Sensor-Free Stress Estimation Model for Steel Beam Structures Using a Motion Capture System

As a new paradigm for safety assessment of beam structures, this paper proposes a sensor-free monitoring model to estimate the stress distribution of steel beam structures with uncertain loads. The model consists of three steps: the use of a sensor- and wire-free measurement step using a motion capture system; a deformed shape estimation step employing cubic smoothing spline interpolation; and a stress distribution and maximum stress estimation step using the radius of curvature of the estimated deformed shape or a finite-element method. Therefore, unlike the conventional sensor-based structural health monitoring with lengthy cables, the model can determine the maximum stress in a non-contact manner without the deterioration of the measurement accuracy. The sensor-free stress estimation method was applied to estimate the stress distribution of a steel beam structure subjected to static loads applied at the mid-span of the beam by a hydraulic jack. The validity of the proposed method was confirmed by comparing the estimated stresses with stresses measured in static loading tests.