Influence of free field variability on linear soil-structure interaction (SSI) by indirect integral representation

2002 ◽  
Vol 32 (1) ◽  
pp. 49-69 ◽  
Author(s):  
E. Savin
Keyword(s):  
Integral Representation ◽  
Soil Structure ◽  
Free Field ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Field Variability

Vertical soil-structure interaction effects

1979 ◽  
Vol 69 (1) ◽  
pp. 221-236
Author(s):  
R. R. Little ◽  
D. D. Raftopoulos
Keyword(s):  
Nuclear Power ◽  
Soil Structure ◽  
Power Plants ◽  
Structural Model ◽  
Free Field ◽  
Interaction Effects ◽  
Soil Structure Interaction ◽  
Response Curves ◽  
Transformation Techniques ◽  
Structure Interaction

abstract An analytical expression describing the three-dimensional vertical soil-structure interaction effects is developed using Laplace and Hankel transformation techniques. Utilizing these transformation techniques and normal mode theory of vibration, an N-mass structural model is coupled to an elastic half-space representing the earth. The resulting interaction equation is solved by numerical iteration techniques for a model of a nuclear power plant subjected to actual earthquake ground excitation. The effects of the soil-structure interaction are evaluated by comparing free-field acceleration spectrum response curves with similar curves determined from the foundation motion. These effects are found to be significant for structures typical of modern nuclear power plants subjected to seismic ground motions.

scholarly journals Effect of Soil Classification on Seismic Behavior of SMFs considering Soil-Structure Interaction and Near-Field Earthquakes

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Shahrokh Shahbazi ◽  
Iman Mansouri ◽  
Jong Wan Hu ◽  
Armin Karami
Keyword(s):  
Soil Structure ◽  
Near Field ◽  
Free Field ◽  
Soil Structure Interaction ◽  
Nonlinear Time History Analysis ◽  
Type Ii ◽  
Steel Buildings ◽  
Moment Frames ◽  
Structure Interaction ◽  
Soil Flexibility

Seismic response of a structure is affected by its dynamic properties and soil flexibility does not have an impact on it when the bottom soil of foundation is supposedly frigid, and the soil flexibility is also ignored. Hence, utilizing the results obtained through fixed-base buildings can lead to having an insecure design. Being close to the source of an earthquake production causes the majority of earthquake’s energy to reach the structure as a long-period pulse. Therefore, near-field earthquakes produce many seismic needs so that they force the structure to dissipate output energy by relatively large displacements. Hence, in this paper, the seismic response of 5- and 8-story steel buildings equipped with special moment frames (SMFs) which have been designed based on type-II and III soils (according to the seismic code of Iran-Standard 2800) has been studied. The effects of soil-structure interaction and modeling of the panel zone were considered in all of the two structures. In order to model radiation damping and prevent the reflection of outward propagating dilatational and shear waves back into the model, the vertical and horizontal Lysmer–Kuhlemeyer dashpots as seen in the figures are adopted in the free-field boundary of soil. The selected near- and far-field records were used in the nonlinear time-history analysis, and structure response was compared in both states. The results obtained from the analysis showed that the values for the shear force, displacement, column axial force, and column moment force on type-III soil are greater than the corresponding values on type-II soil; however, it cannot be discussed for drift in general.

The effect of soil-structure interaction on seismometer readings

1978 ◽  
Vol 68 (3) ◽  
pp. 823-843
Author(s):  
G. N. Bycroft
Keyword(s):  
Ground Motion ◽  
Soil Structure ◽  
Free Field ◽  
Soil Structure Interaction ◽  
Rigid Sphere ◽  
Elastic Space ◽  
Structure Interaction ◽  
Frequency Components ◽  
Low Shear

abstract Rocking and vertical and horizontal translations of typical “free-field” seismometer installations lead to magnification of the ground motion record. This magnification can be significant for the higher frequency components if the terrain has a relatively low shear-wave velocity. Seismometers placed on foundations which cover a significant part of a wavelength of a horizontally incident wave, experience an attenuated ground motion. A method of correcting the seismograms for these effects is given. Compliance functions for a rigid sphere in a full elastic space are derived and are used to show that, in practical cases, down-hole seismometer installations are not significantly affected by interaction. These compliance functions should be useful in discussing the soil structure interaction of structures erected on bulbous piles. They may be also used as the basis of a method of determining elastic constants of ground at depth, in situ, and at different frequencies.

