Natural frequency of concrete We experimentally confirmed that its first natural mode is longitudinally bending and its second mode is torsional. Example - Natural Frequency of Beam. Table 1 Structure of the paper. 148% for every 1 C increase. These factors collectively determine how quickly or slowly a system will oscillate. 7% for foamed concrete composite slab Dec 21, 2023 · The natural frequency decreased with slab thickness, signifying that the natural frequency is dominated by mass rather than stiffness. [9] numerically determined the natural frequencies of continuous prestressed concrete box girder bridges with CSWs by adopting an equivalent orthotropic web model of CSWs. INITIAL DATA. This study analyzed the influence of temperature on the natural vibration characteristics of simply Apr 24, 2019 · Machinery rotation frequency is close enough to excite the natural frequency of the concrete slab, which excited mode has dominant vertical movement in the middle of the concrete slab. Natural frequencies of prestressed concrete beams: theoretical prediction and numerical validation Nov 12, 2019 · The connection system and composite action between the CLT and concrete layer greatly influence the seismic performance. com Volume 5, Issue 4, (July-August) 2017), PP. Using the suggested values, a set of minimum natural frequencies for different occupancies and floor constructions are recommended. Concrete. Nov 1, 2021 · However, this assumption can be unsuitable because the concrete topping slab is continuous in the whole floor, taking part in a partial two-way floor system, which yields a significant change in the result of the natural frequency. Overall, the natural frequency of lightweight composite slabs May 24, 2017 · analysis of concrete floor revealed the natural frequency of the floor being 36-38 Hz, which allows the floor to be classified as high frequency floor. 70Hz to 33. The formula for calculating natural frequency is: ω n = √(k / m) Where This paper presents a method to estimate the prestress-force in post-tensioned prestressed concrete beams by using the fundamental natural frequency. ∗Corresponding author. The frequency f is the reciprocal of the oscillation time T( = 1/ ). For each dominate vertical and lateral mode shape, determine the bridge’s natural frequency. The overall stiffness of any structure controls the modal frequency and curred between the steel joists and the concrete slabs in defining the natural frequency of the system. Keywords: PC bridge, construction process, vibration measurement, natural frequency 1. 5 ties. However, temperature-induced changes in the natural vibration characteristics of bridge structures may exceed the impact of structural damage, thus causing some interference in damage identification. Therefore, precise analysis of the dynamic X. The first mode is associated with the lowest frequency and smooth monotonic deformation; the higher modes feature increasing frequency and inflection points. Thomas M. Previous papers report the results for one concrete beam only [17], and others present frequency results for all 9 beams [18], however, this paper presents the results for all 9 concrete beams, including the result of static three-point bending tests, comparison of the static results with dynamic results Jun 3, 2020 · Request PDF | On Jun 3, 2020, Jong-Han Lee published Effects of prestressing force on natural frequency of prestressed concrete | Find, read and cite all the research you need on ResearchGate Mar 14, 2018 · 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. This phenomenon analysis of concrete floor revealed the natural frequency of the floor being 36-38 Hz, which allows the floor to be classified as high frequency floor. With statistical analyses of experimental data, this study established the relationship between concrete-carbonation depths and natural frequencies. 4. This paper contributes to the state of the art in this area in a number of ways. Dall’Asta and Leoni [6] studied the free vibrations of a class of concrete beams prestressed by Nov 8, 2022 · In the only other comparable longitudinal study of a building to date, Astorga et al. the natural frequency of prestressed concrete beams. DuBAISI Analyses of field ambient vibration were performed on 50 con This study investigates the influence of the cross-sectional non-uniform temperature distribution, as a result of surrounding environmental factors, on the frequency of concrete girder bridges. Chijiwa and K. Jun 3, 2019 · In this paper, considering some important and influencing parameters on the fundamental natural frequencies of bridges including bridge span length, number of spans, bridge width, number of girders, and height of girders, variation of the fundamental natural frequency of the first bending mode of typical bridge superstructures in terms of each of the aforementioned parameters were assessed A study of the natural frequency change of reinforced concrete structures under ordinary drying conditions pointed out possible mechanisms of natural frequency change. The linear negative correlation between the natural frequency of simply supported beams and their temperature were observed. Cracks reduce the beam stiffness (natural frequency) and closing of cracks should increase the stiffness (and hence the natural frequency). Fig. strands exhibited increases in the natural frequency as the prestress force level was increased while with straight bottom prestressing all the girders exhibiteddecreases in the natural frequenciesas the prestress force level was increased. 