Mechanical Technology January 2015

Mechanical Technology — January 2015

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Special report

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The Malapa fossil excavation site took

top honours at the Steel Awards 2014.

The Waterfront Silo Development,

Architectural category winner, used struc-

tural steelwork to provide slender support

to the facades, walkways, bridges, lifts

and feature stairs.

The Tugela River Pedestrian Bridge

(KwaJolwayo), Bridge Category winner at

the Steel Awards 2014.

ning the heritage silo and buildings

constructed in the 1920s was a great

challenge to the structural engineers

and contractor.

No.1 Silo has been awarded a six-

star rating by the Green Building Council

of South Africa and is the country’s lat-

est and largest green office building. It

is only the second office building to be

awarded this rating in South Africa and

the first in the Western Cape.

In awarding the Tugela Pedestrian

Bridge the top spot in the Bridge cat-

egory, the judges agreed with the project

team that this bridge “merits an award

in view of its portrayal of the benefits

that technical solutions and efficient

design using structural steel can bring

to rural communities.”

This 134 m structural steel suspen-

sion bridge over the 8.0 m deep Tugela

River at KwaJolwayo, upstream of the

Tugela Ferry in the Msinga area of

rural KwaZulu-Natal, has resulted in a

life-changing, safe crossing option for

communities on both sides of the river,

enabling them to access commercial

and educational opportunities that were

previously inaccessible, particularly dur-

ing the summer months.

The design focused on the fact that

the lower the mass of a structure, the

less material is required, with cor-

respondingly lower capital and envi-

ronmental costs. Structural steel was

chosen as the ideal material to prove

the above and the inaccessible, deep

gorge provided the ideal situation for

the engineer.

The final design consists of four

suspended cables supporting a row of

steel Y-frames, which in turn support a

1.2 m steel deck, with the suspension

portion of the bridge structure consisting

of two equal spans of 60 m.

The Corporate Office Building cat-

egory was won by 30 Jellicoe, a

building situated in the heart of the

Rosebank CBD. The judges said that

the slenderness and proportion of the

tapered tubular steel columns give the

building an elegant aesthetic that sets

it apart from its neighbours. “The ripple

that is created by the louvre blades adds

another level of detail that finishes off

the overall concept,” they reported.

In the light steel frame building

(LSFB) category, McDonald’s was

declared the winner for its entry of

seven fast food outlets: Goodwood,

Rustenburg, Silverlakes, Somerset

West, Epping, Tembisa and East

London. These buildings not only

displayed excellence in the use of light

steel framing but also clearly demon-

strate why 500 000 m² of LSFB floor

area has been built in the past year.

McDonald’s chose LSFB because it

could meet its energy efficient building

goal and because speed of construc-

tion is one of light steel framing’s main

advantages. By using LSFB McDonald’s

not only reduced material waste by

30% and transport costs by 80% but

also the insulating layers reduced the

building’s energy requirements by 17

to 20%, compared to conventional

building designs.

The first LSFB McDonald’s outlet

was in Goodwood, Cape Town and the

entire shell of the building, including

internal walls and exterior painting, was

completed in two months. Roadworks

and the installation of kitchen equip-

ment took a further month, giving a total

construction period of three months. A

comparable double-storey building us-

ing conventional masonry construction

would have taken at least seven to eight

months to complete.

The Mining and Industrial category

winner was the Bakubung Platinum

Mine headgear. “This is a structure

with thousands of bolts, all fitting

without modification and tightened to

specification, which is testimony to 3D

detailing using Tekla and the accuracy

of fabrication. What a pleasure to see

and experience the exceptional quality

and final presentation of the steel work,”

said Erling.

In the final award of the evening, the

Rosh Pinah Zinc Corporation (RPZC)

in Lüderitz, Namibia, won the Factory

and Warehouse category for its zinc

and lead storage warehouse, a 90 by

67 m building surrounded on four sides

by buttressed concrete retaining walls.

The challenge was how to sup-

port the arch roof across an area that

spans 65 m using steel that could be

fabricated and erected in Lüderitz, well

known for its strong onshore winds and

corrosive environment.

Square hollow sections (SHS) for

all the truss members were the natural

choice for reason that included: ease of

fabrication; internal members can be

cut by saw; no special developments

are necessary for connections; the

perimeter of the SHS is big enough to

permit straightforward fillet welds for

end connections; and, by keeping the

members straight, the curvature for

the roof can be created using different

purlin lengths.

In addition, no wasting of top and

bottom chords is incurred as would

happen had the members been curved;

and tubular profiles are ideal for dealing

with the prevailing winds.

Erling says that each year the ability

of South African architects and engi-

neers to build aesthetic steel structures

becomes increasingly apparent. “The

quality of the entries improves each

year and 2014 was no different. I con-

gratulate the winners and all those who

entered,” he says.