توضیحات
ABSTRACT
This paper presents a method to identify damage in bridge structures based on the flexibility matrices in the modal strain space. In the tudy by the Ritz vectors extracted from flexibility matrix, the damage is identified. The localization approach is applied to low levels of damage on the prestressed concrete girder of simply supported bridge, with a focus on using a small number of sensors and only the fundamental mode of vibration. The validity of the method is also demonstrated using experimental modal data of a plate girder from I-40 Bridge over the Rio Grande. The predictions were found to closely match the actual response of the bridges. The proposed method can detect the damage in bridge structures using a limited number of sensors and vibration modes.
INTRODUCTION
Damage detection and health monitoring of large-scale structures are important challenges to engineering research. One common approach is to employ vibration characteristics of a structure to predict the damage locations and to estimate the amount of damage. owever, it has been shown that damage in an early stage may not cause significant changes in the modal parameters. To overcome the sensitivity problems of modal parameters to damage, several alternative methods have been proposed. Among these methods, it is well recognized the methods that utilize the mode shapes are more efficient in damage identification. To show the damage localization and severity, the mode shapes must be analyzed and rearranged in appropriate form For this purpose, the methods such as strain mode shapes, strain energy and flexibility matrices have been proposed. Pandey et al. showed that damage occurred in the structure, led to local changes in the shape of curvature mode shapes. Salawu and Williams evaluated the performance of some procedures for locating damage using mode shape curvatures. Mode shape curvatures that introduced as modal strains are widely used to damage identification methods. Wahab and DeRoeck , investigated the curvature damage factor in a restressed concrete bridge. Maeck and DeRoeck , calculated the bending and torsional stiffness changes using modal curvatures or modal strains. The strain based approaches require the direct measurement of dynamic strains or computing the second derivatives of measured modal displacements. In these methods, the noise induced by the measurement causes the errors in numerical procedures to compute the curvature of mode shapes.
Year: 2011
Publisher : Sixth National Congress on Civil Engineering
By : Neda Baghiee, Mohamad Reza Esfahani and Kazem Moslem
File Information: English Language/ 8 Page / size: 303 KB
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سال : 1390
ناشر : ششمین کنـگره ملی مهنـدسی عمـران
کاری از : ندا باغیه، محمد رضا اصفهانی و کاظم مسلم
اطلاعات فایل : زبان انگلیسی / 8 صفحه / حجم : KB 303
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