Uncertainty quantification is an important issue in the seismic fragility analysis of bridge type structures. However, the influence of different sources of uncertainty on the seismic fragility of the system is commonly overlooked due to the costly re-evaluation of numerical model simulations. This paper aims to present a framework for the seismic fragility analysis of reinforced concrete highway bridges, where a data-driven metamodel is developed to approximate the structural response to structural and ground motion uncertainties. The proposed framework to generate fragility curves shows its efficiency while using a few finite element simulations and accounting for various modeling uncertainties influencing the bridge seismic fragility. In this respect, a class of single-bent bridges available in the literature is taken as a case study, whose three-dimensional finite element model is established by the OpenSees software framework. Twenty near-source records from different sources are selected and the Latin hypercube method is applied for generating the random samples of modeling and ground motion parameters. The Kriging metamodel is then driven on the structural response obtained from nonlinear time history analyses. Component fragility curves of the reinforced concrete pier column are derived for different damage states using the Kriging metamodel whose parameters are established considering different modeling parameters generated by Monte Carlo simulations. The results demonstrate the efficiency of the proposed framework in interpolating the structural response and deriving the fragility curve of the case study with any input conditions of the random variables.

This paper aims to comprehensively evaluate the performance of a series of ground motion intensity measures (IMs) used in the seismic vulnerability assessment of steel storage tanks with unanchored support conditions. Sixteen well-known IMs are thus selected, which are classified into amplitude-, frequency-, and time-based categories. A comparative study is then performed on four different unanchored steel storage tanks subjected to a suite of 140 ground motion records that is comprised of seven different bins of records with different hazard levels. In this regard, the tanks are appropriately modeled based on a simplified approach, whose uplift and sliding nonlinear behaviors are properly implemented based on a three-dimensional nonlinear pushover analysis of the tanks. Four characteristics of the examined IMs including efficiency, practicality, proficiency, and sufficiency are evaluated based on a probabilistic seismic demand model of two critical failure modes of the tanks, i.e., plastic rotation of the shell-to-bottom connection and elephant's foot buckling of the shell plate. According to the comparative study, frequency-based IMs demonstrate their superior performance for all criteria compared with other groups; in particular, the average spectral acceleration gains the highest ranking. Finally, an appropriate range of the upper period considered in the average spectral acceleration IM is then proposed to optimize the efficiency of this IM for the examined tanks.

The double friction pendulum (DFP) bearing is adapted from the well-known single friction pendulum (SFP) bearing. This type of bearings has been widely used for structural vibration controls. The main advantage of the DFP is its capacity to accommodate larger displacements as compared with the SFP one. This paper aims to assess the effect of the vertical earthquake component on the seismic behaviour of a base-isolated high-rise building. In this respect, the mathematical model of the building subjected to earthquake excitations with an implementation of a DFP bearing system is established. The model presented herein considers earthquake excitations in horizontal (X and Y) and vertical (Z) directions. A series model of two friction elements is presented for the bearing, where the friction load of the bearing surface is governed by a modified Bouc-Wen model, which is dependent on the sliding velocity and the contact pressure. The numerical results of an example of a base-isolated 9-story steel building subjected to near-source and far-field earthquakes show the high effectiveness of the bearing system in reduction of the seismic response of the building, especially in the near-source region, as well as exhibit considerable effectiveness of the vertical earthquake component on the bearing and structural behaviour.

A free standing, slender body may experience rocking motion followed by overturning when it is subject to strong seismic motions. When the free body is submerged in water, it will also be subject to lateral forces acting along the side of the free body as a result of water sloshing. This highly non-linear situation is of particular interest to engineers in the nuclear industry in need to assess the stability of transfer casks containing spent fuel and submerged in a confined pit or pool. In this work, a three-dimensional finite element dynamic transient model of a free standing cask is developed and analyzed using ANSYS. Both dry and submerged conditions are considered. Cask to floor friction, buoyancy force, and sloshing are accounted for in the assessment. The model is validated against well-accepted contributions on sloshing and rocking provided by G.W. Housner.

Accurately determining the effective impact radius of construction-induced vibrations, such as those caused by vibratory roadbed compaction, pile driving, and rock blasting, is essential for ensuring the safety of adjacent structures and minimizing disputes in infrastructure projects. This study experimentally investigates the propagation and attenuation of shock waves generated by blasting and pile-driving activities in typical geological conditions in Central Vietnam. Field measurements of peak particle velocity, acceleration, and noise levels were conducted using calibrated sensors in accordance with national standards (TCVN 7378 and QCVN 27:2010/BTN-MT). The experimental data were analyzed to derive empirical relationships between vibration intensity and distance from the source, enabling the estimation of safe construction distances for various structural types. The results show strong agreement between theoretical models and in-situ measurements, validating the proposed approach and offering practical guidance for infrastructure design, construction planning, and regulatory compliance.

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.