Tetsuo ABE
Experimental study on difference of creep behavior of concrete under compression and tension
Takumi SHIMOMURA
Until now, many studies concerning concrete compressive creep have been made, so the fundamental nature of this phenomena has been clarified and it is considered in the design of concrete structures. On the other hand, when calculating the effect of stress due to shrinkage and predicting crack formation, creep under tension (tensile creep) needs to be considered. However, research on tensile creep is very limited, and its effect has not been clarified. Verification is insufficient and the cases where the assumption that nature of compressive and tensile creep are the same are common. For this study, tensile and compressive creep test is carried out in order to investigate the difference between the two. For tensile creep test, a special high accuracy and stability sustained load machine was used.
For tensile and compressive creep behavior under constant load, with non-drying conditions, the tensile basic creep coefficient is bigger than the compressive creep coefficient. During drying, added strain (so-called drying creep) exists under tension as same as compression. In this case, tensile drying creep is greater than compressive drying creep, so tensile creep is more susceptible to drying conditions. Overall, tensile creep is greater than compressive creep. If tensile creep strain is plotted, a linear relation between compressive-tensile creep and load stress is shown and according to the linear creep law, it is correct to consider tensile creep as equal to compressive creep.
Under variable stress and non-drying conditions, tensile creep can”Ēt be calculated accurately using the superposition law. For this, it is suggested that tensile creep changes due to previous stresses are compared with virgin creep behavior. This was also true for dry conditions. For drying conditions, regardless if compressive or tensile creep, divergence of calculation values and experimental values is big due to using creep curves affected by drying on superposition. From the above, in order to accurately calculate tensile creep under variable stress, it is necessary to consider creep curves which take into account the effect of previous stress, and drying degree.
Please use "previous botton" to return the previous page