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Re: Prestressed Precast Hollow Core Slabs

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These slabs are structurally sound due to the arching effects  of the
masonry cross walling. It is very important that the party walling may
support the overlying loads from above, as most of the upper floor loading
is transfered to this load bearing element.
The guarantee from the manufacturer is not sufficient, as the structural
engineer has to decide on the severity of the overlying loading. The load
from a cross wall may have arching effects, whilst a masonry pier, obtained
from an room divided by a series of arches would impose a high load due to
restrictive arching effects.
The shear capacity of these panels are also very important, as point loads
close to a support impose high shear values.
Besides tracing the load paths of the overlying loads by drawing a 60deg
arching line, the wall panel may be treated as a deep beam. For a panel
with no openings, the effective BM for overlying loads reduces to wl^2/100,
whilst with openings present is in the wl^2/40 region.
I am not aware of the work by Stanton and would appreciate a copy-either by
e-mail or fax No --356-233376.

Denis.

----------
> From: Anthony Ellul <alexellu(--nospam--at)keyworld.net>
> To: seaint(--nospam--at)seaint.org
> Subject: Prestressed Precast Hollow Core Slabs
> Date: 15 April 1999 5:12p
> 
> I am a structural engineer from Malta, Europe.
> 
> Locally it is common practice to use Prestressed Precast Hollow Core
> Concrete Slabs which are 1.2 metres wide, to span over spaces 6 to 8
metres
> in length.
> 
> Once they have been grouted together these slabs are then loaded with
> substantial point and line loads from internal masonry partition walls
> which however carry the loading from the floors above.
> 
> This type of construction is used for buildings up to 3 or 4 storeys in
> height and they are employed in order to do away with downstand beams
which
> would then limit headroom in the commercial premises at ground floor.
> 
> If one tries to calculate theses slabs in order to take these loads,
hardly
> a situation occurs where they would be suitable from calculation alone,
> however the current practice is to achieve assurance and approval from
the
> respective manufacturer.
> 
> I would therefore greatly appreciate any indication or information about
> similar use of these slabs and their behaviour and failures if any over a
> number of years, and also the techniques used in practice to calculate
> them. I personally use the work carried out by Stanton, whose work was
> supposed to be incorpoarted in Chapter 16 of ACI code 318.
> 
> The reason why many of these "strong floors" stand is somewhat of a
mystery
> to myself and I would be grateful for any comments.
> 
> Thanks in advance,
> Fred.
> 
> 
>