This study was not carried out in a manner that would validate the intent of the proposed anchor spacing chart, which is to eliminate the need for soil classification.
On page 1-3 of the MHRA report it states, "The commonly used measure of the holding capacity of soil -torque test- is not a particularly helpful tool in designing the anchor system". On page C-4 it states, "the soil torque probe can still be used to help determine the type of anchor that will be required at individual sites, however the torque probe can sometimes provide misleading classification information".
It would appear that there is no consensus on whether or not the soil torque probe has any value. If the torque probe test provides misleading information as to the soil classification, then the wrong anchors will be selected, and the anchor effectiveness could not be assured.
The affects of installation on anchor hardware, and the problem of installing anchors to their full-intended depth, which were discussed in detail in the original report, would both increase the COV, which has been excluded from calculating the load values recommend by MHI/MHRA. Also discussed in the previous report were the affects of corrosion on the anchors. The level of corrosion in sandy soils is close to that of air, and sandy soils are most common in wind zone II and II. At least most should have a basic understanding of what happens to unprotected steel in the air of a coastal environment. The helix on an anchor is constructed of relatively light gauge steel. This will insure that it will yield to the effects of corrosion, sooner rather than later. In addition, an anchor shaft exposed to the effects of corrosion will have a loss in its structural integrity. As noted earlier, Pearson recorded that even an increase of 1/8=inch in anchor shaft diameter can make an apparent difference in the stiffness of the anchor. It can be assumed, based on Pearson's finding that a loss of shaft diameter, to the effects of corrosion, will cause an apparent decrease in the stiffness of the anchor, and therefore to its resistance to horizontal displacement. In a coastal environment, the COV for anchors not protected against the effects of a coastal environment, will more than likely increase, until failure is imminent, within a relatively short period.
The Manufactured Housing Research Alliance, its members, consultants, contractors, and representatives make no representations, warranty or guarantee, express or implied, as to the accuracy or appropriateness of any material or information in this manual for use in a specific home, nor damages arising from any such use.
This manual, which no one wants to claim responsibility for the accuracy, or the appropriateness of the information contained within, was used to produce the MHI/MHRA, "Anchor Spacing Chart", and the anchor spacing chart contains the following disclaimer.
The Engineering Analysis used in developing this chart was reviewed by T.R. Arnold & Associates, Inc., PFS Corporation and RADCO - US Department of Housing and Urban Development accepted third party inspection agencies - and is deemed to be in conformance with the federal Manufactured Home Construction and Safety Standards. The Manufactured Housing Research Alliance and its members, the Manufactured Housing Institute, and the aforementioned third party agencies assume no liability for errors and/or damages in anchor system design, spacing, and installation resulting from the use of this information.
The engineering analysis used in developing this chart is deemed to be in conformance with the federal standards, not the chart itself, and/or the recommended load values used in developing this chart. Carrying out an engineering analysis simply means the analysis was done in a manner that was acceptable by engineering standards, which meets the MHCSS. An Engineering Analysis is carried out for determining if something meets a specification. This does not mean that the results of this engineering analysis, met the intended specification, or standard for what was being analyzed.
"Strict liability", does not depend on actual negligence or intent to do harm, but that is based on the breach of an absolute duty to make something safe. Producing a product that can cause serious harm does not make the manufacturer of such a product liable for accidents or injuries to person or property, that result from its use or misuse; after all, an automobile is considered a product that can cause serious harm. However, if a product that is capable of causing serious harm is incautiously made, and accidents or injuries occur because of this incaution, then the manufacturer of this product can be held liable. The manufacturer of such a product owes a duty of care in the design, inspection, and fabrication of the product, a duty not only owed to the immediate purchaser, but to all persons who might foresee-ably come into contact with the product. The disclaimers do not mean anything if it can be shown, that a product was incautiously made, and this resulted in serious harm to people and property. What follows, in our opinion is the true intent of this industry driven exercise.
