Near-Fault Forward Directivity Effect on the Estimation of Ground Motion Amplification Factors

2021 ◽  
Vol 147 (12) ◽  
pp. 04021139
Author(s):  
Bo Li ◽  
Yang Lu ◽  
Zhongdong Duan ◽  
Zhen Cai
Keyword(s):  
Ground Motion ◽  
Amplification Factors ◽  
Ground Motion Amplification ◽  
Directivity Effect ◽  
Near Fault ◽  
Forward Directivity

scholarly journals Near-Fault Ground Motion Influence on the Seismic Responses of a Structure with Viscous Dampers considering SSI Effect

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Jinping Yang ◽  
Peizhen Li ◽  
Hang Jing ◽  
Meng Gao
Keyword(s):  
Ground Motion ◽  
Hanging Wall ◽  
Wall Effect ◽  
Seismic Responses ◽  
Viscous Dampers ◽  
Directivity Effect ◽  
Near Fault ◽  
Forward Directivity ◽  
Hanging Wall Effect ◽  
Near Fault Ground Motion

This paper studies the influence of the characteristics of the near-fault ground motion on the seismic responses of the structure with energy dissipation devices including soil-structure interaction (SSI). A ten-story reinforced concrete frame rested on soft site is introduced, and the viscous dampers added in the frame are designed. The numerical analysis method of the soil-structure system with viscous dampers is established through ANSYS program. In addition, the response spectra of the main characteristics of the near-fault ground motion, like hanging wall effect, velocity pulse-like effect, and forward-directivity effect, are investigated carefully to learn the features of spectra energy distribution. And then, the dynamic time-history analysis is performed on the SSI system with and without viscous dampers subjected to the selected near-fault ground motion. The study reveals that the seismic responses of the structure subjected to near-fault ground motion with hanging wall effect are obviously larger than those of the footwall effect, indicating the distinct hanging wall effects on the structural dynamic responses. In addition, the performance of the structure with viscous dampers is more influenced by the ground motion containing fling-step effect than that with forward-directivity effect. Moreover, the influence of the horizontal component of forward-directivity ground motion on the seismic responses of the structure is more obvious than that of parallel component ground motion. Consequently, the hanging wall effect, velocity pulse, and horizontal component in forward-directivity effect of the near-fault ground motion have distinct influence on the seismic responses of the structure with energy dissipation devices considering SSI effect, providing insight towards the performance-based seismic design of buildings rested at the near-fault sites considering the seismic SSI effect.

Within- and Between-Event Variabilities of Strong-Velocity Pulses of Moderate Earthquakes within Dense Seismic Arrays

2021 ◽  
Author(s):  
Ming-Hsuan Yen ◽  
Sebastian von Specht ◽  
Yen-Yu Lin ◽  
Fabrice Cotton ◽  
Kuo-Fong Ma
Keyword(s):  
Ground Motion ◽  
Structural Engineering ◽  
Strike Slip ◽  
Physical Factors ◽  
Velocity Amplitude ◽  
Seismic Arrays ◽  
Directivity Effect ◽  
Forward Directivity ◽  
Significant Damage ◽  
The Impact

ABSTRACT Ground motion with strong-velocity pulses can cause significant damage to buildings and structures at certain periods; hence, knowing the period and velocity amplitude of such pulses is critical for earthquake structural engineering. However, the physical factors relating the scaling of pulse periods with magnitude are poorly understood. In this study, we investigate moderate but damaging earthquakes (Mw 6–7) and characterize ground-motion pulses using the method of Shahi and Baker (2014) while considering the potential static-offset effects. We confirm that the within-event variability of the pulses is large. The identified pulses in this study are mostly from strike-slip-like earthquakes. We further perform simulations using the frequency–wavenumber algorithm to investigate the causes of the variability of the pulse periods within and between events for moderate strike-slip earthquakes. We test the effect of fault dips, and the impact of the asperity locations and sizes. The simulations reveal that the asperity properties have a high impact on the pulse periods and amplitudes at nearby stations. Our results emphasize the importance of asperity characteristics, in addition to earthquake magnitudes for the occurrence and properties of pulses produced by the forward directivity effect. We finally quantify and discuss within- and between-event variabilities of pulse properties at short distances.

