Using new techniques of geomatic and structural control in the old city center of L’Aquila after the June 6, 2009 earthquake

"The old city center of L’Aquila is a place rich in historical buildings of considerable merit. The earthquake of April 6th caused significant structural damages, affecting especially historical and monumental masonry buildings. Thus, was immediately emerged the need of intervening with a variety of techniques, combining both structural controls and the modern methods of geomatic surveys. In this paper we present the results of a survey carried out on a monumental building of the XVI century, headquarter of the Humanities Faculty of the University of L'Aquila, situated in the heart of the old city center seriously hit by the earthquake. In particular, after identifying representative points on the structure that can describe, with their motion in time, the evolution of any kinematic collapse mechanism (such as overturning of the facade or other forms of either local or even global structural collapse) all the results and the information obtained by the structural monitoring, performed by repeated partially automated topographical measurements, were analyzed and discussed. The survey methodology was indeed based on the use of 30 mini-reflectors set on the building’s structures and observed by a motorized total station TS30. The instrument is equipped with a piezoelectric motor that guarantees a stable repositioning of a few milliseconds. After clearing a three-dimensional angle and distance compensation made automatically by the instrument, the estimation of structural deformation respect to the fixed points was concluded –in real time- with the accuracy of the mm. The results confirm the extreme accuracy and the interesting possibilities offered by modern techniques of geomatic surveys in the monitoring of important buildings both during the immediate post-earthquake period and certainly during their total reconstruction and recovery."