Temperature Dependency Research And Seismic Response Analysis Of Long Irregular Base-isolated Structure Based On SHMS

With the improvement of living level and the construction needs of urban modernization, a number of large-scale structures with styles of large spans, super-long, high-rise, high flexibility and new types have emerged constantly. Because of the seismic energy is dissipated by flexible isolation layer, base-isolated structures subjected to strong seismic action perform well and isolation technology have been fully developed and applied in large-scale structures. Contrary to the non-isolated structures, the property loss and casualties caused by strong seismic action are greatly decreased by isolation technology. However, the specification concerning the influence regularity of environmental loads such as temperature, humidity, wind on the performance of long irregular base-isolated structures has little concrete requirement. It is the premise of assessing structural performance accurately and reasonably that researching the evolutionary regularity of static and dynamic characteristics of base-isolated structure influenced by environmental loads based on the monitoring data recorded by structural health monitoring system of base-isolated structure. However, the structural health monitoring system of base-isolated structure is different from large-span bridge, tunnel and high-rise structure because of the flexible isolation layer. In this paper, the main research contents of the life-cycle monitoring of long irregular base-isolated structure include following several aspects:(1) Structural health monitoring system of base-isolated structure on basis of the features of base-isolated structure is investigated in reference to those of non-isolated structures. The main monitoring contents, requirements of overall design, system grade, principles of sensor selection and arrangement plan of sensor location, methods of design verification and safety evaluation are proposed. The system of long-term online monitoring and regularly real time monitoring for a long irregular base-isolated structure is designed and implemented.(2) The mechanism of initial displacement of isolation bearings induced by concrete shrinkage is researched. The dependency relationship between environmental temperature and initial displacement of isolation bearing are revealed based on monitoring data and the temperature dependency models of isolation bearings of structural typical location are proposed. Results show relatively strong dependency between environmental temperature and initial displacement of isolation bearing. The dependency coefficients of structural end bearings are higher than those of structural central location, and which are more significant in construction period.(3) The equations representing environmental temperature effect on the dominant frequency of base-isolated structure are deduced theoretically. The dependency relationship between environmental temperature and structural dominant frequency are researched based on monitoring data, and the dependency models and influence coefficient curves are proposed. Combining temperature dependency experiments of isolation bearings, the analysis results are validated, and which show good consistency with the experiments.(4) According to the dependency models and the dependency experiments, the dynamic responses of base-isolated structure subjected to strong seismic action are analyzed with the consideration of environmental temperature and initial displacement of isolation bearings. The dynamic responses of isolation layer and superstructure with the conditions of different temperature and initial displacement are researched. The dynamic responses of superstructure increase significantly and the peak values of displacement of isolation bearings decrease comparatively with decreasing of environmental temperature and increasing of initial displacement of isolation bearings.