Reinforced Floor Slabs to Support Mobile Racking


Client:Storax and Melt Wahl Concrete Services
Location:Various Warehouses throughout the country.
Structural Value:Depends on size but the largest to date was R600 000.00 (ex VAT)
Description & Conspec's Role:
Mobile racking allows much larger storage capacity since the passages between racks are eliminated. The racks run on rails and the point loads from the rack supports can be in a large combination of positions. The floors are fully reinforced and designed using finite element analysis with shell elements supported on springs-spring stiffness determined from the subsoil bearing characteristics. The rails are fixed to first cast reinforced strips to allow for accurate positioning and secure anchorage during casting. Protruding rebar connects the strips to the floor to give the benefit of the strips to the final structural strength.
Conspec does the coordination with the mobile rack supplier, FEA analysis, design, layout drawings, rebar layouts and bending schedules as well as the site inspections.  





Paarman Foods New Factory-Joint winner of the SAISC Steel Awards 2013 for Building Refurbishment.


Client:Graham Paarman
Location: Cape Town
Building Value:R50 million in 2013
Description & Conspec's Role:
Conspec were appointed as:
Principal Agent
Project Manager
Civil/Structural Engineer
The new factory built on top of existing factory which was removed during a two week shut down.
The client required a new factory due to growth, however due to the production downtime (estimated to be at least 6 months) when relocating to a new factory, this would have been very costly.
It was decided instead to build a new factory on top of the existing factory in such a way that factory production was never disrupted during construction of the new factory, except to remove the old roof. The total downtime was 2 weeks.
The new structure had to have a minimum number of columns penetrating the existing roof due to food contamination concerns plus clashes with existing plant and piping. To achieve this large lattice girders span across the existing factory in both directions with hangar columns supporting the cladding rails. New offices spanning across the factory on Vierendeel type girders were also constructed as well as a walkway suspended from the roof. Lateral stability was provided by portal action in both directions with additional restraint provided by concrete shear wall which formed part of a refrigeration slab through which the steel columns pass.
This new structure could only be achieved with structural steel which could be placed by crane over the existing building. Parts of the structure were designed to be assembled on the ground and lifted in modules to avoid the amount of night work at height.
The old roof had numerous items of plant and ducting on top which had to be relocated to ensure no clashes with the new steel structure. These relocations took place at night or on Sundays to avoid disrupting production.
Where plant and other obstructions could not be moved the structure was modified to accommodate them.
The accuracy of the surveying and building of 3 dimensional computer models was essential. The new structure, in places, was a few millimeters from clashing with existing plant and structure. Any clash would have been catastrophic to the program as steel would have had to be sent back for modifications. Not a single day could afford to be lost.
All the heavy steel erection took place at night from a narrow alley. The alley had to be vacated daily to give the client access, hence the amount of steel delivered to site had to be erected that night. The planning and logistics was challenging to say the least.
The project manager/structural engineer was responsible for the interface between the various contractors. The wet works contract was a separate contract and the accuracy of cast in bolts required numerous intricate surveys. The bolts were required to be within 10 mm. The fact that all the bolts were accurately positioned was axiomatic to the success of the project.
The programming of the work had to be accurate and realistic, all the dates were achieved by numerous independent contractors.
We considered the job to be high risk from a safety point of view due to working at night at height on top of an existing asbestos sheeted roof. We endeavored at all times to work in accordance with the H and S Act. There were no accidents other than small cuts and bruises. 
The pressure was intense during the shutdown as the old asbestos roof and structure had to be removed in accordance with all the Health and Safety regulations and the government inspectorate, all in a very short time.
The entire envelope is insulated with ‘Alucushion’ on top of 25 mm thick ‘Isopanel’ insulation-this to reduce energy and create a clean food environment.
This project is only possible with the use of structural steel which allowed a ‘Meccano’ type construction to proceed in stages.



Asmus House Extensions

Client: Arndt Asmus
Location: Cape Town
Building Value: Approx. R10 million in 2010.
Add new balconies and third floor to existing house.
The client and architect desired new balconies at the existing and new levels. Initially a clip on steel framed structure with beams and columns was proposed. Conspec had the idea of using orthogonal cantilevers at the corners-the shape allowed this. The existing house was concrete framed and this allowed the new structure to be bolted into the existing concrete. Extensive rebar scanning was done to ensure that bolts were enclosed by rebar as well as to check for clashes. All bolts are stainless grade 316 epoxy fixed and pull out tests were done on each bolt

Conspec's Role:All the Structural design, detailing and site supervision.  

