The noticeable brittleness of lightweight aggregate concrete limits its vast application. Using steel fibers will improve the disadvantage contrived in this type of concrete. Steel fiber increases the ductility and prevention of brittle failure of the concrete. In this paper, the influence of steel fiber on the ability of lightweight concrete to absorb energy during the response in compression has been investigated. For this purpose, steel fiber ratios of 0, 0.5, 1 and 1.5 percent by the volume of the sample were used. The sample with 0.0 percent steel fiber ratio was used as a reference to be compared with other samples. Two types of steel fibers, including hooked-end and crimped, were used. All of the fine and coarse aggregates were lightweight. The results show that there is no noticeable improvement in the pre-peak energy absorption by adding steel fiber to the composite. The increase of steel fiber ratio changes the shape of the descending branch of the stress-strain curve in compression and increases the compressive toughness of lightweight aggregate concrete. Furthermore, based on the experimental data, the relationship between compressive strength and steel fiber volume fraction was derived.
