networkgaq.blogg.se

Additional equations must be obtained on the basis of deformations permitted on the knowledge, for example, that a fixed end permits no rotation.

For those beams, there are more unknowns than equations. The equations of equilibrium, however, are not sufficient to determine the reactions of the beams in Figs. They are classified as statically determinate beams for that reason. 5.11, 5.12, and 5.15 may be found from the equations of equilibrium. When a beam extends over several supports, it is called a continuous beam (Fig. The overhangs have a free end, like cantilever, but the supports permit rotation. 5.15 is shown a beam that overhangs both is simple supports. Most support conditions are intermediate between those for a simple beam and those for a fixed-end beam. Some rotation of the beam ends generally is permitted.

In actual practice, a fully fixed end can seldom be obtained. No rotation or vertical movement can occur at either end. It has one end fixed, one end simply supported. If a simple support is placed under the free end of the cantilever, the propped beam in Fig. It has only one support, which restrains it from rotating or moving horizontally or vertically at that end. The load carried by each support is called a reaction. The distance between the supports is called the span. In that case, horizontal restraint at one support is generally sufficient. When the loads have a horizontal component, or when change in length of the beam due to temperature may be important, the supports may also have to prevent horizontal motion. Supports near its ends, which restrain it only against vertical movement. 5.11 is called a simply supported, or simple beam.

Some of the more common methods are shown in Figs. There are many ways in which beams may be supported. Usually, the term beam is applied to members with top continuously connected to bottom throughout their length, and those with top and bottom connected at intervals are called trusses. In a more general sense, they are structural members that external loads tend to bend, or curve. Beams are the horizontal members used to support vertically applied loads across an opening.