Isuzu Truck Centre

Client: Mr Ian Bell of Reeds Delta
Location: Epping, Cape Town
Building Value: Approx. R35 million in 2007.
Description: New truck centre
Conspec's Role: All the Structural/Civil design, detailing and site supervision including the following:
The Office component consists of a reinforced concrete frame with approx 1200 m2 of suspended slab.
The Workshop component consists of curved roof structure with rows of roller shutter doors on each side. An innovative and quick method of framing and supporting these doors was developed.
The showroom has a high (approx. 5 m) curved glass façade. The facade is too high for a single sheet of glass and an intermediate support was required. This consisted of a curved torsion beam which was also used to support a curved cantilever sunscreen.
The roof over the entrance is a 10 meter cantilever supported with struts bolted to strategically placed, orientated and reinforced concrete columns. The weight of water in the gutter is a significant part of the cantilever load.
The traffic loads on the interlocking block paving are significant and the pavement design
specified cement stabilised layers to avoid settlement of the block paving. A system of subsurface drains was installed to release pore pressures during the wet Cape winters.
During construction it was discovered that an existing concrete lined storm water canal traversed the site. After an in depth study of the strength of the existing concrete lining and the hydraulics Council allowed us to cast a slab over the canal and place 1.5 meters of fill above for displaying vehicles for sale.

Reeds Car Showroom and Workshop in Durbanville

Client: Mr Ian Bell of Reeds Delta
Location: Durbanville, Cape Town
Building Value: Approx. R35 million in 2007.
Description: New car showroom and service centre.
Conspec's Role: All the Structural design, detailing and site supervision including the following:
There is a basement below the entire ground floor slab with the service center in the basement and the car showrooms on the ground floor.
The structure above the first floor is steel with a circular showroom and a curved glass façade.
The service centre is in the basement and the car lift requirement for servicing forced the basement to be approx. 6m deep. The area has a high water table throughout the year and the building footprint extended to the boundaries/building lines.
The basement excavation required temporary/permanent lateral support which was done with cantilever piles supporting gunnite arches.
An extensive system of basement drainage was installed with pump chambers and emergency back-up pumps.
To date there has been no damp penetration in the basement despite the pumps running intermittently for 24 hours a day throughout the year.
External ground floor slab cast to falls. The showrooms are at different levels and hence the casting of the suspended ground floor slab was complicated.
The ground floor slab is a combination of flat slab and coffer slab.
Curved torsion beam to support a cantilever sunscreen around the circular showroom.

Reeds Car Showroom and Workshop in Cape Town

Client: Mr Ian Bell of Reeds Delta
Location: Foreshore, Cape Town
Building Value: Approx. R45 million in 2005.
Description: New car showroom and service centre.
Conspec's Role: All the Structural design, detailing and site supervision including the following:
Reinforced concrete frame with approx. 4000 m2 of suspended coffer slabs.
The site is on reclaimed land consisting of hydraulic fill. Conventional pad footings were used. These were sized to allow for predicted settlement of the fill, in addition the building is jointed to allow for differential settlement. Connections to an existing pile supported building had to allow for expected settlement. This solution costs considerably less than a piled foundation.
Double volume areas to allow headroom for car lifts required long slender columns and free standing shear walls all positioned to suit the operation.
The one suspended slab stopped short of the column support line and the connections to the columns carry high shear stresses and place eccentric loads on these columns.
Very slender barrel roof steel structure with trusses spanning 35 meters on the top of the third floor subject to high wind loads. This structure is open on the sides and all the steel is hot dip galvanized.

Luxury House in Bishops Court

Client: House Owner
Location: Bishopscourt, Cape Town
Building Value: Approx. R20 million in 2005.
Description: New luxury dwelling which can be described as a sculpture in reinforced concrete. Large cantilevers around the perimeter of the slabs create a floating effect. Many of these cantilevers are curved and punctured.
Conspec's Role: All the Structural design, detailing and site supervision including the following:
The design was demanding because the large open plan areas on the ground floor made it impossible to have columns running from ground up to roof slab. In addition the bedrooms and bathrooms are on the first floor and the walls are susceptible to creep deflections of the slabs. The height restriction meant that deep beams could not be used.
The solution is a combination of hangar columns with concealed up-stand beams on the roof slab, shallow heavily reinforced down stand beams as well as articulating the walls by adding joints in concealed areas (behind cupboards etc.).
Careful 3-D modelling was required to ensure that no visible sagging of the cantilevers will occur. Allowance for long term deflections was also specified at the large glass fronts to ensure that the glass does not crack or the doors stick in future as the concrete deflects downwards.
The site was half in cut and half in fill-great care was required with the front of the house sitting on approx. 4.5 meters of un-compacted fill to ensure that differential settlement does not occur. Pads founded at depth on the undisturbed in-situ soil were used.


