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- Subject: Fwd: Interior partitions and pre-mfg trusses
- From: rlewis(--nospam--at)techteam.org (Richard Lewis)
- Date: 06 Aug 1997 13:53:36 GMT
I agree completely with Dennis that the conventional framing section of the code is something that should go by the way of the dinasours. At least in zones 3 and 4...too many things can go wrong, and they're all in the details! I was talking to an engineer of veritable seniority over myself about home construction and pre-manufactured trusses resting on interior walls. Of course, the code requires that a gap be left between the interior partition walls not designated as bearing walls and trusses for obvious reasons. He told me that people simply didn't build homes that way. They toe nail the trusses to the partition walls and omit the gaps. My experience is that some inspectors let this simple item, which has major implications, slip by. Contractors don't care that trusses have specific load paths and points of support! I called one manufacturer of trusses based in Portland, Oregon to talk to an engineer on a custom home they were providing trusses on (with a tile roof and 25 PSF ground snow load) only to find out that their nearest engineer was in Sacramento, California and that the "designer" who specified the job was a salesman without any engineering background with a computer program to crunch numbers! OK, so houses are small structures, and their costs touch many aspects of what it means to have a family in the US. Making them more expensive deprives people of the American Dream, right? Maybe so, but as a community of professionals, don't we have an obligation to the public to expose deficient practices when we see them? And even if homes are small, they are some of the MOST IMPORTANT STRUCTURES built! These are places where people spend copious amounts of time, store their stuff and shelter their familys. Engineers should be involved. Prescriptive paths should be severly restricted with numerous stipulations and exceptions. Inspections should be by educated individuals, and contractors should have a rudimentary understanding of basic statics. Down with the current conventional framing section of the code! ---------- From: Dennis S. Wish PE <wish(--nospam--at)cyberg8t.com> To: 'seaoc(--nospam--at)seaoc.org' Subject: Conventional Framing in UBC Date: Friday, April 04, 1997 3:07 PM Pardon my duplication of Bill Allen's comments, but I started a new thread regarding this issue: -----Original Message----- From: Bill Allen, S.E. [SMTP:ballense(--nospam--at)concentric.net] Sent: Friday, April 04, 1997 10:29 AM To: seaoc(--nospam--at)seaoc.org Subject: Re: plywood shear transfer detail This response may apply to two threads. Based on the "Conventional Framing Provisions" of the UBC, the top plates are nailed with 16d @ 16". Of course, this is only good for about 140 PLF. I believe that the nailing of the top plates together should be part of the shear wall schedule as would be the sole plate nailing, etc. Now for the "Convention Framing Provisions" issue. While this seciton of the Code is handy for a junior engineer to get a feel for what the "minimums" might be, this section of the Code is perceived by many (Contractors and Architects) as "Standard" framing. As soon as we specify anything greater than this, we are subject to the criticism of over-engineering. There are several sections to this Code where it is not appropriate even for the simplest of structures. For example, the face nailing of the roof rafter to the ceiling joist will not transfer the tension forces induced by truss action of roof framing. Top plate splices are another example. I believe either this section should be removed from the Code or the disclaimers should me made more obvious so that it doesn't mislead Contractors or Architects. I compare this section of the Code to the standard details provided by many building departments for the "famous" 6'-0" block fences which don't calc. either. Regards, Bill Allen [Dennis S. Wish PE] It is time that we start to act as a group to obliterate the conventional framing section of the code. This section does not address connections of interior braced walls (shearwalls) to the roof. It also does not reference the provisions of Chapter 16 except to make a prescriptive measure out of an already complicated design procedure. Another example is section 2326.11.4 where it describes an alternative braced wall panel without concern for tributary area of shear transferred to the panel or concern of uplift exceeding the 1800 pounds that it prescribes. It does not address connections of interior braced panels except to limit their spacing to 25 feet. I actually inspected a building where the panels were spaced 25 feet. They were anchored (an with holddowns) placed into a 3 1/2" thick slab (into the dirt) and stopped at the ceiling rafters. The walls were parallel to the roof framing and stopped at the Gypsum ceiling. When questioning the "designer" he indicated that he thought it was odd, but that the code did not instruct how the walls were to be connected and that the building official (who did not have a CE employed to do over the counter plan check) accepted it since it was in accordance with this section of the code. LUDICROUS!!!! I suggest that each of you who are interested in this section read it and document its deficiencies. The purpose of this section is to provide the minimum prescriptive method to construct a "conventionally" framed wood structure by other than a licensed professional (Architect or Engineer) and assumes, but does not demand, that the designer have knowledge of other sections of the code such as 1806.6. Must I remind each of you that the requirements for the licensing of General Contractor does not test the applicants ability to "know" framing sections of the Uniform Building Code. Therefore, why should ICBO empower the non-professional with a