Fatigue of Plain Concrete under Biaxial Cyclic Loadings

haltingnosyUrban and Civil

Nov 29, 2013 (3 years and 11 months ago)

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Fatigue of Plain Concrete under Biaxial Cyclic Loadings

Yupu Song, Professor and doctorate graduate tutor ,Structure Engineering Research
Division, Dalian University of Technology, Dalian 116024 ,China.

E
-
mail:
sy
u
p
u
@dlut.edu.cn


Damage investigations show that many concrete structures such as bridges have
emerged fatigue cracks under long cyclic loadings caused by trucks etc. The cracks
have strong effect on the normal use and durability of the structure. Analysis
reveals
that unreasonable fatigue strength and unreasonable design rule are main reasons.
Nowadays, because of the limitation of experiment method, structures are wholly
designed by uniaxial stretch fatigue strength or uniaxial compression fatigue strength

under equal
-
amplitude loading no mater what the cases are. Practice proved that the
result is conservative or dangerous. Last year we did some experiments on uniaxial
tensile strength and uniaxial compression strength of plain concrete under
equal
-
amplitu
de cyclic loading in our laboratory. As for the experiment on biaxial
stretch
-
compression strength or biaxial compression strength of plain concrete,
nobody has done it in our country. In other countries, some scholars have done only a
few experiments on b
iaxial compression strength under equal
-
amplitude or
variable
-
amplitude loading since 1980’s. But the experiments and analysis on biaxial
stretch
-
compression strength haven’t been done yet until now.


Though we can’t safely draw a conclusion about the tens
ile fatigue strength of plain
concrete under biaxial cyclic stretch
-
compression loadings. We can judge that it is less
than that under uniaxial cyclic tension
-
compression loading generally by the test
results under biaxial static stretch
-
compression loadin
g. We will do some experiments
on biaxial stretch
-
compression fatigue strength of some standardized specimens of
plain concrete under cyclic equal
-
amplitude and variable
-
amplitude loadings so that
we can find out the regularity of the stretch strength and
compression strength.
Analysis proved that Miner’s Rule isn’t wholly suitable to the fatigue crack of
concrete material. So we will have to establish a more suitable fatigue crack model in
order to put forward a more suitable fatigue crack rule.