The Study Of Dynamic Sensitive Parameter For Nondestructive Identification On Steel Truss Structures

Steel structures have been extensively used in different constructions, because they possess many merits, for example, light deadweight, high strength, good plasticity and toughness, high industrialization and beautiful form, etc. However, the condition of the steel structures' damage are increasing day by day with the courses of corrosion and overload, and so on. So, many interior and oversea scholars devote all out to finding the methods that can accurately judge the conditions of the steel structures' damage. These studies solve a lot of problems, but many shortcomings also exist. Especially, only the intact structure initial data is known, can these methods be used to measure the condition of the structure's damage. But in fact, it's difficult to know the intact structure initial data. To solve this problem, in this paper, a dynamic sensitive parameter to the steel structure's damage in the view of flexibility ,naming as "the abrupt coefficient of flexibility curvature", was found on the basis of the research achievements of many other scholars. This coefficient can be used to judge whether the structure is damaged, find the damage position and determine the damage degree of the structure in the case of unknown structures' initial data. At first, the programming code of ANSYS's APDL is used to compile procedures and the numerical simulation are carried out by taking a plane steel truss as an example in this paper. According to the structure's behavior, if the structure's damage was given, the abrupt coefficient of flexibility curvature can be calculated out. Using this coefficient, the structure's damage position can be found and it's damage degree could be determined initially. On the other hand, damaged structure's abrupt coefficient of flexibility curvature can be obtained on the basis of the measuring data from a practical plane steel truss. The result shows that the plane steel truss's damage position of single member or many members can be found accurately, and the structure's damage degree can also be determined initially using the abrupt coefficient of flexibility curvature. At the same time, the theory of numerical simulation is proved correct. A new theory considering the nodal mass's increasing as a form of damage was put forward. The numerical simulation and practical experiment results indicate that single or several nodes' mass increasing can be measured by the abrupt coefficient of flexibility curvature. This method can be used only if the data of the real structure is known. And using this method to test structure is simple, high-efficient and with high practical value. According to theformer analyses, the method of the nondestructive testing and the problems needed to solve in the steel structure is presented.