Each construction material deals with specific mechanical properties, their distribution, damage mechanisms, and degradation processes. Therefore, each material requires a particular assessment approach in order to derive a reliable description of the residual performance of the structure, correctly remove the cause of damage, and proceed with the correct design of interventions. The aims of this paper are, first, the definition of a process of assessment and retrofitting of existing timber structures, both for engineered and heritage/traditional timber structures, and second, a comparison between the defined assessment process and its contents, and the content of existing guidelines, codes, and standards. In order to gain a definition of the process of assessment and retrofitting of existing timber structures, the content of scientific papers and articles was analyzed, and on this basis, an assessment process with six main steps and three milestones was developed. The content of the guidelines, codes and standards was afterwards analyzed basing on this six-steps assessment process. From a comparison among the current literature, guidelines, codes, and standards, interesting results emerged that gave us a picture of the European knowledge and interests on the assessment of existing timber structures. Not only agreement, but also discrepancies, variances, and incongruities were identified as possible topics for future research.

The process of ageing in construction materials is natural and expected, and the technologies to contrast and reverse any damage due to the passing of time are well known in the field of civil engineering. This is true for structures themselves as well as the reinforcement technologies such as, for example, fiber reinforcements (FRP or FRCM). In fact, studies [1,5] have brought attention early on to severe mechanical characteristic reduction caused by the ageing process of specific resin matrices used in composite reinforcement materials, or, even more perilous, their exposure to extreme conditions of temperature. In this project, the authors have set up an experimental campaign on mortar prisms reinforced with different types of fibers and subjected to cycles of ageing through heat exposure. This paper presents the results obtained by three point flexural testing performed at the Testing Laboratory of the University of Florence, comparing the results of the reinforced and aged prisms with those of the non-aged and non reinforced prisms, providing a precedent on how ageing influences the structural behavior of fibers and mortar.

ABSTRACT:The work analyses the historical roof of Derneburg Castle, in the municipality of Holle, Hildesheim's district, Lower Saxony, Germany. The roof is assembled according to Laves Balken's system (Laves beam's system), developed by the architect Georg Ludwig Friedrich Laves (1788 -1864). The system has the peculiarity to consist of beams that are split along the half of the cross section, and maintained diverged by wooden wedges, distributed along the length of the beam. The system increases the height of the beam, and elevates the bending capacity of it (Weber, 1964). The work has been developed in the frame of an interdisciplinary project in the fields of architecture, engineering and photogrammetry. Main aim of the project is the developing of a structural model to understand the load-carrying capacity of Laves Balken's system from the laser-scanning model. For this reason, extensive surveys and photo documentation were collected on three areas of the roof construction, characterized by three peculiar usage of Laves Balken's system. The work presents the survey of the pagoda-roof that covers the tower of the castle, and problems that can be encountered during the survey of very complex timber constructions.

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The present paper describes the first steps of the research project by the title "Repair connection with wooden wedged dowels. New and alternative repair method that meets the demands of Monument Protection of built substance's gentle care and material fairness". The project aims to develop guidelines for static-constructive use of wood-wood repair connections with wooden wedged dowels. In the research project, the first steps for the description of the mechanical model for the wooden wedged dowels have been approached. Literature about wooden pegs and dowels and built examples of wooden wedged dowels in existing buildings have been analyzed; more, preliminary laboratory tests and FEM simulations have been implemented. In this paper, the results of the preliminary laboratory tests and the parallel development of a FEM model with the aim of describing the deformation behavior of the wooden wedged dowels for the most used wooden species will be presented. The main aims are: a) Analysis of the distribution of the strains / deformations in the dowel and in the connected building components when inserting the wedge. b) Analysis of the risk of opening of cracks in the materials. c) Analysis of distribution of stresses in the dowel and in the connected building elements utilizing FEM modeling calibrated on the experimental results. Thanks to the evaluation of deformation behavior in the proposed geometrical configuration and material combinations of wedge, dowel and connected building elements, it has been possible to understand the general framework of deformation behavior and failure modes for different combinations of timber density of the connection components.