian terdahulu umumnya mengembangkan kurva kerentanan berdasarkan idealisasi perilaku sendi plastis pada kolom jembatan yang mengalami mekanisme keruntuhan lentur akibat beban gempa. Studi ini menyampaikan tinjauan terkini (state-of-the-art) yang meliputi penelitian struktur jembatan beton bertulang dengan kolom pendek, khususnya yang perilaku keruntuhannya tidak didominasi oleh mekanisme lentur. Tinjauan ini juga mengusulkan kerangka kerja untuk penilaian risiko seismik dan pengembangan kurva kerentanan yang lebih sesuai untuk struktur jembatan dengan kolom pendek. Hasil tinjauan ini dapat memberikan gambaran yang lebih jelas mengenai risiko seismik yang dihadapi oleh jembatan dengan kolom pendek, serta menunjukkan potensi penelitian lanjutan yang dapat dilakukan untuk pengembangan kurva kerentanan yang lebih akurat dan relevan. Kata-kata Kunci: Analisis kerentanan seismik, jembatan beton bertulang eksisting, kolom pendek, kurva kerentanan, mekanisme keruntuhan geser Abstract Existing reinforced concrete bridge structures designed based on older regulations often do not consider seismic design concepts and lack adequate seismic detailing. This issue is particularly concerning for existing bridges with short columns and aspect ratio (a/h) below 2.5, which has the potential of shear or flexural-shear failure mechanisms. These failure mechanisms result in a high level of uncertainty in the seismic performance of bridge structures.Seismic fragility analysis of existing bridge structures can be performed by developing fragility curves using the incremental dynamic non-linear time history analysis method, which is capable of providing damage probability for various levels of seismic intensity. Previous studies typically developed fragility curves based on idealized plastic hinge behavior in bridge columns subjected to flexural failure mechanisms.This study presents a state-of-the-art review of reinforced concrete bridge structures with short columns, especially those whose failure behavior are not dominated by flexure mechanism. This review also proposes a framework for seismic risk assessment and for the development of more suitable fragility curves for bridge structures with short columns.The findings of this study can provide an understanding of the seismic risk in bridges with short columns, while also highlighting the potential for future research to develop more accurate and relevant fragility curves. Keywords: Seismic fragility analysis, existing reinforced concrete bridges, short columns, fragility curves, shear failure mechanisms

Corrosion can accelerate the deterioration of the mechanical properties of steel structures. However, few studies have systematically evaluated its impact on seismic performance, particularly with respect to seismic economic losses. In this paper, the seismic fragility and loss assessment of a multi-story steel frame with viscous dampers (SFVD) building are investigated through experimental and numerical analysis. Based on corrosion and tensile test results, OpenSees software 3.3.0 was used to model the SFVD, and the effect of corrosion on the seismic fragility was evaluated via incremental dynamic analysis (IDA). Then, the economic losses of the SFVD during different seismic intensities were assessed at various corrosion times based on fragility analysis. The results show that as the corrosion time increases, the mass and cross-section loss rate of steel increase, causing a decrease in mechanical property indices, and theprobability of exceedance of the SFVD in the limit state increases gradually with increasing corrosion time, with an especially significant impact on the collapse prevention (CP) state. Furthermore, the economic loss assessment based on fragility curves indicates that the economic loss increases with corrosion time. Thus, the aim of this paper is to provide guidance for the seismic design and risk management of steel frame buildings in coastal regions throughout their life cycle.

Reinforced concrete (rc) beams are significant elements which are designed to resist shear, bending and torsional forces. However, sudden impact loads whose effects may reach very high values in a short span of time are ignored in the design phase. So, rc beams with insufficient stirrups exhibit reduced shear capacity, making them vulnerable to impact loads, which generate high strain rates and rapid stress distribution. This study aims to investigate the impact effect on rc beams having two different stirrup configurations. As, carbon fibre reinforced polymer (cfrp) has been widely used to strengthen the structural elements in recent years, rc beams are strengthened by cfrp strips under impact loading. Non-linear incremental dynamic analysis is performed by Abaqus finite elements analysis software. Acceleration, displacement and impact load values are obtained for the first drop of the loading hammer from the software. These values are exhibited by time dependent graphs. In addition, fracture patterns of the rc beams are visually presented. The analysis outputs are evaluated, and suggestions are proposed in the end.