Cash Crusaders Head Office in Cape Town

Client: Brent Topat MD of Cash Crusaders
Location: Capricorn Park, Muizenberg, Cape Town
Building Value: Approx. R20 million in 2006.
Description: New distribution warehouse and offices. This is not an ordinary building in that the Client and Architect wished to create a building that is appropriate as the company’s head office and the aesthetic details were therefore demanding.
Conspec's Role: All the Structural and Civil design, detailing and site supervision including the following:
The office component is a reinforced concrete frame with infill brickwork.
There is a reinforced concrete shear wall at the entrance which was used as an aesthetic element by embossing the surface using a standard plastic drainage layer fixed to the shuttering.
The warehouse is a structural steel frame approximately 12 meters high. The site is exposed to high wind loads and a horizontal wind girder spanning between braced gable columns was used to reduce horizontal wind deflections and importantly the weight of steel.
The site is also highly corrosive due to the proximity of the sea and wind blown sand necessitating aluminium sheeting and cladding to be used together with hot dip galvanizing of all exposed steel.
Due to the high racking and sensitive nature of the stored goods (electronic goods) to vibration during transfer a high tolerance floor was specified with special load transfer devices at the floor joints to ensure that the forklifts crossing the joints do not jerk, even after shrinkage opening of the joints.

Lesedi Nuclear Services-New Head Office

Client: Lesedi Nuclear Services
Location: Century City, Cape Town
Building Value: Approx. R40 million in 2008.
Description: New head office for a young company formed to service the nuclear energy industry.
Conspec's Role: All the Structural/Civil design, detailing and site supervision including the following:
Reinforced concrete frame with approx 3500m2 of suspended slab.
Architectural structural steel roofs as features.
Seismic load calculations and design of shear walls
Computer modelling and optimisation of structure.
Automatic rebar generation.
Basement waterproofing and pumped drainage system.
Coordination of services to ensure that no clashes occurred.

Retail Store for Mica Hardware

Client: Mica Hardware
Location: Tokai, Cape Town
Building Value: Approx. R10 million in 2005.
Description: New retail store.
Conspec's Role: All the Structural and Civil design, detailing and site supervision including the following:
The site was covered by approx. 2.5 meters of dumped fill. This fill was strip mined and re-compacted to allow for shallow footings and paved parking and truck offloading areas.
The Warehouse is approx 2500 m2. The roof is curved with faceted rafters strut supported on a central lattice girder. The weight of steel is approx. 22 kg/m2.
The site is drains into the Kaiser’s river which is ecologically sensitive. A detention/infiltration pond was designed so that the storm water runoff is filtered before entering the river.

Extensions to Existing Freezer Store for Breco

Client: Breco
Location: Montague Gardens, Cape Town
Building Value: Approx. R3.5 million in 2007.
Description: Extensions to existing cold store due to an increased demand for freezer storage space.
Conspec's Role: All the Structural design, detailing and site supervision including the following:
The structure is 14 m high and designed for high wind loads and fixing of insulation panels.
Accurate on site measurement to match the new building profile to the existing.
Reinforced un jointed reinforced concrete floor designed for Storax mobile racking as well as temperature and shrinkage stresses.
Jointing details of new floor to existing floor to allow for shrinkage and temperature contraction during freezing without losing vertical load transfer for the forklift trucks.
Detailing of structure to suit freezer room requirements for a temperature of -20 C.
Support of freezer plant and POD.
Forklift protectors and guide rails

Paarman’s Foods Extensions to Existing Factory

Client: Graham Paarman of Paarman’s Foods
Location: Diep River, Cape Town
Building Value: Extensions to existing building with a total cost of approx R2 million in 2007.
Description: Extensuions to existing wet preparation areas
Conspec's Role: All the Structural and Civil design, detailing and site supervision including the following:
Tender documentation, calling for tenders, adjudication and appointment of contractors.
Administration of contracts.
New un-jointed reinforced concrete floors to falls with cast in stainless drainage channels.
Tiling details and specification of adhesives and grout to withstand hot acid conditions.
Stainless basket trap to catch solid waste.
Stainless lined bucket wash areas.
Effluent drainage system.
Walls and bund walls designed to take tiles without cracking at the floor/wall joint.