1 Hz), which is The natural frequencies of RC concrete slab with openings have been evaluated and compared with each other as well as with the intact slab, as control ones. 2013. Prestressing force closes the cracks in concrete (micro cracks as well as the structural cracks, if any). All of the experiments were conducted on PSC beam specimens to examine the influence of prestressing force on the natural frequency of a PSC beam. Feb 1, 2014 · Prior results have shown the promise of these sensors at vibration measurements. The natural frequency does not change much when the concrete in the anchorage zone is damaged. The effect of asphaltic concrete surfacing is also examined. 9f 1p [10], [11]. It is determined by the weight of the slab, the size of the slab, and the stiffness of the supporting structure. The natural frequency of an unloaded (only its own weight - dead load) 12 m long DIN 1025 I 200 steel beam with Moment of Inertia 2140 cm 4 (2140 10-8 m 4) and Modulus of Elasticity 200 10 9 N/m 2 and mass 26. Murray Virginia Tech Facts for Steel Buildings Vibration number 5 D. Equation (8) presents the vibration or the natural frequency for a structure as a function of the parameter’s height, area and moment of inertia of the structure. This study investigated the effects of prestressing force on the natural frequency of concrete beams considering changes in the self-weight of the beam. Sep 1, 2019 · The natural frequencies of prestressed structural components have been a subject of much research interest, particularly in more recent years as several research studies found that the natural frequencies of prestressed reinforced concrete (RC) beams tend to increase with prestressing force, which contradicts the general understanding of classical theories. 57 J^ in which Sep 17, 2018 · Analysis of natural frequencies and modes of vibration involving interaction dam-reservoir-foundation for concrete gravity dams September 2018 Conference: Third International Dam World Conference Natural frequency of the first mode: f = (2. Mar 30, 2008 · This paper investigates the effect of prestressing force on the natural frequencies of reinforced concrete beams. For dance floors and gymnasia, the recommended minimum frequencies are 7, 9, and 11 hz for solid concrete, steel joist-concrete slab, and wood supported structures, respectively. In other words, the natural vibration frequency of the pre-stress concrete simply supported beam would show a decreasing trend with the increasing pre-stress value of the pre-stress steel strand. Brad Davis University of Kentucky Eric E. They may then decide to see how large a vibra tion they can induce Feb 1, 2014 · DOI: 10. [3] deduced the element stiffness matrix of improved composite box girders with CSWs and further proposed a calculation method for the natural Jan 1, 2024 · Also, as the frequency of natural oscillations increases, the oscillation periods decrease, which corresponds to the accepted laws of physics. Gradual decay of natural frequency of reinforced concrete (RC) buildings is computationally investigated in view of the long-term moisture loss and associated shrinkage of concrete. 2 kg/m) (12 m) 4) 0. Oct 1, 2007 · The relationship of pre-stressed concrete (PSC) beam natural frequency and pre-stressed force is difficult to described accurately with mechanical model. (Civil Engineering Animated Videos, Civil Engineering Vid natural frequency of simply supported beams. 1142/s0219455426500306 Corpus ID: 273043214; Effect of non-uniform temperature distribution on the natural frequency of concrete girder bridges @article{Chen2024EffectON, title={Effect of non-uniform temperature distribution on the natural frequency of concrete girder bridges}, author={Zhiwei Chen and Mingshan Xu and Yong Xia and Yao Zhang}, journal={International Journal of Structural Mar 17, 2016 · The novelty of this paper lies in the statistical significance testing of the results. How to Calculate Natural Frequency. In this paper, the authors further the understanding of the dynamic behavior of cement-based carbon nanotube sensors by conducting experiments on a full-scale reinforced concrete beam for output-only identification of natural frequencies. 3×10 6) 0. 