USE OF COMPOSITE TIMBER-CONCRETE STRUCTURE WHILE TIMBER FLOOR RECONSTRUCTION IN EXISTING BUILDINGS

The paper is focused on the issue of timber ceiling reconstruction in existing buildings. The condition of timber beams as a part of the structure is mostly insufficient based just on a visual assessment of mechanical properties of the structural members. It is necessary to determine the strength and modulus of elasticity of timber as accurately as possible in order to preserve this kind of structures. Many non-destructive methods are available to use, especially those operating with ultrasound waves and stress waves because they are absolutely non-invasive. Velocity of wave propagation depends on both quality of timber (its density) and presence of defects (knots, cracks). It is also possible to use less invasive methods, e.g. resistance drilling or pushing of a pin into wood. In a case that higher resistance and stiffness of the ceiling are needed, it could be reinforced by slim concrete desk that is coupled with timber beams by various connectors. Also the impact sound insulation and fire resistance is improved by this way of reinforcement. The type of composite structure fulfils the goals of sustainable development because it uses ecological and recyclable materials and minimizes the waste while construction.