Influencing factors on creep displacement assessment of bonded fasteners in concrete

Stierschneider, Elisabeth; Tamparopoulos, Alexios E.; McBride, Kenton E.; Bergmeister, Konrad

doi:10.1016/j.engstruct.2021.112448

Cited by 3 publications

(4 citation statements)

References 11 publications

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“…The sustained bond stresses were normalized acc. to Equation (7). Three out of four sustained loads fulfilled the test criteria of EAD, 8 as shown in Figure 17b.…”

Section: Fe-simulation For the Long-term Confined Pulloutmentioning

confidence: 94%

“…After these accidents, many research teams have engaged in the investigation of the creep behavior of bonded anchorage and concrete substrate. [3][4][5][6][7] Based on the research results the qualification guidelines were reexamined, and the design guidelines were amended to reduce the design sustained load to ensure the safety application of bonded anchors. The current European and US qualification guidelines EAD 330499-00-0601 8 and AC355.4 9 provide a sustained load test method to evaluating the sustained load of bonded anchors on the lifetime.…”

Section: Introductionmentioning

confidence: 99%

“…The two accidents in the Big Dig Tunnel 1 and the Sasago Tunnel 2 drew attention to the potentially deadly consequence of the creep behavior of bonded anchors. After these accidents, many research teams have engaged in the investigation of the creep behavior of bonded anchorage and concrete substrate 3–7 . Based on the research results the qualification guidelines were reexamined, and the design guidelines were amended to reduce the design sustained load to ensure the safety application of bonded anchors.…”

Section: Introductionmentioning

confidence: 99%

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FE‐analysis of long‐term performance of an epoxy bonded anchor based on nanoindentation and CT‐scan

Zhu

Bergmeister

2023

Structural Concrete

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Epoxy‐based adhesive mortars are applied as bonding materials for the heavy‐duty fastener in buildings and constructions worldwide. The long‐term behavior of the adhesive mortars is a significant influencing factor on the sustained load and lifetime of bonded anchors. An adhesive mortar is a heterogeneous material consisting of resin and fillers. For the analysis of the long‐term performance of the bonded anchor, it is fundamental to understand the long‐term behavior of the bonding material on the microscale. This contribution presents a novel prediction approach for the long‐term load capacity of the epoxy‐based bonded anchor by using nanoindentation and FE‐simulation. The long‐term mechanical properties of the adhesive mortar were measured by using the precise nanoindentation technology on the micro level for the investigation of: (a) the loading rate effect on the load behavior of the resin, (b) the heterogeneous mechanical phases of the mortar, (c) the aging of the microstructures, and (d) the long‐term load behavior of the components of the mortar. Based on the experimental nanoindentation results, the numerical long‐term time‐independent material parameters were characterized in a concrete model by means of stochastic simulation. For analysis of the imperfection effect of a real bonded anchor, the nanoindentation was employed on the micro level to investigate the error load transfer on the interface between mortar and concrete drillhole without drill‐hole cleaning. On the macro level, the macroscale defects of an installed bonded anchor were found by using the computer tomography. It is demonstrated that the FE‐model based on the nanoindentation results can correctly predict the long‐term performances of a bonded anchorage system.

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“…The sustained bond stresses were normalized acc. to Equation (7). Three out of four sustained loads fulfilled the test criteria of EAD, 8 as shown in Figure 17b.…”

Section: Fe-simulation For the Long-term Confined Pulloutmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

FE‐analysis of long‐term performance of an epoxy bonded anchor based on nanoindentation and CT‐scan

Zhu

Bergmeister

2023

Structural Concrete

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“…This is typically characterised by an abrupt and significant change in the load-displacement curve. The respective displacement is also set as the limit of long-term displacements to determine the maximum allowable displacements throughout a bonded anchor service life for various assessment approaches [ 20 , 21 , 22 ], but also in accordance with current design standards [ 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

Multilateral Assessment of Anchorage Bond Characteristics in Steel Fibre Reinforced Concrete

et al. 2022

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Anchorage to concrete is a recurring application in construction. For such applications, bonded anchors, formed by means of a polymer adhesive injection into a borehole, are a widely used product due to their flexibility in regards to the construction logistics and positioning of the attached element as well as high load capacities. At the same time, fibre-reinforced concrete is the material of choice for many engineering applications where anchors have to be installed. Moreover, the use of steel fibre-reinforced concrete is likely to increase, since it now falls in the scope of the second-generation Eurocode 2 (exp. 2023). Therefore, the condition of the anchor installation borehole—mainly the roughness and grip of its internal surface—is known to play a critical role in the stress transfer from the attached component, through the fastening and into the concrete, and, hence, to the load-bearing performance. At the same time, drilling through the steel fibre reinforcement, along with the accelerated wear of the drilling tools, can in turn influence the borehole’s roughness and the overall installation quality. Furthermore, steel fibre may lead to an additional local stiffening of the concrete where the anchor is installed. These complex elements are discussed herein on the basis of multiple tests on anchors in plain and steel fibre concrete, as well as numerical analyses. The results indicate particular aspects of bonded anchor design and product certification for different polymer-based construction adhesives.

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Freeze-Thaw Behaviour of Post-Installed Bonded Anchors under Changing Climate Conditions

2022

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The freeze-thaw behaviour of bonded fasteners in concrete is assessed according to the European Assessment Document 330499-01-0601 with freeze-thaw condition tests, which include 50 temperature cycles with a duration of 24 h between −20 °C and +20 °C on constantly loaded anchors. It is assumed that one cycle is equivalent to the temperature difference, which a bonded fastener undergoes in one year. Based on an analysis of a 28-year time series of air temperature data for Austria respecting the Alpine region, a modified test protocol with a temperature amplitude of 65 °C between −20 °C and +45 °C is compiled without a predefinition of the number of cycles, in order to simulate temperature differences that occur under real climatic conditions. The experimental test results obtained for both test procedures demonstrate that the stabilization of the displacements for the modified test series occurred after 185 temperature cycles, compared to the 50 cycles for the standard method. This means that an increase in the temperature amplitude of 25 °C in the higher temperature range leads to an approximately 3.5 times higher number of required temperature cycles until displacement stabilization is reached. It is concluded that the definition of the used temperature range for freeze-thaw testing in conjunction with climatic data should be critically considered, in order to possibly adapt pure freeze-thaw tests towards experiments that take into account real annual temperature differences.

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Influencing factors on creep displacement assessment of bonded fasteners in concrete

Cited by 3 publications

References 11 publications

FE‐analysis of long‐term performance of an epoxy bonded anchor based on nanoindentation and CT‐scan

FE‐analysis of long‐term performance of an epoxy bonded anchor based on nanoindentation and CT‐scan

Multilateral Assessment of Anchorage Bond Characteristics in Steel Fibre Reinforced Concrete

Freeze-Thaw Behaviour of Post-Installed Bonded Anchors under Changing Climate Conditions

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