TIMBER CONNECTORS

Various types of metal connectors designed to connect individual pieces of wood are called timber connectors and consist of metal rings, plates, and discs embedded in the surfaces of the 2 members. The embedment prevents sliding, thereby stress is transmitted from member to member. Joints with these connectors are much more effective that simple bolted joints. Metal connectors have greatly extended the possibilities of timber construction for trusses and aches.

Many kind of joints have been devised, but only a few are used; split ring, toothed ring, shear plates, claw plates. Many require bolts passing through the centers of the connectors to hold the timbers in contact; with others, the bolts force the connectors INTO the timbers, may require some pre-cut groove preparation. In either case, the stress is transmitted between the members by shear in the bolt.

Each type of connector is available in several sizes and capabilities. The number of connectors required in any joint is determined by the stresses in the members and the properties of the wood.

Sheet metal connectors of various types are manufactured to replace the usually NAILED JOINT in wood framing, designed for driving into pre-punched holes. Some have toothed nails and are pressed into an assembled wood truss to handle stresses of erection. The joist hanger is held together by length nails. Some are nailed into the side of the supporting wood, others hang from the supporting beam. Framing bases may support posts anchor bolted in supporting concrete.

Sheet metal tie downs resist seismic and wind loads by stabilizing a structure against lateral and uplifting forces and embedded into concrete.

WIND PRESSURES

The wind pressures, WIND LOAD, on buildings vary with the location and the height above ground surface. Winds are assumed to act in any horizontal direction in spite of the prevailing wind. There are positive pressures on the windward side of the building and negative pressures, or partial vacuums, on the leeward side. Design pressures are based on the TOTAL RESULTANT PRESSURE, sum of these pressures. Building codes include factors for adjusting horizontal wind loads to sloping roofs and for the uplift pressures on roofs caused by wind loads. Wind pressures tend to OVERTURN buildings as a whole and parts of buildings above any elevation.