Joint discrepancy evaluation of an existing steel bridge using time-frequency and wavelet-based approach

Abstract

An effective form-finding method for form-fixed spatial network structures is presented in this paper. The adaptive formfinding method is introduced along with the example of designing an ellipsoidal network dome with bar length variations being as small as possible. A typical spherical geodesic network is selected as an initial state, having bar lengths in a limit group number. Next, this network is transformed into the ellipsoidal shape as desired by applying compressions on bars according to the bar length variations caused by transformation. Afterwards, the dynamic relaxation method is employed to explicitly integrate the node positions by applying residual forces. During the form-finding process, the boundary condition of constraining nodes on the ellipsoid surface is innovatively considered as reactions on the normal direction of the surface at node positions, which are balanced with the components of the nodal forces in a reverse direction induced by compressions on bars. The node positions are also corrected according to the fixed-form condition in each explicit iteration step. In the serial results of time history, the optimal solution is found from a time history of states by properly choosing convergence criteria, and the presented form-finding procedure is proved to be applicable for form-fixed problems.

Wavelet Energy Accumulation Method Applied on the Rio Papaloapan Bridge for Damage Identification

“…They found that damage can be located more accurately for low vehicle speeds and long bridges, indicating the level of damage by the maximum Wavelet Transform (WT) coefficient from Morlet-type mother wavelets. On the other hand, there are works developed by Reddy and Swarnamani [9] and Walia et al [10] focused on analyzing the sensitivity of wavelet coefficients to detect and quantify damage on structures. Recently, Quiñones and Montejo [11] evaluated two techniques based on wavelets to identify damage in civil structures.…”

Analysis of Stiffness of Clamped Joints versus Bolted Joints in Steel Structures by Means of Accelerometers and Shaking Table Tests

“…The use of natural frequency measurement from accelerometers as a means of measuring the variation in stiffness of steel structures has already been used in numerous works, such as the analysis on steel structure that had changes in its structural stiffness due to renovation processes [ 24 , 25 ]. It has also been used for the calibration of numerical models of actual steel structures and subsequent analysis of their behaviors [ 26 , 27 ], to the monitoring of the static and dynamic displacements of railway bridges with the use of inertial sensors [ 28 ], to measure the earthquake behavior of steel structures in the laboratory [ 29 , 30 ] and has also been used to dynamic assessment of masonry towers based on terrestrial radar interferometer and accelerometers [ 31 ].…”

Time–frequency and wavelet-based study of an old steel truss bridge before and after retrofitting

“…The modal parameter identification can be divided into two categories, namely, frequency-domain identification and time domain identification. It transforms measured time domain data to frequency domain with FFT and is identified with power spectral density (PSD) [8]. The Fast Fourier transform (FFT) is a perfect tool for finding the frequency components in a signal [9].…”