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.

scholarly journals Effect of Height Ratio and Mass Ratio on Structure—Soil—Structure Interaction of Two Structures Using Centrifugal Experiment

2019 ◽  
Vol 9 (3) ◽  
pp. 526 ◽  
Author(s):  
Van-Linh Ngo ◽  
Jae-Min Kim ◽  
Soo-Hyuk Chang ◽  
Changho Lee
Keyword(s):  
Soil Structure ◽  
Soil Structure Interaction ◽  
Geotechnical Centrifuge ◽  
Structure Interaction ◽  
Structure Response ◽  
Centrifuge Tests ◽  
Adjacent Structures ◽  
Soil Foundation ◽  
Period Lengthening ◽  
Significant Increment

: In a megacity, structure response during an earthquake could be increased or decreased due to effects from neighboring structures, through structure-soil-structure interaction (SSSI). In the present study, a series of dynamic geotechnical centrifuge tests are carried out to investigate SSSI effects on responses of structure with various characteristics of mass, height, and natural frequency. Experimental observations are focused on the effects of the distance between two structures, type, and peak acceleration of input excitation. A period lengthening is observed in the soil-foundation-structure interaction (SFSI) effects of all structures. It is monitored that an increment in response of smaller structure and a decrement in response of larger structure, compared to isolated structure, due to SSSI effects. Unfavorable distance reveals that the most significant increment in response of S2 structure occurred at approximately one-fourth of wavelength transmitted from the vibrating adjacent structure. More severe SSSI effects are found under a lower input earthquake acceleration. It is found that both height and mass ratios, between two adjacent structures, are particular parameters on SSSI, resulting in increment or reduction of structure response.

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.

Effects of Slenderness and Fundamental Frequency on the Dynamic Response of Adjacent Structures

2019 ◽  
Vol 19 (09) ◽  
pp. 1950105
Author(s):  
Gonzalo Barrios ◽  
Vinuka Nanayakkara ◽  
Pramodya De Alwis ◽  
Nawawi Chouw
Keyword(s):  
Dynamic Response ◽  
Fundamental Frequency ◽  
Soil Structure ◽  
Numerical Models ◽  
Ground Motions ◽  
Soil Structure Interaction ◽  
Reference Case ◽  
Maximum Acceleration ◽  
Structure Interaction ◽  
Adjacent Structures

In conventional seismic design, the structure is often assumed to be fixed at the base. However, this assumption does not reflect reality. Furthermore, if the structure has close neighbors, the adjacent structures will alter the response of the structure considered. Investigations on soil–structure interaction and structure–soil–structure interaction have been performed mainly using numerical models. The present work addresses the dynamic response of adjacent single-degree-of-freedom models on a laminar box filled with sand. Impulse loads and simulated ground motions were applied. The standalone condition was also studied as a reference case. Models with different fundamental frequencies and slenderness were considered. Results from the impulse tests showed that the top displacement of the models with an adjacent structure was reduced compared with that of the standalone case. Changes in the fundamental frequency of the models due to the presence of an adjacent model were also observed. Results from ground motions showed amplification of the maximum acceleration and the top displacement of the models when both structures have a similar fundamental frequency.

Generalized dynamic Winkler model for nonlinear soil–structure interaction analysis

2008 ◽  
Vol 45 (4) ◽  
pp. 560-573 ◽  
Author(s):  
Nii Allotey ◽  
M. Hesham El Naggar
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Soil Structure Interaction ◽  
Winkler Foundation ◽  
Deep Foundations ◽  
Structure Interaction ◽  
Design Engineers ◽  
Winkler Model ◽  
Centrifuge Tests ◽  
Cyclic Degradation

The beam on nonlinear Winkler foundation (BNWF) model is widely used in soil–structure interaction (SSI) analysis owing to its relative simplicity. This paper focuses on the development of a versatile dynamic BNWF model for the analysis of shallow and deep foundations. The model is developed as a stand-alone module to be incorporated in commercial nonlinear structural analysis software. The features of the model discussed are the loading and unloading rules, slack zone development, the modeling of cyclic degradation and radiation damping. The model is shown to be capable of representing various response features observed in SSI experiments. In addition, the predictions of the model for centrifuge tests of piles in weakening and partially weakening soil are shown to be in good agreement with the experimental results. This agreement demonstrates the potential of the model as a useful tool for design engineers involved in seismic design, especially performance-based design.

Sign in / Sign up

Export Citation Format

Share Document