Structural evaluation of an earthen building from operational modal analysis

This paper evaluates the structural behavior of a nineteenth century historical construction of rammed earth built in Lima (Perú). The dynamic response of the building was experimentally analyzed from Operational Modal Analysis tests. A FE model was built in order to approach the experimental behavior. Manual calibration of material properties and interaction with surrounding buildings were considered in order to achieve this goal. Due to the complexity of the structure, the level of damage and possible non-linear effects, only the first two modes were considered to be clear enough for calibration purposes. The building is a three story construction made of adobe masonry and a traditional composite material made of wood, cane and mud known as “quincha”. Experimental and numerical results evidenced the different behavior of the quincha and adobe walls in terms of flexibility. Moreover, loss of connectivity or stiffness between floors and walls is observed from the relative displacements between different parts of the building. The paper contributes to the application of vibration based structural health monitoring techniques to earthen historical constructions.