When one designates framework after the gaps, which are called technical or Gefach, a construction, in which only staffs on pressure or course are stressed and not on bend.

After the expansion we differentiate between an even and a spatial framework.

For wing units each kind is used by elements from wood, prestressed concrete or steel (e.g. sheet metals, pipe, structural steels and flat steel bars) for it.

With building constructions, which of a framework consist, very large spans can be bridged and large heights be achieved, since they have a very small weight in relation to their load-carrying capacity.

Apply their to framework:

• in the building of buildings - in particular as half timbered house and in the hall construction; see also above ground construction and foundation engineering.
• in the bridge construction.
• in crane and building of masts.
• in the scaffold construction
• in mechanical engineering
• in the meeting technology.

Framework in the mechanics

In the mechanics are framework wing units, which exist out articulated connected staffs. The investigation of the stability of specialized works is a subsection of the strength theory.

Ideal one framework

Ideal a framework is given, if in the joints, which are called also knots, no moments will transfer. They are to be regarded thus as frictionless.

Forces are transferred in the ideal framework only along the staff direction; Loads attack only in the knots.

These acceptance are justified in the fact that in the reality staffs are mostly clearly longer than broad. Errors result with the computation also from the fact that the staffs have a dead weight and this does not evenly only attack as load in the knots, where one accepts her for the computation.

The condition

2k = s + f

with

• k: Number of knots
• s: Number of staffs
• f: Number which can be determined of bearing forces (binding),

for an even framework (two-dimensional) is a necessary, but no sufficient condition for the static certainty of a framework. Statically certainly is a framework exactly if all arising in it can be computed. This condition is fulfilled, if it concerns a simple framework: With this on the basis of a staff in each case two further staffs and a knot are added.

In the spatial, three-dimensional case the condition reads

3k = s + f.

For the computation of the in the ideal framework there are different computing procedures:

Junction procedure

With the junction procedure the can be determined by setting up a set of equations. For each knot the two balance conditions - the sum of the forces in x and in y-direction must be zero - are noted. Thus results a set of equations, which can be solved with static certainty of the framework.

In the three-dimensional case in each case three equations are set up.

With simple specialized works it is sufficient to compute the bearing forces with the solidification principle and itself then along the knots "durchzuhangeln".

Ritter Schnittverfahren

The Ritter Schnittverfahren serves for the direct computation of in the framework. Thus always three can be computed in two-dimensional or six in the three-dimensional framework, without knowing the others or to compute before have.

Staff exchange procedure

The Hennberg staff exchange procedure is used with not simple specialized works.

Cremonaplan

see Cremonaplan

Not ideal framework

Material ones framework are subjected to the occurrence of bends except the friction also. The deformation and stress calculations are accomplished nowadays generally with the finite element method.

Related links

• Truss bridges

Articles in category "Framework"

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