The choice of boundary conditions and mesh for scaffolding FEM model on the basis of natural vibrations measurements

Cyniak, P.; Błazik‐Borowa, Ewa; Szer, Jacek; Lipecki, Tomasz; Szer, I.

doi:10.1063/1.5019155

Cited by 9 publications

(8 citation statements)

References 6 publications

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“…On the other hand, low natural frequencies cause the scaffolds to be susceptible to wind induced vibrations and vibrations generated by the movement of the users at the scaffolding. In the ORKWIZ project, it was found that the movement of the structure is perceptible to the users while walking on the scaffolding, and in work [9] the increase in scaffolding structure effort due to dynamic interactions was confirmed.…”

Section: Discussionmentioning

confidence: 97%

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Dynamic properties of façade frame scaffoldings

Bęc

Błazik‐Borowa

2019

MATEC Web Conf.

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The paper presents data on natural frequencies and damping parameters of scaffoldings. The analyzes were made mainly on the basis of acceleration measurements made on scaffoldings on construction sites. These studies were supplemented by numerical analyzes, which allowed to show changing of the natural frequencies of the scaffoldings as the effect of the structure exploitation. Finally, it was found that the scaffoldings are structures with low natural frequencies ranging from 1.0 Hz to 4.0 Hz and a logarithmic decrement of damping at 0.06 in most cases, however differences can be observed with the values as low as 0.03.

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Section: Discussionmentioning

confidence: 97%

“…[1], [6], [7]), parameters of the work environment (comp. [8]) and measurements of accelerations of scaffolding vibrations (comp [1], [9]) were made. Based on measurements of scaffolding accelerations, frequencies of free vibrations were determined.…”

Section: Introductionmentioning

confidence: 99%

Dynamic properties of façade frame scaffoldings

Bęc

Błazik‐Borowa

2019

MATEC Web Conf.

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“…3. The detailed description of the principles of scaffolding modeling along with verification of the results can be found in [60,61]. The 27.2 m high scaffolding was obtained by reducing the 55.2 m scaffolding height.…”

Section: Examination Of Scaffolding Response To Worker's Movementmentioning

confidence: 99%

Influence of dynamic properties on scaffoldings safety

Błazik‐Borowa

Bęc

2021

Archiv.Civ.Mech.Eng

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Scaffoldings are used for works at height and in places that are hard to reach, which makes such works dangerous to employees and accidents occur frequently. Loads generated by scaffolding users cannot be avoided. Moving workers excite low-frequency (1–2 Hz) vibrations and scaffoldings as slender structures are prone to such dynamic action. The method for determining the probability of vibrations excitation is presented here. The quantity representing this probability is called the predictor of occurrence of a dangerous situation due to vibrations induced by a walking employee. The predictor of resonance with ith natural frequency requires an analysis of the scaffolding dynamic behavior. The frequencies and the natural mode shapes of vibrations were determined. Numerical dynamic simulations of the worker's movement on the penultimate decks of two scaffoldings were carried out, as well. Predictor analysis was made for single frequencies and combinations of frequency pairs. The predictor values calculated for the first frequency or combinations with it are the highest ones, however the probability of resonance is not only affected by the first frequency. To improve safety, the natural frequencies should be increased. For longitudinal vibrations, this can be done by adding more bracing or reducing lengths of anchors. Increasing the number of anchors gives good results in both directions. During scaffolding design of both typical and atypical constructions, one must determine the natural frequencies and then, if the first natural frequency is less than 4.0 Hz, perform a dynamic scaffolding analysis.

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“…From the graphs obtained this way, the free vibration frequency values were read, which correspond to the ordinates of points with signal power peaks. The research methodology and the process of determining the frequency of free vibrations was described in [15,19,27]. For the L12 scaffolding the first free vibration frequency was equal to 1.94 Hz.…”

Section: Description Of the Scaffolding At The Construction Sitementioning

confidence: 99%

“…In the case of L12 scaffolding, it was found that obtaining such low natural frequencies in FEM (Finite Element Method) analyses is possible only if the anchors' connection to the wall is modelled as hinged support. The methodology used to select the boundary conditions in the scaffolding was described in [27]. The dynamic deformation modulus of subsoil E vd was measured using the lightweight deflectometer ZORN ZFG3000 of ZORN Instruments GmbH & Co. KG from Stendal, Germany.…”

Section: Description Of the Scaffolding At The Construction Sitementioning

confidence: 99%

Influence of Foundation Quality on the Stress in the Elements of Steel Façade Scaffolding

2020

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The purpose of this paper is to show the influence of incorrect scaffolding foundations on the stress in their elements. Static stress analysis was performed for exemplary steel façade scaffolding. The scaffolding was formed using the Plettac 70 system and was composed of 16 modules and 13 working levels. The total dimensions of the scaffolding were 45.0 × 26.36 × 0.74 m. The scaffolding was set up partly on concrete and partly on a created ground classified as coarse sand with discontinuous graining. The boundary conditions modelling the foundation considered the heterogeneity of the ground both along the scaffolding and in the direction perpendicular to the façade. The effect of uneven subsidence on the scaffolding frames was checked, adopting a constant stiffness of 3500 kN/m in half of the supports, while in the rest of them the stiffness varied from 35 to 3500 kN/m. Due to additional bending moments, normal stresses in stands and transoms of the frames increased. Incorrect scaffolding foundation has the greatest negative effect on normal forces in anchors and bracings. Because these elements are responsible for the stability of the scaffolding, their damage may result in scaffolding failure and would certainly lead to a reduction of the values of free vibration frequencies, thus resulting in the discomfort of the workers on the scaffolding and a lack of safety.

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The choice of boundary conditions and mesh for scaffolding FEM model on the basis of natural vibrations measurements

Cited by 9 publications

References 6 publications

Dynamic properties of façade frame scaffoldings

Dynamic properties of façade frame scaffoldings

Influence of dynamic properties on scaffoldings safety

Influence of Foundation Quality on the Stress in the Elements of Steel Façade Scaffolding

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