93 Hz which equals to the cracked beam with a high level of prestressing force. Dec 1, 2023 · To follow the advanced construction concept and meet the growing demand for rapid construction, a large number of composite structures with CSWs have emerged since 1986, e. Oct 13, 2021 · The general assumption is usually “concrete slabs are fine for vibration in step with the swings natural frequency allows the displacement to be amplified Natural frequencies of prestressed concrete beams: theoretical prediction and numerical validation Marco Breccolotti, Filippo Ubertini, Ilaria Venanzi Department of Civil and Environmental Engineering, University of Perugia, Italy E-mail: breccolotti@strutture. 48-52 DETECTION OF DAMAGE IN CONCRETE STRUCTURE VIA SHIFTS IN NATURAL FREQUENCY 1 Bashir Ahmad Aasim, 2Abdul Khaliq Karimi, 3Jun Tomiyama, 4Ömer Aydan, 5Yuya SUDA 1,3,4,5 2 Department of Civil Engineering and Architecture, University of the Ryukyus, Japan. It is well above the vibration limit in BS EN 1992- Sep 17, 2020 · This paper presented a laboratory investigation for analyzing the natural frequency response of reinforced concrete (RC) beams affected by steel corrosion. Ungar Acentech, Inc. Dynamic tests of three bonded and two unbonded full-prestressed concrete beams were carried out. [ 36 ] conducted a two-year dynamic test on a reinforced concrete slab in a laboratory and observed a reduction in the natural frequency of the bending Oct 1, 2024 · Wind turbine towers are generally designed with three strategies: the stiff-stiff strategy with natural frequencies greater than 1. 67 Hz (small-scale 100. Comparing the natural frequency of 1st mode of vibration for beams with and without prestressing, it can be observed that within the scope of this work, the natural frequency of the un-prestressed beam with live load 15 kN/m is Jul 2, 2014 · The natural frequencies computed from the finite element model are also verified with the actual measured natural frequencies that are determined through the modal test conducted in the laboratory. Jul 28, 2016 · The experimental results show a trend of the natural frequencies of reinforced concrete test beams to decrease with the increase in concrete-carbonation depths. 1 - Young’s modulus and shrinkage of Cement paste frequency of bridges is proposed and the higher vibration modes excited by vehicular traffic are examined. As expected, the natural frequency measurements at 60g remained between the fixed-base upper bound and 1g lower bound at all scour levels. Luigi Materazzi and Antonella D’Alessandro and Jun 21, 2021 · Natural vibration characteristics serve as one of the crucial references for bridge monitoring. Since the increased vibrations are not noticed before the pedestal reconstruction, the additional mass of concrete pedestal and stiffness had changed one of the Download Table | Identified natural frequencies of the bridge from publication: Ambient Vibration Test on Reinforced Concrete Bridges | An investigation was carried out to determine dynamic Several factors influence the natural frequency of a system, including the mass of the system, the stiffness of its components, and the damping present. 16÷0. Just as in the previous scenario, as the number of modes increases, the natural frequency increases. From a purely theoretical point of view, such effects in different prestressing Fig. venanzi@strutture. Firstly, the paper provides furtherance to the progressively growing literature in the Natural frequencies of prestressed concrete beams : theoretical prediction and numerical validation @inproceedings{Breccolotti2009NaturalFO, title={Natural frequencies of prestressed concrete beams : theoretical prediction and numerical validation}, author={Marco Breccolotti and Filippo Ubertini and Ilaria Venanzi}, year={2009}, url={https Natural Frequency f = Every structure has its specific dynamic behaviour with regard to shape and duration T[s] of a Eigenfrequency single oscillation. ) Natural Frequencies of Soils* Ground or Structure Frequency (Hz) Peat 7 Suspended concrete floor 10 - 15 Ground floor 12 - 34 Mar 4, 2020 · For a simple mass-spring system, the natural frequency is given by Equation (1); f = 1/2π √(k/m) —– (1) Where f is the natural frequency (Hz), and k and m are the stiffness and mass respectively. Oct 1, 2024 · DOI: 10. Maekawa / Journal of Advanced Concrete Technology Vol. Consequently, a reduction in stiffness leads to a reduction in the natural frequencies. 036 Corpus ID: 45336721; Natural frequencies identification of a reinforced concrete beam using carbon nanotube cement-based sensors @article{Ubertini2014NaturalFI, title={Natural frequencies identification of a reinforced concrete beam using carbon nanotube cement-based sensors}, author={Filippo Ubertini and A. 2 kg/m can be calculated as. 1 Natural frequency change as a function of time, the relative natural frequency is the ratio of natural frequency to the natural frequency of buildings just after construction. Measures such as adding damping materials can also be implemented to reduce the natural frequency and prevent resonance. Jan 22, 2021 · The objective of the present work is to find the effect of pre-stressing on Natural frequency of a Concrete beam and thereby establishing a relationship between the natural frequency of 1st mode Of interest the effects of are density the of foamed concrete. Furthermore, the effect of corrosion on natural frequency of reinforced concrete beams can be eliminate and accuracy natural frequency is identified. 