Research On Multi-parameter Monitoring Technique And Earthquake Emergency Response Based On Smartphone

The structural health monitoring is very significant to ensure the lives and property safety,and has been made a great development.Meanwhile,most SHM systems reported were designed,integrated and installed into large-scale infrastructures by professionals,and equipped with expensive sensors,data acquisition devices,data transfer systems,etc.SHM system is impossible to be installed for every civilian building,and it is difficult to be applied in a large scale.Especially the structure responses under earthquake excitations were monitored by the existing installed SHM system after earthquake occurs,leads to the difficult monitoring for the real-time response.Moreover,public people cannot participate in the disaster prevention and reduction positively and acquire the structures performance timely.In order to improve the current SHM system,enhance the public involvement and realize the large-scale cluster monitoring,the novative monitoring mthod utilizes the most popular smartphone,which integrated with networks,sensors,and storage capability,was proposed in this paper.And some works aiming to develop smartphone sensing techniques,improve the monitoing methods and emergency response under earthquakes were studied.The primary research contents of this dissertation comprise six aspects as follows:(1)The multi-parameter monitoring technique was studied start with the research on smartphone built-in sensors.All the built-in sensors' performance were discussed,including the CPU,acceleration sensor,gyroscope,camera,data transmission and storage performance,etc.Emphases research on the acceleration sensing technique,inclination sensing technique and external board sensing technique.The feasibility on vibration data collection of the built-in accelerometer and gyroscope as well as the external sensors board was validated by laboratory experiment.The smartphone collection stability among different types was studied as well.(2)Smartphone-based monitoring systems were developed.First,standalone software"Orion-CC" was developed to integrate the functions of data collection,data storage and calculation,data updaing.User c-an log-in to collect acceleration,inclination,pictures and GPS information,and process the acceleration data by FFT,then obtain the cable force directly combine the cable parameters.The data of Orion-CC can be uploaded and shared to the website www.cloudshm.com,which make the monitoring big data collecting possible.The laboratory and field tests validate the high-efficiency,portable and convenience of the Orion-CC.Then a real-time smartphone monitoring system which allows the data collection system and control system work together was studied.This system consists of collection program,controller program and web server.The functions of instruction control,data collection,real-time monitoring and threshold alarming were validated by the application on the movement and orientation monitoring of a girder during hoisting on a cross-sea bridge in real time.(3)The monitoring method using smartphone for the frame response under earthquake excitations was expolored according to the current monitoring status.Smartphones were utilized for monitoring the acceleration and inter-story displacement in a three-story steel frame structure with three artificial damage states subjected to shaking table earthquake excitations,special focus on the inter-story displacement monitoring.Conventional sensors'and smartphones' responses were collected and compared to prove the smartphone-based monitoring methods are feasible on the response monitoring under earthquake excitations.Compared to the conventional sensors,smartphone is more convenience,quick and portable for public.(4)The smartphone monitoring data were analyzed to obtain the damage index from the wavelet packet energy ratio variation difference and residual displacement,which proved the feasibility of the smartphone data for damage features extraction.And then for the displacement-acceleration fusion,acceleration integration in the frequency domain was adopted.The integration modified method with high-low cut-off frequency based on one-story monitored displacement and first modal frequency was studied to reduce the integration error caused by uncertain cutoff frequency.(5)The communications in the quake-hit area always cut-off from outside after the earthquake,and traditional seismic field investigation method goes against timeliness of the emergency rescue.Therefore,an emergency communication and quick seismic damage investigation method is proposed based on the developed APP E-Explorer.The communication is available by using the Multipeer Connectivity Framework technology even without external network.And the quick damage investigation can be realized with the questionnaire and pictures collection.A website www.e-explorer.cn,which can collect and release personal information to provide guidance for rescue workers,can also collect damage information for quick intensity evaluation,was built.