Structure diagnosis apparatus, structure diagnosis method, and computer-readable recording medium

A structure diagnosis method performed by a computer and comprising:

• acquiring vibration information indicating an acceleration measured by each of a plurality of sensors provided in a structure;
• setting a damping free vibration section for the acquired vibration information;
• converting the acceleration from a time domain to a frequency domain in the damping free vibration section set for each of the sensors;
• calculating a representative spectrum by combining spectra of all of the sensors or the spectra of two or more preselected of the sensors;
• extracting a frequency at which an amplitude of the representative spectrum is greater than or equal to a predetermined value;
• setting the extracted frequency as a natural frequency;
• setting a frequency band including the natural frequency;
• extracting spectral shape information used to indicate a spectral shape from a measurement spectrum by using an amplitude and phase of each of a plurality of frequencies within the set frequency band;
• calculating an index based on information regarding a fitness function fitted to a function using the spectral shape information and information regarding a reference fitness function fitted to a function using reference spectral shape information;
• and
• estimating a state of the structure based on the index.

A non-transitory computer-readable recording medium storing a program executable by a computer to perform processing comprising:

• acquiring vibration information indicating an acceleration measured by each of a plurality of sensors provided in a structure;
• setting a damping free vibration section for the acquired vibration information;
• converting the acceleration from a time domain to a frequency domain in the damping free vibration section set for each of the sensors;
• calculating a representative spectrum by combining spectra of all of the sensors or the spectra of two or more preselected of the sensors;
• extracting a frequency at which an amplitude of the representative spectrum is greater than or equal to a predetermined value;
• setting the extracted frequency as a natural frequency;
• setting a frequency band including the natural frequency;
• extracting spectral shape information used to indicate a spectral shape from a measurement spectrum by using an amplitude and phase of each of a plurality of frequencies within the set frequency band;
• calculating an index based on information regarding a fitness function fitted to a function using the spectral shape information and information regarding a reference fitness function fitted to a function using reference spectral shape information;
• and
• estimating a state of the structure based on the index.