Bulletin of Earthquake Engineering最新文献

Past earthquakes have shown that reinforced concrete (RC) wall buildings are vulnerable to seismic damage. Identifying vulnerable buildings before future events enable the implementation of prevention strategies, such as retrofitting vulnerable structures. Assessing the seismic vulnerability of a large building stock is complex, and a rapid and effective evaluation is necessary to identify vulnerable buildings. Different methods have been proposed to evaluate the seismic vulnerability of buildings, ranging from complex analytical methods to simplified empirical methods that rely on the statistical treatment of observed damage after past earthquakes to calculate seismic indices. However, limited studies have been conducted to relate seismic indices to observed damage for Chilean buildings. The main objective of this research is to evaluate seismic indices to assess the seismic vulnerability of RC wall buildings using empirical data from the 2010 Maule earthquake. A database of 158 undamaged buildings and 30 damaged buildings following the 2010 Maule earthquake is considered. For each building, three capacity-based indices, two demand-based indices, and six demand-to-capacity indices are calculated. The demand-based indices are calculated using both the actual seismic demand and the seismic design demand. The ability of each seismic index to identify undamaged and damaged buildings is quantified using Receiver Operating Characteristic (ROC) analysis. Results suggest that capacity-based indices alone are not adequate to identify damaged buildings, while demand-based and demand-to-capacity based indices are more accurate at identifying damaged buildings. Although demand-based indices using seismic design demand are less accurate than those using the actual seismic demand, they remain practical when detailed seismic data is unavailable.

The present study aims to identify the optimal criteria for the Normalization Measure (NM) and Intensity Measure (IM) in the two-criteria scaling process of earthquake Ground Motions (GMs) to reduce uncertainty in the development of Probabilistic Seismic Demand Models (PSDMs) for more reliable seismic risk assessment. For this purpose, five 2-, 4-, 8-, 12-, and 20-story steel buildings with a seismic force-resisting system consisting of perimeter Special Moment-resisting Frames (SMFs) located in Los Angeles, California, are selected as the case study. Four sets of GMs including 160 real GMs with mid to large magnitudes at near to moderate distances are selected from Baker’s GM database. The maximum values of transient and residual inter-story drift ratios and peak floor accelerations are considered as Engineering Demand Parameters (EDPs). A total of 85 potential candidates for selecting suitable NM and IM are investigated, categorized into four groups: (I) acceleration-related, (II) velocity-related, (III) displacement-related, and (IV) hybrid criteria. Accordingly, each set of GMs is normalized and scaled with 85 × 85 different combinations for NM and IM. Then, PSDMs for each investigated building are developed using Incremental Dynamic Analysis (IDA) on 2D nonlinear frame models under the scaled GM sets. The developed PSDMs with different NMs are employed for probabilistic seismic risk analysis and the estimation of seismic demand hazard curves. The optimal criteria for developing PSDMs are identified based on efficiency, practicality, proficiency, sufficiency, and reliable seismic risk assessment. The obtained results reveal the high sensitivity of the optimal NM to the building vibration period, the selected set of GMs, and the EDP under study. For instance, while Peak Ground Acceleration (PGA) is the optimal NM for estimating the risk of the acceleration response parameter, a unique criterion cannot be proposed for the transient and residual drift response parameters that would perform optimally under most conditions; however, I_Np is the best NM for most short-period (2-story) SMFs, and Sv_avg and MVSI are the two superior NMs for most long-period (4- to 20-story) ones. This study provides valuable insights into the impact of the mentioned factors on the selection of the optimal criteria.

Sustainable structures or structural components as one of the frontiers in civil engineering can solve the problem of construction and demolition waste and also enhance the reuse of structural components at the end of their service life or after damage. In terms of sustainable assessment, steel-concrete composite beams with or without novel demountable shear connectors were performed in this work. Structural configuration and mechanical properties of proposed sustainable steel-concrete composite beams were firstly presented and then the nonlinear analysis of this composite beams using the Abaqus software was validated. Three specimens with different types of shear connectors were designed and tested under two-point loading to investigate the flexural behavior and deconstructability. Results from this research showed that these composite beams exhibited a flexure-shear or flexural behavior, presenting the typical failure modes of yielding of steel beam, slab concrete split or concrete crushing of plug. Compared to that of traditional composite beam with embedded welded bolts, specimens with demountable shear bolts and demountable shear connections experienced reduced initial flexural stiffness (about 29.8% and 37.2%), yield strength (by about 18.3% and 32.1%) and ultimate strength (about 12.9% and 24.9%) due to the relative slip between the steel beam and precast concrete slab, respectively. Whereas these of composite beams developed a better deformation capacity and ductility coefficient. Additionally, sustainable steel-concrete composite beam with demountable shear connections could easily allow for easy installment and disassemble to achieve the recycle of these structural members and also replacement with new plugs to permit a quick seismic rehabilitation after earthquake. Finally, some suggestions of this sustainable composite beam and demountable shear connections were proposed to provide references for the design in practice.

