An experimental study of static and dynamic responses of prestressed concrete box irder bridges

Abstract

Experimental data from static and dynamic tests on [Formula: see text] direct models of simply supported, one- and two-cell, box girder bridges are presented. Variation of flexural and torsional stiffnesses and dynamic characteristics, such as the natural frequency of vibrations and damping ratios of the bridge models at different levels of cracking damage, are examined; in turn, these dynamic characteristics can be used to estimate the cracking damage in the bridge. The physical model proved to be an adequate tool for the study of static and dynamic responses of box girder bridges at all load levels. Key words: box girder bridges, direct physical models, damping ratio, flexural and torsional stiffnesses, level of cracking damage, load–deformation response, load distribution characteristics, longitudinal and transverse strains, natural frequency of vibrations, simulated OHBDC truck.

Low Frequency Damage Analysis of Electric Pylon Model by Fuzzy Logic Application

“…As noted in literature (eg. in [17]), the measuring frequency is changing in elements where stresses are maximum and where significant changes of natural frequencies can be observed. This allows us to carry out global damage detection applied to such a complex structure as an electric pylon.…”

Free vibrations of cracked prestressed concrete beams

“…This approach is valid only when the beam vibrates around some cracked static equilibrium state, and its amplitude is limited to small displacements. Mirza et al [3] have used this approach to determine the dynamic characteristics of cracked prestressed concrete box girders, such as natural frequencies and damping ratio, at different levels of damage. They have assumed that the reduced flexural rigidity of the cracked girders is uniformly distributed along the span and does not change during vibrations.…”

“…The brief literature survey reveals that the free vibration of cracked bonded prestressed concrete beams has not been investigated analytically, and only limited experimental results are available; see Mirza et al [3]. Here, an analytical model for the free vibration analysis of cracked prestressed beams with bonded cables is conducted.…”

Non-contact based structural damage assessment using stochastic subspace identification and finite element model updating.

“…It is always defining one of the states as "initial condition" that the other states will be compared with (Kawchuk et al 2009;Patil and Maiti 2005;Salawu 1997). Mirza et al (1990) report a decrease in the fundamental natural frequency with progressive damage. Support failure, cracks in structures, joints disconnection and overloading can cause the change of frequencies (Ågårdh 1991;Salane and Baldwin Jr 1990).…”