the support tower then moved on wheels to the next truss. Once all the trusses had been
erected, the mobile tower was then incorporated into the permanent works.
“The design of the boxed trusses was a complex process that required careful
consideration of erection safety and stability,” Tim Dubber, principal technologist:
structures at Hatch Goba in the Eastern Cape, comments. The springing of each truss
consisted of a double pin support, thereby providing sufficient lateral stability to
individual trusses, even without lateral bracing.
The design and detailing of the bolted and welded connections using square hollow
sections meant that special attention had to be paid to the higher design and fabrication
complexities of the connection type.
Another design and detailing challenge was posed by the wind load transfer from the
door pockets to the arch, given the load magnitude, arch geometry and bracing stiffness
required. An innovative lateral bracing system was introduced that involved the use
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