  When dealing with timber structures, the characteristic strength and
stiffness of the material are made highly variable and uncertain by the
unavoidable, yet hardly predictable, presence of knots and other defects. In
this work we apply the sparse grids stochastic collocation method to perform
uncertainty quantification for structural engineering in the scenario described
above. Sparse grids have been developed by the mathematical community in the
last decades and their theoretical background has been rigorously and
extensively studied. The document proposes a brief practice-oriented
introduction with minimal theoretical background, provides detailed
instructions for the use of the already implemented Sparse Grid Matlab kit
(freely available on-line) and discusses two numerical examples inspired from
timber engineering problems that highlight how sparse grids exhibit superior
performances compared to the plain Monte Carlo method. The Sparse Grid Matlab
kit requires only a few lines of code to be interfaced with any numerical
solver for mechanical problems (in this work we used an isogeometric
collocation method) and provides outputs that can be easily interpreted and
used in the engineering practice.