Reinforced concrete (RC) wall buildings are multi-storey structures comprising several modes of response that contribute to both the displacement-based and force-based demands acting on them during seismic shaking. This research investigates how code-specified methods for selecting ground motion records affect this response, with particular attention to higher-mode contributions. The study contrasts two target spectra: the uniform hazard spectrum (UHS) and the conditional spectrum (CS), both now permitted in the upcoming Eurocode 8 revision. It examines the influence of their choice for several shear wall buildings designed using Eurocode 8 (EC8). By assessing record selection strategies, including UHS alone and different CS with conditional periods beyond the primary mode, T₁, impacts on engineering demand parameters (EDPs) such as peak-storey drift, wall shear demand, and overturning moment are quantified. The findings indicate that the UHS approach generally leads a more conservative higher structural demand estimate across all EDPs, which is not always very cost-effective. Not surprisingly, using the more advanced CS approach tends to yield much lower demands, but is found to be heavily dependent on the conditioning criteria used. While drift demands can be well-represented when conditioning to the first mode period, CS(Sa(T₁)), EDPs such as shear forces and bending moments can be severely underestimated. More critically, when other conditional selection strategies are used (e.g., CS(Sa(T₂)), CS(Sa(T₃)), etc.), these EDPs increase notably, which could lead to uncon servative designs. This study emphasises the importance of understanding the trade-offs between the presumed increase in accuracy when using the CS versus the UHS for RC wall buildings. It is also an important clarification for the next generation of Eurocode 8 that engineers must be aware of.

The use of non-ergodic approaches for calibrating ground-motion prediction models is increasingly well established in the seismological and engineering literature. Specifically, the residuals (logarithmic difference between observed and predicted intensity measures) obtained from the calibration of a parametric model are decomposed to identify repeatable effects related to event, station and any other recurring properties (e.g. source and propagation effects). For the empirical estimation of the site effect, we refer to the repeatable station term, usually called δS2S (site-to-site), which measures the systematic deviation of seismic motion at a station from a reference ground motion prediction for that site category. In order to obtain an amplification function from δS2S estimates, the prediction of a rock site, real or modeled on the basis of a Ground Motion Model, can be taken as a reference prediction. In this work, we discuss our experience in estimating empirical amplification functions from δS2S of permanent and temporary recording stations in Italy, highlighting limitations and advantages of this approach. The results are also discussed in the perspective of the estimation of the amplification factors, useful for the seismic microzonation studies. The values of δS2S (with associated aleatory uncertainty) are published on the ITACA (ITalian ACcelerometric Archive) web page for 916 recording stations for PGA, PGV, 36 ordinates of the acceleration response spectrum (damping 5%) in the range T = 0.01–10 s.

Recent seismic events in Turkey, as well as in Croatia and Bosnia and Herzegovina, have underscored the region’s vulnerability to earthquakes and the need for comprehensive seismic risk assessments. Determining seismic risk requires the integration of three key components: seismic hazard data, structural vulnerability assessments, and population exposure analysis. However, accurately conducting structural vulnerability assessments depends on the identification of building typologies and the development of a corresponding database. This study addresses the lack of a standardized building typology for residential structures in BiH, a critical component for accurate seismic vulnerability evaluations. A key contribution of this study is the development of a residential building classification system, considering historical construction practices, regulatory frameworks and standards, and regional characteristics. Additionally, thermal imaging technology was utilized to validate construction systems, improving the accuracy of structural assessments. The findings emphasize the importance of aligning local typologies with broader regional frameworks while addressing BiH’s unique architectural landscape. The study contributes to national disaster risk management efforts by proposing a standardized exposure model aligned with European guidelines. Future research should expand the building typology database to include commercial and public structures, further enhancing seismic risk mitigation strategies.

