Damage Assessment of Beam by a Quasi-Static Moving Vehicular Load

Abstract

This paper presents a new approach of health monitor using the curvature of the influence line. The study included numerical simulation and experimental test of H-beam to demonstrate the effectiveness of the new approach. The specific work includes: loading test method for moving vehicular to measure displacement influence line of beam structure, obtaining Eigen-damage intrinsic mode function (IMF) of displacement influence line with ensemble empirical mode decomposition (EEMD), processing the second-derivative on displacement influence line to obtain curvature influence line of Eigen-damage IMF, fitting against which through polynomial to obtain quasi-undamaged curve, using the product of absolute difference from both curvature influence line and quasi-undamaged curve to identify damage location of beam structures by means of the product of curvature difference map after fitted. Theoretical development and experimental verification are carried out on H-beam in this paper. In the experiment, measures of displacement influence line at middle span (L/2) of the H-beam when moving vehicular pass by. EEMD, curve fitting and calculating curvature of displacement influence line, etc. methods are used to process displacement influence line. The advantages of this experimental method are fast, time-saving, simple equipment set-up, and can avoid the disturbance of surrounding environmental vibration, but also trouble in a shortage of undamaged condition for the structure. ANSYS software in the paper simulates displacement influence line at middle span under loading test for H-beam to understand the change of displacement influence line for damage identification, which is used as a basis of theoretical development. Finally, conduct loading test method for moving vehicular to measure displacement influence line at middle span of H-beam; connecting with EEMD, curve fitting, and calculating the curvature of displacement influence line can effectively and quickly identify damaged location.

Damage Detection in Beam Bridges Using Quasi-static Displacement Influence Lines

“…As mentioned in previous research [12][13][14], applying the same loading conditions before and after damage is fundamental to successfully detecting the state of damage of a bridge by using the difference in the displacement ILs between the healthy and damaged states. However, during the practical implementation of a quasi-static load test on a bridge, it is impossible to ensure that the weight of the loading vehicle remains constant for every test.…”

“…The difference between displacement ILs before and after damage is commonly used for damage detection [12][13][14] and this method is called the traditional method in this study. In this section, a simply supported bridge is taken as a numerical example and the performance of the proposed method is evaluated and compared with the traditional approach.…”

“…The static influence line (IL) technique can be used to effectively overcome limitations on the number of sensors because, in theory, only one sensor is needed to obtain the complete IL. Taking advantage of the above property, some researchers have focused on identifying damage in structures using ILs [12][13][14] and have identified the location and extent of structural damage using displacement IL curvatures [14,15], the stress IL curvatures [16], the second derivative of displacement IL [17,18] and so forth. Therefore, the IL technique has been deemed a promising damage index [19,20].…”

Constrained observability method in static structural system identification

“…When only the estimation of stiffnesses is targeted, the static SSI methods might be more interesting than the dynamic ones in some cases . In nondestructive tests of bridges, slow moving loads can be applied as quasistatic loads . Providing that the structure behaves linearly, Maxwell law of reciprocal deflections can be applied to reduce the number of sensors in the structure under moving load .…”

“…Providing that the structure behaves linearly, Maxwell law of reciprocal deflections can be applied to reduce the number of sensors in the structure under moving load . The irregular variations in curvatures, which are obtained from the displacement influence lines between the damaged and undamaged structures under moving load, can be used to locate the damages . Boumechra approximated the inverse of the global stiffness matrix by a Neumann series and used optimization technique to find the optimal correction coefficients of structural parameters such that the predicted response from these parameters is closest to the measured static response under moving loads.…”