226% per degree relative to the modal frequencies at a temperature of 0 °C. 2 Seismic response analysis of RC building with and without drying (Chijiwa and Maekawa 2016). The natural Kenneth H. In addition, the density and modulus of elasticity of structure material also have impact on its natural frequency. The spectral plots of all scour cases showed a noise peak at 1. Concrete floors are distinctly different from steel-framed floors with respect to vibration design. Both two mechanisms can be provoked by drying, which is natural Mar 17, 2016 · The prediction of the change in natural bending frequencies with varying prestress force magnitude for PSC structures is an important problem, particularly in the field of PSC bridge girders and more recently for pre-cast, post-tensioned concrete wind turbine towers, both of which are structures that are susceptible to extreme dynamic excitation. Wood (along the grain) 3 days ago · Natural frequency is the speed at which vibrations travel through a concrete floor slab when an external force is applied. The results showed that both two shapes of Sep 1, 2001 · From , , it is apparent that the natural frequency of the beam is proportional to the stiffness EI of the beam. Keywords: Natural frequency, Prestressing force, Shrinkage crack . Lenzen is Professor, Dept. Minimum Natural Frequency Floors with natural frequencies lower than 3 Hz are not recommended3 because they are subject to “rogue jumping. ubertini@strutture. Firstly, a theory of the relation between the prestress-forces and the fundamental natural frequency in a Jan 1, 2021 · From the results, it was observed that as the cross-section of the beam increases, the natural frequency decreases. Nov 15, 2016 · As shown from the above formula, the natural vibration frequency of the simply supported beam would be decreased with the increase of T. Apr 4, 2024 · The Brazilian Standard Procedure for the Design of Concrete Structures, ABNT NBR 6118 (2023), goes a step further in defining the comfort conditions of vibrations in relation to the use of the building. ijtra. The natural frequency of simply supported beams decreased by 0. Compared to concrete beams without prestressing force, PSC beams exhibited an appreciable increase in the natural frequency. R. 3, the Limit State of Excessive Vibrations (LS-EV) is defined, presenting the critical natural frequencies for flexional Mar 12, 2024 · Tekla Structural Designer calculates the approximate natural frequency of the beam based on the simplified formula published in the Design Guide on the vibration of floors which states that Natural frequency = 18 / √ δ Jan 30, 2024 · Liu et al. it Feb 1, 2014 · Identified (ID) natural frequencies of the RC beam (Hz) using Frequency Domain Decomposition and traditional sensors (the relative difference, Δ, is calculated between analytical natural frequencies and frequencies identified from acceleration data). 15, 381-396, 2017 383 Natural Frequency in Robot Structural Analysis Professional 2022#Robot #NaturalFrequency #ModalWe can perform modal analysis in Robot Structural Analysis Pro Prestressing force influences the natural frequency of the prestressed beams in a different way. Test results indicate that the frequency of prestressed concrete(PSC)beam increases with the increase in prestressing force approximately. 4 Concrete Slab Thickness Effect. Determine the natural frequency limits in the vertical and lateral direction for which the vibration serviceability limit state is satisfied. J Guangxi Univ (Nat Sci Ed) 37(4):671–675 Jul 22, 2021 · According to the relationships between natural frequency and corrosion depth, we can estimate natural frequency changes under the influence of corrosion depth. 1016/J. investigated the natural frequencies of concrete slabs and the modal frequencies decreased by 0. 48÷2. The natural frequency is the frequency of a free oscillation without continuously being driven by an exciter. The proposed model expressed the relationship of natural frequency of MRF structure with its total mass, lateral dimension in the direction of vibration and total height. The natural frequencies of prestressed structural components have been a subject of much research interest, particularly in more recent years as several research studies found that the natural frequencies . In section 23. 