Bulletin of Earthquake Engineering最新文献

This study evaluates the seismic performance of prefabricated reinforced concrete industrial structures following the February 6, 2023, Kahramanmaraş earthquakes. A total of 595 industrial structures located in Organized Industrial Zones in Kahramanmaraş province were evaluated in terms of post-earthquake damage data officially obtained from the Republic of Türkiye Ministry of Environment, Urbanization and Climate Change. The results indicate that approximately 20% of the industrial structure was severely damaged or collapsed. In the assessments conducted by local municipalities on 96 incomplete prefabricated industrial structures, approximately 13% were found to have sustained heavy damage. The field observations showed that the damage was largely due to inadequacies in the design and manufacturing processes, incompatibilities between project design and field applications, and deficiencies in critical joint details. Especially, the hinged connections at the column-to-rafter beam and column-to-foundation joints are one of the most sensitive points against earthquakes and have played a decisive role in structural damage. The changes in natural vibration periods were assessed through numerical analyses performed in SAP2000 for nine moderately damaged prefabricated industrial buildings examined under three different scenarios: undamaged, damaged, and retrofitted conditions. Findings strongly advocate for revisions in seismic code provisions, strengthened quality control in construction practices, and the adoption of performance-based design approaches for prefabricated systems. This study provides critical empirical evidence to inform future seismic design guidelines and enhance the resilience of industrial facilities against large-magnitude earthquakes.

Passive cooling systems (PCS) are installed in third-generation nuclear power plants (NPP). The mass of the water tank constitutes a non-negligible portion of the total system mass. Existing studies demonstrated that PCS tanks have remarkable influences on the seismic response of NPP. However, the influence mechanisms are not fully understood due to the lack of experimental testing. Through numerical analysis and real-time hybrid simulation, this work investigates the influence of the PCS mass and liquid sloshing on the horizontal seismic response of NPP, respectively. The findings revealed that the addition of the PCS tank reduced the first-order frequency of the NPP by 12%. The reduced frequency was closer to the main frequency of ground motion specified in the RG1.60 code, which amplified the seismic response of the NPP. Given that the liquid sloshing frequency is approximately 60 times lower than the PCS-NPP system frequency, and the impulsive mass constitutes only 0.65% of the total system mass, the contribution of water to the seismic response of the NPP is negligible. Consequently, passive cooling systems can be considered as added mass while neglecting liquid sloshing in the seismic analysis and design for NPP.

The resilience of school buildings in high seismic regions is widely emphasised and evaluated. However such resilience in low-to-medium seismic regions are generally overlooked due to the lower probability of occurrence and low-to-medium intensities expected. Nonetheless, nominal seismic provisions should be provided for the life safety of pupils occupying these school buildings. Therefore, this study was focused on assessing the level of seismic resilience of school buildings in low-to-medium seismic regions, where the archetypal school buildings in Sri Lanka and the seismic demand in the country were taken as the case study. A framework to quantify resilience, incorporating social recovery aspects, was adopted to evaluate the seismic resilience. The resilience of the same archetypal school buildings subjected to different nominal retrofitting methods was also assessed to verify the improvement in resilience compared to un-retrofitted buildings. The epistemic and aleatory uncertainties were incorporated by using 25 different recorded seismic accelerograms and Monte-Carlo simulation of material properties (twenty sets of randomised values), respectively; with 500 combinations (aleatoric and epistemic) being analysed for each building type considered. Seismic resilience indices (RIs) obtained indicate that the school buildings with retrofitted configurations are certainly better than un-retrofitted ones, especially for higher hazard levels. Increases in the RIs are in the range of 36.6–91.2% for the highest hazard level. Sensitivity analyses were also carried out to ascertain parameter influence on RIs. The proposed nominal retrofitting solutions for these school building archetypes generate adequate resilience against the seismic hazards demarcated for the country.

