Research On Symptom-based Reliability And Holistic Structure Reliability In Spatial Structure Based On Reliability Block Diagram

The traditional reliability analysis varying in time has wide application at the structural design stage, but displays some limitations when dealing with the existing structures. With the emergence and the rapid development of structural health monitoring technology, the real-time information of existing structures such as sectional dimension of components and the structural static and dynamic responses for reliability analysis makes the results much more approaching to the actual condition of engineers, which is of realistic value. The reliability analysis of structures can be undertaken at two different levels, namely at system level and at component level. The ultimate limit state method used in current structural design is based on the reliability of the structural components, not the system, which may be inadequate in the safety of the structural system. The calculation from component reliability to system reliability is a difficult and hot research in the reliability field in the following years.In order to determine the behavior deterioration of cable dome due to stress relaxation, symptom-based reliability analysis method with stress variations in the members as main symptom is established. In the structural engineering, the system reliability which affirms the global failure as its criterion, is an important index that scales the whole performance of structures. Moreover, the whole structural failure would be inevitable caused by component failure. In order to determine the relationship between system reliability and component reliability, reliability block diagram method which emphasizes on depicting the connection mode among all the components of a system is proposed. And the paper investigates the geometric relationship between components formed a stable structure, which aimed at modeling the reliability block diagram.The case study show that, the variation of the structural symptom reliability over the symptom values is featured with the characteristics of slowly decline in nonlinearity at early time and sharply decline basically in linearity at the later time. Based on the finite element software ANSYS, combined with specific cases, the modeling of reliability block diagram of grid structure and cable dome are carried out by the component removal method, and the system reliability is easily computed according to the predetermined component reliability. The analysis results show that, for Geiger cable dome, the components except for the inner ring notochord are "the essential components"; for grid structure, the movable components exist in the winding layer and the web layer, and the majority of the web components are "the essential components". Thus, it is considered to be that the web layer is more important and significant than the winding layer and the lower chord.