Experimental and computational study into the onset of light damage of Dutch masonry structures
P.A. Korswagen, M. Longo, J.G. Rots
Delft University of Technology, Faculty of Civil Engineering and Geosciences, the Netherlands
An experimental and computational campaign, ongoing at the Delft University of Technology over the past years, aimed to improve the knowledge of the underlying physics of crack initiation and propagation in typical, unreinforced masonry structures, ubiquitous in the Netherlands. Herein is an overview of this study. First a scalar damage parameter is matched to a damage scale to objectively quantify cracking damage and its progression as a function of crack width, length and number. Next, cracking is observed experimentally in walls and spandrels subjected to in-plane loading using high-resolution Digital Image Correlation to detect the formation and evolution of cracks. The experimental results are then interpreted to establish drift intervals for which light damage can be expected.
Subsequently, orthotropic composite continuum models were calibrated against the test results. Modelling and constitutive improvements were made in these 2D models. Then, the validated models were extrapolated to real building cases, also included herein. The combination of existing damage due to e.g. differential settlement, and new damage due to the seismicity is evaluated with these extrapolation models. Finally, the models provide a relationship between the variability in e.g. material strength, earthquake intensity, and damage; this is then employed to determine probabilities for light damage.
Key words: Damage, unreinforced masonry, nonlinear finite element analysis, cracking, experimental tests