Abstract:
There are increasing concern over the impact of thermal and shrinkage effect on the
structural behaviour of concrete and specially, its influence on the serviceability
prediction of cracking and deformation of concrete structures. The effect is considered
significant in tropical and arid environmental conditions where extreme heat, wind and
relative humidity conditions can set up challenging shrinkage and thermal conditions.
As concrete strength properties build up gradually over time, effect of extreme
environmental conditions expected to be significant in concrete than any other
composite materials. However, none of the existing codes consider thermal and
shrinkage behaviour for serviceability limit state performance. As a result most of the
structures we live especially in the tropical climates run the risk of being deformed and
cracked differently to what is predicted by code formulas. Accounting the concrete
contribution, in tension, is the key for accurate modelling of serviceability performance
of concrete structures and the tension stiffening effect is widely adopted in modelling
tension behaviour of concrete. This paper looks at the possibilities of capturing the
influence of thermal and shrinkage effect on the tension stiffening behaviour of concrete
as a means of improving serviceability performance of reinforced concrete subjected to
harsh environmental conditions. In order to simulate thermal and shrinkage effect, 42
Nos. of test specimens subjected to different shrinkage regimes varying; +2200
pe(expansion) -500 pe(shrinking) were studied. Results confirm that effect of shrinkage
and expansion conditions are consistently reflected on the tension stiffening behaviour
of concrete. From the results it is clear that the tension stiffening is invaluable means to
incorporating thermal and shrinkage effect on serviceability prediction of reinforced
concrete. However, the current method for accounting shrinkage base on free
shrinkage/expansion is found over estimate expansion and shrinkage effect of simulated
test specimens. Based on test results a comprehensive method to account tension
stiffening effect of concrete found based on interaction of concrete and reinforcement
and free shrinkage/expansion measurements is currently underway.
