Engineer's Report: Seismic Performance Evaluation and Tire Construction Analysis

Michael Reynolds

Description

This engineering analysis is a compilation of studies and calculations conducted between 1990 and 1993 by Thomas E. Griepentrog, P.E. of Buckhorn Geotech, Consulting Engineers and Geologists of Montrose, Colorado and Kenneth D. DeLapp of DeLapp Engineering in Santa Fe, New Mexico. This report is a thorough analysis of all structural aspects of the Earthrammed Tire Walls of the Earthship design by Architect Michael Reynolds.

This book also includes relevant parts (specific to Earthships) of a F.E.M.A. (Federal Emergency Management Agency) evaluation that researches many types of alternative building.

Sujets

• Arts visuels
• Architecture

Informations

• Publié par: eBookIt.com
• Date de parution: 09 juin 2017
• Nombre de lectures: 0
• EAN13: 9781456608019
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

Engineer's Report: Seismic Performance Evaluation and Tire Construction Analysis
 
 
Compiled by
Earthship Biotecture
 


Copyright 2012 Michael Reynolds,
All rights reserved.
 
 
Published in eBook format by eBookIt.com
http://www.eBookIt.com
 
 
ISBN-13: 978-1-4566-0801-9
 
 
No part of this book may be reproduced in any form or by any electronic or mechanical means including information storage and retrieval systems, without permission in writing from the author. The only exception is by a reviewer, who may quote short excerpts in a review.
 
Introduction
 


This engineering analysis is a compilation of studies and calculations conducted between 1990 and 1993 by Thomas E. Griepentrog P.E of Buckhorn-Geotech, Consulting Engineers and Geologists of Montrose Colorado and Kenneth D. DeLapp of DeLapp Engineering in Santa Fe, New Mexico. This report is a thorough analysis of all structural aspects of the Earth-rammed Tire Walls of the Earthship design by Architect Michael Reynolds.
This booklet also includes relevant parts of a F.E.M.A (Federal Emergency Management Agency) evaluation that researches many types of alternative building. Only the portion specific to Earthships is included here.
The F.E.M.A. discussion of foundations for earthen walls is included as a discussion of earthen building foundations which is relevant to the use of Earth-rammed buildings. The appendix C closes the booklet. This is pertinent information for an engineer.
The enclosed summary and calculations show the strength of the structural components of the standard Earthship Design. Charts, graphs and formulas are provided for the owner and the engineer to analyze the Earthship with site specific conditions. The information required for these calculations are: snow load and wind load, (available from a local building department) and frost depth and soil conditions (to be determined by a soils engineer on site).
 
The following information must be determined before construction in order to adapt each Earthship to its particular site :
 
1. Soil analysis: It is recommended that a licensed soil engineer be brought in to insure that your building site is suitable for construction of an Earthship. Minimum bearing capacity can be determined using the information found in Section II. This figure will vary based on the design snow load for your location. Actual bearing capacity at the site can be determined by the soils engineer. See section IV.
 
2. Earth cliffs: Some site conditions may require shorter earth cliffs than indicated on the Generic Earthship Construction Drawings. The stability of the earth cliff depends on the unit cohesive strength of the soil, the soils internal angle of friction, the total weight of the tire wall, and the potential failure plains. The formula and information necessary to determine the allowable  height of the earth cliff is found in Section II.
 
Additional information must be provided by a soils engineer based on an inspection of your site. See section IV. This inspection is typically scheduled to coincide with the initial excavation.
 
3. Lateral loads:The tire walls will impart small loads to the roof diaphragm as a result of the Earth Berms. These loads can be determined by the soils engineer based on his/her calculation of soil pressure. See Appendix B. These results will determine if additional bracing will be required on the roof.
 
Section I
Relevant letters
 

The following original letter was sent May 5, 1989 from Thomas E. Griepentrog, P.E. of Buckhorn Geotech Constulting Engineers and Geologists to Max Clark, the Ouray County Building Inspector in Ouray, Colorado:
 

 
Transcription (to allow for readability in ebook form) of the original letter (as seen above):
 
 
May 5, 1989
 
Max Clark
Ouray County Building Inspector
P.O. Bin C
Ouray, Colorado 81427
 
RE: Weaver Residence
 
Dear Max,
 
As you know, the Dennis Weaver residence being constructed near Ridgway, Colorado, is an innovative structure incorporating alternative materials and methods of construction. The use of rammed earth-filled tires for wall construction incorporates the time-proven concepts of adobe construction with the utilization of recycles materials to hold the earth in place and prevent untimely deterioration.
 
I have observed the initial stages of construction and discussed the applied concepts with Michael Reynolds, project architect. It appears that the proposed construction is at least the equivalent to the general quality, strength, effectiveness, fire resistance, durability, and safety that is required by the Uniform Building Code. In fact, in several instances, the final structure will probably exceed the standards generally accepted by the code.
 
It is my intention, as we discussed at the building site, to conduct some field testing of the wall components to verify their lateral stability and bearing capacity. When the tests are completed, I will submit a report of my findings to you. In the meantime, please do not hesitate to contact me regarding your concerns and/or comments.
 
Very truly yours,
 
Thomas E. Griepentrog, P.E.
 
 
TEG: dc
 

The following original letter was sent April 14, 1990 from Kenneth D. DeLapp, P.E., Structural Engineer to Michael Reynolds, Architect behind Earthships:
 


 

Transcription (to allow for readability in ebook form) of the original letter (as seen above):
 
 
April 14, 1990
 
Mr. Michael Reynolds
P.O. Box 1041
Taos, New Mexico 87571
 
Dear Mr. Reynolds:
 
This is in further reference to footings for the houses built with the tires and rammed earth.
 
Typical walls are about two feet four inches (2‘-4”) wide, the diameter of a tire, filled with rammed earth. Tires are places in staggered manner, similar to adobe blocks, concrete blocks, and brick. A typical roof span is about 16 feet, constructed of wood vigas. The interior surfaces are plastered with mud plaster, similar to adobe walls.
 
This wall is built about seven to ten feet high, to provide roof slope for drainage to the rear. Total weight at the bottom of the wall, at floor level, is approximately 3,600 pounds maximum. Since the width is about 2’-4”, the pressure on the soil is about 1550 pounds per square foot.
 
If a concrete footing were to be used, a minimum width footing of 16 inches would give a total load pressure of just 2,700 psf. This footing width is just over half the wall width. In my opinion, the soil pressures under the 2’-4” walls should cause no excessive settlements, at 1,550 psf.
 
Since the pressure under the walls is so low, it eliminates the need for a wider footing, built of concrete.
 
In my opinion, the other purposes of concrete footings are to provide a base to begin constructing the stem wall and to provide some ability to spread loads along the wall in case there is a region of softer soil under the wall. If the tire walls are used only on sites where the soil is uniformly firm and undisturbed, the concrete footing is not necessary. The walls and the soil need only to be protected from moisture incursion.
 
Examples of adobe houses, churches, and schools built on simple foundations of stones can be found around the state. Where these buildings have been kept dry and the foundations have been kept dry, they last for many years.
 
When the house is built on dry competent natural soil, and is kept dry, it is my opinion that the concrete foundation may be omitted.
 
Very truly yours,
 
Kenneth D. DeLapp, P.E.
Structural Engineer