Restaurierung antiker Tempel: Experimentelle Untersuchungen zum Ausziehverhalten von Verankerungen im Marmor

Kourkoulis, Stavros K.; Papanicolopulos, Stefanos‐Aldo; Marinelli, Aikaterini; Vayas, Ioannis

doi:10.1002/bate.200810010

Cited by 11 publications

(10 citation statements)

References 20 publications

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“…Tafreshi et al [30] report that the outer-most thread caries most of the pullout load and therefore is the most likely to fail first. Similarly, recently reported results from tests where titanium threaded bars were pulled-out from marble blocks indicated again that the outer-most thread is the worse loaded one [31]. These differences of the mechanical behaviour can be explained by the relative differences in the material properties for these cases (see online supplementary data).…”

Section: Discussionmentioning

confidence: 55%

A parametric study of cylindrical pedicle screw design implications on the pullout performance using an experimentally validated finite-element model

Chatzistergos

Magnissalis

Kourkoulis

2010

Medical Engineering & Physics

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Abstract:The present study aims to the design of a finite-element model simulating accurately the pullout behaviour of cylindrical pedicle screws and predicting their pullout force. Three commercial pedicle screws, subjected to pure pullout from synthetic bone, were studied experimentally. The results were used for the design, calibration and validation of a finite-element model. Special attention was paid to the accurate simulation of the failure inside the host material. For this purpose a bilinear cohesive zone material model was adopted to control mode-II debonding of neighbouring elements in the vicinity of the screw and simulate this way the failure in shear of the hosting material. Comparison between experimental and numerical results proved that the implementation of this method can significantly enhance the accuracy of the numerical simulation of a screw's mechanical behaviour under pure pullout loads. The numerical model was used for the parametric study of various factors affecting the pullout performance of a cylindrical pedicle screw. It was concluded that the major parameters influencing the pullout force is the outer radius and purchase length of the screw. Significantly weaker was the dependence of the screw's pullout force on its thread inclination, depth and pitch.

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Section: Discussionmentioning

confidence: 55%

A parametric study of cylindrical pedicle screw design implications on the pullout performance using an experimentally validated finite-element model

Chatzistergos

Magnissalis

Kourkoulis

2010

Medical Engineering & Physics

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“… The mechanical behaviour of the mortar. Specimens subjected to: (A) specimen subjected to compression; (B) specimen subjected to Brazilian test; (C) stress‐strain curve under uniaxial compression [27] …”

Section: Experimental Investigationmentioning

confidence: 99%

“…The stress–strain curve is compatible with what is expected for such a well‐documented material in the literature. The modulus of elasticity is estimated at 210 GPa, the conventional 0.2% off‐set yield stress around 490 ΜPa, the tensile fracture stress around 575 MPa, Poisson’s ratio at 0.29 and the ductility about 10% [27].…”

Section: Experimental Investigationmentioning

confidence: 99%

The Pull‐Out Problem in Restoring Marble Fragments: A Design Criterion Based on Experimental Results

Marinelli¹,

Papanicolopulos

Kourkoulis

et al. 2009

Strain

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For the development of innovative connections for the restoration of the integrity of structural elements of ancient stone temples, it is imperative, among others, to understand the reasons of the ‘pull‐out’ phenomenon. Pull‐out can be defined as the gradual or abrupt removal of the reinforcing bars from the body of the structural member, without prior failure of neither the marble nor the bars. An analytic solution is not yet available and in this context, a combined experimental and numerical analysis was undertaken in an effort to enlighten the failure mechanisms activated during the phenomenon. The experimental part included a series of pull‐out tests with prismatic specimens made from Dionysos marble in which threaded metallic bars were planted in drilled holes. The adhesion between the marble and the bar was achieved using a suitable cementitious material. The criterion adopted for the design of the connections is to avoid completely the failure of marble. The parameters studied included the depth and the pitch of the thread of the reinforcing bars. The experimental set‐up comprising suitable supporting and measuring systems was improvised, given the absence of a standard, relevant to this particular problem. Based on the experimental results, a design criterion is introduced allowing for a predefined amount of slip between the reinforcing bar–cement interface and the marble body. In addition, a numerical model is developed, calibrated on the basis of the experimental results. It is concluded that the form of the thread influences considerably the carrying capacity: denser pitches lead to higher ultimate load and energy consumption while the coarser ones favour parasitic bending effects and a flexible behaviour. In addition, the medium depth for each pitch leads to a stiffer and stronger behaviour.

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“…Up to this step, the analysis was carried out considering that the cement layer is described as linearly elastic material. However, a more detailed study of stress–strain curves of the cement [23, 24] indicates that it could be described better using a linear elastic–linear hardening model. The mechanical properties adopted for this model were Young’s modulus E c = 15.4 GPa, Poisson’s ratio v c = 0.26, hardening modulus H c = 1.5 GPa and yield stress σ y = 10 MPa.…”

Section: Bending Of Restored Marble Architraves Using a Bilinear Cemementioning

confidence: 99%

“…Up to this step, the analysis was carried out considering that the cement layer is described as linearly elastic material. However, a more detailed study of stress-strain curves of the cement [23,24] indicates that it could be described better using a linear elasticlinear hardening model. The mechanical properties The mechanical and physical properties of the other two materials (marble and titanium), the geometrical characteristics of the model, the meshing operation, the contact options and the boundary conditions were considered exactly the same as in the previous model with the linear cement layer.…”

Section: Bending Of Restored Marble Architraves Using a Bilinear Cemementioning

confidence: 99%

Joining Fragmented Epistyles Using Threaded Titanium Bars: A Numerical Analysis

Ganniari-Papageorgiou

2009

Strain

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The mechanical behaviour of marble architraves, restored with titanium bars and suitable cementitious material, is studied with the aid of the finite‐element method. The study was motivated by the needs of the conservation project in progress on the Parthenon Temple of the Acropolis of Athens. A realistic numerical model was created taking into account the exact geometry of the threaded bars as well as the exact mechanical properties of the materials involved. The architrave was considered as a prismatic beam of rectangular cross section, centrally fractured and restored with one threaded titanium bar. The bar was inserted in a hole of slightly greater diameter drilled in the member and filled with suitable cementitious material. In this way, a sequence of three materials appears (marble–cement–titanium) giving birth to two interfaces (marble–cement and cement–titanium). Emphasis was given to the influence of the cement layer on the stress and strain fields. The cement was modelled as either linear or bilinear material and the analysis indicated the crucial role of this layer for the drastic reduction in the strain discontinuities.

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Restaurierung antiker Tempel: Experimentelle Untersuchungen zum Ausziehverhalten von Verankerungen im Marmor

Cited by 11 publications

References 20 publications

A parametric study of cylindrical pedicle screw design implications on the pullout performance using an experimentally validated finite-element model

A parametric study of cylindrical pedicle screw design implications on the pullout performance using an experimentally validated finite-element model

The Pull‐Out Problem in Restoring Marble Fragments: A Design Criterion Based on Experimental Results

Joining Fragmented Epistyles Using Threaded Titanium Bars: A Numerical Analysis

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