Advanced Materials Research Vols. 133-134

Abstract: Progress does not amount to destroying the future, but to preserving its essence, to generate the impetus to do it better today (Y. Ortega Y Gasset 1951). Working in the areas of history and construction technology, the spirit of these statement guided my research: developing a research method for buildings not listed (yet) as monuments but needed to be analysed before the next approach. When studying buildings it is essential to consider not only the art history, social and urban planning factors, but especially the construction engineering aspects. In this way, a deeper understanding of the underlying design and building methods used in our built environment can be developed. There have been many historical and architectural studies of buildings. The period since the Second World War has received particular interest. Unfortunately, most of these studies do not address the technical aspects of the construction of these buildings. However, these issues were covered by publications at the time these buildings were constructed. Technology provided me with the inspiration to develop a more comprehensive research method to assess buildings: Analysing Buildings from Context to Detail in time: ABCD research method. Technology, at academic level, should be considered in the analysis of a building. Here we are concerned with construction engineering, the study of the requirements associated with constructing buildings. The Analysing Building Construction in time research matrix (ABC matrix) can be used in practice. It incorporates the study outcomes which relate to the building itself. Contextual aspects as well as building aspects are included. They can be analysed at the three time levels to draw conclusions which are relevant to the future existence of the building. The case study of the Friesland Provincial Library in Leeuwarden will be worked out in the conference paper.

Abstract: The architectural heritage is subjected to various risk factors like the lack of maintenance, the material decay and the external solicitations. Nowadays, due to the ever-increasing demand for urban space, a relevant cause of structural damage that the historical buildings experience is the ground settlement due to excavation works. In the city of Amsterdam, for example, the construction of the new North-South metro line will involve an area characterized by the presence of many ancient masonry buildings. A fundamental phase of the design of this kind of projects is the assessment of the risk of subsidence which can affect the existing structures. The actual method to perform this assessment provides for a preliminary screening of the buildings located in the area surrounding the excavation, in order to evaluate which structures are at risk of settlement induced damage. It is based on the simplification of the building as a linear elastic beam and the assumption of the absence of interaction between the soil and the structure. An improved classification system should take into account the main parameters which influence the structural response, like the nonlinear behaviour of the building and the role played by the foundation in the soil-structure interaction. In this paper, the effect on the damage mechanism of the excavation advance and the location of the tunnel with respect to the building is evaluated. Numerical analyses are performed in order to understand the effect of different settlement profiles of the ground. A coupled model of the structure and the soil is evaluated, taking into account a damage model for the masonry building and the nonlinear behaviour of the soil-structure interaction. This paper demonstrates the importance of 3D modelling; neglecting the tunnel advance can lead to an underestimation of the damage.

Abstract: The Ebe schooner-brig was built in 1921 and sailed the Mediterranean’s sea for almost forty years, before being dissected into ninety parts to be transported in Milan (Italy). There, the schooner was reassembled and the naval pavilion of the National Museum of Science and Technology was built up all around the ship. After forty years in the museum, the ship presents significant deformations of both the deck and the keel, particularly in correspondence of the external supports. Despite several interventions in the past and a recent restoration, the deformation phenomenon is still worrying, and the understanding of the real cause is lacking from many aspects. Experts have already advanced some hypotheses, often in opposition to one another, and unfortunately, a continuous monitoring of the ship deformation has not been started yet. In the present paper, the schooner structure is modeled with the commercial finite element code Diana, considering a two-dimensional model of the ship cross-section. The obtained results allow for a deeper understanding of the stress-strain field in the schooner, providing a first safety assessment and useful hints for the design of the monitoring and future interventions.

Abstract: A scaled model of a two-span masonry arch bridge has been built in order to investigate the effect of the central pile settlement due to riverbank erosion. The bridge model has been equipped with different Non Destructive Testing (NDT) instruments and subjected to incremental settlement of the pier. The evolution of the pier scour has been investigated experimentally by means of a hydraulic model and reproduced accordingly. The numerical interpretation of damage, carried out by finite element analyses, has been compared with the results of the Acoustic Emissions (AE) monitoring. Several ultrasonic emissions have been detected and main damage source areas have been localized.

