The article analyzes the stress-strain state arising in the middle of a wooden element of a double-sectioned nailed connection on metal plates. The mortise of the wooden element is reinforced with a pressed-in fiberglass bushing. Wood cracks development has been analyzed from the point of fracture mechanics (at different angles between the direction of the acting force and the direction of the wood fibers). The values of stress intensity factors for pine wood have been determined. The graphic dependencies between the stress intensity factors for various crack opening models have been developed. There are recommendations for the calculation of nailed connection modified with a pressed-in fiberglass bushing by the methods of fracture mechanics.