Abstract
To study the relationship between the fundamental frequency and pre-stress value of pre-stressed concrete beams, this paper adopted the hammering method to excite concrete beams under different pre-stress values, eccentricities and counterweights based on two kinds of methods including experiments and numerical simulation, processed and analyzed the collected mid-span acceleration of beams to quantitatively analyze the relationship between the fundamental frequency of beams and pre-stress. Research results showed that pre-stress value had little influence on the fundamental frequency of concrete beams, which was consistent with published research results. The experimental result in this paper was reliable. The experimental and numerical simulation of pre-stress value showed small relative errors. The finite element method in this paper was effective. When the eccentricity is the same, the fundamental frequency of pre-stressed concrete beams showed small changes with the increase of pre-stress value. When the pre-stress value is the same, the fundamental frequency of concrete beams gradually increased with the increase of eccentricity because the increase of eccentricity would improve the effective stiffness of concrete beams. When the counterweight is the same, the fundamental frequency of pre-stressed concrete beams showed small changes with the increase of pre-stress value. When the pre-stress value is the same, the fundamental frequency of concrete beams gradually decreased with the increase of counterweights, which was because counterweights could increase the distributed mass of concrete beams. Finally, the deflection of pre-stressed concrete beams under the variable load was obtained through experiments and finite element method. Experimental and numerical simulation results showed good consistency. It was also effective to use the finite element method to study the dynamic deflection of concrete beams. In addition, experimental and numerical results indicated that applying pre-stress tendons to concrete beams could play an important role in crack resistance. The research in this paper not only further verified existing results, but also provided reference for studying the fundamental frequency and dynamic characteristics of pre-stressed concrete beams.DOI: http://dx.doi.org/10.5755/j01.mech.23.4.18981
Highlights
In recent years, pre-stressed concrete structures have been widely applied in many civil engineering structures gradually by virtue of their characteristics including economic efficiency, practicability, strong carrying capacity, durability and so on
The fundamental frequency of the tested model had increased by 4.5% while the fundamental frequency of the finite element model increased by 5.3%
Results showed that pre-stress value had little influence on the fundamental frequency of concrete beams, which was consistent with published research results
Summary
Pre-stressed concrete structures have been widely applied in many civil engineering structures gradually by virtue of their characteristics including economic efficiency, practicability, strong carrying capacity, durability and so on. Pre-stressed concrete structures have the advantages of improving the crack resistance and stiffness of components, saving materials, reducing weight and enhancing the antifatigue performance of components Due to these advantages, pre-stressed concrete structures have been widely applied in civil engineering including bridges, building structures, ocean platforms and so on since the 1930s. Miyamoto [3] studied the performance of unbonded pre-stressed concrete beams, provided the formula of beam modal frequency in the case of a given pre-stress value and used the results of experiments and tests for correction. Reference [16] thought the natural vibration frequency of pre-stressed beams in tests increased with the increase of pre-stress, which was opposite to the conclusion obtained by isotropic materials under the action of axial force of classical dynamics.
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