A system and method for measuring dynamic properties of a structure, and for using the measured dynamic properties to assess the dynamic performance of the structure. The system and method can separate the measured response into low amplitude and high amplitude data to reduce the influence of outside forces and mass. The system and method measures dynamic properties of the structure such as frequencies of resonance, mode shapes, and non-linear damping, and uses them in an analysis of the structure to compare the dynamic response of the structure with the anticipated properties of a structure built according to applicable building code requirements. The system and method thus quantifies a risk of failure of the structure by determining a risk ratio that compares an as-is condition of the structure with an as-designed condition of the structure.

A measurement method includes: a step of acquiring first observation point information; a step of acquiring second observation point information; a step of calculating a path deflection waveform at a third observation point; a step of calculating a path deflection waveform at a central position between the first observation point and the second observation point; a step of calculating a measurement waveform as a physical quantity at the third observation point; a step of calculating an amplitude coefficient at which a difference is minimized between the measurement waveform and a waveform obtained by multiplying the path deflection waveform at the third observation point by the amplitude coefficient; and a step of calculating, based on the path deflection waveform at the central position and the amplitude coefficient, an estimation waveform as a physical quantity at the central position.

A measurement method includes: a step of acquiring first observation point information including a time point when each part of a moving object passes a first observation point and a physical quantity which is a response to an action; a step of acquiring second observation point information including a time point when the each part passes a second observation point and a physical quantity which is a response to an action; a step of calculating a deflection waveform of a structure generated by the each part; a step of adding the deflection waveforms to calculate a moving object deflection waveform, and calculating a path deflection waveform based on the moving object deflection waveform; a step of calculating a displacement waveform by twice integrating an acceleration of a third observation point; and a step of calculating, based on the path deflection waveform, a value of each coefficient of a polynomial approximating an integration error, and correcting the displacement waveform based on the value of each coefficient.

A measurement method includes: a step of acquiring, based on observation information obtained by an observation device, first observation point information including a time point when each of a plurality of parts of a moving object passes a first observation point of a structure and a physical quantity which is a response to an action of each of the plurality of parts on the first observation point; a step of acquiring, based on the observation information, second observation point information including a time point when each of the plurality of parts passes a second observation point and a physical quantity which is a response to an action of each of the plurality of parts on the second observation point; a step of calculating, based on the first observation point information, the second observation point information, a predetermined coefficient, and an approximate expression of deflection of the structure, a deflection waveform of the structure generated by each of the plurality of parts; and a step of calculating a deflection waveform of the structure generated by the moving object by adding the deflection waveform of the structure generated by each of the plurality of parts.

A measurement method includes: a step of calculating, using first observation point information and based on a time from a leading time point when a leading part of a moving object passes a first observation point to a time point when each of a plurality of part passes the first observation point, and a time from the leading time point to a time point when a total sum of first physical quantities, which are responses to an action of each of the plurality of part on the first observation point, is distributed at a predetermined distribution ratio, a correction coefficient that corrects the first physical quantities; a step of calculating a deflection waveform of a structure generated by the plurality of parts based on the first observation point information, second observation point information, a predetermined coefficient, the correction coefficient, and an approximate expression of deflection of the structure; and a step of calculating a deflection waveform of the structure generated by the moving object by adding the deflection waveform of the structure.

A measurement method includes: a physical quantity acquisition step of acquiring, based on observation information obtained by at least one observation device that observes first to N-th observation points of a structure arranged along a second direction intersecting a first direction in which a moving object moves along the structure, physical quantities at the first to N-th observation points; and an action calculation step of calculating actions x.sub.1 to x.sub.N on the first to N-th observation points based on the acquired physical quantities at the first to N-th observation points, on the assumption that, when a function indicating a correlation between an action x.sub.j on a j-th observation point and an action that the action x.sub.j has on an i-th observation point is set as y.sub.ij, an acquired physical quantity at the i-th observation point is equal to a sum of values of functions y.sub.i1 to y.sub.iN.

A measurement method includes: a step of acquiring first observation point information including a time point when each part of an m-th moving object passes a first observation point and a physical quantity which is a response to an action; a step of acquiring second observation point information including a time point when the each part passes a second observation point and a physical quantity which is a response to an action; a step of calculating a deflection waveform of a structure generated by the each part; a step of adding the deflection waveforms to calculate an m-th moving object deflection waveform; a step of calculating a displacement waveform at the third observation point; and a step of calculating first to M-th amplitude coefficients by assuming that a waveform obtained by multiplying an m-th amplitude coefficient by the m-th moving object deflection waveform is an m-th amplitude adjusted deflection waveform, and that a sum of first to M-th amplitude adjusted deflection waveforms is approximated to the displacement waveform.

The invention discloses a method and a system for predicting the corrosion fatigue life of prestressed concrete bridges. A corrosion level of the strand is predicted to obtain the residual tension force of a structure. A stress concentration factor is integrated to consider the stress concentration effect caused by pitting corrosion, and a growth model of the elastic stress of the strand under the coupled effect of corrosion and fatigue is proposed. A growth model of the plastic stress of the strand is established using a cross-section loss of the strand as a fatigue damage parameter based on a degenerated elastic modulus of the concrete after fatigue. Failure criteria for the concrete, the strand, and a longitudinal tension bar are defined, so that a set of methods for analyzing the life of a prestressed concrete bridge subjected to corrosive environment and fatigue load are formed.

A damage diagnosis device is provided with: a detection unit for detecting that, immediately after a vehicle crossing a bridge has exited from the bridge, another vehicle is not crossing the bridge; a determination unit for determining whether the weight of the vehicle satisfies a criterion; and a diagnosis unit that, when the detection unit has detected that no other vehicle is crossing the bridge and the determination unit has determined that the weight of the vehicle satisfies the criterion, diagnoses damage to the bridge on the basis of information representing free vibration generated in the bridge due to the crossing of the vehicle, thereby improving the precision of diagnosis when damage to a bridge is diagnosed on the basis of information representing free vibration generated in the bridge due to the crossing of a vehicle.

Structural health monitoring relating to an automatic method for tracking structural modal parameters. First, Natural Excitation Technique is used to transform the random responses into correlation functions and Eigensystem Realization Algorithm combined with the stabilization diagram is used to estimate modal parameters from various response segments. Then, modes from the latter response segment are classified as traceable modes or untraceable modes according to correlations between their observability vectors and subspaces of the existing reference modes. Final, traceable modes will be grouped into specified clusters with the same structural characteristics on the basis of maximum modal observability vector correlation and minimum frequency difference. Meanwhile, union of the untraceable modes and existing reference modes are updated as the new reference modes which can be applied into the next tracking process. This can track the modal parameters automatically without artificial thresholds and the specified reference modes.