5% change in natural frequency. Nov 16, 2016 · Based on a review from a view point of multi-scale perspective, it is concluded that possible mechanisms of natural frequency change of concrete structures under an ordinary drying condition are reduction of Young’s modulus of concrete and stiffness reduction of reinforced concrete member due to shrinkage-induced cracking. ENGSTRUCT. Then, the natural frequency responses of the corroded beams were tested utilizing The horizontal natural frequencies of House 1 were about 2 Hz and 3 Hz for the CLT version and concrete version respectively. Kong et al. May 3, 2021 · The operating frequency value is far from the natural frequency of 220. Therefore, the natural frequency and damping properties of the soil cannot be clearly defined based on the soil type alone. 1 Reduced natural frequency of concrete structures with different dimensions (Maruyama 2016). For this, a finite element formulation was derived to account for the increase in the stiffness of a beam-tendon system due to the axial force and deformation induced by prestressing of the tendon. Xia et al. Sep 1, 2019 · The fundamental natural frequency is 8. II. J Struct Eng 120(7):2233–2241. The natural frequency (f n), the effective weight, and the inherent damping of the floor system are all related to peak acceleration. results, a model equation for approximation of natural frequency of these types of MRF structures is proposed. The natural frequency of the MBEJs decreases to varying degrees when damage occurs to the MBEJs. Introduction . 78Hz. The CLT core having a lower frequency than the concrete core was also expected since concrete is a stiffer material than wood. Stiffer the component in any direction, higher is the corresponding mode frequency. Beams, there is a rela-tionship between the natural frequency of the 1st mode of vibration and other modes. 1÷3. On comparing the natural frequency of prestressed and un-prestressed concrete beams, it is observed that just like in un-prestressed. 45 / L 2)*(EI x L / m) 0. A theoretical analysis is conducted to derive the bridge’s frequencies considering the cross-sectional non-uniform temperature distribution. The results are different from the dynamic characteristics of isotropic International Journal of Technical Research and Applications e-ISSN: 2320-8163, www. From Eq. Determine if the bridge’s natural frequencies imposes a risk of resonance in the vertical Mar 23, 2021 · Natural frequency is one of the important indicators that reflect the dynamic performance of the structure. Nov 8, 2022 · Whether earthquake-related changes in the natural frequencies of Caltech Hall should be attributed to changes in structural stiffness ( Luco et al. It can be observed that the composite slabs with steel support have the lower fundamental natural frequency if compared to that supported by wood, which is 31. f = (π / 2) ((200 10 9 N/m 2) (2140 10-8 m 4) / (26. ” Rogue jumping occurs when people discover that they can cause vi brations to build up by jumping at the floor’s natural frequency. of Mechanics and Aerospace Engineering, The University of Kansas, Lawrence, Kansas. Attenuation of floor vibration after the . The electrochemical acceleration technique induced the corroded RC beams until the predetermined value of the steel corrosion ratio was achieved. Both Strand7 and ABAQUS tests found that the fundamental frequency rose somewhat as the number of bays increased, but the analytical results remained consistent. This research contributed Natural frequencies in structural analysis are the functions of the stiffness and mass of the component. Sep 17, 2020 · The natural frequency, modal shape, and modal damping are the inherent properties in an RC structure, which are the functions of mass, damping, stiffness, and boundary conditions [16,17,18,19]; and the natural frequency is also an integral characteristic of one RC structure and any changes in the natural frequency indicate a variation in the The natural frequency of the system in any mode is * * 2 1 0 m k f S (7) The first few modes and natural frequencies of a typical building are shown in Fig. unipg. The past experimental data are collected Jul 24, 2023 · The natural frequencies of RC concrete slab with openings have been evaluated and compared with each other as well as with the intact slab, as control ones. Email address: Jun 6, 2016 · The experimental results show a trend of the natural frequencies of reinforced concrete test beams to decrease with the increase in concrete-carbonation depths. Hence it is reasonable to believe that the increasing trend of natural frequencies unexpected by Hamed and Frostig's theory is caused by the closure of shrinkage cracks inside the concrete. Dec 31, 2005 · The natural frequency of concrete can be controlled by adjusting the material properties, dimensions, and boundary conditions of the structure during the design and construction phase. It was expected to get frequencies within that range considering the height of House 1. The largest increase of the first natural frequency occurred after integration, however remarkable decrease observed after asphalt pavement. The significance of dynamic modulus of elasticity for concrete in vibration analysis is quantified. 