Eventually I have managed to implement the full code for a simple Direct Stiffness calculator.
The previous post has been conveniently modified to reflect this.
The results have been fairly discouraging for my intemptions to use it as a basis for the SBRA: initial research led me to the wrong idea that the most computationally intensive part was that of assembly of the stiffness matrix, but my own experiments have proven the opposite.
The code provided, on a 1.66 GHz processor (the computer is actually dual core, but no parallelization was used), with 2GB RAM, takes 46 seconds only in the solving part. The modelled structure is 1000 nodes and 1800 elements large.
According to the paper, about 10⁷ iterations are needed over the solver to get a proper reliability assessment. Hence, grosso modo, applying SBRA to this structure on this computer would take 46*10⁷ seconds, some 14.5 long years.
It is likely that, for smaller structures and using parallelization, times become significantly smaller.
Nonetheless, the point I wanted to make here is that of the solving step being the most computationally intensive, instead of the presumed assembly step.