Learning Forum

[Ricardo Azevedo]

What type of contact element is most suitable for simulating a concrete joint in a block subjected to a bending test?

[peteroznewman]

Please reply with more details about your question. What do you mean by a "concrete joint"  Describe the block and the bending test.

[Ricardo Azevedo]

Thank you for your reply.Let me try to clarify: by concrete joint I mean the union of two solidified parts of concrete, having been concreted with an interval of, say, 24 hours. The block is 15 cm wide, 15 cm high and 50 cm long and the load is applied statically in the mid-span (top of the "beam").

[peteroznewman]

What do you know about the strength of the concrete block?

What do you know about the strength of the joint material?

What do you know about the adhesion of the joint material with the concrete block material?

What is the shape of the joint?  Butt Joint, Lap Joint?

Is any reinforcement used: rebar?

[Ricardo Azevedo]

1) I know its compressive strength

2) I intend to select the properties by using Granta (the joint material is epoxy)

3) We assume complete adhesion between the blocks

4) Butt joint

5) No reinforcement

[peteroznewman]

You need to know the tensile strength because a bending test creates tensile stress on one side of the joint and compressive stress on the opposite side of the joint.  This is important because the tensile strength is much lower than the compressive strength for concrete.

Do you have a different strength for the joint material and the concrete block material, or are they the same?

If the strengths and properties of the two materials are the same, the adhesion is perfect and the joint covers the entire area of the ends of the blocks, that seems equivalent to having no joint. Instead of analyzing two 50 cm long blocks that are joined, you can just analyze one 100 cm long block of concrete.

[Ricardo Azevedo]

 

Thanks again peteroznewman for your comprehensive answer. Yes, I totally agree that we should specify the tensile strength of the concrete. In short, we’re trying to simulate two scenarios: 1) one scarified block joined to another (the total length is 50 cm); 2) a 25 cm long block joined to another one using an epoxy adhesive. In both cases the joint covers the entire area of the ends of the blocks. There is a 24-hour delay in the concreting date of the 2 blocks. Thanks in advance.