A bolt is a cylindrical fastener that consists of a head shaped to facilitate turning with a wrench and a threaded shank of smaller diameter (Fig. 11.89). To fasten two or more building components together, the bolt is placed in a prepared hole that extends through the components and is slightly larger than the shank. A nut, usually of a type shown in Fig. 11.89, is threaded onto the shank and tightened to draw the parts together.
Bolts used in connections subjected to heavy loads, such as connections in structural framing, are described in Secs. 7 through 10.
A washer often is placed under the head of a bolt and under a nut. A washer can accomplish several purposes: (1) Distribute the compressive force exerted by a tensioned bolt over a wider area than that of the contact surface of the bolt head or nut. (2) Prevent the head or nut from turning and thus prevent the components of a connection from separating. (3) Serve as a seal against moisture penetration.
(4) Insulate incompatible materials from each other. (5) Prevent the head or nut from being pulled into the hole when the hole has about the same diameter as the head or nut.
ACOUSTICS
Acoustics, derived from a Greek word meaning to hear, refers to generation, detection, transmission, absorption, and control of sounds. Acoustics is part science and part art, but modern studies are stripping away much of its mystique. As a result, it is possible to plan and predict the acoustics of finished spaces with reasonable certainty.
