String structure damage combination identification method based on modal parameters

Abstract

The invention relates to a string structure damage combination identification method based on modal parameters. The method is characterized in that an acceleration signal arranged at on a string structure is collected, inherent frequency before and after damage and a displacement modal of an upper truss part before and after damage of the structure can be respectively obtained, according to the inherent frequency before and after damage of a grid part, first five-order regularization frequency change rate index can be calculated, a frequency-position curve is drafted, a frequency fingerprint database is established, then the frequency fingerprint parameter under practical damage condition can be calculated, positioning is carried out on the fingerprint curve of the corresponding frequency,and the damage position corresponding to each frequency fingerprint is found and then screening is carried out, first three-order curvature difference modal indexes are respectively calculated according to the curvature modals before and after damage of the truss part, and according to the curvature difference modal indexes, a first three-order curvature difference-position curve is drafted, a curve mutation position which is the damage position is found, and the mutation is larger, the damage degree is larger. According to the invention, the string structure is subjected to damage positioning for single damage and multiple damage conditions in an effective mode, and the damage degree can be accurately indentified.

Description

Technical field: [0001] The invention relates to the technical field of damage identification and diagnosis of long-span steel structures, in particular to a damage combination identification method for tension-string structures based on modal parameters. Background technique: [0002] Long-span steel structure is one of the important symbols to measure the level of a country's construction technology. Due to its beautiful shape, reasonable economy and strong spanning ability, long-span steel structures have developed rapidly in my country. Among them, the string beam structure is a space hybrid structure formed by combining the upper rigid arch truss and the lower flexible cable through the struts. It is used in Harbin Sports Convention and Exhibition Center, Guangzhou International Convention and Exhibition Center, Shenzhen Convention and Exhibition Center, Shanghai World Expo Theme Pavilion, National It has been successfully applied in many major projects such as gymnasi...

AI Technical Summary

Problems solved by technology

[0013] The large-span steel structure has a large scale and various members, especially in the prestressed string beam structure, there are different types of members such as cables, struts and trusses, and the force mechanism is more complicated. The damage identification is different from that of conventional bridge structures or multi-story structures Significant differences exist in the building structure

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