Historic masonry towers represent a significant part of the cultural heritage, which is often subject to retrofitting for preservation purposes. Due to the poor quality of the mortar, if present at all, the connection of existing towers to the foundation is generally such that it cannot ensure their monolithic behaviour under seismic action. When choosing a retrofitting technique, engineers often find themselves in a dilemma, whether to strengthen the connection between the tower and the foundation in order to enable the transfer of bending moments from the tower to the foundation due to seismic action, or to leave the towers freely rested on the foundation in order to enable the rocking motion mechanism. The aim of this paper was to investigate how the connection between the tower and the foundation affects the seismic resistance of masonry towers. For this purpose, a series of numerical analyses were performed on 2D numerical models that were created based on the geometry of five towers from the Italian region. In these numerical analyses, each of the towers is subjected to an incremental dynamic analysis in time for the case that it is freely supported on the base and for the case that it is freely rested base. The numerical analyses showed that: (i) unretrofitted towers have relatively low seismic resistance and rocking mechanisms cannot be realised to a significant extent; (ii) retrofitted masonry towers resting freely on the base have a significantly higher seismic resistance compared to the same towers connected to the base due to the rocking motion mechanism. The conclusions drawn on the basis of the conducted studies can serve engineers when choosing a technique for strengthening masonry towers.

This paper aims to investigate the feasibility of machine learning methods for the vulnerability assessment of buildings and structures. Traditionally, the seismic performance of buildings and structures is determined through a non-linear time–history analysis, which is an accurate but time-consuming process. As an alternative, structural responses of buildings under earthquakes can be obtained using well-trained machine learning models. In the current study, machine learning models for the damage classification of RC buildings are developed using the datasets generated from numerous incremental dynamic analyses. A variety of earthquake and structural parameters are considered as input parameters, while damage levels based on the maximum inter-story drift ratio are selected as the output. The performance and effectiveness of several machine learning algorithms, including ensemble methods and artificial neural networks, are investigated. The importance of different input parameters is studied. The results reveal that well-prepared machine learning models are also capable of predicting damage levels with an adequate level of accuracy and minimal computational effort. In this study, the XGBoost method generally outperforms the other algorithms, with the highest accuracy and generalizability. Simplified prediction models are also developed for preliminary estimation using the selected input parameters for practical usage.

ABSTRACT Within the context of performance-based seismic engineering, the categorization of damage levels in fragility analysis often depends on the use of limit state thresholds. Nevertheless, the implementation of fragility analysis in practice may be rather complex since the growth of damage levels in hydraulic tunnels (HTs) is a continuous and transitional process, with fuzzy thresholds between neighboring damage states. In addition, the uncertainty related to the random seismic ground motions (SGMs), input angles, and material parameters may further exacerbate the discretization of the probability of damage states of HTs. Apparently, this contribution of the uncertainties and fuzziness should be revealed in structural performance evaluation. This paper extends the traditional framework for underground structure vulnerability analysis by proposing a method that considers both coupled uncertainties and the fuzziness of damage thresholds. The nonlinear rock-structure-fluid interaction analysis model is established for hydraulic tunnels, employing the generalized F-discrepancy point selection method to select random parameter points for generating artificial seismic motions through the spectral representation method, as well as random points for rock mass parameters. Subsequently, 230 artificial SGMs obtained from the spectral representation method are transformed and amplitude-adjusted using the oblique incident SV wave equivalent node force input method, serving as input seismic loads for nonlinear incremental dynamic analysis. Different membership functions are introduced to calculate the fuzzy failure probabilities for various damage states and seismic intensity levels. The proposed method enables the establishment of vulnerability curves for hydraulic tunnels, considering the fuzziness of damage thresholds and the randomness of seismic events. Analysis results demonstrate that the vulnerability curves obtained through the fuzzy evaluation method tend to be more conservative, prioritizing safety. Incorporating the fuzziness of damage thresholds increases the dispersion of the seismic vulnerability curves for hydraulic tunnels. Additionally, the choice of membership function type and fuzzy interval significantly influences the results of fuzzy seismic vulnerability analysis, emphasizing the importance of judiciously selecting appropriate membership functions and fuzzy intervals.