Light Steel Frame training courses making their mark
The series of CPD-accredited training courses arranged by the Southern African Light Steel Frame Building Association (Sasfa) have made their mark in 2016. This is according to Sasfa director, John Barnard. “We are seeing a growing interest in these courses in line with the excellent growth in popularity of LSFB in South Africa,” Barnard says adding that the RSA market for LSFB is estimated to already be worth about R1 billion per annum.
The first course deals with SANS 517 Light Steel Frame Building and is aimed at all architects, engineers, quantity surveyors, developers and other LSF practitioners, who should all have a working knowledge of the building code.
The second is a course on Cold-formed steel and LSF design to SANS 10162:2 and is aimed specifically at design engineers.
The courses are presented by John Barnard (SASFA) and Mike Hull (Hull Consulting) – from foundations and the steel frame to floors, walls and roofs, including insulation and installation of services.
The SANS 517 1-day course consists of an introduction to LSFB, as well as an overview of the development of this building method and industry in Southern Africa. The advantages of LSFB are discussed and explained – ranging from speed of construction, enhanced insulation and the resulting energy efficiency, low mass and the corresponding logistical cost advantages, through to accuracy, ease of installation of services and durability. “The steel frame will last several 100 years if installed correctly,” Barnard says.
The correct terminology is dealt with, the major LSF elements described and the properties of the major materials used in LSFB are presented. Apart from the high-strength galvanised steel sheet used to manufacture the cold-formed sections for the light steel frame components (wall frames, roof trusses or floor beams), LSFB makes use of:
fibre cement cladding (exterior),
gypsum board lining for walls and ceilings (interior),
insulation (thermal and acoustic)
vapour permeable membrane (external walls), and
fasteners – screws, rivets and anchor bolts or screws.
The main components of a LSF structure are described: foundations with cost saving potential compared with masonry building, the steel structure, walls, floors, ceilings, insulation and the installation of services. This is followed by spelling out the requirements for these components to comply with SANS 10400 – structural stability, weather resistance, durability, energy efficiency, acoustic insulation, fire resistance and fire rating and prevention of air infiltration and robustness. “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 Do’s 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 RSA, 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 1-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 1 kN load, or doing a dynamic analysis to calculate the response frequency. Should the frequency be below 8 Hz, 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.