RICERCA ITALIANA     

Research program

ATELIER, WORKSHOP, YARD. TECHNIQUES AND CULTURE OF THE PRODUCTION IN THE ROMAN WORLD

University Co-ordinator

Università degli Studi di BOLOGNA - INGEGNERIA DELLE STRUTTURE,TRASPORTI ,ACQUE,RILEVAMENTO DEL TERRITORIO - ()

Research Unit Leader

Antonio Zanutta

Description

The Research Unit’s activities are directed to supply a cognitive surveying relative to the evolution and to the characteristics of historical building on sample area chosen inside Ercolano’s site. The proposed research involves two scientific fields of engineering, survey and structural engineering to start an integrated multidisciplinary analysis that goes to complementary the activities of the other Research Unit participant in the Project.
The research proposed, founded on the pluriannual experience of the members of the Research Unit in the field of the survey and in structural analysis, is planned following a multi-scale approach, from a general to a particular analysis, each phase supported by a rigorous scientific reply. The metric survey if realized at pyramidal level from the urban scale, to the building scale until the object scale, supplies a three-dimensional metric documentation, vectorial and raster, fundamental for the knowledge of the archaeological site.
The three-dimensional reconstruction of the whole excavation area to the smallest particular have an high descriptive geometric value, furthermore constitutes the starting point for the modelling and the structural analysis of ancient masonries.
Only integrating various instruments of multidisciplinary scientific knowledge such as the historical analysis, the chemical analyses of the materials, the non-destructive tests finalized to the experimental valuation of the mechanical characteristics of the present masonries typologies, it is possible to generate a fundamental documentation for the restoration purpose and the Cultural Heritage preservation. For the component connected to the Science of the Survey, the search will be carried out with the adoption of the more appropriate techniques and technologies to the multi scales of operation, accordingly to a modern approach based on digital data and structured database.
In fact, among the main problem that afflict the survey activities traditionally conducted in archaeological contexts, there is the difficulty to carry out crossed analyses at various levels, for the incompatibility of collected data coming from various and not homogenous methods, different reference systems etc. The proposed search offers a first reply in this direction.
The activity of survey to general urban-scale will be realized mainly by means of aerial photogrammetry from flights at a low altitude. The aim will be to obtain images, three-dimensional archives large-scale cartography of the selected area, and thematic maps (distribution of the building’s heights; the verticality of masonries, etc) inserted in an unique GIS system.
The raster and vectorial products coming from these topographic and photogrammetric integrated surveys will be used in order to come down to the analysis of superior detail, at building level. Will be realized analysis on the interconnections between the buildings, their modality of aggregation and structuring, and other valuations will be carried out jointly with the structural engineering participant in the Research Unit.
The activities at building level will be tied to one rigorous geometric description of single buildings or parts of them, chosen on the basis of the previous research.
The Survey techniques will be the terrestrial photogrammetry and the laser scanner and new modalities of taking and assemblage of information will be tested.
A problem connected to the survey of ancient masonries in Ercolano is constituted from the narrow dimension of the spaces, often not sufficient for the realization of traditional topographic and photogrammetric surveys. Therefore methods called "not conventional" will be tested in relation to the geometry and the execution of the taking.
For example it is believed to the employment of mobile elevators having contained dimensions, such to be easily transported by hand, on which screwing laser scanner and/or photogrammetric cameras that allow the execution of scansions and/or images at different height, in order to solve the problems relative to the perspective occlusions and to the geometric tie between different areas; to the execution of photogrammetric surveys in absence of control points by experimental stereo vision systems; the metric use of panoramic images panning to 360° obtained by high resolution rotating cameras.
At the level of masonry detail, the structural element will be surveyed substantially on photogrammetry and laser scanner, with greater precision instrumentation to furnish more complete metric elaborated.
The goal will be to integrate the poor availability of the existing documentation of a sample House located in Ercolano, in order to constitute a data bank essential for the contained scientific information.
The results of the surveys in Ercolano will supply an indispensable line of departure for the structural analyses realized from the structural engineering belonging to the same Research Unit, finalized to the valuation of emergency’s degree of the zones subject of study.

