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Re: IRC Braced Panels - shorter and more to the point[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: IRC Braced Panels - shorter and more to the point
- From: "Dennis S. Wish, PE" <dennis.wish(--nospam--at)verizon.net>
- Date: Thu, 13 Jan 2005 20:26:49 -0800
Scott:UBC code section 1626.1 Purpose states: "The purpose of the earthquake provisions herein is primarily to safeguard against major structural failures and loss of life, not to limit damage or maintain function." This is new to the 97 UBC and reflects a "change" in attitude that was pressured most likely caused by lobbyists from the Insurance Industry and pressure on the engineering community.
I believe it is as incredible to me that you would sit back and tell me that educating the public and expecting change is futile. The public is complacent because they have been held in the dark by non-professionals (Agents, Bankers, Home Inspectors, Escrow Companies etc.) who buy and sell homes and arrange loans. Our professional representation has failed to improve the industry as they have not taken the important issues to the media that all homes are not designed alike!. The professional community has not invested in the education of the public by write articles in local papers, speaking with prospective home buyers in seminars, teaching classes or lecturing to community programs offered free to the public or sponsored by insurance underwriters.
Instead the engineering representatives (and I am speaking of the SEA type Associations since the trade organizations are interested in working both sides of the chasm) believes as you that you can't educate the public - and have never tried. Much of this stems from the relatively recent interest in light-framing by the structural engineering community after the natural disasters of the last twenty years. The Insurance industry started the ball rolling when they walked out of California and the Southern States within the reach of Hurricanes and refused to underwrite new policies. California started their own plan that was poorly organized and the state Comptroller was accused of fraud and removed from office. The second time around, a state policy still exists and I believe it is All State that has underwritten this plan but one or two others are backing the state as long as there is a high deductible equal to 15% of the insured value of the policy. The real problem is those families who can not afford a mortgage as well as earthquake coverage in California and go bare.
The engineering community is complacent about the issues that pit us against HUD, NAHB, the BIA and other organizations that support the only the idea of affordable housing. They have a valid argument so don't misunderstand my acknowledgment of good intent, but HUD and NAHB only want to provide affordable housing and are not concerned with the dynamics of real estate escalation. BIA on the other hand represent the Building Industry and because of this, they support the developers of large tracts and small projects. They do not represent the quality of homes or the education and qualifications of their members - it is purely an associate supported by the building business partners (developers and builders).
Instead of telling me what I can't accomplish, why aren't you and others helping to improve matters one community at a time. When the word spreads and people discover the resources that help them decide between two homes that seeming look identical but are constructed to different codes they will ultimately decide which home they would prefer to own. Those who you claim would rather put their money in the appearance rather than structure are ignorant of the forces of nature and until a wakeup call occurs, they will not add the additional 1% to the framing costs that would help protect their family and property. This is why you are correct for the moment, but the driving reason why I can not be complacent as you wish to give up on the public. They are our last holdout because you and I end up paying for the clean up of the damage that can be prevented or we end up paying higher premiums to make up for what the homeowners insurance must cover.
My ideas are not infallible, but they are reasonable; * Require the name of the engineer of record to be placed on the application for permit * Require the code that the residence was designed to - full-compliance or prescriptive - to be placed on the application for permit and on the drawings. * Storage space is no longer an issue - it is easy to archive thousands on homes on a recordable DVD or Hard drive. Building departments destroyed paper storage years ago and can now take electronic drawings in a universal format (say PDF) with the analysis package to be archived for future reference when changes are made. We no longer have a high cost of document storage toworry about and a record of drawings and analysis (where needed) can include all revisions and updates or remodels.
* Certify framers. Require special licensing and education for anyone who constructs the structural system of the home either prescriptively or engineered. Most important is to make sure the Framer has basic skills, but most important that he or she can read the details on the plans. * Remember that a Framer who builds tract homes is not nearly as proficient as the Framer who understands how to build one custom home. The issue here is repetition where a framer learns from his mistakes. Custom Home Framers need more training to interpreter drawings and details and to work closer with the engineer when obsticals are discovered that need to be addressed in construction. Tract framers need less experience as they can spend years working on one project where there are three or four plans. * We already have a decent requirement for Structural Observation and Special inspection in the code but I've found in certain areas it is not adhered to by the building inspector. I was not called out for a pre-wrap inspection of shearwalls and anchorage as required by the Structural Observation even though it was required on the plans. * Require Engineers to have a pre-construction meeting with Framers, General Contractor and others necessary to have reviewed the structural plans and details. Understand the framing issues before breaking ground and this will save the homeowner nearly 10% in overcharges during the construction process. If the contractor misses it up front, he can't complain about it after the pre-construction meeting. Require the list of attendees to be signed and submitted to the building department and added to the permit file.. * Make sure that city inspectors maintain continuing education to deal with new materials and code revisions or problems specific to local areas. Encourage local professionals to meet with the city personnel and help resolve code interpretation or construction questions. The engineers get a good education on whether or not their details are practical and can change them later to developer a standard of practice. * Separate structural engineering and architecture. I'm not suggesting eliminating A&E firms, I am suggesting that Architects not design or wet seal structural plans and calculations and that Engineers not design or wet-seal Architectural plans and specifications. This law that allows both professions to cross platforms without having to prove before damage occurs that they are capable or qualified is where the problem stems. * Set a limit on the type of community and the risk to natural disaster that qualifies the IRC for use. If a formerly new low-income housing community escalates in value to be accessible to the more affluent, then consider the cost/performance issues and disqualify the IRC from use then on in that area. In time, older homes will be remodeled or replaced and if remodeled, the structural system will most likely be upgraded to current code compliance. If the city maintains records as noted above, engineers can enter a project better informed and able to design properly..There is a two sided edge on this sword. On one side we can improve prescriptive construction by adding resistance to "assumed uplift" at a nominal cost and on the other side of the sword, we can be less restrictive in code requirements as quality of construction improves. This begins to close the gap that exists between engineers and the building industry.