Performance of Seismic-Isolated Bridges in Relation to Near-Fault Ground-Motion and Isolator Characteristics

2006 ◽  
Vol 22 (4) ◽  
pp. 887-907 ◽  
Author(s):  
Murat Dicleli
Keyword(s):  
Ground Motion ◽  
Seismic Isolation ◽  
Elastic Stiffness ◽  
Rupture Directivity ◽  
Directivity Effect ◽  
Critical Design ◽  
Near Fault ◽  
Near Fault Ground Motion ◽  
Isolated Bridges ◽  
Forward Rupture Directivity

This paper investigates the performance of seismic-isolated bridges (SIBs) subjected to near-fault (NF) earthquakes with forward rupture directivity effect (FRDE) in relation to the isolator, substructure, and NF earthquake properties, and examines some critical design clauses in AASHTO's Guide Specifications for Seismic Isolation Design. It is found that the SIB response is a function of the number of velocity pulses, magnitude of the NF ground motion, and distance from the fault. Particularly, a reasonable estimation of the expected magnitude of the NF ground motion according to the characteristics of the bridge site is crucial for a correct design of the SIB. It is also found that the characteristic strength and post-elastic stiffness of the isolator may be chosen based on the characteristics of the NF earthquake. Furthermore, some of the AASHTO clauses are found to be not applicable to SIBs subjected to NF ground motions with FRDE.

Evaluation of amplitude-scaled and spectrum-matched motions to estimate ground-motion amplification factors

2020 ◽  
Vol 18 (10) ◽  
pp. 4659-4679
Author(s):  
Bo Li ◽  
Yang Lu ◽  
Mahesh D. Pandey ◽  
Gao Ma ◽  
Yang Liu ◽  
...  
Keyword(s):  
Ground Motion ◽  
Amplification Factors ◽  
Ground Motion Amplification

Near-Fault Directivity Spectrum for Nuclear Structure Design on Rock Site

2011 ◽  
Vol 243-249 ◽  
pp. 3820-3823
Author(s):  
Long Jun Xu ◽  
Sheng Chao Yang
Keyword(s):  
Nuclear Structure ◽  
Ground Motions ◽  
Response Spectra ◽  
Structure Design ◽  
Design Spectra ◽  
Directivity Effect ◽  
Near Fault ◽  
Forward Directivity ◽  
Rock Site ◽  
Large Earthquakes

This study is aimed at evaluating the safety implications of near-fault directivity effect on nuclear structure and facilities designed according to the Chinese code. To this end, a set of near-fault ground motions at rock site with typical forward-directivity effect is examined with emphasis on several key parameters and response spectra. The bi-normalized response spectra in terms of different corner periods are utilized to derive nuclear design spectra. It was concluded that nuclear design spectra on rock site derived from typical directivity records are significantly influenced by both magnitude and distance. The nuclear design spectra specified in the code need to be adjusted to reflect the near-fault directivity effect of large earthquakes.

Effects of Soil Parameter Variabilities on the Estimation of Ground-Motion Amplification Factors

2019 ◽  
Vol 35 (2) ◽  
pp. 907-928 ◽  
Author(s):  
Bo Li ◽  
Mahesh D. Pandy ◽  
Kao-Shan Dai ◽  
Yang Lu ◽  
Yu-Zhou Zhou ◽  
...  
Keyword(s):  
Ground Motion ◽  
Soil Column ◽  
Response Analysis ◽  
Soil Profiles ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Amplification Factors ◽  
Soil Parameter ◽  
Ground Motion Amplification ◽  
The Mean

Ground-motion amplification factors (GMAFs) are used to characterize amplification of a ground motion propagating from the bedrock to the ground surface. They are usually determined by ground response analysis, in which the soil parameter variabilities and input motion uncertainties contribute to their uncertainty. The construction of design response spectra requires mean GMAFs or GMAFs with different probability levels. Thus, it is significant to study the sensitivity of soil parameter variabilities and the number of random soil profiles for the estimation of GMAFs. This study investigates the minimum number of random soil profiles required to represent the extent of the epistemic uncertainty in the GMAFs obtained from ground response analysis. It shows that at least 20 and 60 random soil profiles are respectively required to estimate the mean and standard deviations of GMAFs with the maximum relative difference below 10%. In addition, potential reasons for a reduction in the mean GMAFs resulting from randomization of the soil column properties are discussed.

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