Robust design optimisation (RDO) of performance-based seismic design (PBSD) has been established as a rigorous approach for obtaining optimal solutions that are minimally sensitive to record-to-record (RTR) variability of ground motions used in nonlinear response history analysis (NLRHA). However, this method is not able to explicitly account for the suite-to-suite (STS) variability due to the epistemic uncertainties associated with ground motion selection, especially when each suite is selected and scaled based on the requirements of the seismic design codes currently in force. To account for this uncertainty, this paper proposes a novel formulation for robust optimisation, which explicitly accounts for ground motion suite variability. In this method, one objective is to minimise the dispersion in the probability of limit state violation due to STS variability and the other objective is to minimise the economic costs. To increase the computational efficiency of the proposed method, surrogate seismic demand models are developed and applied to assess the probability of limit state violation. The application of the proposed framework is demonstrated using a case study of a typical reinforced concrete (RC) highway bridge with cylindrical piers, and the ability of the RDO framework to account for the STS variability is discussed. Finally, the Pareto-optimal solutions obtained from the proposed approach are compared with those given by the conventional RDO approach.
Monopile-supported wind turbines (MWTs) are increasingly deployed in seismically active regions, where seismic loads can significantly affect their structural safety. Meanwhile, over a service life of 25-30 years, MWTs are continuously subjected to wind loads and 1P/3P loads. These lateral forces lead to the continuous evolution of soil properties, resulting in time-dependent seismic performance of MWTs. This study specifically focuses on onshore MWTs with the water table located below the pile tip, for which the effects of offshore environmental loads such as waves and currents are not considered. On this basis, a framework is proposed for evaluating the seismic response of MWTs after long-term operation, with comprehensive consideration of wind-structure-soil interaction. The framework can effectively characterize the long-term evolution of soil properties and analyze its influence mechanism on the seismic response. On this basis, the incremental dynamic analysis (IDA) method is employed to conduct a time-dependent seismic fragility analysis, and the seismic fragility curves under different operational histories are obtained. The results indicate that, with increasing operational duration, the probability of the wind turbine structure exceeding the serviceability limit state and the ultimate limit state increases significantly. Moreover, the influence mechanisms of factors such as wind characteristics and seismic characteristics on the structural seismic performance change significantly. Overall, the operational history of onshore MWTs has a pronounced degrading effect on their seismic performance.
Near-fault ground motions may cause severe damage to railway embankments due to their significant pulse components. However, the effects of pulse characteristics (i.e., period, amplitude, and count) on the seismic performance of railway embankments are not well understood. To quantify the effects of pulse characteristics on the seismic performance of railway embankments, seismic fragility analyses are performed incorporating pulse-like ground motions with controlled pulse period, amplitude, and count, which are synthesized using a high-low frequency superposition method. The seismic responses of railway embankments to the generated pulse-like ground motions employing incremental dynamic analyses, and the maximum shear strain increment and peak permanent settlement at the embankment crest are evaluated for various pulse parameters and corresponding limit states are defined. The optimal intensity measure (IM) is then identified based on the criteria of correlation, practicality, efficiency, and proficiency, along with residual significance test. The results indicate that effective design acceleration is optimal IM for the pulse period effect, and acceleration spectrum intensity is optimal IM for the pulse amplitude and count effects. Furthermore, seismic exceedance probabilities of the railway embankments under different pulse parameters are obtained by conducting fragility analysis. Results demonstrate that increasing pulse period, amplitude, and count amplifies the seismic response of railway embankments and elevates their exceedance probabilities. However, the pulse period and count play a substantially more significant role than pulse amplitude. These findings provide a quantitative basis for the performance-based seismic design of railway infrastructures in near-fault regions, and underscore the necessity of accounting for pulse period and count.
This engineering-geological study evaluates the vibrational impact of high-speed rail traffic on subsoil and its implications for future buildings, in the context of environmental protection and sustainable infrastructure development. The research concerned a planned high-speed railway line from Warsaw to Vienna, on the section between Zawiercie and Grodzisk Mazowiecki in Poland. A unique and technically demanding large-scale field investigation was carried out through three case studies at distinct locations, based on measurements from multiple passes of the same high-speed train. The train successively traveled through the sites at increasing velocities, reaching a record speed for Poland, while measurements of vibrational impacts in the subsoil were conducted.Results reveal a clear relationship between increasing train speed and elevated vibrational acceleration in the subsoil, exceeding 5 cm/s2, which suggests that current safety limits and mandatory measurement distances of 25 m may not adequately reflect real conditions. Excessive vibrational influence was observed at all sites, with variability caused by four main factors: hydrogeological conditions, engineering-geological structure, railway embankment geometry, and the presence of underground anti-vibration barriers. The strongest negative factor was identified as water-saturated geological conditions combined with fluvial gravel sediments characterized by low vibration damping. Conversely, the most effective positive factor was the underground anti-vibration barrier, which significantly increased vibration attenuation.The observed trend—rising train speeds and increasing vibrational impact—represents a growing environmental and engineering challenge. The findings underline the need to update vibration standards and mitigation measures to protect both the built and natural environment. The proposed methodology and evaluation approach can be broadly applied to similar case studies related to sustainable transport infrastructure.
