The influence of surface Rayleigh waves (SRWs) on the seismic behavior of three archetype nonconforming reinforced concrete (RC) buildings including weak first story with four, six, and eight stories when subjected to earthquake ground motions (EQGMs) recorded during the strong September 19, 2017 Mw7.1 earthquake in Mexico City, is discussed in this paper. For this purpose, ground acceleration time histories corresponding to the retrograde and prograde components of SRWs were extracted from EQGMs collected at the accelerographic stations placed at the transition and soft soil sites. It was found that the SWRs contribute to about 50% of the median maximum IDR demand (IDRmax) triggered by the as-recorded earthquake ground motions at the ground level of the four- and six-story building models, while their contribution is about 30% of IDRmax for the eight-story building model. It should be noted that that SRWs induce median IDRmax demands to the four-story building model larger than about 11% and 49% than those to the six- and eight-story models, respectively, for soft soil sites. Moreover, the prograde component can trigger IDRmax demands in the four-story building model larger than 73% and 45% than those for the six- and eight-story models, respectively, for the transition sites. Particularly, it was shown that SRWs induce median IDRmax demands in excess of 0.35% at the first level of the archetype building models, which is associated to the light cracking damage state of nonductile RC columns, and even in excess of IDRmax of 0.71% associated to the severe cracking damage state when the record-to-record variability is considered in the IDRmax demand (i.e. the 84th percentile of IDRmax). Although the earthquake ground motion component of the surface Rayleigh waves was negligible in the median IDRmax, this study showed that the effect of the directionality of IDRmax is important for the CH84 station, where significant polarity of spectral ordinates was identified in previous studies.

Shallow subway tunnels in both the intermediate and far fields are significantly affected by Rayleigh surface waves, which typically induce substantial vertical seismic motion and exhibit high seismic destructiveness. However, current vulnerability assessments of underground tunnels primarily focus on body waves. This study aims to identify the optimal ground motion intensity measures (IMs) for evaluating the seismic fragility of shallow circular subway tunnels subjected to Rayleigh waves. A detailed dynamic analysis of soil-tunnel interaction is performed using the two-dimensional Finite Element Method, with particular emphasis on the influence of tunnel burial depth and site classification on the tunnel's response to Rayleigh waves. The input of Rayleigh wave motion is modeled by transforming the motion into a series of equivalent forces, applied through viscoelastic boundaries. This study examines 15 widely used ground motion IMs, with diameter deformation ratio (DDR) serving as the damage measure (DM). Linear regression analysis is conducted to explore the relationship between IMs and DDR. The optimal IMs are evaluated based on criteria including efficiency, practicality, proficiency, and correlation. The results indicate that for sites classified as Class III and IV, the optimal IM is root mean square velocity (vrms), while for Class II sites, spectral mean velocity (SMV) is more suitable. Fragility curves for shallow-buried tunnels in Class II, III, and IV sites are presented. These curves demonstrate that tunnels are most vulnerable to damage in Class II sites, followed by Class IV, and least vulnerable in Class III sites. In Class II sites, shallower tunnel depths are associated with increased seismic damage, while deeper tunnels in Class III and IV sites experience greater seismic damage. The primary factor influencing seismic damage to tunnels is the vertical relative deformation of the surrounding soil layers.

The city of A & iuml;n T & eacute;mouchent, located in northwest Algeria at the westernmost part of the Lower Cheliff Basin, has experienced several moderate earthquakes, the most significant of which occurred on 22 December 1999 (Mw 5.7, 25 fatalities, severe damage). In this study, ambient noise measurements from 62 sites were analyzed using the horizontal-to-vertical spectral ratio (HVSR) method to estimate fundamental frequency (f0) and amplitude (A0). The inversion of HVSR curves provided sedimentary layer thickness and shear wave velocity (Vs) estimates. Additionally, four spatial autocorrelation (SPAC) array measurements refined the Rayleigh wave dispersion curves, improving Vs profiles (150-1350 m/s) and sediment thickness estimates (up to 390 m in the industrial zone). Vs30 and vulnerability index maps were developed to classify soil types and assess liquefaction potential within the city.

