A utility tunnel is an infrastructure that consolidates multiple municipal pipeline systems into a shared underground passage. As long linear structures inevitably cross different soils, this paper aims to accurately assess the seismic damage to a shallow-buried utility tunnel in a non-homogeneous zone by employing a viscous-spring artificial boundary and deriving the corresponding nodal force equations. The three-dimensional model of the utility tunnel-soil system is established using finite element software, and a plug-in is developed to simulate the three-dimensional oblique incidence of SV waves with a horizontal non-homogeneous field. In this study, the maximum interstory displacement angle of the utility tunnel is used as the damage indicator. Analysis of structural vulnerability based on IDA method using PGA as an indicator of seismic wave intensity, which considers the angle of oblique incidence of SV waves, the type of seismic waves, and the influence of the nonhomogeneous field on the seismic performance of the utility tunnel. The results indicate that the failure probability of the utility tunnel in different soil types increases with the incident angle and PGA. Additionally, the failure probability under the pulse wave is higher than that under the non-pulse wave; Particular attention is given to the states of severe damage (LS) and collapse (CP), particularly when the angle of incidence is 30 degrees and the PGA exceeds 0.6g, conditions under which the probability of failure is higher. Additionally, the failure probability of the non-homogeneous zone is greater than that of sand and clay; the maximum interlayer displacement angle increases with the incident angle, accompanied by greater PGA dispersion, indicating the seismic wave intensity. The maximum inter-layer displacement angle increases with the incident angle, and the dispersion of the seismic wave intensity indicator (PGA) becomes greater. This paper proposes vulnerability curves for different working conditions, which can serve as a reference for the seismic design of underground structures.

This paper deals with the contribution of the soil-structure interaction (SSI) effects to the seismic analysis of cultural heritage buildings. This issue is addressed by considering, as a case study, the Mosque-Cathedral of Cordoba (Spain). This study is focussed on the Abd al-Rahman I sector, which is the most ancient part, that dates from the 8th century. The building is a UNESCO World Heritage Site and it is located in a moderate seismic hazard zone. It is built on soft alluvial strata, which amplifies the SSI. Since invasive tests are not allowed in heritage buildings, in this work a non-destructive test campaign has been performed for the characterisation of the structure and the soil. Ambient vibration tests have been used to calibrate a refined 3D macro-mechanical-based finite element model. The soil parameters have been obtained through an in situ geotechnical campaign, that has included geophysical tests. The SSI has been accounted for by following the direct method. Nonlinear static and dynamic time-history analyses have been carried out to assess the seismic behaviour. The results showed that the performance of the building, if the SSI is accounted for, is reduced by up to 20 % and 13 % in the direction of the arcades and in the perpendicular direction, respectively. Also, if the SSI is taken into account, the damage increased. This study showed that considering the SSI is important to properly assess the seismic behaviour of masonry buildings on soft strata. Finally, it should be highlighted that special attention should be paid to the SSI, which is normally omitted in this type of studies, to obtain a reliable dynamic identification of the built heritage.

The seismic response of reinforced concrete buildings depends on the interaction between the superstructure, foundation type and soil properties, making accurate fragility assessment a complex engineering challenge. This study focuses on constructing fragility curves specific to building vulnerability assessment by incorporating various damage parameters that account for soil-structure interaction effects. Using finite element analysis software, Incremental Dynamic Analysis was performed on RC building models with both fixed and flexible bases founded on varying soil conditions. Fragility curves were developed using three engineering demand parameters: maximum roof displacement, inter-storey drift and plastic energy dissipation. Findings reveal that maximum roof displacement parameter consistently yields the highest probabilities of exceedance, reaching up to 90-100% for soft soil at a PGA of 0.3 g, identifying it as the most conservative measure, while plastic energy dissipation displays the lowest probabilities (10-50% across all soil types), indicating its limitations in capturing deformation demands. To streamline vulnerability assessment for buildings incorporating the effect of supporting soil stratum, fragility modification factors are proposed to efficiently adjust existing fragility curves for incorporating SSI effects based on different damage measures and soil conditions, providing a comprehensive approach to efficient vulnerability analysis.