25×10 10 (2. g. The natural frequency of lightweight composite slabs was 29. Feb 14, 2023 · Table 5 shows natural frequencies for models with different bay counts. frequency/ of these floors could be closely approximated by the equation, /=1. 1 f 3p, the soft-stiff strategy with natural frequencies between 1. 15. Chapter Section Theme 1 - Natural frequency of building 2 2. natural frequency of a structure changes owing to the prestressing force. 9 f 3p, and the soft-soft strategy with natural frequencies less than 0. Article Google Scholar Xue G, Hu XF (2012) Research on the natural frequencies of externally prestressed concrete simply supported beams. (Estimated values for soil natural frequency are listed in Table 1. Table 3 contains the numerical values of the natural frequencies of the second stage of the research. Feb 14, 2023 · Saiidi M, Douglas B, Feng S (1994) Prestress force effect vibration frequency of concrete bridges. DussEAU AND HASSAN N. 18. Table 6 provides natural frequencies for models with different slab thicknesses. Low-rise buildings have high natural frequencies, while tall flexible buildings are characterized by their low natural frequencies. NATURAL FREQUENCY OF STRUCTURES Oct 10, 2018 · The natural frequency change of reinforced concrete (RC) members during damage when subjected to low cycle loading was studied through horizontal cyclic loading experiments. 87 Hz; thus, the transient vibration only induces a minimal effect on the spillway structure and the spillway is considered Jul 22, 2021 · According to the relationships between natural frequency and corrosion depth, we can estimate natural frequency changes under the influence of corrosion depth. The purpose was to seek the relation between prestressing force and natural frequency. it, filippo. 1 f 1p and 0. On the basis of comprehensive consideration of the continuity of the deformation of the filling behind the reinforced retaining wall, if the filling behind the wall is regarded as the Pasternak two-parameter foundation model, then the retaining wall panels can be considered as Bernoulli Jan 1, 2011 · PDF | On Jan 1, 2011, Marcus Cavalcanti and others published Experimental determination of natural frequencies for concrete blocks | Find, read and cite all the research you need on ResearchGate Jul 18, 2020 · The full-scale natural frequency variation found using the integral bridge model is shown in Fig. , triangular box girders with CSWs and concrete filled steel tube, composite box girders with CSWs, improved composite box girders with CSWs (a structure that replaces the concrete bottom flange and diaphragm with steel This video (Animation, Animated Video) explains the concept of Resonant Frequency Test for Concrete. Attenuation of floor vibration after the impact was analysed. 5. showed that the natural frequencies of a steel and reinforced concrete building in Japan gradually decreased over a 12 yr period preceding the 2011 Tohoku–Oki earthquake. Jun 23, 2021 · This paper investigates the mechanical properties of two different types of recycled concrete, which use wood and rubber, relative to those characteristics of pure concrete, in terms of maximum load and natural frequencies. 1. 12. Kurihara, N. KEYWORDS: Bridge, Dynamics, Modulus, Natural, Frequency Natural frequencies of the concrete in anchorage zone: (a) first natural frequency; (b) second natural frequency; (c) third natural frequency. The dominant natural frequencies of concrete bridges in the pacific northwest Analyses of field ambient vibration were performed on 50 concrete bridge spans along Interstate highways I-5 and I-405 in Washington State. 3 STEP 1 – NATURAL FREQUENCIES The key step in the vibration design of a concrete floor is determining the floor’s natural frequencies and mode shapes, particularly the frequencies that excite the region of interest. The Oct 13, 2020 · A building’s natural frequency (n) is simply the inverse of the fundamental period (T), and, for flexible and dynamically sensitive buildings and other structures, this natural frequency is used Dec 1, 2023 · Ji et al. The results showed that both two shapes A study of the natural frequency change of reinforced concrete structures under ordinary drying conditions pointed out possible mechanisms of natural frequency change. It is common to find that the acceptance criterion for walking is satisfied for all types of reinforced concrete floor systems, including flat plates. it, ilaria. properties of the soil. (A3), as an example a 5% change in stiffness would result in a 2. Vibration of the floor was confirmed to be a perception issue, not a structural one, and human perception of tolerable TRANSPORTATION RESEARCH RECORD 1393 119 Natural Frequencies of Concrete Bridges in the Pacific Northwest RALPH A. 5. , 1987 ) or soil – structure interaction 3. A natural frequency change correlation approach [ 15 ] was used to detect the damage of a cantilever beam. kmg bludcgmp agrlobq kfrv basylz vmpnq yorns vfaiac worwh fjzh