The S-wave velocity (SWV) is a crucial parameter in seismic site characterization and seismic microzonation. In Varanasi city, we determined the shear wave velocity through a dual approach, employing joint inversion of microtremor array survey and the Horizontal to Vertical Spectral Ratio (HVSR) method. This combined analysis from two distinct methods enhances the reliability of our S-wave velocity model for the subsurface soil strata. To assess the S-wave velocity profile in shallow subsurface soil layers, we conducted forward and inverse modelling of geophysical data. This evaluation was cross-referenced with geotechnical borehole data to ensure accuracy. Microtremor measurements were conducted at 115 single stations and 12 array stations in the city. Joint modelling of HVSR and Rayleigh wave phase velocity dispersion provided insights into the site characteristics. Utilizing neighbourhood algorithms, we inverted dispersion curves from microtremor array measurements to obtain the S-wave velocity profile. The results were validated using geotechnical borehole data in the study area. The microtremor-derived S-wave velocity disclosed significant impedance contrasts in the topsoil layer, reaching a depth of approximately 12 m, with velocities ranging from 180 to 250 m/s. The second layer, extending to around 40-50 m, exhibited velocities between 300 and 400 m/s, while the bottom layer surpassed 600 m/s. Comparisons with SPT-derived S-wave velocity confirmed a well-correlated S-wave velocity profile for the top layer. The various methods converged to an average S-wave velocity of 360 m/s up to a depth of 50 m.

Large deformation of sand due to soil liquefaction is a major cause for seismic damage. In this study, the mechanisms and modeling of large post-liquefaction deformation of sand considering the significant influence of water absorption in shearing and seismic wave conditions. Assessment of case histories from past earthquakes and review of existing studies highlight the importance of the two factors. Based on the micro and macro scale mechanisms for post-liquefaction shear deformation, the mechanism for water absorption in shearing after initial liquefaction is revealed. This is aided by novel designed constant water-absorption-rate shear tests. Water absorption in shearing can be classified into three types, including partial water absorption, complete water absorption, and compulsory water absorption. Under the influence of water absorption in shearing, even a strongly dilative sand under naturally drained conditions could experience instability and large shear deformation. The mechanism for amplification of post-liquefaction deformation under surface wave load is also explained via element tests and theoretical analysis. This shows that surface wave-shear wave coupling can induce asymmetrical force and resistance in sand, resulting in asymmetrical accumulation of deformation, which is amplified by liquefaction. A constitutive model, referred to as CycLiq, is formulated to capture the large deformation of sand considering water absorption in shearing and seismic wave conditions, along with its numerical implementation algorithm. The model is comprehensively calibrated based on various types of element tests and validated against centrifuge shaking table tests in the liquefaction experiments and analysis projects (LEAP). The model, along with various numerical analysis methods, is adopted in the successful simulation of water absorption in shearing and Rayleigh wave-shear wave coupling induced large liquefaction deformation. Furthermore, the model is applied to high-performance simulation for large-scale soil-structure interaction in liquefiable ground, including underground structures, dams, quay walls, and offshore wind turbines.

Rayleigh waves are crucial in earthquake engineering due to their significant contribution to structural damage. This study aims to accurately synthesize Rayleigh wave fields in both uniform elastic half-spaces and horizontally layered elastic half-spaces. To achieve this, we developed a self-programmed FORTRAN program utilizing the thin layer stiffness matrix method. The accuracy of the synthesized wave fields was validated through numerical examples, demonstrating the program's reliability for both homogeneous and layered half-space scenarios. A comprehensive analysis of Rayleigh wave propagation characteristics was conducted, including elliptical particle motion, depth-dependent decay, and energy concentration near the surface. The computational efficiency of the self-programmed FORTRAN program was also verified. This research contributes to a deeper understanding of Rayleigh wave behavior and lays the foundation for further studies on soil-structure interaction under Rayleigh wave excitation, ultimately improving the safety and resilience of structures in seismic-prone regions.

Rayleigh waves are vertically elliptical surface waves traveling along the ground surface, which have been demonstrated to pose potential damage to buildings. However, traditional seismic barriers have limitations of high-frequency narrow bandgap or larger volume, which have constraints on the application in practical infrastructures. Thus, a new type seismic metamaterial needs to be further investigated to generate wide low-frequency bandgaps. Firstly, a resonator with a three-vibrator is proposed to effectively attenuate the Rayleigh waves. The attenuation characteristics of the resonator are investigated through theoretical and finite element methods, respectively. The theoretical formulas of the three-vibrator resonator are established based on the local resonance and mass-spring theories, which can generate wide low-frequency bandgaps. Subsequently, the frequency bandgaps of the resonator are calculated by the finite element software COMSOL5.6 based on the theoretical model and Floquet-Bloch theory with a wide ultra-low-frequency bandgap in 4.68-22.01 Hz. Finally, the transmission spectrum and time history analysis are used to analyze the influences of soil and material damping on the attenuation effect of resonators. The results indicate that the resonator can generate wide low-frequency bandgaps from 4.68 Hz to 22.01 Hz and the 10-cycle resonators could effectively attenuate Raleigh waves. Furthermore, the soil damping can effectively attenuate seismic waves in a band from 1.96 Hz to 20 Hz, whereas the material of the resonator has little effect on the propagation of the seismic waves. These results show that this resonator can be used to mitigate Rayleigh waves and provide a reference for the design of surface waves barrier structures.