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Table 1 Overview of possible test setups.

From: Methodology for Testing Rebar-Concrete Bond in Specimens from Decommissioned Structures

Test setup

Advantages

Disadvantages

Direct pull-out

Simple test setup

Force in the bar is known

Well-defined embedment length, unless a cone failure occurs

Compressed concrete while the bar is in tension

Friction at the bearing end

Cone failure near the loaded end needs to be considered when evaluating results

Challenge of grabbing bars

Indirect pull-out

Force in the bars can be calculated with reasonable accuracy

Risk of asymmetry can cause bending and rotation

Clamping can be difficult to manage

Specimens need a lot of modifications

Beam-end

Forces in bars are known

Well-defined embedment length, unless inclined cracking occurs

Challenge of grabbing bars

Bond capacity or embedment length needs to be small enough to avoid bars yielding

Effect of support pressure

Beam tests, general (all advantages and disadvantages hold for all sub-groups of beam tests)

Relevant as they closely approximate real application

Gripping of bars is avoided

Requires thorough design to obtain anchorage failure instead of other failure modes. E.g. choice of three or four-point bending, spans etc.

For symmetrical test setups, the side that will fail is not known in advance, which increases need for instrumentation

Forces in bars need to be calculated

Beam test, suspended supports

Experience exists, (Lundgren et al. 2015a; Tahershamsi et al. 2014)

Specimens with spalled concrete cover can be tested

Likely requires strengthening to withstand hanging support reactions

Relatively complicated setup

Inclined shear cracks will interact with spalling cracks. Thus, the available anchorage length might not be well-defined

Beam test, direct support

Simple and straightforward

Available anchorage length rather well-defined. Inclined shear cracks expected towards direct supports

Effect of support pressure

Support area may need repair

Beam test, narrow direct support

Simple and straightforward

Limits the effect of support pressure

Risk of tilting

Balancing the anchored force may entail having a stirrup just outside the support area

Support area may need repair

Beams with spliced reinforcement

Simple and straightforward

Relevant, as they closely approximate real application

Can be difficult to locate splices, or splices may not be suitably positioned