The geometric properties and spatial characteristics of crack patterns are significant indicators of the extent of damage on reinforced concrete structures. However, manual visual assessment is subjective and depends highly on the inspector's skills. The current study proposes an automated approach for the quantification of digitally documented crack patterns on reinforced concrete shell elements subjected to reversed cyclic shear loading. Multifractal analysis is proposed as a feature extractor for images depicting crack patterns and a set of artificial cracks is analyzed, to quantify how the properties of crack patterns vary as a function of cracking inclination. The results of the parametric study motivated the training of a multiclass classification model, which is used to provide damage level estimates for cracked reinforced concrete members. The training of the classifier is performed using experimental data of reinforced concrete shell elements under well‐defined and idealized two‐dimensional pure shear stress loading conditions. A dataset with 119 images from crack patterns of reinforced concrete shells is used for training. The multifractal features successfully translate the shape of the crack patterns into meaningful information about the extent of damage; achieving an overall test accuracy of 89.3%.

A series of framed unreinforced masonry (URM) infill walls were retrofitted with modern materials to evaluate the abilities of these materials to mitigate blast effects. The walls were constructed from traditional and alternative masonry materials to assess the applicability of using a wood-fiber fly ash material for infill construction. The walls were tested in the laboratory under static conditions and were evaluated using several criteria: energy absorption, out-of-plane load resistance, out-of-plane deformability, and the reduction of masonry debris scatter upon collapse. Due to the presence of the surrounding frame structure, all of the walls in this program experienced some form of an arching mechanism. The use of a spray-on polyurea material was found to be highly effective in improving URM energy absorption and reducing masonry fragmentation. Infill walls retrofitted with a combination of fiber-reinforced polymer (FRP) grids and polyurea material were found to fail prematurely due to a lack of anc...

This study investigated the fractal and multifractal characteristics of crack patterns observed in prestressed concrete girders. In particular, it focused on cracks that form in the end regions of prestressed girders during the fabrication phase and attributed to prestress transfer operations (i.e., end-region cracks), and shear cracks that form due to subsequent structural (i.e., mechanical) loading. Synthetic crack patterns and experimental data collected during the fabrication and bending test of two large-scale girder specimens were used in this study. The results supported one of the key contributions of the study, which is using fractal analysis to quantify the extent of cracking that develops in prestressed concrete members. Another contribution of the study is that both fractal and multifractal analyses can be used to identify the development of different cracking mechanisms.