Structural health monitoring (SHM) for evaluating and maintaining structural integrity of a building is a very important research field. This paper proposes the use of squared modal frequencies, to detect damage to individual parts of the structures as well their extent by using a limited number of sensors, as proposed by Mita and Hagiwara1. This damage assessment method evaluated in numerical simulations of a five-story shear structure and in shake-table tests of a five-story steel model. The damage to the structure was simulated by reducing the stiffness of each floor. The study showed that it is possible to identify, localize, and evaluate the magnitude of the real damage in a multi-story structure from shifts in its natural frequencies.
Proc. SPIE. 8345, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2012
KEYWORDS: Earthquakes, Data modeling, Structural health monitoring, Signal processing, Structural dynamics, Damage detection, Detection and tracking algorithms, Reliability, Digital signal processing, System identification
After a large earthquake, the evaluation of damage of structures is an important task for structural health assessment.
Therefore, the structural health monitoring (SHM) has become major researches which focus in the area of structural
dynamics. As we known, the presence of damage or deterioration in a structure can be detected by the changes in the
natural frequencies of the structure. Furthermore mode shape changes can be categorized as damage localization1.
Besides, many damage detection algorithms based on the modal properties of structure such as modal frequencies, mode
shapes, curvature mode shapes and modal flexibilities have been studied for several decades. However, in most
algorithms, identifying the precise location and magnitude of the damage is difficult. If not completely impossible, the
accuracy and reliability is not sufficient2. Using only modal frequencies and their mode shapes changes to qualify
damage seems very difficult to get the real damage in many previous studies. This research desires to test the
applicability of mode-based damage assessment method to the real-size building, in order to give correlation between
simulation models and real building with the changes in frequencies and mode shapes. The data of the simulations and
E-defense Tests on the full-scale four-story steel building will be used to test this exiting method.
Proc. SPIE. 7981, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2011
KEYWORDS: Earthquakes, 3D modeling, Defense and security, Mathematical modeling, System identification, Error analysis, Systems engineering, Structural health monitoring, Structural dynamics, Systems modeling
Evaluation of damage of structures after large earthquake is an important task for health assessment. Vibrations of
buildings give us valuable information on it. Among the representative structural characteristics, natural frequencies
provide the global information. However they are relatively simple, accurate to measure and easy to obtain. Besides, the
changes in frequencies must be considered to identify a damage of structures. This study will consider the frequencies
and mode shapes shifts with various levels of seismic excitations. The excitations are represented by different intensity
levels of the 1995 Hyogoken Nanbu Earthquake that are obtained in JR - Takatori Station. The acceleration data of E-
Defense tests on full scale 4-story steel building will be analyzed. These will allow us detecting and localizing structural
damage as well as evaluating the structural performances. The changes in frequencies and mode shapes are achieved
from multi-input multi-output (MIMO) models. Those will be compared so as to get the results with reasonable
accuracy. The aim of this paper is to propose a damage identification method in order to give correlation between the
models and real damage of a steel building using real-size shake table tests.