Detection of member overall buckling in civil space grid structures based on deviation in normal strain along the member

Abstract

A number of structural collapses are initiated from losing stability locally. The monitoring and detection of instability is rarely studied in both research communities of structural health monitoring and structural stability. In order to capture member buckling at an early stage to prevent a local instability from propagating into an overall structural failure, in this study, an approach to detect one type of instability (member overall buckling) is proposed for civil large-scale space grid structures. The foundation of this approach lies in: once a member buckles, a large bending stress due to buckling is developed and dominates the total normal stress of the member. Since the bending stress varies along a member, the total normal stress varies along the member, so does the total normal strain on the surface of the member. Therefore, by identifying the deviation in normal strain at two different cross sections of a member, overall buckling of the member can be detected. This study will justify that strain gauges can pick up all the bending stress induced by buckling as long as they are deployed before buckling. Numerical simulations have been conducted on large-scale space grid structures with different types of connections between members and loading situations. The obtained results have shown that once a member buckles, the strains measured at two different cross sections on the member deviate from each other significantly, verifying the efficacy of the proposed approach.

Identification of existing stress in existing civil structures for accurate prediction of structural performance under impending extreme winds

“…For the cases where the limit state of the component is buckling (instability), the time instant when the measured strain is used as ε m _ existing in equation (3) will be when the member buckles, and ε current is the buckling strain of the material, which can be calculated from the design critical buckling stress and Young’s modulus of the material. How to determine when the member buckles can be referred to Yan et al (2017, 2018). As long as it is elastic buckling, once the “Added Load” is removed, the deformation due to buckling will disappear and no damage will occur due to this identification process.…”

Fitting the Approximate Equation to Estimate the Global Buckling Load of Cylindrical Single-Layer Space Frames

“…As the first stage of this study, the analysis models are settled as ideal linearly elastic structures, all initial imperfections are ignored 24) .…”

Automated inspection of member deformation in grid structures using three-dimensional laser scanning

“…The structure state is estimated by processing the obtained information by sensors, such as strain gauge, Fiber Bragg Grating sensor, and displacement meter. Yan et al [5] proposed a method for capturing member buckling at an early stage using strain gauges, and its foundation is identifying the deviation of normal strain at two different cross-sections of a member. Zou et al [6] employed a distributed Brillouin fiber sensor to detect localized pipe-wall buckling by measuring the longitudinal and hoop strain distributions along the outer surface of the pipe.…”