Innovative Methodologies for Structural Control of Masonry Building under Preservation or Reconstruction Using Geomatic and Topographic Techniques

Abstract

Operating a deformation analysis on masonry and ancient monumental buildings is not a simple operation. This type of extremely complicated structures present great irregularities and a variety of construction techniques that not always are visible. Thus, the measurement's network has to be wisely projected in order both to reveal all possible kinematic mechanisms, displacements, eventual deformations and to guarantee an elevated reliability of the whole surveying network. For this reason a preliminary deformation analysis is crucial to identify representative points on the structure that will manifest its dynamic characteristics. In our case, an L-shaped monumental masonry building, seriously damaged by the earthquake that hit L'Aquila almost three years ago was chosen to curry out this experiment. The survey methodology was indeed based on the use of 30 mini-reflectors installed on the building's facades and observed by a robotic fully-motorized total station Leica TS30. Extra mini prisms that are also installed on stable surrounding structures are used to orientate the instrument before any set of measurements. All the stable points and especially the base where the total station is positioned for each survey are periodically monitored by a GNSS triangulation in order to guarantee their stability over time. After an immediate estimation of all coordinates made automatically by the instrument a detailed statistical adjustment of the whole network is performed to enhance both the network's reliability and accuracy. With periodic repeatability of all measurements the final position of each point is calculated, adjusted and integrated to the final database. In this way a complete knowledge for the structure's dynamics also considering the seasonal changes is gathered in order to evaluate possible final deformations of the whole structure.