RESULTS OF RESEACH OF THREE LAYER REINFORCED CONCRETE BEAMS FOR THE CRACK RESISTANCE

The growth of residential buildings conditioned the wide use of industrial constructions including multi - layer wall panels and blocks made with use of lightweight concrete. The experimental studies of these wall panels are described in the works [2, 3, 6-8]. Knowing features of different kind of concrete, their optimal chose can bring not only immediate benefit but also to provide energy efficient accommodation of durable materials . An important indicator of these structures is their low weight, which significantly reduces not only the load on the bearing structures of the building but also delivery costs to the building site. Purpose. Performing the analysis of results of tests of experimental three-layer 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. The formation of often located inclined cracks in the middle layer in the support zone was observed during the test of samples This means that more durable outer layers create resistance to development of inclined cracks and increase supporting capacity. Force of formation inclined cracks for three-layer beam specimens with a middle layer of polystyrene concrete decreased with the increase of the shear span. The coefficient φв4 of the concrete of three-layer elements was lower than the experimental.