Effective moment of inertia of reinforced medium strength concrete beams

Abstract EN

The effects of the loading type, and consequently the shape of the bending moment diagram, and reinforcement ratio on the effective moment of inertia needs to be studied for the case of medium strength reinforced concrete beams so that accurate estimates of the deflections are obtained.

This paper deals with the short-term deflection of reinforced concrete beams made of medium strength concrete.

Experimental work was carried out to investigate the effects of compression reinforcement ratio, tensile reinforcement ratio, yield strength of reinforcement, span / depth ratio and loading type on the short-term deflection.

The ratio of compressive reinforcement to tensile reinforcement was found not to affect the short term deflection except before failure.

It was recorded that the maximum deflection of beams with high reinforcement ratio is lower than that of similar beams with low reinforcement ratio.

The grade of the tensile reinforcement generally had a small effect on the short term deflection.

The increase in the span / depth ratio was associated with increase in the deflection.

It was found that for the same level of total load, the deflection becomes smaller as the number of concentrated loads increases.

The ACI Code [1] equation for the effective moment of inertia was modified along with another generalized equation for the effective moment of inertia to account for the effects of loading type and reinforcement ratio in the case of medium strength concrete.