AS3600 concrete elastic modulus
AS3600 concrete elastic modulus
(OP)
Hi all,
I'd like to know how elastic modulus for 32MPa of various curing day concretes can be determined
e.g. 7days/ 14 days/ 28 days/ 30yrs
Is it okay to assume that because creep and shrinkage effects are so miniscule in 7 , 14 and 28 day concretes,
modulus of elasticity are taken as:
(rho^1.5) x (0.043x SQRT(fcmi)) for fcmi <40MPa
(rho^1.5) x (0.024x SQRT(fcmi)+0.12) for fcmi > 40MPa
Whilst for 30yr concretes, since creep and shrinkage must be accounted for, one must use coefficient of shrinkage to find
Ec.
Plus,could anyone englighten me on matters associated with the behaviour of 7day,14day and 30yr concrete cylinder before/after they're cracked and how the the choice of concrete may influence the calculations of Ix or Ec and etc etc. Anything relevant would be good.
cheers
I'd like to know how elastic modulus for 32MPa of various curing day concretes can be determined
e.g. 7days/ 14 days/ 28 days/ 30yrs
Is it okay to assume that because creep and shrinkage effects are so miniscule in 7 , 14 and 28 day concretes,
modulus of elasticity are taken as:
(rho^1.5) x (0.043x SQRT(fcmi)) for fcmi <40MPa
(rho^1.5) x (0.024x SQRT(fcmi)+0.12) for fcmi > 40MPa
Whilst for 30yr concretes, since creep and shrinkage must be accounted for, one must use coefficient of shrinkage to find
Ec.
Plus,could anyone englighten me on matters associated with the behaviour of 7day,14day and 30yr concrete cylinder before/after they're cracked and how the the choice of concrete may influence the calculations of Ix or Ec and etc etc. Anything relevant would be good.
cheers





RE: AS3600 concrete elastic modulus
The modulus of elasticity is the material stiffness of the concrete. It varies with concrete strength growth but not by shrinkage, creep, or cracking. The 2nd moment of inertia, I, can be calculated for either uncracked or cracked conditions. The inertia would also account for different composite materials (different E) by transforming them to a base E, and would be time dependent as the E of the concrete varies with strength growth. Deflections can then be calculated from E and I. Long term growth of those deflections can then be calculated to account for creep. Differential shrinkage and creep in composite beams should also be accounted for, particularly for deflections.
RE: AS3600 concrete elastic modulus
I do not understand how shrinkage is going to affect Ec. There is no relationship between them. For deflection calculations, it is possible to allow for creep by modifying the Ec for a long term value but not shrinkage.
Also creep and shrinkage are not miniscule at 28 days. About 50% of shrinkage and creep would occur over the first 28 days.
RE: AS3600 concrete elastic modulus
Not sure I would be prepared to use it for a flexural member like a slab or beam but I would be using it for shortening calculations.
RE: AS3600 concrete elastic modulus