Structural engineers and concrete professionals will need to follow a new set of rules relating to construction projects as the new SANS 51992 1 1 cod
Structural engineers and concrete professionals will need to follow a new set of rules relating to construction projects as the new SANS 51992 1 1 code for structural concrete is introduced.
Following her introduction to the new specification at the Concrete Society of Southern Africa (CSSA) roadshow seminars, Dr Kim Timm of Stellenbosch University, said the introduction of the code changes the way South African professionals approach design and analyse concrete structures. Following a five-year lead-in period adherence to the code becomes mandatory in December 2026.
“It is however important to know while the framework may look different the fundamentals of concrete behaviour remain unchanged. “Concrete is still concrete and if you end up with three times the reinforcement, for example, you’ve made a mistake in the calculations because the code does not change physics.
“This also applies to the long established South African loading code which remains intact and was already adapted from Eurocode principles in earlier revisions. The familiar SANS 10160 continues to govern actions with permanent, variable and accidental loads ensuring continuity in practice. What changes is the way these actions are integrated with material resistances through the Eurocode’s reliability framework,” Timm said.
She explained the concept of characteristic values which underpin the partial factor method. Instead of relying on mean values of material strength or loading, engineers now design with values that statistically account for variability. For materials this means assuming that only five percent of the concrete or steel will be weaker than the design value. For loads, this means factoring them so that only five percent of cases exceed the assumed maximum to ensure that resistance always remains on the safe side of applied actions. South Africa’s reliability class adopts a slightly different beta value than Europe and reflects local balances of risk, cost and consequence but the principle remains the same.
The local interpretation applies primarily for reliability class 2 structures such as office blocks, residential buildings and public facilities where failure would have significant but not catastrophic consequences. For lower risk structures such as farm sheds reduced factors may be applied. Conversely for hospitals, communication hubs or other critical infrastructure require higher reliability demands either through increased load factors or enhanced design and construction supervision.
In terms of structural analysis where code introduces more explicit guidance than its predecessor professionals are required to consider not only the completed structure but also the stages of construction and recognise that transitional phases can impose different load effects. Analysis methods therefore range from linear elastic to plastic and nonlinear approaches, each with their own rules for application. Linear elastic analysis remains the baseline assuming materials behave proportionally within their elastic range.
Limited redistribution of moments is permitted, acknowledging that concrete will crack and forces will shift, but within controlled limits that are typically around fifteen percent. Plastic analysis, yield line methods and strut and tie models are available for more advanced cases while nonlinear analysis offers the most accurate results but demands significant computational effort and expertise.
Although shortcuts do exist she cautioned against over reliance on these as the original code provides conservative default options and where efficiency is required these may not be the most suitable. “The more shortcuts you take, the less efficient and more costly your buildings become and professionals should strike a balance between streamlined design and rigorous analysis. It is also important to correctly model foundations for different structures rather than relying on shortcuts as flexible superstructures distribute loads differently from rigid ones and that settlement behaviour must be properly accounted for,” Timm cautioned.
She concluded that although the new SANS 51992-1-1 uses unfamiliar terminology and more complex layouts the underlying engineering principles remain consistent. By adopting Eurocode methods while tailoring them to South African conditions the code provides a framework that is aligned with modern techniques and materials.