Soil-structure interaction at CDMG and USGS accelerograph stations

1989 ◽  
Vol 79 (1) ◽  
pp. 1-14
Author(s):  
C. B. Crouse ◽  
Behnam Hushmand
Keyword(s):  
Soil Structure ◽  
Transfer Functions ◽  
Ground Motions ◽  
Free Field ◽  
Soil Structure Interaction ◽  
Imperial Valley ◽  
Structure Interaction ◽  
Fundamental Frequencies ◽  
Vibration Tests ◽  
40 Hz

Abstract Forced harmonic and impulse-response vibration tests were conducted at several California accelerograph stations operated by the California Division of Mines and Geology (CDMG) and U.S. Geological Survey (USGS) to determine the extent to which soil-structure interaction may be affecting the recorded ground motions. The results of the tests on the foundations comprising USGS Station 6 in the Imperial Valley and CDMG Cholame 1E and Fault Zone 3 stations in the Cholame Valley indicated the presence of highly damped fundamental frequencies between 20 and 40 Hz. However, at the much larger Differential Array station, a masonry-block structure approximately 6 km southwest of Station 6, a moderately damped fundamental frequency of 12 Hz was observed. Approximate transfer functions between earthquake motions recorded at the stations and the free-field motions were computed from the response data obtained from the forced harmonic vibration tests. For the three smaller stations, these functions showed peak amplification factors ranging from 1.25 to 1.4 at frequencies between 20 and 40 Hz. The amplification at smaller frequencies was insignificant. For the Differential Array station, the amplification factor was 1.5 at 12 Hz and was roughly 0.6 for frequencies between 14 and 25 Hz. These results suggest that soil-structure interaction will have little effect on ground motions recorded at the smaller stations provided that most of the energy in these motions is confined to frequencies less than approximately 20 Hz. However, at the Differential Array station, soil-structure interaction probably has had, and will continue to have, a significant influence on the motions recorded at this station.

A Centrifuge Study of Seismic Structure-Soil-Structure Interaction on Liquefiable Ground and Implications for Design in Dense Urban Areas

2018 ◽  
Vol 34 (3) ◽  
pp. 1113-1134 ◽  
Author(s):  
Peter Kirkwood ◽  
Shideh Dashti
Keyword(s):  
Urban Areas ◽  
Soil Structure ◽  
Free Field ◽  
Mitigation Strategies ◽  
Soil Structure Interaction ◽  
Minimal Risk ◽  
Seismic Structure ◽  
Structure Interaction ◽  
Centrifuge Tests ◽  
Adjacent Structures

Current practice in seismic design often assumes free-field conditions for the estimation of liquefaction-induced building settlement. This is inaccurate, as a structure places additional stresses on the soil, resulting in changes to the spatial and temporal occurrence of liquefaction, accelerations, and deformations. Further complications arise in dense urban environments where closely spaced structures may interact through structure-soil-structure interaction (SSSI). Previous studies have shown that SSSI may have positive or negative effects on the response of adjacent structures in terms of permanent settlement, rotation, and flexural deformations. However, little is known regarding how to maximize the benefits of SSSI with minimal risk of adverse consequence. In this study, centrifuge tests were conducted on both isolated and closely spaced structures to identify how the building separation and ground motion characteristics affect the response of adjacent structures founded on a layered, liquefiable soil profile. Results indicate that properly planned configurations and interactions may be employed in combination with traditional mitigation strategies to improve the settlement-rotation response of adjacent structures, while also reducing the demand imposed on the superstructure.

Kinematic Soil-Structure Interaction Effect in Layered Liquefiable Soils on Foundation Input Motion

2013 ◽  
Vol 353-356 ◽  
pp. 240-246
Author(s):  
Li Hui Tian ◽  
Guang Yi Sun ◽  
Xian Zhang Ling ◽  
Zi Yu Wang ◽  
Juan Wan
Keyword(s):  
Soil Structure ◽  
Free Field ◽  
Low Frequency ◽  
High Amplitude ◽  
Shaking Table ◽  
Soil Structure Interaction ◽  
Fourier Amplitude ◽  
Structure Interaction ◽  
Earthquake Motion ◽  
Input Motion

