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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 202 Abstracts search results
March 19, 2021
Sponsors: Sponsored by ACI Committee 351
Editor: Carl A. Nelson
This special publication grew out of the Technical Session entitled “Application of ACI 351-C Report on Dynamic Foundations,” held at the ACI Spring 2019 Convention in Québec City, Québec. Following this event, Committee 351 decided to undertake a special publication with contributions from those session participants willing to develop their presentations into full-length papers. Three papers included in the current publication were contributed by these presenters and their coauthors, with six additional papers provided by others. All but one of the papers deal with the subject matter of ACI 351.3—Foundations for Dynamic Equipment—updated in 2018. The one exception (the paper of Wang and Fang on wind turbine foundations) provides valuable information to engineers dealing with a lack of consistent design criteria among various codes for reinforced concrete foundations subjected to high-cycle fatigue loads.
I would like to thank the members of ACI Committee 351 for their support, in particular the current main Committee and Subcommittee C Chairpersons Susan Isble and Dr. Mukti L. Das, respectively. I also wish to express my gratitude to the authors for their perseverance through the difficult circumstances of 2020, and to the reviewers who generously contributed their time and expertise to this publication.
Last, but not least, I want to thank my wife Cindy for tolerating me (and the growing piles of paper) over the past several months as the deadline approached.
Carl A. Nelson
On behalf of ACI Committee 351
Minneapolis, December 2020
March 1, 2021
Ping (Philip) Jiang, Ron McDonel
A more than 50-year old Steam Turbine/Generator (STG) table-top concrete foundation was retrofitted to
support a new STG/Condenser unit. This new machine unit is set on a sub skid with spring/damper assemblies
underneath and located on existing concrete table top columns. This paper presents a case study of the seismic
design and evaluations of the existing foundation structure that were performed to assess and qualify the structure’s
service and strength capabilities. Based on these evaluations, modifications to the existing STG foundation were
minimized allowing the cost effective reuse of the existing foundation resulting in significant savings for the overall
installed cost of the project.
David L. Pederson, Anthony J. Baxter and Carl A. Nelson
This paper discusses steps for both computing vibration from equipment foundations using the elastic halfspace
theory and then computing the decrease in vibration amplitude from the foundation to receivers. The steps are
demonstrated on an existing foundation at a project site in Ohio that was subjected to dynamic loading from a hydraulic
vehicle test rig. Several approaches are discussed to estimate the dynamic shear modulus of different soils, along with
a methodology to establish an equivalent dynamic shear modulus for soils with varying shear wave velocities.
Vibration transmission through the soil can affect people and sensitive equipment both near and far from the source.
This paper shows a hybrid method and an SRSS method to compute the vibration attenuation through the near field
and far field. The calculated results for this site were found to be very close to the measured values. Finally, vibration
levels are compared for variations in stiffness, damping and attenuation to evaluate the sensitivity to calculations
and/or field measurements. Variations in stiffness result in a nearly proportional change in vibration level while
variations in damping and attenuation produce relatively small changes in the results.
Mukti Lal Das
The availability of high-speed computers at a reasonable price resulted in various sophisticated analysis
and design methodologies for the elevated flexible pedestal (Tabletop) foundations replacing the rule-of-thumb
processes based on static equivalent principle which used to produce either unsafe or overly conservative structures.
A thorough study is undertaken with four typical models usually selected for static and dynamic analyses
in the structural/mechanical engineering practice. It is found that all the models provide comparable results. However,
each one has its own advantages and disadvantages. These will be highlighted in the Summary and Concluding
Remarks of this paper.
O. S. Ali Ahmed and Damon G. Reigles
This paper discusses the factors that affect the dynamic response of machine foundation systems,
which include (1) the soil dynamic properties, (2) the geometric properties of the foundation, (3) mass of the machine
and foundation, and (4) the amplitude and frequency of the applied dynamic loads. The primary objective in any
machine foundation design is to limit the foundation response below a specific amplitude threshold. A foundation
response exceeding this limit may adversely affect the performance of the machine and damage the machine internals,
resulting in costly repairs and lost revenue. Also, the excessive vibrations may result in structural degradation of the
foundation, additional excitation stresses on the machine, and increase the compressor unbalance loading. This paper
presents dynamic analysis results of a four-cylinder compressor foundation originally designed without consideration
for soil-foundation interaction and suffering from excessive vibration. The foundation block supports a 4-cylinder
Dresser-Rand compressor, suction and discharge bottles, a crank, and a driving motor with a total weight of
approximately 300 kip (1334 kN). A three-dimensional, finite element model representing the soil–foundation system
was developed to determine the dynamic characteristics and assess the foundation response under applied dynamic
loading from the compressor crank. Results showed that the response of the soil-foundation system is governed by the
response of the individual support piers (blocks) and not the global foundation response. This paper also provides a
recommended modification to the foundation geometry to reduce the effect of the individual piers' local modes and
enhance the foundation dynamic performance.
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