Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

Vibration analysis was conducted for large rotating fans mounted on adjacent rectangular concrete foundation blocks, 66 ft x 22 ft x 10 ft depth, with the adjacent long sides 10 ft apart. The blocks were embedded in medium dense sands and gravels with a variable shear-wave velocity profile. The purpose of the analysis was to determine whether (1) the dynamic interaction of the blocks through the surrounding soil would cause unacceptable vibratory response of the fans, and (2) the foundation stiffness criterion set by the vendor was satisfied. Solutions were obtained using the 3-D dynamic version of the FLAC computer program, which was first used to compute the response of a single block-fan system. The introduction of the second block-fan system into the model resulted in less than 10% amplification in dynamic response of the two-block system relative to the single block-fan response, when the excitation forces of both fans were in phase (i.e. 0° lag). However, a maximum amplification of 100% was computed when the phase-angle difference in forces was between approximately 90° and 120°. The results ultimately demonstrated that the vibration and foundation stiffness criteria could be met, which would have been more difficult without the use of a 3-D numerical modeling code.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

Vibration Analysis of Rotating Fans Mounted on Adjacent Rectangular Foundation Blocks

San Diego, California

Vibration analysis was conducted for large rotating fans mounted on adjacent rectangular concrete foundation blocks, 66 ft x 22 ft x 10 ft depth, with the adjacent long sides 10 ft apart. The blocks were embedded in medium dense sands and gravels with a variable shear-wave velocity profile. The purpose of the analysis was to determine whether (1) the dynamic interaction of the blocks through the surrounding soil would cause unacceptable vibratory response of the fans, and (2) the foundation stiffness criterion set by the vendor was satisfied. Solutions were obtained using the 3-D dynamic version of the FLAC computer program, which was first used to compute the response of a single block-fan system. The introduction of the second block-fan system into the model resulted in less than 10% amplification in dynamic response of the two-block system relative to the single block-fan response, when the excitation forces of both fans were in phase (i.e. 0° lag). However, a maximum amplification of 100% was computed when the phase-angle difference in forces was between approximately 90° and 120°. The results ultimately demonstrated that the vibration and foundation stiffness criteria could be met, which would have been more difficult without the use of a 3-D numerical modeling code.