Response Reconstruction Of A Substructure Based On Limited Vibration Sensors

Structural dynamic responses are crucial for an effective structural health monitoring,which relies on the sensory system.Due to the limitation of costs,test equipments and field environments,the number of sensors is limited compared to the large scale of structures,causing the unavailable measured responses at some key locations.Therefore,response reconstruction at those key structural locations where sensors are not available is essential and has attracted many interests.However,.the increasing.large size and complexity of civil engineering structures,lead to high time-consuming calculation process and massive unknown pa rameters,causing convergence difficulties and uncertainties’ for the existing response reconstruction methods.Thus,this dissertation is devoted to response reconstruction at the locations where sensors are unavailable using substructuring and limited measurements.The main contributions are as follows:The thesis firstly proposed a method of displacement response reconstruction of a substructure based on limited displacement measurements.Based on the dynamics and substructuring theory,the displacement response reconstruction equation and errors between reconstructed and analyzed response were derived.The locations of limited number of sensors were optimized by minimizing the reconstructed errors.Then the measurements at the optimal locations were applied to reconstruct the responses.Numerical investigations using a three-storey steel frame were conducted.The results demonstrated that response reconstruction method using substructring can improve the computational efficiency while ensuring the accuracy compared with the global method.The displacement and strain response reconstruction method using substructuring based on limited number of displacement trancducers and strain gauges was further developed.Considering the geometrical relationship between the displacement and strain,a unified modal expression of displacement and strain is established and regularized.Then the errors between the reconstructed and analyzed displacement and strain responses are deduced.By minimizing the errors,the positions and numbers of the two types of sensors are determined.The fused displacement and strain measured responses were then employed to reconstruct the displacement and strain responses at the other unmeasured locations.The three-storey steel frame was again utilized as annumerical example to verify the accuracy and efficiency of the substructuring response reconstruction method.Finally,experimental investigations of the proposed methods were performed by using a laboratory three-storey steel frame.Two experiments were conducted,including displacement response reconstruction of a substructure and displacement and strain response reconstruction of substructure based on limited measured responses.The experimental results demonstrated that the reconstructed response is in good agreement with the measured response,which further verifies the effectiveness and practicability of the proposed methods.