Measured hospital building vibrations induced by air conditioning systems and elevators

Abstract

A recent large campaign of vibration measurements has been conducted on a hospital building in Italy to perform an operational modal analysis of the structure utilized for model updating. Subsequently, the updated model has been used to carry out a vulnerability analysis of the hospital structural system. The building is composed of 41 structural subsystems separated by technical joints. At the same time, several subsystems are differently interconnected, especially through a roof sustained by large-span wooden beams. Long acceleration time histories have been measured by wireless sensors located at the top level of the building in two days of testing. During the tests conducted in operational conditions, in different locations of the building air conditioning systems and elevators were functioning and they were affecting the measures in the high-frequency content. This work aims to investigate the structural identification of the complex structure, the effectiveness of technical joints, and the influence of the wooden roof connection on the dynamic structural behavior. In pursuing these goals, the main challenge is considering the influence of air conditioning and elevator systems on the natural frequency identification of the structure. Therefore, based on the location of the sensors, the similarities in the geometry, and the vicinity of the sensors to the mechanical equipment, all the sensors have been classified into different groups to observe the dynamic response. Furthermore, an Artificial Neural Network (ANN), trained on numerical model results, is applied to experimental data to establish a relation between increasing prediction error and the influence of the air conditioning system and elevator frequencies.