We are looking at a number of station platform extensions/new platforms for Network Rail. As I'm sure you know, one of their standard platform designs use blockwork crosswalls with hollowcore planks spanning longitudinally. At some sites it is necessary for the platform to be tapered and obviously this presents a problem with this type of construction.
Can you please advise whether there is any practical way of incorporating a longitudinal taper into a hollowcore floor, either during manufacture on site? If so, are there are any preferred details and/or limitations on the geometry and what are the manufacturing cost implications?
hollow core units can be manufactured with a tapersd side.
the minimum angle from one side of the unit to the splay is 10 degrees.the unit must be 1200mm wide for a minimum of 1.0m before the side splay starts.
the above is all subject to design and plans forwarded to bison for confirmation.
Where two H/C units sit on a 140 block wall (70 bearing each unit) a rebar is shown in slots in the pc units and concreted in. What is the bar size ?
T10 min reinft @ 400c/c max
I am looking at the hollowcore floor units, and wonder if you have any software or guidance for using point loads and partial areas loads to specify a size of unit? I understand you have load/span tables for general area loading, but I need guidance for specific force applications, can you help?
load / span tables for hollowcore units : hollowcore composite units and solid composite planks on bison web site.
for specific design queries, please contact the technical dept.
My previous question was regarding tying of hollowcore planks - continuting on with this;
Which direction can cast in troughs be provided? - parallel to voids or perpendicular?
The voids are 60mm wide, what is their depth?
the 500mm lg troughs cast in the end of the unit run parallel to the span and for units upto 260mm dp, the depth of trough is 70mm.
We are designing a building using the bison hollowcore slab which spans onto precast twin walls (insitu infill) however the aim is to now have an insitu topping for the slabs - if this is the case how is the robustness tying requirement achieved?
for hollowcore unit, upto 4no : 500mm lg troughs can be cast in a 1200w unit.reinft placed in troughs and tied to twinwall lattice reinft.
for hollow composite the reinft can be placed in the structural topping and tied to the twinwall reinft.
I have a brochure from Bison entitled Hollowcore Floors for Multiple Occupancy, dated on rear as Feb 2007. Is this still current or has it been updated - can details still be used for category 2A buildings?
This brichure was produced by Bison Concrete Products, who no longer trade.
For current details please refer to Bison Manufacuring web site.
www.bison.co.uk
regards.
Hollowcore strength
Hollow core offers maximum structural efficiency with minimum slab depth, reducing the floor dead weight and providing longer spans.
Bearings
Refer to Bison website for Hollowcore floor bearing details, nominal bearings on masonry 100mm and on steel beams 75mm.
Disproportionate collapse
Can we use Hollowcore for class 2B building – Bison manufacturing units with open troughs and side pockets suitable to tie units to the structure as engineers details.
Natural frequency
Contact Bison technical department for confirmation of the natural frequency rating for Hollowcore units.