Single accelerometer-based inter-story drift reconstruction of soft-story for shear structures with innovative transformation function

The health monitoring of soft-story is vital during earthquakes. Inter-story drift can reflect the structural damage state and provide evidence for assessment. However, installing numerous accelerometers in buildings is labor and cost intensive. This study proposes an innovative transformation function to estimate the inter-story drift of soft-story of shear structures using only a single accelerometer, hence simplifying the sensing system and hampering time-consuming and tedious procedures. In the current research, linear shear structures are considered, laying the foundation for more complex situations. First, the substructure method is used to analyze the softstory. Next, the boundary forces are transformed to structural responses in the frequency domain. By proposing the concept of a transformation function, the relationship between the inter-story displacement and absolute acceleration is established. Further, a robust scheme to identify the transformation function is presented using auto- and cross-spectrum. Subsequently, a numerical simulation is implemented to verify the proposed method for different types of excitations, locations of the weak-story, sampling time lengths and sampling rates, and noise levels. Finally, a laboratory experiment is conducted to validate the proposed algorithm in a real environment. Simulation and test results indicate that the transformation function and inter-story drift of the soft-story can be identified easily and accurately once the sampling time exceeds the duration of structural vibration. The sampling rate requirement is prone to be satisfied for a common accelerometer. This method is effective regardless of the location of the soft-story and type of load, and demonstrates robust performance against environmental noise. Moreover, the proposed method does not require global parameters of the structures, and only requires the characteristics of a soft-story.