building standard that he neither understands or knows how to interpret. This is the job of a trained professional. I challenge anyone to poll the construction industry to see how many copies of the UBC are owned and regularly used by General Contractors (specifically Framers) who do not also poses an engineering or architectural degree or license. To make matters worse, the building official had the power to interpret the definition of "Conventional Framing" in the 1991 UBC. At this time, Conventional framing was widely believed to represent the small 800 to 1000 square box constructed after the end of the second world war - when it was necessary to meet the housing demand of the returning soldier. The 1994 code extends the provisions to irregular shaped structures up to and including two stories. Furthermore, it includes structures with plated or fabricated wood trusses as well as proprietary hardware without instruction as to its installation and use. Isn't there enough problems in the industry with the discontinuity of responsibility between the truss manufacturer and the engineer of record? We have already identified a lack of proper detailing when the Contractor provides the plan of the home and the truss manufacturer provides the roof plan. Who coordinates how the trusses are to be connected to the walls when an engineer or architect is omitted from the equation????? Now lets talk about the building official. In Los Angeles and other large cities, the building official has the power to deny this section of the code. The building official in a smaller community is at odds with the City Council and the Developer/Builder who constructs more than a few of these monstrosities in his jurisdiction. If ICBO allows it and the UBC is adopted for all of its other sections, the building official is forced to accept the provisions of this section - unless he wants to look for another job or has a VERY understanding City Council. The lobby for construction dollars and low cost housing is so strong that the councils would rather claim ignorance of the code frailties than lose the construction revenue. The politics is too strong to overturn the building officials ruling. If he disagrees with the provisions, the council will find someone that will accept it. I spoke with an engineer in Northern Calfornia (I don't know if he wants me to mention his name) the other day to expound on this issue. If the engineering community is not able to (or does not have the voting power on the floor of ICBO) to remove or revise this section of the code, we at least have an ally. The Insurance industry wants to minimize their loses by improving construction quality and strengthen weak designs. Without the lobbying that the Insurance industry did, we would not have adopted the UCBC Appendix Chapter 5 for retrofit of lighweight wood framed structures. Enlist their help! Stop making this California's problem - it extends to every area of the country that is affected by wind, water and earthquakes. If we are moving toward a national code, then we need to enlist the opinions and help of engineers accross the country. Don't neglect the rural or low density area's since the building booms will probably be headed in their directions (ie, Southern Utah, Blue Mounds Wisconsin to name a few). These areas are quickly increasing in ecconomic potential by their proximity to major citys and highways. We need to help these areas build quality structures. Finally, it is not a matter of just personal safety any longer when the financial burden to rebuild damaged homes will either strap a family or force them to abandon their obligation as what happened in Loma Prieta and areas of the country ravaged by floods and hurricanes. Every one of you that is concerned should make sure that each board member of your SEA chapter (and CASE) be made aware of the consensus of the Internet community and create the proper channels to promote legislative change. Unfortunately matters will only get worse unless we start to empower our professional community (nationally) on these issues. Copy the threads, stick them in an envelope, pay the 32 cents and send them to as many structural engineering professionals, building officials, insurance executives and architects as you can. Demand that the proper steps (committees) be taken to accumulate, assimilate, and draft change. Lobby for the votes necessary to adopt the changes in the name of safety in structural engineering! I'm off the soapbox now - NEXT? Dennis Wish PE ---------- --- Internet Message Header Follows --- Received: from server1.seaoc.org (bqe.com [126.96.36.199]) by host1.texramp.net (8.8.5/8.8.5) with SMTP id WAA25641 for <rlewis(--nospam--at)techteam.org>; Sat, 5 Apr 1997 22:21:31 -0600 (CST) Received: from SHERMAN by server1.seaoc.org (NTList 3.02.10) id sa016632; Sat, 5 Apr 1997 20:20:06 -0800 Received: from scott-s-machine ([188.8.131.52]) by sherman.dnc.net (Netscape Mail Server v2.02) with ESMTP id AAB84 for <seaoc(--nospam--at)seaoc.org>; Sat, 5 Apr 1997 20:18:03 -0800 From: jmccormi(--nospam--at)dnc.net (Joe McCormick) To: <seaoc(--nospam--at)seaoc.org> Subject: Interior partitions and pre-mfg trusses Date: Sat, 5 Apr 1997 20:22:47 -0800 X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Message-ID: <19970406041801187.AAB84@scott-s-machine> Reply-To: seaoc(--nospam--at)seaoc.org Error-To: seaoc-ad(--nospam--at)seaoc.org X-Loop: seaoc(--nospam--at)seaoc.org X-Info: [SEAOC] Owner: seaoc-ad(--nospam--at)seaoc.org X-POP3-Rcpt: seaoc-ad(--nospam--at)seaoc.org X-Sender: seaoc-ad(--nospam--at)seaoc.org Precedence: list X-ListMember: rlewis(--nospam--at)techteam.org [seaoc(--nospam--at)seaoc.org] __________________________________________________ Richard Lewis, P.E. Missionary TECH Team rlewis(--nospam--at)techteam.org The service mission like-minded Christian organizations may turn to for technical assistance and know-how.
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