• Dr Erick Saavedra Flores, researcher at the Department of Civil Works Engineering of Universidad de Santiago de Chile, is studying new mathematical techniques to computer simulate the performance of wood at extreme ranges of deformation, cracking and ductile processes and its possible progressive collapse.

Wooden structures in a seismic country like Chile require constant inspection to check on its resistance in case of critical events such as earthquakes.

Dr Erick Saavedra Flores, researcher at the Department of Civil Works Engineering of Universidad de Santiago de Chile, is studying new mathematical techniques to computer simulate the performance of wood at extreme ranges of deformation, cracking and ductile processes and, eventually, in a progressive collapse.

Dr Saavedra explains that failures in wooden structures are divided into two groups: brittle and ductile failures. Both will determine the time before wood collapses. “Usually, structures fail abruptly, without previous notice. This type of failure is classified as ‘brittle’. However, at a local level, close to metal joints or fittings, wood fails in a “ductile” manner, i.e., it fails gradually in time. This latter type of failure is very common in very high buildings made of wood,” he says.

With the resources provided by a Fondecyt Regular project, Dr Saavedra will present a new model based on a mathematical technique called “homogenization”, which seeks to detect cracking and irreversible deformation processes at different spatial scales.

Worldwide efforts

“Achieving this goal will be a big challenge, because we require to extend the existing theory to incorporate the damage factor, i.e., degradation, loss of material stiffness and cracks into the multi-scale mechanical response of the material. In the past few years, big efforts have been made worldwide; however, predicting the mechanical performance of materials in this context remains to be a problem without a solution that is fully accepted by the scientific community,” he says.

He explains that he intends to incorporate this new material model to the advanced analysis of large-scale structures, because the big challenge posed by this goal is to computer simulate the progressive collapse of structures during seismic events.

In this regard, modeling this problem is extremely difficult as it involves extreme deformation processes, the interaction of elements that fall during the collapse process and their consequent fragmentation.

The project also considers experimental testing to validate the numerical predictions obtained during the study. Running these tests will be possible with the acquisition of a vibrating table for the Department of Civil Works Engineering.

As a final result of this study, the researcher expects to have material advanced models able to capture extreme deformation processes that allow to calculate ductility measures.

“I believe that the major impact my project may have is in the area of design and construction of buildings and large-scale structures. In the case of wood, particularly, it is possible to promote the use of radiata pine to construct tall buildings if we have a more precise knowledge of its performance during failures or eventual structural collapse,” Dr Saavedra explains. 

The study will be conducted in the context of the Fondecyt Regular project 2016 (1160691), “Advanced Modelling of Ductility and Damage in Mass Timber Structures by Computational Homogenization.”

Translated by Marcela Contreras