In highway expansion and reconstruction projects, existing slopes often lead to significant variations in pier heights, forming Irregular Slab-Column Bridge Structures (ISCB). When subjected to seismic loading, such structures exhibit complex mechanical behavior, thereby highlighting the necessity of seismic mitigation design. This study is based on an irregular double-column slab-column highway bridge structure (with a short column of 3 m and high columns of 4 to 9 m) and conducts seismic response analysis using a finite element model. Subsequently, buckling-restrained braces (BRBs) were introduced to evaluate the influence of BRB force ratio on seismic mitigation performance. On this basis, an optimization design method was proposed based on the relationship between the BRB stiffness factor and force ratio. By adjusting the ratio between the BRB force ratio and the computed BRB stiffness factor KF, the structure can achieve optimal seismic mitigation and self-centering performance under earthquake loading, effectively preventing local over-deformation and unbalanced responses, thereby significantly enhancing the overall seismic performance of the structure. The results indicate that the short column exhibits greater seismic responses. When the short column is 3 m and the high column is 6 m, the disparity in seismic responses between the two columns tends to diminish with increasing high column height. The incorporation of BRBs can significantly reduce the structural base shear, reinforcement strain at the column base, and displacement at the column top. Moreover, the reduction in seismic response becomes more pronounced with increasing BRB force ratio. The proposed optimization design method takes into account both the seismic mitigation performance of the BRBs and the self-centering capability of the ISCB. Using this method, the optimal BRB design parameters for the example ISCB are determined (FR_BRB = 0.3, KF = 3.3). The proposed method for integrating BRB components into bridge pier design can significantly enhance the seismic performance of the prototype structure and facilitate rapid functional recovery after strong earthquakes.

Prolonged service leads to significant degradation in the mechanical performance of ancient timber structures, increasing the risk of sudden failure during earthquakes. To address this issue, this study proposes a friction energy-dissipation brace (FEDB) for emergency collapse risk mitigation of ancient timber structures. A scaled experimental model, based on a partial structure of the Yingxian Wooden Pagoda, was designed and fabricated. Quasi-static tests were conducted to comparatively analyze the deformation, load-bearing capacity, stiffness, and energy dissipation characteristics of the structure before and after reinforcement. The results demonstrate that the proposed FEDB integrates well with the timber structure. While preserving the rocking deformation characteristics of the original structure, the FEDB significantly enhances the load-bearing capacity, stiffness, and especially energy dissipation capability, with an improvement of up to 382%. Furthermore, parametric analysis using the finite element software ABAQUS revealed that the structural load-bearing capacity, stiffness, and energy-dissipation increase with increasing bolt preload and friction coefficient of the FEDB. The installation angle of the FEDB also notably influences the reinforcement effectiveness, with the optimal performance achieved when the FEDB is horizontally arranged. This study provides valuable insights for the preventive conservation and seismic reinforcement of existing ancient timber structures.

Two major earthquakes occurred on the East Anatolian Fault Zone in Türkiye on February 6, 2023. The epicenter of these earthquakes was Pazarcık and Elbistan, distinct from Kahramanmaraş province. These earthquakes occurred on the same day, 9 hours apart, and effected a very large area. This study evaluates the damage in reinforced concrete buildings during the Kahramanmaraş earthquakes. Firstly, this study examined Türkiye’s seismicity, fault lines, and recent earthquakes in Türkiye. Then, the fault rupture of the Kahramanmaraş earthquakes and the affected regions from these earthquakes were examined. Acceleration records of the Pazarcık and Elbistan earthquakes were evaluated by comparing them with the Türkiye Building Earthquake Code-2018 (TBEC-2018). These acceleration records were compared with the largest earthquake (DD1) and design earthquake (DD2) defined in TBEC-2018. Requirements for earthquake-resistant building design and the deficiencies in the current Türkiye building stock were discussed. Damages in RC buildings were evaluated in terms of design and construction perspectives. It has been observed that deficiencies are frequently made in the application of reinforcement details in RC buildings. Brittle shear damage has been commonly observed in reinforced concrete buildings, even though they are expected to behave ductile. Design and construction deficiencies have been observed to be widespread even in buildings still under construction.

To enhance the seismic resilience of structures, there is a persistent demand for metallic dampers that combine high energy absorption capacity with manufacturing simplicity. This paper presents a novel A-Shaped Steel Damper (ASSD), featuring monolithic elements composed of inner and outer rings, fabricated solely via laser-cutting technology to ensure high precision and manufacturing reliability. The ASSD is designed to absorb seismic energy via a combined flexural-shear yielding mechanism and can be installed in diagonal braces. An analytical model based on plastic mechanism analysis was first developed to predict the damper’s ultimate capacity in its buckling-restrained state. The cyclic behavior of four 1:2-scale specimens was then experimentally evaluated, and the influence of key geometric parameters was examined through a parametric study. Experimental results revealed that effective buckling restraint is critical for achieving stable hysteretic behavior. The restrained specimens exhibited desirable performance, with an equivalent viscous damping ratio up to 0.4, confirming the damper’s substantial capacity for seismic energy absorption. Furthermore, the proposed analytical model accurately predicts the ultimate capacity. The ASSD also displayed a remarkable energy absorption-to-mass ratio of up to 7.9 kJ/kg. However, observations revealed localized strain concentrations at the ring junctions, highlighting a key area for future design optimization to further enhance its efficacy. Ultimately, its simple fabrication process and easy post-earthquake replaceability position the ASSD as a promising and practical solution for seismic protection.