Experimental and finite element dynamic analysis of incrementally loaded reinforced concrete structures

Abstract

full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription.For more information, please contact the WRAP Team at: publications@warwick.ac.uk This paper has been published under the following reference: Pešić, N., Živanović, S., Experimental and finite element dynamic analysis of incrementally loaded reinforced concrete structures. Engineering Structures, Vol. 103, pp. 15-27, doi:10.1016/j.engstruct.2015 ABSTRACTThis work investigates influence of damage in reinforced concrete (RC) structures on their dynamic properties through modal testing and non-linear finite element (FE) analysis. Five RC beams were designed with the fundamental flexural mode frequencies in the range of 6.5-18.0Hz for the uncracked state. Mechanical properties of concrete, such as static and dynamic elastic moduli were determined from standard tests and ultra-sonic pulse velocity readings.The beams were incrementally loaded until the span/250 deflection limit was reached and their natural frequencies were measured from the free decay vibrations. The progressive damage reduced fundamental frequencies of tested beams by up to 25%. The non-linear FE analysis was carried out for RC beams and one two-span slab and the calculated reduced frequencies of the 1st and 2nd vibration modes were in excellent agreement with measurements. This led to the conclusion that, given that the non-linear analysis can capture degradation of dynamic stiffness due to cracking, the future dynamic performance and damage identification on the RC structure can be reliably determined from the same FE model. The results reveal potential of the combined modal testing and FE analysis to improve inspection and assessment of the inservice RC structures.Keywords: Concrete; Modal testing; FE analysis; Structural dynamics; Damage assessment This paper has been published under the following reference: Pešić, N., Živanović, S., Experimental and finite element dynamic analysis of incrementally loaded reinforced concrete structures.

Influence of steel–concrete bond damage on the dynamic stiffness of cracked reinforced concrete beams

“…It was found that the static stiffness E I s can be used to calculate the static deformations but underestimates the stiffness of cracked concrete beams under dynamic excitation E I d (Jerath and Shibani, 1985). Similar results were reported by several authors showing that the dynamic stiffness E I d is remarkably larger than the static stiffness E I s for cracked reinforced concrete beam (Eccles, 1999; Hamad et al, 2015; Maeck et al, 2000; Musial, 2012, 2017; Neild et al, 2003; Pešić et al, 2015; Tan, 2003; Xu and Castel, 2016). Pešić et al (2015) investigated the influence of damage on the dynamic properties of the cracked reinforced concrete beam experimentally and proposed an updated finite element analysis model with static measured elastic modulus and recommended tensile strength (5% of the characteristic compressive strength).…”

“…Similar results were reported by several authors showing that the dynamic stiffness E I d is remarkably larger than the static stiffness E I s for cracked reinforced concrete beam (Eccles, 1999; Hamad et al, 2015; Maeck et al, 2000; Musial, 2012, 2017; Neild et al, 2003; Pešić et al, 2015; Tan, 2003; Xu and Castel, 2016). Pešić et al (2015) investigated the influence of damage on the dynamic properties of the cracked reinforced concrete beam experimentally and proposed an updated finite element analysis model with static measured elastic modulus and recommended tensile strength (5% of the characteristic compressive strength). Moreover, Musial (2017) studied the effect of the load level on the natural frequency of cracked reinforced concrete beams and observed that the dynamic stiffness of the unloaded cracked beam was higher than that of the loaded cracked beams with ballast masses.…”

“…For the in-service performance of concrete structures, the compressive concrete behavior can be considered linear elastic, that is, the elastic modulus E c of compressive concrete is assumed constant. According to the experimental results by Pešić et al (2015), the value of the elastic modulus of concrete E c can be considered as equal to the static modulus obtained from the standard cylinder compression tests as shown in Table 1. Hence, the moment of inertia distribution I ( s ) along the cracked beam becomes the key parameter in the stiffness EI ( s ) governing the bending problem.…”

Determining the Young’s modulus of concrete by measuring the eigenfrequencies of concrete and reinforced concrete beams

“…[15][16][17][18][19], were shown to affect eigenfrequencies), but in the analysis of the results one should separate the decrease in stiffness due to the reduction in the moment of inertia caused by cracking. It should be noted, however, that this may introduce additional errors (besides the ones described in conclusion No.…”

“…Other research papers dealing in part with the problem considered here describe the determination of the Young's modulus of concrete on the basis of the longitudinal vibration frequency by means of an analytical procedure [13], and investigations of the dynamic gain in the Young's modulus over time [14]. A substantial number of analyses are devoted to the study of the dynamic flexural stiffness of reinforced concrete beams [10,[15][16][17][18][19], including RC beams strengthened with CFRP materials [20]. Dynamic test methods can also be used to identify defects in reinforced concrete beams [21].…”