Abstract: An adaptive washer assembly comprises a washer body which provides an inner flat surface which is abuttable against a base structure such as a timber bridge member to which a conventional bolt and the attached washer body will be attached in for example, timber construction. The washer body is provided with an outer curved surface, the outer surface and the inner face intersecting to form a periheral edge portion to said washer body. In the preferred embodiment, the washer body is thicker at the center portion thereof, and a substantially cylindrical bore is provided through the washer body at the thickened central portion thereof. The central bore can be provided with a diameter substantially equal to or larger than the diameter of the shaft portion of the bolt to be attached through the washer bore to the base structure which could be, for example, a wooden timber member.