Milad Jahangiri

The present paper focuses on the acquisition of the seismic responses of the masonry structures for evaluating the variations of the predominant frequency, damping ratio, and vulnerability index during their construction process. For this purpose, the seismic responses of three confined masonry structures against the ambient vibrations were acquired during their construction process in three sequential stages: (I) once their bearing walls in connection with the confined structural members and ceiling diaphragms were constructed; (II) once their partition walls in conjunction with plaster and mechanical equipment were performed; (III) once their facade and parapet elements in interaction with flooring and whitewashing were accomplished. Subsequently, the measured signals in accordance with the seismic responses of the masonry structures were processed through floor spectral ratio (FSR) and random decrement method (RDM) to exploit their predominant frequency, damping ratio, and vulnerability index in each individual stage. The measured seismic responses of three confined masonry structures demonstrated that the variations of the modal properties have substantially amplified throughout the construction process. Recursively, the vulnerability index has remarkably attenuated over entire stages. Ergo, it can be evolved that all aforementioned intrinsic characteristics of the studied masonry structures have significantly augmented during the construction process.