Results of tests of experimental three-layer reinforced concrete beams on the moment of cracking

Raising of problem. Construction of residential buildings increases. In the construction of such buildings sructures, which are manufactured at the plant, are used. Such constructions are multi - layer wall panels and blocks with the use of lightweight concrete. The experimental studies of these wall panels are described in the works [1-5]. Different types of concrete have their own characteristics. The optimal selection of different concretes strength and density can provide energy efficient dwelling of durable materials. An important indicator of these structures is their low weight, which significantly reduces the load on the bearing structures of the building and delivery costs to the construction site. Purpose. The analysis of results of tests of experimental threelayer reinforced concrete beams with insulating layer of polystyrene concrete on the moment of cracking and the strength of the cross sections, inclined to the longitudinal axis of the element. Conclusion. During the test appearance of often located inclined cracks was observed in the middle layer in the support zone of the samples. This means that more durable outer layers create resistance to development of inclined cracks and increase carrying capacity. Force of inclined cracks appearance for sandwich beam specimens with a middle layer of polystyrene concrete decreased with the increase of the shear span. The coefficient φв4 of the concrete of threelayer beams were lower than the experimental.