For the member belonging to the scientific field of Structural Engineering.the determination of the structural properties will be start from three consecutive analysis level, based on a deductive path: from the general to the particular. The ideal path will be characterized by three dimension: the “insula” dimension (quarter area), the building dimension and the structural element dimension.
The first phase will be characterized by a strong interdisciplinary cooperation between the members of this research Units and those of the other units in order to carry out all possible global information regarding the historical evolution of the insula.
This task is necessary to highlight all the structural interactions among the buildings of the insula. The knowledge of such interactions is important both in the structural design, in particular against seismic hazard, and in the historical and archaeological evolution (growth). This point requires/brings together the knowledge of the structural designer and the archeologist.
For example in a typical scenario such the archeological site of Ercolano, characterized by several buildings of different highs chained, the first level of this ideal path, would give the necessary structural information regarding the behavior of each building its boundary conditions.
The second phase focused on the determination of seismic vulnerability of a single building . The vulnerability would be determined by studying the entire building as a whole, as well as considering the macro structural components interactions (wall-wall, wall-floor). In addition the misalignment between walls and their verticality will be measured since they affects the structural performance. Moreover visual surveys will help to reconstruct the use or structural function of the building during the roman age. This task is expected to reveal subsequent structural adjustments, weak connections among walls, differential settlements, and any dangerous deformations. This phase will be supported by static and dynamic numerical simulation using commercial software (ANSYS, SAP2000).
The third phase concentrates on single structural elements, studying their characteristics, construction techniques and details. It has two primary objectives: a) the knowledge of employed masonry techniques, b) the location of previous restoration intervention, both ancient and modern.
As regards the first point, the various masonry patterns present will be surveyed, including the geometry, shape and dimension of the masonry units; further it will be studied the masonry wall sections in order to highlight their masonry leaves (number and thickness), the presence on infills in the section core, the presence of units acting as bond between the section leaves (diatoni) or, on the contrary, solution of continuity and voids. This together with the physico-mechanical characteristics of the single materials composing the masonry and their decay due to the presence of moisture and salts as well as to the crack patterns.
With regard to the second point, archaeological masonry such as that in the Vesuvian area has been subjected to cycles of damage due to ancient and modern quakes (such as that in 1980) as well as to damage during the exploration and excavation operations happened with different modalities in various ages (wells and tunnels through the houses and their walls in 18th and 19th Century, and open-air excavation with provisional shore up measures and cases of collapse in the 20th Century). As a consequence, also repairing works and structural strengthenings are very differentiated along time and some camouflage intervention are difficult to recognise. Others have been little effective or even have damaged the building stability. Nevertheless, information about their shape and extent is vital in order to correctly proceed with new interventions.
It is foreseen to investigate on site the characteristics and problematics described above via experimental measurement campaigns carried out joining visual inspections to non destructive testing techniques based upon elecromagnetical waves (georadar-GPR), acoustic waves (impact-echo and sonics) and thermal waves (infrared thermography ). The use of these techniques based on different physical principals will give more insights on the structure. All the detected data will be processed and organized in bi-dimensional maps allowing for an easy visual comparison with the real photo of the object. This approach will guarantee an easy data interpretation for all the players of this project.
All the information acquired during this phase will be used to calibrate the numerical model of the structures. The numerical analyses will give the element structural strength, its seismic vulnerability and will drive possible feature remodeling.
All the above cited aspects are also important for the safety regular activity in an archeological sites such the Vesuvian one.
The combination of the information acquired during the three phases allow to highlight accurately the presence of damage and the vulnerability of each kind of building. This set of information about the insula will generate a database accessible to all the research units of this projects.
The activities described will be performed in synergy with the Center of Studies and Research for Structural Identification – CIMEST (www.cimest.ing.unibo.it) and using the structures and resources of the Laboratory of Computational Mechanics – LAMC (www.lamc.ing.unibo.it), of the Laboratory of Resistance of Materials – LaRM (www.larm.ing.unibo.it) and of the Laboratory of Topography, Photogrammetry and Geological Survey, which refer to the DISTART department (University of Bologna).