This study experimentally investigates the flexural performance of heat-cured low-calcium fly ash-based geopolymer concrete (GPC) beams reinforced with ribbed steel bars, focusing on the effects of reinforcement ratio, alkaline activator concentration (SS/SH), and curing regime. Fifteen full-scale beams, including twelve GPC and three OPC specimens, were tested under four-point loading to evaluate load-deflection and moment-curvature behavior. Despite a lower compressive elastic modulus, the results showed that GPC beams exhibited comparable or superior cracking and ultimate moment capacities relative to OPC beams. Increasing the reinforcement ratio enhanced load capacity but reduced ductility in both systems, with GPC beams showing more brittle post-yield behavior. Numerical models based on OPC parameters were developed in SAP2000 to compare with experimental GPC moment-curvature data, revealing good agreement in the linear range but notable differences in post-yield response. The study also examined the microstructure of failed GPC beams via SEM, XRD, and EDX analyses to correlate matrix morphology with mechanical behavior. Finally, moment capacities calculated according to ACI 318 and TS 500 provided conservative estimates, supporting the safe applicability of current design codes to heat-cured GPC beams. These findings demonstrate that GPC, when properly proportioned and cured, is a viable structural alternative to OPC for reinforced concrete members.

The ongoing revision of Eurocode 8 includes updates encompassing new ductility classifications, limits on damage control, conditions for local ductility, and corresponding detailing guidelines. It is crucial to thoroughly examine and compare these revisions with the existing provisions of Eurocode 8. The present research examines structural behaviour factors (q) for varying strut inclination angles (45° and 22°) and compares them against prEN 1998-1-2:2023 recommendations. Findings reveal consistent overperformance, highlighting the conservative estimations for structural redundancy offered by prEN 1998-1-2:2023. Plastic hinge lengths obtained through nonlinear analysis and FprEN 1998-1-1:2024 calculations are compared, showcasing conservative estimations prioritising safety. Observations indicate distinct trends in tension shift (a_l) and critical height (h_cr) compared to plastic hinge length (l_pl), aligning with conservative approaches outlined in EN 1998–1:2004 and prEN 1998-1-2:2023. Additionally, the observed shear magnification factors (ɛ) may indicate a potential overestimation of shear forces attributed to the amplified effect of higher modes in the inelastic range combined with flexural overstrength.

Seismic fragility functions for non-ductile and limited ductile RC walls under in-plane loading scenarios are presented in this paper. In the absence of comprehensive experimental studies, a hybrid approach was adopted, in which the experimental data available from the literature and numerical data generated in this study were combined to establish the fragility functions. An experimental database was developed for non-ductile (with single layer of reinforcement) and limited ductile walls (double layer of reinforcement). Gaps in the RC wall datasets were identified in terms of missing aspect, slenderness and compression stress ratios for various concrete strengths, which were then analysed through a numerical approach. A macro element modelling concept of analysing RC wall was developed by incorporating plastic-hinge formation, compression crushing, shear failure, bond slip and bar rupture as they are the common failure characteristics of non-ductile and limited ductile walls. Three sets of damage states were defined according to the failure sequence that corresponded to the in-plane load-displacement responses of the analysed RC walls. The established fragility functions revealed that the non-ductile RC walls are more vulnerable under in-plane loading than the limited ductile RC walls. In general, the probability of exceedance to ultimate damage state was about 57 to 77% higher in the non-ductile walls than limited ductile walls. The fragility functions established through this study can be used for vulnerability and loss assessments of buildings comprised of these RC walling systems.

For Eurocode_8 as well as for other similar design standards, acceptance criteria are based on the concept of ductility capacity of structures or structural elements. However, in the process of Eurocode_8 generation, an issue was raised because the concept is not adequate for rigid-plastic behaviour, as exhibited by some ancillary elements. Consequently, a specific formula was introduced in the code to deal with this situation. The purpose of this communication is to present the scientific background of this formula. In a first step, the response of a sliding block, with Coulomb friction model, on a support animated with a harmonic motion is considered. Three regimes of response are identified, designated by stick regime, stick-slip regime (sliding phases separated by sicking phases), and slip-slip regime. Considering a non-dimensional input motion level, (lambda ), with (lambda = 1) at the transition between stick and stick-slip regimes, it is analytically established that the slip-slip regime is attained for ({lambda _1} = 1.862). Concurrently, a non-dimensional sliding (H_{text{ }}left( lambda right)) is introduced, an expression of it established for (lambda < {lambda _1}), and turned into the Eurocode_8 formula. In a second step, the same approach is applied, considering a set of 100 natural accelerograms. For every of them, the friction coefficient is calibrated so that the stick-slip regimes is attained. Then, (lambda _1^0) is the amplification factor that should be applied on the input motion so that the slip-slip regime is attained. Concurrently, an expression of the induced non-dimensional sliding, (H_{text{ }}^0left( lambda right)), is established. In a third step, the same approach applies with seismic input motions transferred to floors 2 and 5 of a 5-storey structure. Corresponding (lambda _1^2) and (lambda _1^5) values are identified as well as non-dimensional sliding (H_{text{ }}^2left( lambda right)) and (H_{text{ }}^5left( lambda right)). Based on steps 2 and 3 outputs, it is eventually concluded that the Eurocode_8 formula need not being amended.