New Factory

Client: Graham Paarman of Paarman’s Foods
Location: Ottery, Cape Town
Building Value: Approx R60 million in 2007.
Description: Proposed new factory. To cater for the rising demand Paarmans acquired a new site in Ottery. Unfortunately the electricity problems and economic uncertainty have caused the project to be postponed.
Conspec's Role:
Preliminary design of structures and civils for costing purposes.
Detailed design and site supervision of new access road.
Detailed design and site supervision of new perimeter wall and security fencing.


Chaswill Process Technology Head Office

Client: Charles Copping of Chaswill Process Technology
Location: Paarden Eiland Cape Town
Building Value: Approx R6 million in 2005
Description: The new head office on a prominent site next to a busy road. The Client and Architect wished to create a building which would show the company’s ethos of precision combined with innovation. Polished granite and glass cladding on a curved façade with a floating steel roof and stainless steel cladding to the exposed columns achieved this.
Conspec's Role: Design and detailing of all the reinforced concrete and structural steel components including the following:
Reinforced concrete frame with edges of floor slabs cast on curves to allow for fixing of curved façade. Floor slabs generally flat slabs since beams would interfere with the sea view.
Special care was required to ensure that the façade cladding is on a smooth curve with no steps in the surface.
The site is exposed to the north westerly gales coming off the sea with no buildings in front to act as shields and therefore the wind loads are high. Design of the cantilever roof and other vulnerable elements such as the façade were done to cater for these high winds.
Detailing and specifications to allow for the highly corrosive atmosphere.

Industrial Structures

We have designed many and varied Industrial Structures such as:
Conveyor for SA Sea Products. A closed conveyor from 3CR12 plate to contain the odour and also act as the tubular structure.
Reconstruction of Ice Plant for SA Sea Products. Due to deterioration of the existing structure a new structure was cast in sequential stages to allow continuous operation of the plant. It is in the wave splash zone and high durability marine concrete with 60 cover was specified. A maintenance free life of 30 years is expected.
Process Plant support structures for Alstom, Paarman’s Foods, Crown Foods, LH Marthinusen.
Numerous reinforced un-jointed concrete floors to support Storax mobile racking.
Retail goods handling/conveyor systems.

Distribution Warehouse for Global Warming

Client: Global Warming
Location: Capricorn Park, Muizenberg, Cape Town
Building Value: Approx. R7 million in 2005.
Description: New distribution warehouse and offices. This facility caters for the import and distribution of foot wear imported from China.
Conspec's Role: All the Structural and Civil design, detailing and site supervision including the following:
Office component is a reinforced concrete frame with infill brickwork.
Ring beam was precast on the ground on site and lifted by crane with in-situ infill concrete at the columns.
Warehouse is a structural steel frame approximately 11 meters high. There are curved lattice trusses supported on a central lattice girder. The weight of structural steel is
20 kg/m2.
Design criteria as for Cash Crusaders described earlier.

Extension of Melville Rd

Location: Extension of Melville Rd in Ottery Cape Town
Building Value: Approx. R1.5 million in 2006.

Conspec's Role:

- Design, Drawings and Tender documents.

- Appointment of Contractor.

- Certifying Payments.

- Site supervision and quality control.

- Completion certificate and final settlement.


Precast Permanent Shuttering
Precast permanent shuttering Trademarked as ‘Shuttercrete’ was developed as an alternative to conventional formwork for beams, columns and staircases as a joint venture with Cobute (a local manufacturer of concrete decking).
After a period of development and trial casting a unique and innovative solution was found. (To form the L shaped element a double cast in a tilting mould is used.).
Stepped staircase stringers are cast in the beam moulds by clamping an adjustable jig
Which allows for any combination of riser and tread dimensions.
The hollow box columns are cast in back to back hinged moulds also with a double cast
A patent was filed and the products are commercially successful with 3 licensed manufacturers.
‘ Shuttercrete’ has many advantages including speed, high quality finish and environmental (no timber shuttering is required).

Adjustable Steel Staircase

This is an adjustable modular system which allows for the angle of the stair to be adjusted on site. Please refer gallery.

Computer Models

The above diagrams show some examples of finite element models of various structures.
These models are used to check code compliance, optimise costs, identify potential problem areas automatically generate rebar schedules etc.
Thes models are used with the necessary caution taking into account the need for simplicity and ease of construction.
For critical areas 'desk top' calculations are done to verify the computer model.

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