In the elastic field, for beams of rectangular cross-section composed of several vertical layers of materials and linked through horizontally arranged mechanical connectors, it is necessary to know the law of horizontal shear stresses (τ_zx) to determine the cross-section and spacing of such connectors. Currently, there are only two methods to solve the problem without taking into account the finite element method: the Empirical Method, without a theoretical basis, and the Rational Method, based on the NDS 2005, which does not take into account the horizontal shear stresses (τ_zx). According to numerous authors, both methods lead to conservative results in the spacing of mechanical connectors. A novel method, based on a simplified equation, describes the law of horizontal shear stresses (τ_zx) and solves the problem simply and with acceptable accuracy. Two equations catalogued as exact solutions to the stress problem that had never been used for this purpose before have been applied to verify the results. In addition, to validate the new elastic method, information from four-point bending tests performed on specimens of wood beams reinforced with steel plates linked with different connection means, such as bolts, screws, nails and combinations, was used to validate the new elastic method. Fifty-four states were analyzed for flitch beams, varying the magnitude of a uniform load and the span for a simply supported beam. The mechanical connector was adopted as ½ inch for all cases. The Rational and Elastic methods used the NDS 2005 specifications to consider humidity and temperature. The results showed that the spacing of the mechanical connectors according to the Rational Method was conservative since it required a design load perpendicular to the grain. In addition, the New Method made it possible to obtain a larger spacing between mechanical connectors, reducing the number of bolts without affecting the resistance to horizontal shear stresses of the beam. The New Method demonstrated great practical utility and potential to be incorporated into the Allowable Stress Design method of the NDS 2005.

horizontal shear stress, composite beam, flitch-beam, elastic