The housing market is currently structured by supply and demand. Cost is not based on quality of construction or expected performance, but on "Comp's" - comparable homes in the area of similar size that have sold in the last month or months. We need to weed out the bad structures and use the power of the public to make offers on what they know of the construction used rather than the assumption that all homes are built to the same standard as permits were issued and inspectors are visiting the site. Let the home buyer control the sale on housing as most people do not intend to tear down the home once they buy it.
So, my friend, I may be an idealist and to you this may seem unreasonable and impossible to cause change - but I say to you that unless we take the responsibility to repair this industry as we know is a rational method of calculating uniformity in construction then we contribute to the problem of complacency. I would rather have people think me a pain in the a*s than give in to something I know is morally and ethically right..
Ted:There are redundant shear resisting systems - stucco, gypsum, plywood etc. In California most tract and spec home developers demand the least materials regardless of the selling price of the home. It is different in other areas of the country. I mentioned my travels by car to Chicago each year and what you say is true, but not the case in the area of the country controlled by the developers of housing and in regions of greatest risk.
The IBC and UBC (at least the UBC since that is all we use in California) does not permit different materials used in lateral load resistance to be additive. Does it have any effect or help - I believe it does, but then we have not tested any systems to the largest forces that the code limit extends to.. Northridge, Loma Prieta, Whittier Narrows, Landers - all of these were moderate quakes, not major events and the damage statistics was significant. One home I fixed was trashed. On the outside, the home looked great, but as I pulled on the stucco at the flashing connected to the foundation, the stucco came away from the wall all the way to the second story roof. The shear resisting system was disconnected from the framing and the racking motion of the framing destroyed the interior walls and finishes. Still we fixed the home and retrofit in shearwalls to take care of the work.
The redundancy does exist, but wood was a living material and each piece is visually or mechanically graded due to imperfections. This and the combination of mechanical hardware and finishing materials is why we need such a high factor of safety on wood (usually 4:1).
What I don't understand is why we are actually debating this issue. The cost to use additional anchorage even if prescriptively added is worth the risk and the builder can honestly say he has a superior product to conventional construction. Simply adding an HD2A or PHD2A to each shearwall or braced panel will improve performance in prescriptive design.
DmitriI purposely left off the eave just to show that on the most conservative design an uplift exists. You are correct about this. Licensed engineers do not need to stamp prescriptive designs unless they were hired to deal with the non-compliant portion of the home. In this case, all of the building officials that I spoke to confirm that this does not make the engineer responsible for the entire structure. However, the code places engineers in an awkward situation because it may be argued that by relative rigidity methods, the engineered walls will redistribute shear and may be the reason for some damage or failure. It is best to avoid dealing with prescriptive design, but I think most of us feel obligated within our smaller communities to help the builder even if we do not agree with the method he chooses. I was on the board of directors for a "Habitat" type program and I submitted a prescriptive design where I replaced the braced walls with proprietary shearwalls donated by Hardy Frames (Simplified Structural Systems) and the City kicked it out claiming that they could not approve the substitution even if I was willing to sign off. The problem was that I did not submit calculations since it was intended to be a prescriptive package. The solution was to build it per the prescriptive plan and retrofit in the Hardy Frames with the blessing of the city. As long as the braced frame was in place they did not care if we added the Hardy Frames. Still I did not have to wet seal the plans. If the client has the money to sue then nothing on earth will stop him from going after you. I use to be in favor of Tort Reform but have changed my position because this limits the punitive damages on those who have justified claims. I think the answer here is to limit the expert witness to the discretion of the judge (the courts) and not to each side. I was recently asked if a judge could pick a good expert and what if the expert is biased. Today it is nothing more than a pi*sing contest as to who has the better qualifications or who is more personable to a jury. This is not adequate as many SE's that have the qualifications have never designed a custom home or tract. Still, if the court determines one or two experts then there is no argument from either side but an evaluation of the facts submitted to the expert by both sides and an evaluation of the claim can be supported or denied by the experts who essentially guide the judge based on their decisions and references.
Hopes this answers each of your questions and offers some constructive suggestions.
Dennis http://www.structuralist.net I've given this much ******* ****** ******* ******** ******* ******* ******* *** * Read list FAQ at: http://www.seaint.org/list_FAQ.asp* * This email was sent to you via Structural Engineers * Association of Southern California (SEAOSC) server. To * subscribe (no fee) or UnSubscribe, please go to: http://www.seaint.org ******* ****** ****** ****** ******* ****** ****** ********
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