Soil-Foundation-Structure Behavior at the Oakland Outer Harbor Wharf

The California Strong Motion Instrumentation Program's Loma Prieta records at Oakland Outer Harbor Wharf maybe used to study the free-field motions, the possible softening of soils surrounding the piles supporting the instrumented wharf, the determination of the motion on the instrumented wharf using free-field motion input and deflection-compatible lateral and vertical pile foundation stiffnesses, and conditions under which a soil-foundation interaction failure or structural failure of the batter piles might have developed.

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Effect of Ground Motion Characteristics on Seismic Soil-Foundation-Structure Interaction

Earthquake Spectra ◽

10.1193/040413eqs089m ◽

2015 ◽

Vol 31 (3) ◽

pp. 1789-1812 ◽

Cited By ~ 11

Author(s):

Majid Ghayoomi ◽

Shideh Dashti

Keyword(s):

Ground Motion ◽

Free Field ◽

Time History ◽

Natural Period ◽

Dense Sand ◽

Structure Interaction ◽

Flexible Base ◽

Soil Foundation ◽

Motion Characteristics ◽

Foundation Structure

A series of dynamic centrifuge experiments involving a soil-structure model were performed to investigate the influence of ground motion characteristics on site performance and soil-foundation-structure interaction (SFSI) on medium-dense sand. When investigating kinematic SFSI, the translational component of the foundation motion was observed to de-amplify compared to the free-field in terms of most intensity parameters primarily during intense shaking and at higher frequencies. The building's fundamental rocking frequency was strongly influenced by the predominant frequency of the base motion. When investigating inertial SFSI, increasing the shaking intensity was observed to increase the flexible-base natural period of the structure. Spectral accelerations at the foundation level were significantly amplified near the building's flexible-base natural period. Structural settlements were greater than those in the free-field, and their rate followed the rate of the Arias intensity time history of the base motion. More holistic ground motion parameters, such as Arias and Housner Intensities, demonstrated a strong and consistent influence on SFSI and site performance.

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Effects of Stratification on Soil–Foundation–Structure Interaction: Centrifugal Observation and Numerical Simulation

Applied Sciences ◽

10.3390/app11020623 ◽

2021 ◽

Vol 11 (2) ◽

pp. 623

Author(s):

Van-Linh Ngo ◽

Changho Lee ◽

Jae-Min Kim

Keyword(s):

Soft Soil ◽

Free Field ◽

Soil Layer ◽

Structure Interaction ◽

Centrifuge Tests ◽

Shear Beam ◽

Soil Foundation ◽

Input Motion ◽

Layered Ground ◽

Foundation Structure

It is essential to reduce structural damages caused by earthquakes in severe conditions, such as layered ground, especially when a soft soil layer is close to the surface. In this study, the kinematic and inertial interactions, two mechanisms of soil–foundation–structure interaction (SFSI), of different soil–foundation–structure systems (SFS) were investigated on uniform and layered grounds. Two layered soil profiles composed of a low stiffness layer laid over another were prepared in an equivalent shear beam container. Nine centrifuge experiments were carried out for three structures located on the surface of each ground and exposed to the Hachinohe earthquake while increasing the peak acceleration of the input motion. Numerical simulations were performed to simulate the centrifuge tests. It was found that roof motion (RM) of the tall structure increased in layered profile even though the free-field motion (FFM) decreased compared to homogeneous ground. The appearance of a soft layer beneath structures modifies the SFS system’s stiffness that causes kinematic and inertial interactions to alter to those on uniform soil profile.

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Peak Accelerations From the 17 October 1989 Loma Prieta Earthquake

Seismological Research Letters ◽

10.1785/gssrl.60.4.151 ◽

1989 ◽

Vol 60 (4) ◽

pp. 151-166 ◽

Cited By ~ 10

Author(s):

David M. Boore ◽

Linda Seekins ◽

William B. Joyner

Keyword(s):

Standard Deviation ◽

Main Shock ◽

Free Field ◽

Strong Motion ◽

Loma Prieta Earthquake ◽

The Mean ◽

Correction For Attenuation ◽

Loma Prieta ◽

Predicted Values

Abstract Peak accelerations of the Loma Prieta main shock have been tabulated from instruments maintained by a number of organizations. We have analyzed a subset of 86 records from nominally free-field sites, which have been subdivided into rock, alluvium, and bay-mud categories according to data available in various reports. After correction for attenuation, the peak accelerations on rock, alluvium, and bay-mud sites are factors of 1.6, 1.8, and 4.5 larger, on the average, than Joyner and Boore’s (1988) predicted values for a M= 6.9 earthquake. The mean motions for the rock and alluvium sites are somewhat greater than one standard deviation away from the predicted value, but the mean acceleration from the bay-mud sites is well outside the range expected from analyses of data from previous earthquakes from rock and alluvium sites. Large amplitudes of motions on bay-mud sites relative to rock sites (a factor of 2.8 for the average of the recordings of the Loma Prieta main shock) has been found previously from recordings of distant earthquakes and explosions, but the Loma Prieta earthquake provided the first opportunity to study the relative amplitudes from strong-motion recordings.

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