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RE: Deflection calculation for Wheel Loads on Timber Bridges

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PCBRIDGE is a cousin of BDS, a program I believe was developed
by either AASHTO or Caltrans in the 70's.  The original BDS
was modified by a variety of private developers, PCBRIDGE being one.
These programs will perform dead load and live load analyses.  They
will also design conventionally reinforced and prestressed concrete
bridges. They do calculate deflections due to dead loads, but do not
calculate live load deflections, at least not PCBRIDGE.

The easiest way to do this for simple spans is to determine an influence
line for deflections.  Once this is established just place your wheel loads
on the influence line where the sum of the influence line ordinates would 
be maximum.  Continuous spans are another story.  I use SAP2000 for
determining live load effects on continuous spans.

Chris Serroels

> -----Original Message-----
> From:	Bdpooley [SMTP:Bdpooley(--nospam--at)aol.com]
> Sent:	Friday, April 10, 1998 9:30 AM
> To:	seaoc(--nospam--at)seaoc.org
> Subject:	Deflection calculation for Wheel Loads on Timber Bridges
> 
> Problem: Calculate the live load deflection for a timber bridge deck for
> simple and continuous spans ranging from 8 feet to 34 feet for HS-15,
> HS-20
> and HS-25 loading. The specific timber bridge deck to be used is the
> longitudinal glulam deck system as described by wood industry brochures.
> 
> For simple spans up to 28 feet, positioning a single wheel (point) load at
> the
> midspan gives the maximum moment and others have told me that this is also
> gives the maximum live load deflection. For longer spans, the deflection
> would
> be based on 2 wheel loads as AASHTO specifications require. 
> 
> I have looked for software on the web, but have not found a reasonably
> priced
> package that will perform the math. One engineer has suggested that a
> software
> program named "PC Bridge" can do the work. Is anyone familar with this
> program?
> If so, do you know who to contact about it?
> 
> Thanks for your help.
> 
> Bruce Pooley
> Timber Design
> 3448 South Newland Court
> Lakewood, CO 80227 
> 
>