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The paper investigates the dynamic characterisation along with the numerical model tuning and the seismic risk assessment of a monumental masonry tower in Italy namely the Santa Maria a Vico bell tower. Full-scale ambient vibration tests were performed under the impact of environmental loads. The technique of modal extraction in the frequency domain was applied. In-situ investigation survey was used in calibrating the refined 3D finite element model. The FEM tuning was carried out by varying the mechanical parameters and accounting for the restraint offered by the neighbouring buildings and the role of soil–structure interaction. The paper shows that the modal identification is a reliable technique that can be used in-situ for assessing the dynamic behaviour of monumental buildings. The tuned FEM model of the tower was usefully employed to determine the theoretical fundamental frequencies, which accurately fit the experiment data. Finally, the seismic performance of the bell tower was assessed using a non-linear static procedure based on the multi-modal pushover analysis and the capacity spectrum method. The results confirm that seismic events of moderate intensity can produce heavy damage to the masonry tower presented in this study.
The paper presents a comparison between different numerical modelling approaches aiming to simulate the in-plain behaviour of three types of earthen materials, namely adobe masonry, rammed earth and cob. For this purpose, uniaxial and diagonal compression tests were carried out, which allowed determining important mechanical parameters, such as compressive strength, Young’s modulus, Poisson’s ratio, shear strength and shear modulus. Furthermore, the tests allowed assessing the level of non-linear behaviour of the respective stress strain relationships as well as the failure modes. The experimental results were then used for the calibration of numerical models (based on the finite element method) for simulating the non-linear behaviour of the earth materials under in-plane shear loading. Both macro- and micro-modelling approaches were considered for this purpose. The procedures adopted for model calibration established the reliability of various modelling strategies for the different loading conditions. The simplified Approach based on macromodelling shows a satisfactory accuracy and low computational costs. The results reproducing the uniaxial compression are in good correspondence with the post-elastic behaviour observed in the experimental campaign. The micro-modelling approach adopted to reproduce the shear behaviour, even with higher computational cost, represents a suitable tool to predict the adobe masonry and rammed earth collapse mechanisms.
Emissions of building materials might have negative impact on human health and well-being. In the EU-funded research project H-House more than 30 natural materials (earthen dry boards and plasters, bio-based insulation materials made of wood, flax, reed, straw, etc.) used for renovation and refurbishment were tested regarding emissions of VOC, formaldehyde and radon. Different to ordinary emission tests on single materials this study focuses on the emissions from complete wall assemblies. Therefore, specially designed test chambers were used allowing the compounds to release only from the surface of the material facing indoors. The testing parameters were chosen in order to simulate model room conditions. The emission results were finally evaluated using the AgBB evaluation scheme, a procedure currently applied for the approval of flooring materials in Germany.
From the last decades the earth construction has a growing interest due to the high sustainability (low C02 emissions), thermal and acoustic performance, fire resistance and cost of the raw material (soil). In fact, earth construction can constitute a feasible solution for a more sustainable construction industry in developed countries. Nowadays the research areas on earthen construction focus from one side on the improvement of the materials for new buildings, on the other side on the Conservation of existing architectural heritage.
Historical earthen buildings are often damaged by static or dynamic loads in form of extensive cracking. All too often these cracks are insufficiently or inappropriately repaired, if at all, because of lack of knowledge and/or technology. In particular, the behaviour of crack repair by grouting poses a challenge in earthen materials and demands specific requirements for the grouting mortar, such as low water content, good water retention, low shrinkage, etc. Cracks in earthen construction can be repaired by grouting to re-establish structural continuity, and can also be used to consolidate voids and gaps, or as a complement to other strengthening techniques such as the introduction of tie-rods.
In the framework of earthen materials for new constructions, the major drawback is that traditional earthen materials are typically considered as non-standard. The great variability and heterogeneity of the properties of the available soils, the lack of quality control in the manufacturing of the earthen materials and in the construction process can be pointed out as the main reasons behind this Situation. Furthermore, only few countries issued Standards and recommendations supporting earth construction, discouraging the design of earth construction by the technical community in countries where these documents are absent.