The current investigation examines the fluctuating behaviour of stiff pavement built on a two-parameter base and is influenced by aircraft loading impacts. This investigation is driven by the necessity for an accurate evaluation of pavement behaviour under elevated stress scenarios caused by aircraft, which can guide pavement design and upkeep. A stochastic numerical model, the vehicle-pavement interaction model (VPI), was created using a comprehensive 3D dynamic model of an aircraft vehicle and stationary runway roughness profiles. The rigid pavement is simulated using a computationally efficient 1D finite element mathematical model incorporating six DOF. The Pasternak model represents the soil medium, incorporating shear interaction between the spring elements. The pavement's irregularities are considered and replicated using a power spectral density (PSD) function. This assembled model was used to investigate the dynamical reaction of concrete pavement vibrations caused by the passing of an aircraft vehicle using MATLAB code. The dynamic governing differential equations of the aircraft's motion are developed and coupled with the pavement system equations. The coupled system is then solved in the time domain using the direct computational integration approach with the Newmark-Beta integration scheme, explicitly utilizing the linear average acceleration method. This approach is employed to resolve the equations that govern and assess the performance of the connected system. The current findings are being compared to existing analytical outcomes to verify the precision of the current coding. The research examined the impact of various pavement and aircraft vehicle behaviors and factors on the dynamic response of pavement, including the speed, main and auxiliary suspension components, mass and the load position of the aircraft, also the damping, random roughness, thickness, span length and elastic constant of the pavement, even, the modulus of subgrade of the foundation, the rigidity modulus of the shear layer. The findings demonstrate notable influences of aircraft speed and pavement surface roughness on various response parameters. Specifically, the results reveal that a higher subgrade modulus leads to decreased deflection, rotation, and bending moments. Conversely, longer span lengths tend to elevate response parameters while simultaneously reducing shear force. In conclusion, the results highlight the significance of critical factors, including velocity and subgrade modulus, in forecasting the performance of pavement subjected to aircraft loads. The present research is confined to the investigation of the dynamic's performance of the VPI simulation of airfield rigid pavement. The findings from this study can be expanded on by paving engineers to improve the structural effectiveness and reliability of the pavement, serving as a basis for subsequent fatigue analysis in response to diverse dynamic loads such as earthquake, temperature and vehicle load.

Huaca de la Luna is a monumental earthen complex near Trujillo, Peru built by the Moche civilization from 200 to 850 C.E. Its principal structure, a stepped pyramid constructed with millions of adobe bricks on sloping bedrock and sandy soil, presents severe structural damage at the northwest corner. A sensitivity study of the static and dynamic response of the pyramid is conducted in Abaqus/CAE Explicit using 2D and 3D nonlinear finite element models derived from archaeological, material, and geotechnical data. Concrete damaged plasticity and Mohr-Coulomb formulations are adopted to represent adobe and sandy soil, respectively. Models undergo quasi-static gravitational loading followed by dynamic application of lateral ground accelerations. Lateral capacity is defined as the applied acceleration that produces collapse and is identified from the time-evolution of elastic strain and plastic dissipation energies. Initial 2D sensitivity analysis investigates the effect on lateral capacity of adobe tensile strength, bedrock/soil configuration, west fa & ccedil;ade profile, eastward architecture, and plastic dilation angle. Critical configurations identified from 2D analysis are expanded into 3D models. All results show stability under gravitational load. At dynamically induced failure, damage corresponds closely to the extant collapse of the northwest corner of the pyramid, suggesting that present damage is due to seismic activity.

This study focuses on the challenge of identifying the most destructive earthquakes to minimize earthquakeinduced damage, with particular attention to the seismic behavior of special reinforced concrete moment frames (RCMFs) and the influence of soil-structure interaction (SSI). To achieve this objective, a numerical model was developed in OpenSEES platform to analyze RCMFs with heights of 2, 6 and 10 stories on four different soil types (Site Classes B to E). Also, to consider the effect of SSI, the study utilized a Beam on Nonlinear Winkler Foundation approach (BNWF), incorporating springs and dashpots. An extensive set of earthquake records, including 274 horizontal ground motion records, categorized based on shear wave velocity for each site class, was employed. Incremental dynamic analysis (IDA) was used to identify the most destructive earthquake scenarios, with maximum inter-story drift serving as the damage measure (DM) for the four seismic performance levels proposed by HAZUS and peak ground acceleration (PGA) as the intensity measure (IM). After performing correlation analysis between the 57 ground motion parameters (GMPs) and the maximum inter-story drift, followed by an inter-correlation analysis among the candidate GMPs, it was ultimately determined that the GMPs: Vmax/Amax, Tm and F5PSD, accurately represent the potential for seismic damage. IDA results highlighted the significant influence of SSI on the seismic performance of structure, especially in taller buildings constructed on softer soil types. Finally, two equations were developed based on the identified GMPs to determine and rank destructive earthquakes for both SSI and no-SSI (NSSI) conditions.

Investigations of seismic response of underground structures often assume homogeneous or layered homogeneous sites. However, significant spatial variability in soil parameters may lead to vastly different underground structure performance from that obtained for homogeneous sites. Based on random field theory, this study models the spatial variability of the soil elastic modulus, cohesion, and friction angle using the Karhunen-Loe`ve (K-L) expansion method. Target acceleration response spectra are generated according to standards, and the trigonometric series method is employed to create artificial seismic waves of four different intensities. Nonlinear dynamic analyses of underground structures under deterministic and random field conditions are conducted using ABAQUS software. The study comprehensively analyzes the structural damage state, internal forces, interstory displacement, and drift ratio to evaluate the station structure's performance under different seismic intensities. Results show that the spatial variability of soil parameters significantly impacts the dynamic response of underground structures, especially for stronger earthquakes. The variability of soil stiffness and strength parameters leads to greater fluctuations and uncertainties in displacement and internal force responses, exacerbating structural damage. It is recommended that when the peak ground acceleration (PGA) reaches or exceeds 0.5 g, the spatial variability of soil parameters should be incorporated into the analysis to ensure a reliable assessment of the structural seismic performance.