First, the "MHI/MHRA Anchor Spacing Chart" is nothing more than a prescriptive standard, since it prescribes the design of the anchoring system, by eliminating the need for the manufacturer, and/or their agents to determine, whether what they have designed, will perform as intended.
By the industry seeking to have the States "adopt" the "MHI/MHRA Anchor testing protocol", and "Anchor Spacing Chart", they shift their "strict liability" for this aspect of manufactured home construction, onto the States, or other government agencies, which by "adoption" would become responsible for the use of the MHI/MHRA Anchor testing protocol, and anchor spacing chart. This is simple if you stop and think about it. The manufacturers of this product can be held responsible for designing a system, which does not comply with standards that require performance. On the other hand, the manufacturers cannot be held liable for an anchoring system, in which the design of the system was dictated to them, by a federal or state jurisdiction, which has authority over them.
Having a uniform anchoring program serves no purpose, if the results are uniformly inadequate anchoring systems, for manufactured housing. If the government prescribes this uniformly inadequate anchoring system, then it is the government who bears the responsibility for the injuries and/or deaths that may result, by dictating the use of an inadequate anchoring system, not the manufactured housing industry. The manufactured housing industry clearly stated in their disclaimers that the information in their manual, and that the anchor spacing chart, could be in error, and therefore they want no responsibility for its use by the States, or/and HUD, or anyone else. The federal standards clearly allow the manufacturers of this product to use this information and anchor spacing chart in the design and construction of a manufactured home, so long as they can show, through testing, an equal or greater performance to what the federal standard provides for. In wind zone I this means that anchor system must resist horizontal movement up to 15 psf, and so on for each respective wind zone. Given this fact, ask yourself why the industry, and the industry's association, MHI/MHRA, is pushing so hard, to have the States adopt their prescriptive standard, and then dictate back to them, the use of this same prescriptive standard?
Anchor Committee Conference Call Minutes, January 4th, 2001
Industry representative statements
The States should adopt the MHRA Ground Anchor Test Protocol and Diagram,
at Appendix A of the MHRA "Guidelines for Anchor System Design: Technical Support
Document," dated January 2000.
While one would think that this MHI/MHRA proposal addresses some of the problems, by lowering the load values, this is not the intent. Since the current soil testing methods, used by the industry are unreliable, and our observations of dozens of manufactured home installations, revealed that installers do not test the soil, to determine the soil classification, it stands to reason that the industry can eliminate soil testing, without changing current practices. In addition, since the MHI/MHRA report, as well as previous reports, reveal that the 3,150-pound nominal working load is not realistic, it stands to reason that lowering the nominal load values, will have no effect on current industry practices. In short, this is nothing more than an attempt to legitimize the current practices of anchoring manufactured housing, using these anchoring devices, and to shift their liability for using inadequate anchoring systems, onto the government.
If all of the various factors that affect the load capacity of this type of anchoring equipment were taken into account, this system of anchoring manufactured homes would not be acceptable by anyone's standards (perhaps the industry's). Hence, the reason for addressing one issue at a time, readdressing old issues by presenting them as different or new issues, ignoring other issues entirely, only serves to keep the effectiveness of soil anchors in a state of confusion. By this means, the manufactured housing industry, and some to remain un-named government agencies, have made it difficult, if not impossible for the casual observer, or reader to understand what the effectiveness of these devices really is. It by no means confused Richard D. Marshall with the U.S. Department of Commerce, National Institute of Sciences and Technology, who in 1994, called the performance of this type of ground anchoring system, "ABYSMAL" (NISTIR 5370).
John Taylor
Founder - "The American Internet Society of Mannufactured Home Owners"
Deborah Chapman
Chair - "The National Foundation of Manufactured Home Owners"
P.S. we decided not to discuss the effects of cyclic loading on anchor capacity, or the unacceptability high mechanical failure rate of anchoring equipment. This would have made an already long response, much longer. We felt that what has been presented made the point that the MHI/MHRA proposal has no way to assure the safety of the public and the user.