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The finite element model of suspension bridge was established according to the actual bridge engineering in Southwest area of China. In order to simulate the random ground motion model accurately and efficiently, the orthogonal random function ground motion modeling method based on Priestley evolution spectrum theory is adopted. The dimensionality reduction simulation of random ground motion is realized, and the simulated ground motion samples are input into the finite element model to carry out the time history analysis. Finally, the seismic response of the bearing and pylon is analyzed and important conclusions are drawn. [ABSTRACT FROM AUTHOR]

Tunnel portal sections located in the soft-hard rock junction are vulnerable to the strong earthquake motions in seismically active regions. The main objective of this paper is to investigate the seismic response of tunnel portals located in the soft-hard rock junction. Taking the Baiyunding tunnel in northeast China as a background, a shaking table test with a geometric scaling ratio of 1:30 was built. Details of test setup and procedures are introduced first and then the test results are presented. The discussion of the results is based on the peak ground acceleration (PGA), the longitudinal, the contact stress, and the safety factor. The results show that the soft section of the soft-hard rock junction suffers remarkable damages under strong seismic motions, while the hard rock section is less affected by earthquakes. The increasing soft rock range causes a rise of the forced displacement of tunnel linings, which, together with the seismic inertia force, leads to the increase of the contact stress of the linings, and ultimately resulting in the deterioration of the tunnel seismic safety. To mitigate the seismic damage of tunnel portals in the soft-hard rock junction, rock grouting, bolt support, and other effective reinforced methods should be considered in the seismic design of the soft section. [ABSTRACT FROM AUTHOR]

Numerous interbedded rock (IR) slopes fail during the Wenchuan earthquake in the mountainous region of western China. Landslides are also triggered in IR slopes with a 60° layer inclination, which are generally stable in gravity-dominant environments. This study examines the effect of seismic motion on the response characteristics and failure patterns of IR slopes with steep layers to develop a landslide hazard assessment tool for earthquake-prone regions. First, we use a centrifuge shaking table test to model the failure process and acceleration responses of two IR slope models with stratigraphic dips of 60° and 80°, respectively, under different seismic intensities. Next, we adopt the Particle Flow Code to examine the crack propagation features and peak ground acceleration amplification effects for the IR slopes. We find that the seismic failure pattern of IR slopes depends largely on rock layer inclination: buckling failure is triggered when rock layers are parallel or nearly parallel to the slope surface, while toppling failure is triggered when the rock layer inclination is significantly higher than that of the slope surface. Following seismic excitation, the damage is mainly observed in the weak rock layers, creating lateral stress on adjacent strong rocks, which undergoes deformation and ultimate macroscopic failure. Further, displacement of the IR slope is negatively correlated to rock layer inclination. Rock layer thickness has a major influence on the damaged area inside the slope mass, while rock layer stiffness mainly affects the deformation distribution near the slope shoulder. • Interbedded slopes with steep layers under earthquake exhibit buckling or toppling. • Using centrifugal shaking table test to reproduce interbedded rock slope failures. • Non-uniform deformation is highly developed in interbedded slopes. • Rock layer inclination is a significant factor on failure type in interbedded slopes. [ABSTRACT FROM AUTHOR]

• The friction spring-based self-centering rocking core (SRC) is introduced to improve the resilience of the beam-through frames (BTFs). • Quasi-static tests and hybrid tests were conducted to investigate the seismic performance of the SC device and the SRC, respectively. • A parametric numerical study was performed to investigate the two stiffness parameters of the SC device on the seismic performance of the system. Beam-through frames (BTFs) are gradually becoming popular as low-to-medium rise buildings in China because of their economic benefits and fast construction. However, BTFs are prone to soft-story failure mechanisms, especially under the ultimate stage. The self-centering rocking core (SRC), composed of a steel truss rocking core and a friction spring-based self-centering (SC) device, is introduced to improve the resilience of the BTF. Quasi-static tests and hybrid tests were conducted to investigate the seismic performance of the SC device and the SRC, respectively. Quasi-static tests demonstrate that the SC device has highly stable flag-shaped hysteretic behavior under two different loading protocols. Hybrid tests reveal that the system could realize the target seismic performance with an effectively controlled deformation pattern under both far-field (FF) and near-fault (NF) pulse-like ground motions. Based on the experimental results, the uniaxial material model of the SC device and the numerical model of the system were verified. Subsequently, a parametric study was performed to investigate the influence of two stiffness parameters (i.e., the ratio of the initial actual (experimental) compression stiffness to the initial theoretical compression stiffness (κ) and the ratio of the initial actual tension stiffness to the initial actual compression stiffness (ρ)) of the SC device on the seismic performance of the system. The incremental dynamic analysis (IDA) results show that the collapse capacity of the system increases first and then decreases with the increase in κ values and a larger ρ leads to a larger collapse capacity of the system. Besides, the influence of such stiffness parameters on the peak responses of the system under various seismic hazard levels was also investigated. The strategy employing the SRC could realize a uniform peak inter-story drift (PID) distribution of BTFs while the peak floor acceleration (PFA) tends to be concentrated on the upper floors. [ABSTRACT FROM AUTHOR]