This study proposes the use of soil bags filled with a rubber sand mixture (SFRSM) to address the issue of weak stability associated with rubber-sand layers for seismic isolation. To evaluate the dynamic characteristics of the SFRSM, large-scale cyclic simple shear tests were conducted to investigate the effects of rubber content, vertical pressure, shear displacement amplitude, fill percentage, and laying scheme. Furthermore, shaking table tests were carried out to evaluate the impact of vibration intensity and frequency on the seismic isolation of SFRSM layers. The results indicate that (1) Compared to the rubber-sand layer, the SFRSM exhibits a lower shear modulus and higher damping, indicating its potential for greater seismic isolation and energy dissipation. (2) The dynamic characteristics of the SFRSM were significantly influenced by the fill percentage and laying scheme, suggesting that an effective isolator capable of withstanding various external conditions could be developed. (3) The isolating effect of the SFRSM layer is attributed to its ability to dampen high-frequency vibration components effectively. Additionally, the threshold frequency required to trigger attenuation decreases with an increasing number of SFRSM layers. In summary, these experimental results provide evidence that the proposed innovative strategy enhances the strength and vertical stiffness of the original rubber-sand layer, making it well-suited for seismic design applications in low-rise buildings in less-developed regions.

Probability-based seismic fragility analysis provides a quantitative evaluation of the seismic performance exhibited by structures. This study introduces a framework to perform seismic fragility analysis of utility tunnel and internal pipeline system considering wave passage effect of the ground motion spatial variation. The numerical model of a double-beam system resting on a nonlinear foundation is established to simulate the soiltunnel-pipeline interactions. 17 pairs of earthquake records are chosen and scaled as inputs at the outcrop. One-dimensional (1D) free-field analyses are conducted to obtain the ground motion time histories at the bottom slab of the utility tunnel, and then incremental dynamic analysis (IDA) is performed for the utility tunnel-internal pipeline system. The damage states (DSs) are defined by the maximum joint opening for the utility tunnel and maximum strain for the internal pipeline, and the peak bedrock velocity (PBV) is determined to be the most representative intensity measure (IM) for developing the seismic fragility curves. The seismic fragility curves of the system are constructed using the joint probabilistic seismic demand model (JPSDM) and Monte Carlo sampling method. The research findings indicate that: (1) the framework proposed in this study is suitable for the fragility assessment of long-extended utility tunnel-internal pipeline system; (2) the utility tunnel and internal pipeline as a system exhibit greater fragility compared to either one of the components, and the JPSDM and Monte Carlo sampling method for the system fragility analysis is more precise than the first-order bound method; (3) the proposed fragility curves in this study provide quantitative damage probabilities for the individual components and system under different seismic intensity levels. (4) The IM values corresponding to 50% exceedance failure probability of the whole system is 1%-3% lager than that of the upper bounds, and it is 3% to 5% less than that of the lower bounds. The conservative upper bound is a more suitable approximation for system fragility. (5) It should be noted that the obtained fragility curves are valid for the considered tunnel-pipeline structure and site conditions. For different tunnel structures and site conditions, the fragility curves can be constructed following the same steps outlined in this study.

The selection of representative ground motion intensity measure (IM) and structural engineering demand parameter (EDP) is the crucial prerequisite for evaluating structural seismic performance within the performance-based earthquake engineering (PBEE) framework. This study focuses on this crucial step in developing the probabilistic seismic demand model for two-story and three-span subway stations exposed to transverse seismic loadings in three different ground conditions. The equivalent linearization approach is used to simulate the shear modulus degradation and the increase in damping characteristics of the soil under seismic excitation. Nonlinear fiber beam-column elements are adopted to characterize the nonlinear hysteretic degradation of the subway station structure during seismic events. A total of 21 far-field ground motions are selected from the PEER strong ground motion database. Nonlinear incremental dynamic analyses (IDAs) are conducted to evaluate the seismic response of the subway station. A suite of 23 ground motion IMs is evaluated using the criteria of correlation, efficiency, practicality, and proficiency. Then, a multi-level fuzzy evaluation method is employed to integrate these evaluation criteria and determine the optimal ground motion IMs in different ground conditions. The peak ground acceleration and sustained maximum acceleration are demonstrated to be the optimal ground motion IM candidates for shallowly buried rectangular underground structures in site classes I, II, and III, while the root-mean-square displacement and compound displacement are found to be not suitable for this purpose.