Mode-I fracture parameters of quasi-brittle materials: direct evaluation using DIC and relationship with Mode-II interfacial parameters

The objective of this thesis is the investigation of the Mode-I fracture mechanics parameters of quasi-brittle materials to shed light onto the influence of the width and size of the specimen on the fracture response of notched beams. To further the knowledge on the fracture process, 3D digital image correlation (DIC) was employed. A new method is proposed to determine experimentally the critical value of the crack opening, which is then used to determine the size of the fracture process zone (FPZ). In addition, the Mode-I fracture mechanics parameters are compared with the Mode-II interfacial properties of composites materials that feature as matrices the quasi-brittle materials studied in Mode-I conditions. To investigate the Mode II fracture parameters, single-lap direct shear tests are performed. Notched concrete beams with six cross-sections has been tested using a three-point bending (TPB) test set-up (Mode-I fracture mechanics). Two depths and three widths of the beam are considered. In addition to concrete beams, alkali-activated mortar beams (AAMs) that differ by the type and size of the aggregates have been tested using the same TPB set-up. Two dimensions of AAMs are considered. The load-deflection response obtained from DIC is compared with the load-deflection response obtained from the readings of two linear variable displacement transformers (LVDT). Load responses, peak loads, strain profiles along the ligament from DIC, fracture energy and failure modes of TPB tests are discussed. The Mode-II problem is investigated by testing steel reinforced grout (SRG) composites bonded to masonry and concrete elements under single-lap direct shear tests. Two types of anchorage systems are proposed for SRG reinforced masonry and concrete element to study their effectiveness. An indirect method is proposed to find the interfacial properties, compare them with the Mode-I fracture properties of the matrix and to model the effect of the anchorage.

The book of Qohelet. A digital scholarly edition of the hebrew text

The objective of the present dissertation is a born-digital critical edition of the Hebrew Old Testament book of Qohelet. The edition is based on an extensive collation of variant readings from indirect sources – the Septuagint, the Peshitta, the works of St. Jerome (the Vulgate and the Commentary), and the Targum – as well as from direct sources such as the Qumran fragments and Hebrew medieval manuscripts. The ultimate goal of the edition is (a) to reproduce the earliest textual form, the Archetype, that can be reconstructed on the basis of the available evidence; and (b) to propose a rehabilitation of the Original of the Author by resorting, when necessary, to conjectural emendation. We date the Archetype to the II century BCE, corresponding to the date of Hebrew fragments from Qumran, while we place the Original between the V and III centuries BCE. Unlike previous critical editions of Qohelet, ours follows the so-called eclectic model, which involves the reconstitution of a critical text and the preparation of an apparatus of secondary variants. Our edition includes, moreover, new data, taken both from primary literature, such as the recently published Göttingen Septuagint, and from up-to-date studies and critical commentaries on the text of Qohelet. The work is made up of five main parts: an introduction, which sets forth the rationale of the edition and the methodology adopted; the collation, where the variants are listed in their original language; the commentary, where they are extensively discussed; the critical text accompanied by the apparatus, which presents a selection of authentic Hebrew variants taken from the collation; and finally, a translation of the critical text. The edition uses the mark-up language of the Text Encoding Initiative (TEI). It is realized in pdf, via LaTeX, and will be available in digital form, via the TEI-Publisher editor.