• Existing dissipators of tension-only braces are prohibited in China. • A new passive mechanical device, namely asymmetrical friction damper (AFD), was designed, fabricated and tested. • An asymmetrical constitutive model is proposed. Equal energy dissipation capacity principle is chosen to modify parameters. • AFD co-works well with slender braces under different levels of earthquake. In this paper, a passive asymmetrical friction damper (AFD), which significantly improves the hysteretic behavior of tension-only braces (TOBs) is introduced. The AFD carries force and dissipates energy under tensile loading and carries nearly zero force under compressive loading without causing TOB slackness. As a result, the AFD prevents the TOBs from buckling and from the impact seen in systems with significant slackness. In this study, twelve tests were conducted. Based on the results, an asymmetrical constitutive model was proposed to describe the mechanical properties of the AFD. In addition, to optimize model parameters, an equal energy method was proposed and verified. Furthermore, nonlinear time history analysis was operated on a six-story benchmark model with comparisons between the AFDs and fluid viscous dissipators (FVDs) systems. With the maximum reduction of 58.1% on the 5th floor and an average 23.8% reduction over six floors under the rare earthquake, the displacement-dependent as well as velocity-dependent AFD proved itself better performance in energy dissipation and making the building deform evenly to redistribute the internal force and avoid local failure. [ABSTRACT FROM AUTHOR]

On 3 July 2015, the Mw 6.5 Pishan earthquake occurred at the junction of the southwestern margin of the Tarim Basin and the northwestern margin of the Tibetan Plateau. To understand the seismogenic mechanism and the post-seismic deformation behavior, we investigated the characteristics of the post-seismic deformation fields in the seismic area, using 9 Sentinel-1A TOPS synthetic aperture radar (SAR) images acquired from 18 July 2015 to 22 September 2016 with the Small Baseline Subset Interferometric SAR (SBAS-InSAR) technique. Postseismic LOS deformation displayed logarithmic behavior, and the temporal evolution of the post-seismic deformation is consistent with the aftershock sequence. The main driving mechanism of near-field post-seismic displacement was most likely to be afterslip on the fault and the entire creep process consists of three creeping stages. Afterward, we used the steepest descent method to invert the afterslip evolution process and analyzed the relationship between post-seismic afterslip and co-seismic slip. The results witness that 447 days after the mainshock (22 September 2016), the afterslip was concentrated within one principal slip center. It was located 5–25 km along the fault strike, 0–10 km along with the fault dip, with a cumulative peak slip of 0.18 m. The 447 days afterslip seismic moment was approximately 2.65 × 1017 N m, accounting for approximately 4.1% of the co-seismic geodetic moment. The deep afterslip revealed that a creeping process from steady-state "secondary" creeping to accelerating "tertiary" creep in the deep of fault. The future seismic hazard deserves further attention and research. [ABSTRACT FROM AUTHOR]

The evaluation of seismic site amplification and its relationship with geological structures play a vital role in earthquake engineering and hazard assessment. This study presents an analysis of topographic and geologic site amplification effects observed in the Qiaozhuang region, Sichuan Province, China. Seismic recordings at several monitoring stations installed on two slopes located at a distance of about 1 km in the study area after the 2008 Wenchuan earthquake provide evidence of strong and variable amplifications. To assess the combined effect of topographic and geological controls in slope response to seismic motions, we built 2D and 3D dynamic numerical models using monitoring data as inputs. Four layers with different P-wave velocities, based on geophysical survey in the study area, are considered in the numerical models. Models that only consider topography give an amplification factor of <3, which is much lower than the amplification factor of 5–6 from the monitoring data, while those models that considered both the topographic variation and four layers agree well with the monitoring data. The 3D modeling results show that the subsurface amplification factor is less than that on the slope surface even at the same elevation. This is also consistent with the monitoring data and further indicates that the combined topographic and geological amplification effect on the slope surface is more significant than the sole geological amplification effect inside the slope. Our numerical simulation results suggest that it is important to consider the combined topographic and geological amplification effects in the hazard assessment of seismically induced slope failures. • This study presents long-term monitoring data of slope seismic response. • Homogeneous numerical models show that topography alone only produces low amplification effects. • The results from three-layer heterogenous 3D model indicat the importance of geological amplification effect. [ABSTRACT FROM AUTHOR]