THE VEE SLAB: What is a Vee Slab?

  At the heart of all buildings is the slab component. It represents about 80% of the structure.  It is the critical component and so the success of a floor structure is largely dependent on the properties of the slab planks.

THE VEE SLAB CONCEPT.

The Vee Slab is a prestressed, precast concrete floor panel consisting of a flat base slab with dovetail shaped concrete ribs and void formers on top.

The Vee Slab derives it’s name from the shape of the intermediate ribs. It is this shape which enables the slab to perform so efficiently. The ribs provide a wide compression flange to resist bending and deflection while at the same time economizing on concrete where it is not needed. The rib shape also allows a high proportion of voids to be included in the module and this results in a panel which can span long distances under construction loads supporting wet concrete and live loads and in the service situation acting compositely with the topping slab. Table 1 details safe spans for various configurations of panels during construction.

 A floor built with Vee Slab panel consists of an assembly of panels joined together with a thin concrete topping to produce a structurally integrated floor with  a smooth surface finish. The insitu topping ties the floor together and creates a rigid shear transmitting structure.

The panels can be built to any depth required but typically the standard range produces a floor depth between 140mm and 400mm.

 PRINCIPAL FEATURES OF VEE SLABS

· Long spans without propping during construction-Up to 16 metres currently  with the potential to span 22m

· High quality steel formed, wet cast flat soffit-ready for jointing and finishing-no need for ceilings in most applications. Minimal  hogging in panel soffit before topping.

· Light weight panels provide for economic transport and more efficient crane usage. Lightweight finished floor structures save on supporting structure and footings.

· Very quick erection typically 2.4  metre typical width panels.

· Our panels are made to  fit your floor exactly with no cutting or make up strips required to complete the floor . Panels are made to fit around other components and voids such as manholes etc are cast in to the Vee Slab panel.

· Easy access to services by utilizing the voids longitudinally  or by penetrating through the panel. Having ribs and cables  at typically 550mm centres it is easy to avoid the cables during coring.

· Very thin overall depth-provides economy of building structure, saving  in height, cladding and  services. 

· Forms into a complete floor building system. Banded slabs and Flat Plates.

· Having a high proportion of voids, VEE SLABS are very efficient for single simply supported spans.

· Panels remain flat after stressing– Minimal hogging.

·  Cross ribs can readily be cast into Vee Slabs allowing them to  sustain concentrated loads to span transversely.

· Panels can be transported on edge to allow wider panels to be carried on road without the need for special permits.

· Panels can be manufactured virtually anywhere  and are not tied to a pretensioning bed. If you have  a project in a remote area, then Vee Slabs can be manufactured near or even at your site.

·  The shear strength of Vee Slabs is enhanced by the high level of prestress  attained by stressing at higher concrete strength ,the higher initial prestress forces allowed for  posttensioned structures, and the lower prestress losses of a posttensioned structure stressed at higher concrete strength. Add to this, the ability to add shear reinforcement ensures that rarely is shear capacity not sufficient.

· Vee Slabs satisfy the requirements of  Part F5 of the BCA

Airborne noise through bare slab without ceiling DnTw+Ctr    52

Impact noise rating for tiles laid directly on bare slab with no

ceiling LnTw + Cl  = 60

· Vee Slabs typically have an insulation R value of 0.5 or better.

VEE PLANKS

An alternative form of the Vee Slab is the VeePlank.

In this form the VeeSlab has a monolithic topping cast with the VeeSlab base forming a Plank which is ready to use in the final application.

The topping slab is of high strength concrete (65MPA) and the surface finish can be anything desired from a rough broom finish to a steel trowelled finish .

The geometry of these planks is considerably different from the VeeSlab and consequently, they hog considerably more under prestress. Compared with equivalent dry packed concrete products, the VeePlank has a more consistent deflection profile with less hog due to the higher quality concrete used stressed at a higher strength. 

CONNECTING VEE SLABS. 

VeeSlabs con be made in any width within the range of 1100mm to 3200mm. Vee Slab fit the project, the project doesn’t have to fit Vee Slabs

In addition to the conventional methods of supporting precast floor panels such as with shelf angles and the like Vee Slabs can be connected to themselves and supporting structures by means of the topping concrete.

By virtue of the open ribbed structure of the Vee Slab and the sloping sided ribs , Vee Slabs are very easy to connect to other structural elements without the need for shelf angles and corbels.

The block outs can be removed for the last 300mm of the panels to allow the insitu concrete to flow between the sloping ribs and into shear keys in wall panels or adjacent  members. This allows the formation of a rigid concrete shear connection between keys and the sloping sides of the Vee Slab ribs.

Shelf angels, when used are temporary. Once the concrete connecting the Vee Slabs has attained enough strength, the shelf angles are removed leaving a clean connection which is fully fire rated.

It is this connectivity which allows members on the same plane to be connected which is a great advantage for such structures as flat plate floor structures as will be seen later.

IMPLEMENTATION

The Vee Slab is a very versatile building element which can be used to form several different types of floor structures. Building structures often combine different structural types.

Currently there are 3 Vee Systems:

1. SIMPLE LINE SUPPORTED VEE SLABS

2. VEE SPINE BEAM SYSTEM

3. VEE FLAT PLATE SYSTEM.

1. SIMPLE LINE SUPPORTED VEE SLABS

In its simplest form the V Slab can be used to span between other structural elements including load bearing walls, precast concrete beams , insitu beams and steel beams.

BARANGAROO HEADLAND

VEE SLABS

 A LARGE AREA OF THE ROOFS OF THE EXHIBITION CENTRE AND PLANT ROOMS ARE SUPPORTED BY VEE SLABS.