This study investigates the seismic performance of large-span SRC beam-column oblique edge joints in practical engineering. Numerical simulations were conducted using finite element software to analyze the influence of various parameters on the seismic performance of the joints, and a calculation formula for the shear capacity of the large-span SRC beam-column oblique edge joints was established. The results show that the core zone of the oblique edge joint undergoes shear failure. As the oblique angle θ increases, the damage in the joint core zone becomes worse, and the joint's bearing capacity decreases accordingly. Additionally, the ductility, energy dissipation capacity, cumulative total energy dissipation, and initial stiffness of the oblique edge joints all show varying degrees of reduction. Furthermore, the bearing capacity of the oblique edge joint is directly proportional to the concrete strength grade, and steel grade but inversely proportional to the axial compression ratio, whereas the ductility of the joint is inversely proportional to these parameters. When θ reaches 45°, the seismic bearing capacity of the oblique edge joint decreases by approximately 40%. When θ does not exceed 10°, the steel grade does not exceed Q355 and the axial compression ratio is no greater than 0.4, satisfactory seismic performance can be achieved. The calculation results from the proposed shear capacity formula for oblique edge joints show an error within 5% compared to the finite element analysis results, demonstrating good agreement.
A statistical assessment of the seismic performance of special truss moment frames is conducted using a series of archetype frames developed in OpenSeesPy. The study investigates how structural configuration and gravity-induced axial loading in special segment chord members affect system-level collapse capacity. The parameters investigated include the number of stories, truss span length (L), special segment length (Ls), and the explicit representation of axial loading on the special segment. Nonlinear static and time-history analyses are conducted for each archetype, enabling the development of fragility curves and the estimation of their collapse capacity. Statistical evaluation is performed at two complementary levels: i) engineering demand parameters (EDP), i.e., peak interstory drift ratios (IDR) and peak rotations in the special segments; ii) fragility curves. Differences in EDP distributions are evaluated using the Kolmogorov-Smirnov (KS) hypothesis test, while fragility curves are compared using a parametric likelihood-based test.Results indicate that the gravity-induced axial load on the special segment significantly affects the collapse fragility of archetypes with relatively short special segments (Ls/L ≤ 0.30). In contrast, for models with Ls/L = 0.50, this effect is negligible. Furthermore, modeling the axial loading on the special segment members has a relatively modest effect on the peak interstory drift ratio (IDR) at the maximum considered earthquake (MCE), but significantly increases peak rotations within the special segment. These findings indicate strong coupling between axial-force demand and chord member plasticity, underscoring the need to explicitly account for these effects in performance-based earthquake engineering (PBEE) fragility assessments.
This study aims at identifying the appropriate scalar- and vector-valued intensity measures (IMs) for seismic damage assessment of arch dams. Appropriate IMs for assessing the seismic damage of arch dams are identified by an interpretable machine learning technique. A total of 300 ground motion records are selected from the NGA-West2 database as input, nonlinear dynamic analyses are then conducted for the numerical model of a 240-m-high arch dam implemented in Abaqus. The damage volume rate (DVR) is considered as the engineering demand parameter (EDP) for quantitatively assessing the concrete damage status of the arch dam. In total, 15 candidate scalar-IMs and 45 candidate vector-IMs as well as 300 EDPs are adopted to establish the seismic damage predicting models of arch dams. The SHapely Additive exPlanations values are utilized to quantify how IMs impact the predicted EDP and to identify the most appropriate IMs. The results show that the spectral acceleration at the fundamental period (Sa(T1)) and the vectors of [Sa(T1), peak ground velocity] can be regarded as the most appropriate scalar- and vector-IMs for seismic damage assessment of arch dams. For severe damage, the most appropriate vector-IM is identified as the vector of [Sa(T1), spectral acceleration at the 1.5-times fundamental period]. The appropriate IMs identified could be used in performance-based seismic damage assessment of arch dams.