The principal objective of this study is to make use of medium and strong motion data from instrumented shaking table tests to evaluate the effects of kinematic soil-structure interaction on foundation input motion (FIM). The shaking table tests consisted of a 2×2 pile group in two-and three-layered liquefiable soils (models 1 and 2). Each test model was subjected to three realistic earthquake motions with peak accelerations ranging from 0.13g to 0.50g, and time step ranging from 0.006 to 0.02 sec. The three input earthquake motion represented the realistic earthquake motion with high frequency, low frequency and high amplitude. The foundation/free-field ground motion variations were quantified in terms of acceleration time histories and Fourier amplitude spectrum. Preliminary analysis of the data suggests that (1) regarding the input motion with high frequency, the higher peak acceleration of the foundation indicates the structure feedback and kinematic interaction between the soil and foundation during shaking; soil layering has little effect on foundation input motion, (2) regarding the input motion with low frequency, the kinematic soil-structure interaction increases the foundation response for model 2 while reduces it for model 1. The soil profile has significant effect on the predominant frequency, (3) regarding the input motion with high amplitude, the higher response of foundation in model 1 indicates the stronger kinematic SSI effect. The small deviation between the free field and foundation in model 2 indicates the coherent motion of the foundation with soil and no obvious kinematic SSI effect, (4) soil liquefaction has significant effect on the values of peak acceleration and peak Fourier amplitude.

scholarly journals Influence of Water-Structure and Soil-Structure Interaction on Seismic Performance of Sea-Crossing Continuous Girder Bridge

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jie Guo ◽  
Kunpeng Wang ◽  
Hongtao Liu ◽  
Nan Zhang
Keyword(s):  
Soil Structure ◽  
Hydrodynamic Force ◽  
Free Field ◽  
Water Structure ◽  
Field Analysis ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Bridge Model ◽  
Continuous Girder Bridge ◽  
Girder Bridge

Based on the Hong Kong-Zhuhai-Macao project, considering the fluid-structure interaction and soil-structure interaction, the seismic response of a sea-crossing continuous girder bridge is analyzed. Three-dimensional nonlinear numerical bridge model is developed, in which the hydrodynamic force is represented by added mass and pile-soil interaction is represented by p-y elements. Meanwhile, stratification of soil is considered in the free field analysis. Through the comparison of responses of the bridge cases, the effects of earthquake-induced hydrodynamic force and pile-soil interaction are studied. For the influence of hydrodynamic force, the results show that it is relatively slight as compared with pile-soil interaction; moreover pile foundation is more sensitive to it than other bridge components. The influence of pile-soil interaction is relatively significant. When both of the interactions are considered, the influence is not a simple superposition of acting alone, so it is recommended to consider both factors in dynamic analysis.

scholarly journals Bridge Digital Twining Using an Output-Only Bayesian Model Updating Method and Recorded Seismic Measurements

2021 ◽  
Author(s):  
Farid Ghahari ◽  
Niloofar Malekghaini ◽  
Hamed Ebrahimian ◽  
Ertugrul Taciroglu
Keyword(s):  
Real World ◽  
Bayesian Model ◽  
Soil Structure ◽  
Model Updating ◽  
Free Field ◽  
Interaction Effects ◽  
Soil Structure Interaction ◽  
Fe Model ◽  
Numerical Verification ◽  
Structure Interaction

Rapid post-earthquake damage diagnosis of bridges can guide decision-making for emergency response management and recovery. This can be facilitated using digital technologies to remove the barriers of manual post-event inspections. Prior mechanics-based Finite Element (FE) models can be used for post-event response simulation using the measured ground motions at nearby stations; however, the damage assessment outcomes would suffer from uncertainties in structural and soil material properties, input excitations, etc. For instrumented bridges, these uncertainties can be reduced by integrating sensory data with prior models through a model updating approach. This study presents a sequential Bayesian model updating technique, through which a linear/nonlinear FE model, including soil-structure interaction effects, and the foundation input motions are jointly identified from measured acceleration responses. The efficacy of the presented model updating technique is first examined through a numerical verification study. Then, seismic data recorded from the San Rogue Canyon Bridge in California are used for a real-world case study. Comparison between the free-field and the foundation input motions reveals valuable information regarding the soil-structure interaction effects at the bridge site. Moreover, the reasonable agreement between the recorded and estimated bridge responses shows the potentials of the presented model updating technique for real-world applications. The updated FE model is considered as the digital twin of the bridge and can be used to analyze the bridge and monitor the structural response at element, section, and fiber levels to diagnose the location and severity of any potential damage mechanism.

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