Need a book? Engineering books recommendations...
RE: Fw: pedestrian bridge[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: Fw: pedestrian bridge
- From: "Fredericks, Douglas/SAC" <DFreder1(--nospam--at)CH2M.com>
- Date: Tue, 2 Mar 1999 18:29:33 -0700
I THINK its misleading, but I've been wrong before.... My version says this: "188.8.131.52 Bridges for pedestrian, equestrian and or bicycle traffic shall be designed for a live load of 85psf. Check equestrian bridge for H10 loading. (end paragraph) For (LL+I), use group IH with BetaLive = 1.0. Apply impact according to Article 3.8." It seems to be saying that BetaLive for pedestrian, equestrian, and truck loading is 1.0. I think what they mean is that, after checking for pedestrian loads with BetaLive = 1.67 (first paragraph) and no impact, check the H10 truck using a BetaLive of 1.0 (second paragraph) and impact. So for pedestrian loads the load factor would be (in my world, anyway) (gamma=1.3)*(BetaLive=1.67)*(No Impact=1.0) = 2.17. Reading the code literally says the load factor is (gamma=1.3)*(BetaLive=1.0)*(No Impact=1.0, say for a long span) = 1.3, which seems low. The LRFD code strikes me as being more logical, since applying impact to pedestrian loads seems sorta silly. Anybody here in California know the status of Caltrans and LRFD? > -----Original Message----- > From: Powers, Tony [SMTP:tpowers(--nospam--at)hdrinc.com] > Sent: Tuesday, March 02, 1999 4:00 PM > To: seaint(--nospam--at)seaint.org > Subject: RE: Fw: pedestrian bridge > > Please explain how the Caltrans specification is misleading. > > > -----Original Message----- > > From: Fredericks, Douglas/SAC [SMTP:DFreder1(--nospam--at)CH2M.com] > > Sent: Tuesday, March 02, 1999 12:23 PM > > To: 'seaint(--nospam--at)seaint.org' > > Subject: RE: Fw: pedestrian bridge > > > > The way I read the AASHTO code, Group IH would be 1.3*(DL+1.67LL), where > > LL > > is 85 psf. Impact is not applied to pedestrian live loads. Note that > the > > Caltrans code has a misleading description of loads for pedestrian > bridges > > (184.108.40.206). > > > > Looking at the AASHTO LRFD code clears this up. Pedestrian live load is > > 85psf (case PL) and it gets a 1.75 load factor. The code specifically > > states > > that impact is not applied to pedestrian loads (220.127.116.11). > > > > Also, AASHTO has produced a pedestrian bridge guide specification. They > > give a service live load of between 85 and 65psf depending on floor > area. > > It is not a LRFD code so there aren't load factors. This code doesn't > > specifically mention Impact, but an example is provided in which impact > is > > not applied. > > > > (They provide some guidance on vibrations as well.) > > > > > -----Original Message----- > > > From: Powers, Tony [SMTP:tpowers(--nospam--at)hdrinc.com] > > > Sent: Thursday, February 25, 1999 9:12 AM > > > To: seaint(--nospam--at)seaint.org > > > Subject: RE: Fw: pedestrian bridge > > > > > > Just to confuse the issue a little more, AASHTO Section 18.104.22.168 > > specifies > > > a > > > live load of 85 psf for pedestrian bridges. Where maintenance > vehicles > > > are > > > expected, Section 22.214.171.124 says that these should be considered > > separately > > > -- an H10 truck (1/2 of an H20) is sometimes used. Caltrans goes > further > > > and > > > specifies that Impact should be included for load group IH with > > BetaL=1.0 > > > (this is normally 1.67) and, if you happen to have equestrians, > Caltrans > > > specifies that the bridge be checked for an H10 truck. So, now you > have > > > three loads. AASHTO/Caltrans includes an impact factor, which might > > > account > > > for the difference between their 85psf and UBC's 100 psf. > > > > > > > > > > -----Original Message----- > > > > From: Jill T. Shuttleworth, P.E. S.E. [SMTP:andeng(--nospam--at)televar.com] > > > > Sent: Thursday, February 25, 1999 8:20 AM > > > > To: seaint(--nospam--at)seaint.org > > > > Subject: Re: Fw: pedestrian bridge > > > > > > > > The 1997 UBC recommends 100 psf for pedestrian bridges Table 16-A. > In > > > > Table 16-B Construction walkways are 150 psf. Does someone know why > > > there > > > > is a discrepancy in these two loads? > > > > > > > > Jill T. Shuttleworth, P.E., S.E. > > > > Sunnyside, WA > > > > > > > > > > > > prosteel wrote: > > > > > > > > what live load should be used for a pedestrian bridge > spanningup > > > > to 210 ft. in some cases, light vehichles may pass rauf akbaba > > > > > > > > > > > > > > > >
- Prev by Subject: RE: Fw: pedestrian bridge
- Next by Subject: Re: Fw: pedestrian bridge-reply
- Previous by thread: RE: Fw: pedestrian bridge
- Next by thread: ACAD Attribute ?