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.

Increasing numbers of complex structures are being constructed with the acceleration of urbanization. The complex dynamic characteristics pose challenges to the seismic design of large chassis. This paper investigates the seismic response and damage evolution of complex structures using linear and nonlinear dynamic explicit analysis under obliquely incident SV waves. A twodimensional finite element model considering soil-structure interaction (SSI) is developed using fiber beam elements. Elastic and elastoplastic damage constitutive models are employed. A comprehensive numerical analysis is conducted to investigate the influence of key parameters, including incidence angles, ground motion characteristics, and site types, on the seismic response and damage evolution of complex structures. The results of this study indicate that, in the elastic stage, the seismic response of the frame-shear wall structure is reduced in the case of oblique incidence compared to vertical incidence. Specifically, the inter-story drift ratio is reduced by 60% at an incidence angle of 30 degrees. In comparison to vertical incidence, the inter-story drift ratio and horizontal acceleration of the underground structure are reduced under oblique incidence. Conversely, in the elastic stage, the beam-end vertical displacement ratio and vertical acceleration exhibit increases of 57% and 36%, respectively. In the elastoplastic stage, as the incidence angle increases, the damage to the beams of the underground structure becomes more significant, while the damage to the frame-shear wall structure relatively decreases. Low-frequency ground motion and soft soil amplify the structural response compared to high-frequency and hard soil.

With the rapid development of infrastructure in western China, numerous arch bridges have been constructed as vital transportation hubs spanning river canyons. Understanding the impact of canyon topography on the seismic response of long-span half-through arch bridges crossing canyons is essential. This study first establishes a seismic input method for oblique P-wave and SV-wave incidence, based on the viscous-spring artificial boundary theory, which transforms ground motions into equivalent nodal loads on artificial boundaries. The feasibility of this proposed method is systematically validated. Subsequently, parametric investigations are carried out to explore the effects of seismic wave incidence angle, canyon depth-to-breadth ratio and soil elastic modulus on the ground motion amplification characteristics in V-shaped canyons under oblique P-wave and SV-wave excitations. Finally, dynamic response patterns of the arch ribs and the stress-strain relationships at critical structural components are thoroughly analyzed. Key findings reveal that SV-waves induce significantly different ground motion amplification effects compared to P-waves, with the wave incidence angle and canyon width-to-depth ratio being crucial influencing factors. The connection between the arch footings and the concrete cross braces constitutes the most vulnerable region, frequently exhibiting maximum stresses that exceed the yield strength of C40 concrete under multiple scenarios. Notably, when the depth-to-breadth ratio (D/B) is 0.75, the peak stress at the arch footings reaches 5.18 x 10(7)kPa, surpassing the yield stress threshold of C40 concrete. These findings highlight the need for special seismic fortification measures at these critical connections during bridge design. This research offers valuable insights into the seismic design of long-span arch bridges in complex topographic conditions.

A horizontal non-homogeneous field adversely affects the seismic resistance of both the utility tunnel and its internal pipes, with seismic waves obliquely incident on the underground structure causing more significant damages. To address these issues, this study, based on a viscous-spring artificial boundary, derives and validates the equivalent junction force formula for the horizontal non- homogeneous field. It then establishes a three-dimensional finite element model of the utility tunnel, pipes, and surrounding soil to obtain the acceleration and strain responses of the utility tunnel and its internal pipes under seismic loading. Finally, it investigates the impact of different incidence angles of shear waves (SV waves) on the response of the utility tunnel and its internal pipes. It was found that as the PGA increases from 0.1 to 0.4 g, both peak acceleration and strain of the utility tunnel and its internal pipes increase. The peak acceleration of the utility tunnel and pipes initially decreases and then increases with the angle of incidence, while the strain increases with the angle of incidence, reaching its peak value when the angle of incidence is 30 degrees. The acceleration and strain responses of the utility tunnel and pipe are higher in sand than in clay, with the peak acceleration strongly correlating with the angle of incidence of ground shaking. The findings of this study provide valuable insights into the seismic design of horizontal non-homogeneous field utility tunnel systems.

Liquid storage tanks are often arranged in rows with small spacing in practical applications, which may cause mutual influence under earthquake action and even aggravate the seismic damage of liquid storage tanks. Adding the vibration barrier (ViBa) into the foundation between the adjacent liquid storage tanks forms a new type of seismic control method. Considering important factors such as liquid-solid-soil coupling, liquid sloshing behavior, and structure-soil-structure interaction (SSSI), a refined 3D numerical calculation model of the adjacent liquid storage tanks with three ViBas is established by ADINA. The influence of seismic wave incidence angle on the seismic responses of the liquid storage tanks and the control effect of ViBa are studied, and the parameter influence analysis is carried out. The results show that the ViBa significantly control the seismic responses and liquid sloshing wave height of the adjacent liquid storage tanks, and the damping ratio of the liquid sloshing wave height is between 30% and 40%. When the seismic incidence angle is between 30(degrees) and 60(degrees), the dynamic responses of the liquid storage tank is larger. With the increase of the seismic incidence angle, the control effect of the ViBa on the effective stress, hoop stress, axial compressive stress, and liquid pressure first increases and then decreases. When the liquid storage tank is close to full state, the control effect is most significant at an incidence angle of 60(degrees), and the control effect of the ViBa on the liquid storage tank with medium height-diameter ratio is the best.