Experimental research and numerical simulation of influence of pre-stress values on the natural vibration frequency of concrete simply supported beams

Abstract

To study the relationship between the fundamental frequencies and pre-stress values, based on experiments and numerical simulation, the simply supported was excited under different pre-stress values through using the hammering method. The collected acceleration signals in the mid-span of the beam were processed and analyzed to obtain the relationship between the fundamental frequency and pre-stress values. As shown from the analyzed result, the relationship between the fundamental frequency and pre-stress values could not be explained better based on the traditional "Euler-Bernoulli Beam Equation" theory. The fundamental frequency of the pre-stressed beam with the hammering method would be increased with the increasing pre-stress value. When the hammering method was introduced into the numerical simulation, its analysis result and the experimental result were very approximate and presented a small error, which indicated the feasibility and accuracy of the analyzed method. When the pre-stress value was a constant, the fundamental frequency of the beam would be increased with the increasing eccentric distance of the pre-stressing tendon. When other conditions were constant, the fundamental frequency of the beam presented a decreasing trend with the counterweight at the upper part of the beam.

Experimental study on the fundamental frequency of prestressed concrete bridge beams with parabolic unbonded tendons

“…6. Conversely, the prominent increase of natural frequencies (and stiffness) with increasing prestress force, as reported in [14][15][16][17][18], may be caused by microcrack closure under the high prestress forces [23][24][25]. In fact, second-order effects greater than 10% of N crE were induced in the concrete beam specimens.…”

“…An experimental study also demonstrated this behavior in prestressed concrete beams with parabolic tendons [13]. Nonetheless, several dynamic tests have reported an increase in natural frequencies with increasing prestress force [14][15][16][17][18] as occurs in tension members within the elastic range [11,12,[19][20][21], thus contradicting the "compression-softening" theory.…”

Aspects of Vibration-Based Methods for the Prestressing Estimate in Concrete Beams with Internal Bonded or Unbonded Tendons

“…The author acknowledges the efforts and value of Breccolotti's work. Additionally, many scholars [35][36][37] strived to persist in experimenting with finite element (FE) methods. They found possible alternatives and obtained some satisfying results, such as [35], who affirmed that a sensitive parameter is a relative ratio of prestressing to the total weight of the structure rather than the prestressing itself.…”