The object of research is a wood (arbolit) concrete for bearing span structures. The purpose of this work is to analyze the empirical structural, mechanical and deformative properties of constructive arbolit standard samples and reinforced beams in comparison with results of design model calculation. Method. The experimental and computational methods were used in the research. The following necessary parameters for the exploiting load calculation model were tested by the standard methods: compressive and tensile strength, compressive and tensile modulus of elasticity (MoE) of arbolit with D600-D1300 density, B1.5-B5 class. The following significant in design mechanical and deformative properties of reinforced arbolit model beams were tested by 4-point bending test: reinforcement’s stress, beams’ bending moment and deflection under bending load. Results. The experimental data have demonstrated the changing of the tensile stress in beams’ reinforcement under bending load depending on the arbolit’s MoE. The model of this dependence was determined. The application of this model has provided high accuracy of arbolit reinforced beams’ bending moment calculation.