Structural Monitoring in the “Santa Maria de la Asunción” Cathedral of Chilpancingo, Guerrero, Mexico; through Topogeodesic-Photogrammetric Surveying and Ambient Vibration. A Methodological Proposal

Abstract

This paper presents a review of the state of the art of structural health monitoring using three inspection techniques and their application in the proposed methodology for the study of a historic structure located in a high seismic hazard area. The proposed approaches are a) use of an unmanned aerial vehicle (UAV), a reliable platform for data acquisition in photogrammetric inspection and surveillance work due to its simple handling and accessibility to human risk zones; b) Global Positioning System (GPS), which offers the capability of static or dynamic monitoring, using kinetic navigation (RTK), precise point positioning (PPP) or combination of both methods; c) ambient vibration (AV), an accelerometer test that determines the dynamic properties of a structure, of which values indicate the structural safety status. The building to be studied is the "Santa María de la Asunción" Cathedral of Chilpancingo in Mexico, which represents a great historical value because it hosted the First "Anahuac" Congress in 1813. The structure covers an area of 1056 sqm and has a height of 33.31 m. The construction began after 1902 and has been affected by several seismic events. Because of the earthquake of December 2011, cracks occurred in the basements and keystones of the arches of the two bell towers, severe damage to the right tower, and moderate to the left one. In the frontispiece, top of the arches, and in front of the central nave vault also appeared cracks. The reinforcement process is currently complete. The expected results are a matrix of distances among control points in the building, high-resolution ortho-images, and values of the dynamic structural properties. According to the architectural and structural characteristics, location, importance, and use of the structure, it is proposed to perform a monitoring every six months