Abstract: The calculation of old existing masonry structures needs a homogeneous mechanical behaviour law under tensile and compressive load until collapse. The samples extracted from existing buildings are necessarily limited in dimension and number and it is not possible to perform tests directly on a representative volume, so the numerical modelling of masonry mechanical behaviour has to be predicted from the behaviour of its constitutive elements. The aim of the study presented here was to develop a method able to define the homogeneous representative law for brick masonry from those of its components, bricks and mortar, in tension and in compression, including linear and non-linear domains. The method is numeric, fitted on experimental results. Tests were carried out on mortar samples, brick samples, and multilayer samples. Their experimental behaviour is described and a damage model is used to describe the behaviour of the masonry. An explanation is given of how the homogeneous characteristics of the masonry were defined and the influence of some parameters is presented.

Abstract: In this paper, following the research line proposed by Milankovicth (1910) and Signorini (1925), a semi-analytical approach for the analysis of masonry walls - treated as horizontally multi-layered strata of no-tension material - is proposed in order to evaluate the stress distribution generated by applied loads. The main applications concern walls subjected only to vertical loads. The goal is to identify in the masonry wall the actual bearing sub-structures by defining at each vertical and horizontal level the transversal sections generated by the unilateral behaviour. The method proposed will allow identifying the partition of the wall into macro-elements, which depend on the centre of applied loads, and wall and bricks geometrical features. The technique adopted to approach the problem can be referred to as the search for the best shape. Two cases are discussed: corbelled masonry walls surrounding windows and arch behaviour of masonry over the window.

Abstract: This paper summarizes the work carried out in the Katholikon of Hosios Loukas Monastery with the aim to study the pathology of the monument. The load bearing structure of the church is briefly presented along with its historical pathology and damages observed after the 1981 earthquake of Boeotia and slightly deteriorated since then. Finally, the results of a preliminary analytical study performed with the purpose to interpret the observed pathology are also presented.

Abstract: The Basilica of Maxentius in Rome features the largest opus caementicium vaults known to have been constructed in the Roman Empire. The present paper presents a structural reconstruction of the building and initial stability analysis of its original geometry. The barrel vaults and groin vaults are analysed, together with the stability of the supporting and buttressing elements. This initial study yields that the original construction was stable. However, two of the three naves of the Basilica have collapsed and further study will be necessary for determining the causes of such structural failure.

Abstract: The presented research concerns the long-term stability of a series of historical monuments, which were constructed with low-strength, ferrous sandstone. The main issues are the overall low compressive strength of the sandstone, the large scatter on these strength values, the sensitivity of its characteristics to water absorption and the lack of new original sandstone to replace the damaged zones. The sandstone reacts poorly under sustained high load levels, a situation which typically occurs at the base of bell towers and medieval city towers, as the dead load is considerably high compared to the compressive strength of the sandstone material. To assess the long-term behaviour of the sandstone, a test program has been set up to obtain information on its strength characteristics under monotonic and sustained loading. Therefore, test specimens were taken from the original material of a collapsed church tower. The results of these laboratory tests were used to adapt the parameters of an existing creep model to simulate the long-term behaviour of the sandstone under specific stress levels. Additionally, a number of strengthening solutions are discussed.

Abstract: This work presents a procedure for the use of probabilistic modelling techniques in the assessment of safety parameters of existing timber structures, when influenced by two types of actions. The parameters of the models have been defined as probabilistic variables, and Monte Carlo simulation technique was taken into account for safety evaluation. The case study here examined concerns four king post trusses on which a safety evaluation method was conducted to determine a target reliability index. Since the structures presented a high level of deterioration, a model considering the variation of the residual cross-section and the influence of environment in resistance was taken into account. Time dependent deterioration models have also been considered. With the results given by the different used models, it was possible to obtain probabilities of failure and respective reliability indices, as well as time evolution deterioration curves for a deteriorated historical structure.