beam creep
beam creep
(OP)
How many years or decades before a beam can creep significantly and big is the strain difference between original and decades later (let's say for a typical beam of 500mm) depth?
How would the rebar react to the creeping concrete. Would it debond or would rebar creep too along with the concrete?






RE: beam creep
RE: beam creep
Quando Omni Flunkus Moritati
RE: beam creep
BA
RE: beam creep
RE: beam creep
What's the strain of this creep?
A carbon fiber reinforced polymer has strain of 1.5% and 4000 MPA. If a beam 500mm in depth creeps. Would it be enough to make the CFRP ineffective and almost invisible 20 years later??
RE: beam creep
RE: beam creep
Concrete does creep under compression. It cracks under tension. You are probably thinking about creep of metals. Steel doesn't creep due to load, but it creeps at high temperatures.
RE: beam creep
You need to do the numbers and check it. If you don't know how to do the numbers you need to find out. It's not something that you can make general statements about.
You should also be aware that creep projections over long periods of time (30+ years) in codes are often highly unconservative, so consider the consequences of failure, and where appropriate add your own degree of conservatism.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: beam creep
Slight correction, Steel does creep under long term high tensile stress. Relaxation in prestressing steel is tensile creep. Normal reinforcing bars cannot be used as "prestressed" steel because their creep under high long term tensile stress is far higher than that of prestressing steels.
RE: beam creep
RE: beam creep
I am not clear about your statement 'Relaxation in prestressing steel is tensile creep'.
Please correct me if I am wrong.
From my basic knowledge of Material science, Creep and relaxation are two different phenomena.
Creep is the continued deformation under sustained constant laoding and relaxation is the loss of stress under sustained constant deformation.
The loss of prestress in steel wires is not due to creep but due to relaxation.
RE: beam creep
RE: beam creep
In any case, in any real structure neither the stress nor the strain is constant. The creeping concrete has changing stress, and the relaxing strand has changing strain.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/