On the fundamental natural frequency of bridge decks: review and applications

Abstract

The fundamental frequency of vibration of a bridge deck is a key parameter that represents the dynamic characteristics and the condition of the superstructure. This paper reviews the different empirical and/or theoretical formulae that have been proposed in the past. The classical vibration theory of beams and plates was simplified in order to clarify and review the general philosophy behind the previously proposed formulae. On the basis of the results obtained from limited dynamic tests performed by the authors on a number of reinforced concrete bridges and the results of limited tests conducted by other researchers, a formula for the first bending natural frequency of a bridge deck was derived. Moreover, as new applications, new practical formulae are introduced that can be used for estimating the initial dimensions of a deck cross-section for simple span bridges, which are particularly suited to bridge-widening projects. The first bending natural frequency/period of the bridge deck and its corresponding cross-sectional properties are considered here as functions of the bridge main span length.

A Simple Conceptual Model for Estimating the First Bending Natural Frequency of Bridge Superstructures

“…It can be seen that the relationships presented by Karimi et al [22] and Akbari et al [21] may be considered as the upper band, the lower band, and the middle line among the proposed formulae for spans longer than 20 m. It is also clear that the dispersion of the results reduces while the MSL increases. It is because of this fact that the dynamical response of the FBM of bridge superstructures of short-span bridges highly depends on the geometric parameters of the deck and its structural system.…”

“…Generally, by reviewing the research results available in the literature and without describing each of which in detail through a typical one-by-one literature review, the final formulae suggested in the past as well as a summary of the related conditions or limitations have been outlined. e results are given in Table 1 (see [21]). In order to better compare the proposed formulae, the formulae are drawn in Figure 2 for SLs between 10 m and 100 m.…”

A Bridge Structure 3D Representation for Deep Neural Network and Its Application in Frequency Estimation

“…In this section, the 3D representation of bridges mentioned above was applied to predict the frequencies of bridges. e frequency is an important parameter reflecting the dynamic characteristics of the structure, especially in the seismic design of the bridge [24].…”

“…On-site testing can undoubtedly obtain accurate bridge frequencies, but this type of testing often requires a lot of time and expense. Finite element analysis is now widely recognized as a powerful and versatile analytical tool with which to estimate the dynamic characteristics of bridge structures efficiently [24]. erefore, all the bridge frequencies in this study were obtained by the finite element method.…”