SA Affordable Housing September - October 2016 // Issue: 60 | Page 9

NEWS

“These are also the criteria tested by Agrément SA when assessing new
building methods,” Barnard says. The structural aspects pertaining to wall
systems are explained, including some dos and don’ts, how and where to
anchor down wall panels, different roof structures (trusses, panel roofs
and rafters), and the requirements of floor elements.
The insulation specification to comply with the energy efficiency
requirements of SANS 10400 XA are set out in SANS 517, for each of the
six climatic zones in South Africa, for floors, walls and roof structures and
how these requirements can be met is explained.
Finally, the session is concluded with a discussion on the design of
foundations, for different soil conditions.

COLD-FORMED STEEL FOR DESIGN ENGINEERS
The second one-day course, cold-formed steel and LSF design to SANS
10162:2, is aimed specifically at design engineers who have to check LSF
structures for structural adequacy. “SASFA has been fortunate to obtain
support from the University of Stellenbosch in presenting the theoretical
and academic part of this course,” Barnard says.
The course begins with the fundamentals of plate buckling theory and
contextualizes this with thin-walled structural elements as encountered
in LSFB. Three buckling mechanisms are generally considered: member
buckling, local buckling and distortional buckling.
Until recently the LSF designer has had to use the effective width (of the
plates making up the cold-formed section) method to calculate the
capacity of the member in each of the failure modes. This is an iterative
and time-consuming method. The latest design method, referred to as the
‘direct strength method’, which simplifies the design calculations
considerably, does away with the need to do iterative calculations. Design
examples are discussed using both analysis methods to illustrate the
application of the theory.
The second half of this course is more practical in nature, covering the
design intent when dealing with LSF structures and highlights the design
criteria provided in SANS 517. The design of floor systems is covered
using an Excel-based design tool for joists. To prevent excessive
vibrations especially in longer floor spans, the designer can use a
simplified approach by calculating the deflection of the floor under a
static 1kN load, or doing a dynamic analysis to calculate the response
frequency. Should the frequency be below 8Hz, damping measures have
to be implemented, such as increasing the depth of the floor beams. The
design output of one of the LSF systems with regard to walls and roof
structures is discussed, and it is shown that the design engineer only
needs to check critical elements in the panels for structural adequacy.
Finally, the design of connections between elements and components are
discussed, using screws, rivets or bolts.
Sasfa ensures the highest levels of professionalism for the courses
including some of the most experienced LSFB experts in the country. This
year, presenters for the SANS 517 course included Mike Hull of Hull
Consulting and Barnard; and for the cold-formed steel course Hull,
Barnard and Etienne van der Klashorst of the University of Stellenbosch
presented.
“As is required by the professional institutes, the attendees are requested
to evaluate and rate the courses, from suitability of the venue,
presentations by the lecturers, course material and handouts. The aspects
of the 2016 courses have consistently been rated between ‘very good’
and ‘excellent’. We look forward to presenting these courses again in
2017,” Barnard concludes.

AFFORDABLE
SA HOUSING

SEPTEMBER - OCTOBER 2016

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