Damage Identification Of Cable Truss-cable Nets Structure Based On Strain Mode Difference

Cable truss-cable nets is a flexible structure which is mainly made of prestressed cable as the force components.Prestressed cable is widely used in large-span space structures,forming a variety of new type of structure such as cable domes,cable truss,cable networks and so on,because it can ensure the safety of the structure and reduce weight and cost at the same time.Reinforcement corrosion and fracture can lead to structure damage under the influence of various environmental factors such as the load,temperature,corrosion.Cable will occur prestressing loss in the process of prestressed cable construction and service because of the tensioning sequence,relaxation and creep of the cable,anchor damage,temperature and other factors.As the mainly stressed members,cable damage and the prestressing loss would cause the destruction of prestressed cable structure,therefore,to identify the damage of prestressed cable structure,obtain the health status,judge the damaged components,determine the injury and damage degree,evaluate residual life of the structure is essential to practical engineering application to reduce the national economic loss and ensure the safety of people's life and property.Cable truss-cable nets damage can be divided into cable elements damage and prestressing loss,Discussing the damage identification based on the strain mode difference theory by studying the research background and status of damage detection method based on dynamic parameters.Modal analysis is carried out on the cable truss-cable nets according to the finite element software,by extracting the strain mode difference between health cases and invalidation cases to identify the structure damage.The research shows that the strain mode difference can accurately identify the cable damage of different locations when the cable damage occurred,it also shows that the method is more sensitive to small injury(damage 10%)at the same time.We can classify the cable by the location of the elements and identify the damage degree of the elements by fitting the relation curve between the first order strain mode difference and damage degree;The research is mainly focused on the overall prestressing loss of cable,using the first order strain mode difference can accurately identify the location of the cable prestressing loss.The cable is divided into bearing cable and stable cable,we can identify the prestressing loss degree of the elements by fitting the relation curve between the first order strain mode difference and prestressing loss degree.It illustrates that the strain mode difference can be well applied to the cable truss-cable nets structure.