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RE: Truck loading

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For an HS20 truck the heaviest axle is 32k (16k/wheel).
The minimum axle spacing is 14'.  Remember however
that this is a fake truck - it is used for design only.
Keep in mind also that some jurisdictions, for instance
the Alameda Corridor Transportation Authority, require
designing for HS25.  This requires factoring the HS20
load by 1.25 (25/20).

For short spans, the alternate military load will usually
govern over HS loads.  This is two axles 4' apart, each

The California Permit Truck has a maximum axle
weight of 48k.  This is a tandem axle but is idealized
as a single point load.  These axles are spaced 18' oc.

Caltrans Bridge Design Specifications (BDS) requires that
HS and Military loads be considered with regard
to serviceability, while the Permit loads only need
to be evaluated for strength.

Refer to the Caltrans BDS has provisions for determining
the effective width of slab available for resisting the
wheel loads.  These provisions are similar those in the
substantially different.

> -----Original Message-----
> From:	Tom Chiu [SMTP:Tomchiu(--nospam--at)]
> Sent:	Friday, March 13, 1998 1:02 PM
> To:	seaoc(--nospam--at)
> Subject:	Re: Truck loading
> It is an underground concrete trench about 12' wide that will have
> commercial truck passing over the trench.  So the heaviest wheel load on
> earth will do it.
> Tom Chiu, SE
> nmoore(--nospam--at) wrote:
> > 
> > Tom:
> > 
> > H20-S16 is the usual loading for more briges, unless you're involved in
> > some sort of an overload, such as purple loading ect.
> > 
> > I think you should really obtain the Caltrans specification as it's just
> > more than loading, it also concerns load distribution depending upon
> > whether you have a concrete slab, t-beam or a wood bridge plus the span
> > length will determine what impact loading you'll use.
> > 
> > Neil Moore, S.E.
> > sometimes a bridge designer
> > 
> > >Does anyone know what is the required truck( wheel) loading on highway,
> > >bridge etc.  I do not have the book handy, the bridge or caltran people
> > >should know this by heart.  The last time I designed something related
> > >to bridge, was more than 16 years ago.  I recall there are wheel
> loading
> > >and also uniform loading criteria.  Thanks.
> > >
> > >Tom Chiu, SE
> > >Thomas Engineering
> > >
> > >
> > >
> > >
> >