BEHAVIOR OF COMBINED REINFORCED GLUED-LAMINATED WOODEN BEAMS WITH A PRE-STRESSED COMPOSITE REINFORCEMENT

Abstract

The performed studies confirm the good results of the use of composite materials based on synthetic fibers for strengthen wooden structures. The development of armoplastics and availability of synthetic fibers have made composite reinforcement an effective alternative as reinforcement for building constructions. Based on previous studies of wooden beams with a combined reinforcement, which contain steel reinforcement in the compressed zone, and composite reinforcement in the stretched zone, an attempt was made to further improve the performance of these beams by pre-stressing the composite reinforcement in the stretched zone. At the same time, the pre-stressing process itself is performed in several simple stages. As first step, a beam with steel reinforcement glued into the grooves of compressed zone was installed on supports in an inverted to working position. At this stage of research, it was decided to load the beam to the limit deflection value, which is normalized according to the current state construction standards. In this position, the tape was fixed with an adhesive mixture. During this, the loading mechanism allowed placing and fixing the tape on top of the beam along its entire length. After the glue solidifies completely, construction was unloaded and turned back into the working position, during which it was further tested until it lost its bearing capacity. During unloading, the tape is included in the work and does not allow the beam to return to its original position and thus receives pre-stress and some bending when the load is completely removed. In this way, we get a wooden beam with pre-stressed reinforcement in the form of a strip in the stretched zone. The purpose of this research was to establish the stiffness, load-bearing capacity, and deformation characteristics of a glued laminated wooden beam with pre-stressed composite tape reinforcement. As a result, diagrams of wood fibers, metal and composite reinforcement deformation during pre-stressing and during determination of the failure moment are presented.