Sensing the restoring force characteristics for detached house structural health monitoring using a camera and accelerometer fusion

A new method to sense the restoring force characteristics using camera and accelerometer fusion was developed. Simple methods for monitoring detached wooden houses are required to minimize earthquake damage. The restoring force characteristics, which are calculated using the interstory drift and response acceleration, must be measured. However, the conventional method requires a complex system to synchronize multiple accelerometers and suffers from acceleration integration errors. In this study, a method that uses a camera in addition to an accelerometer was developed. The interstory drift was measured by a camera, and the response acceleration was calculated by adding the ground acceleration measured by the accelerometer and the interstory acceleration. These can be used to obtain the restoring-force characteristics of a house when assuming a single-mass system. In addition, this method has no integration errors as those in previous studies. The scale model experiments demonstrated that the restoring force characteristics could be measured with a measurement error of 1% using a common camera. A shake table experiment demonstrated that the prototype fabricated utilizing the camera and accelerometer successfully measured the restoring force characteristics of a full-scale two-by-four timber-framed building.