Structural health monitoring of complex structures is often limited by restricted accessibility to locations of interest within the structure and availability of operational loads. In this work, a novel output-only virtual sensing scheme is proposed. This scheme involves the implementation of the modal expansion in an augmented Kalman filter. Performance of the proposed scheme is compared with two existing methods. Method 1 relies on a finite element model updating, batch data processing, and modal expansion (MUME) procedure. Method 2 employs a recursive sequential estimation algorithm, which feeds a substructure model of the instrumented system into an Augmented Kalman Filter (AKF). The new scheme referred to as Method 3 (ME-AKF), implements strain estimates generated via Modal Expansion into an AKF as virtual measurements. To demonstrate the applicability of the aforementioned methods, a rollercoaster connection was instrumented with accelerometers, strain rosettes, and an optical sensor. A comparison of estimated dynamic strain response at unmeasured locations using three alternative schemes is presented. Although acceleration measurements are used indirectly for model updating, the response-only methods presented in this research use only measurements from strain rosettes for strain history predictions and require no prior knowledge of input forces. Predicted strains using all methods are shownmore »
Remaining Fatigue Life Prediction of a Roller Coaster Subjected to Multiaxial Nonproportional Loading Using Limited Measured Strain Locations
High cycle fatigue is a major cause of cracking in steel structures subjected to cyclic loading. It can result in substantial financial losses and structural failures compromising the safety of users. Uniaxial methods are in many cases insufficient for large in-service structures with complex geometry and connections subjected to multiaxial non-proportional loadings. A new method for fatigue life prediction for complex structures is presented using the critical plane method and the Kalman filter. The applicability of the methodology proposed is demonstrated and evaluated in a roller coaster support structure. Strain rosettes and accelerometers were installed on a support bracket near weld lines to measure responses. A substructure model is defined and used to estimate response prediction in the weld of the support bracket. The estimation of the input and the state estimation is performed using the augmented Kalman filter method, based on the response measurements and the substructured model. This new methodology is anticipated to be used for real-time fatigue prognosis of highway bridges.
- Award ID(s):
- 1640693
- Publication Date:
- NSF-PAR ID:
- 10186156
- Journal Name:
- Structures Congress Conference 2019
- Page Range or eLocation-ID:
- 112 to 121
- Sponsoring Org:
- National Science Foundation
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Fatigue-induced damage is one of the most common types of damage experienced by civil engineering structures subjected to cyclic loading such as bridges and rollercoasters. A framework for the analysis of multiaxial fatigue damage using strain rosettes installed on welded connections is proposed. The applicability of this methodology is shown using strain measurements collected in a welded gussetless truss connection of a vertical-lift bridge. Commonly used uniaxial fatigue analysis methods are insufficient in complex structures that experience variable amplitude, multiaxial loading, and non-proportional loading. Strain data with these characteristics are used for the estimation of the number of multiaxial stress reversals induced by in service loads and the number of associated cycles using the rain-flow method. Methods proposed for uniaxial loading and multiaxial non-proportional loading are compared. Results show that non-proportional loading and the accuracy of the critical plane estimation can cause a significant decrease in the estimates of remaining fatigue life. The methodology proposed is anticipated to be used for real-time fatigue prognosis aiming to address critical needs related to maintenance procedures of complex structures, visual inspection techniques and evaluation tools for infrastructure networks.
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.1061/9780784482230.012
