Sabah Shawkat Cabinet of Structural Engineering 2017 3.1-1 Continuous beams Every building, whether it is large or small, must have a structural system capable of carrying all kinds of loads - vertical, horizontal, temperature, etc. In principle, the entire resisting system of the building should be equally active under all types of loading. In other words, the structure resisting horizontal loads should be able to resist vertical loads as well, and many individual elements should be common to both types of systems. A beam may be determinate or indeterminate Statically determinate beams are those beams in which the reactions of the supports may be determined by the use of the equations of static equilibrium. If the number of reactions exerted upon a beam exceeds the number of equations in static equilibrium, the beam is said to be statically indeterminate. In order to solve the reactions of the beam, the static equations must be supplemented by equations based upon the elastic deformations of the beam. The degree of indeterminacy is taken as the difference between the number of reactions to the number of equations in static equilibrium that can be applied. The degree of indeterminacy is taken as the difference between the number of reactions to the number of equations in static equilibrium that can be applied. Continuous beams are those that rest over three or more supports, thereby having one or more redundant support reactions. According to figure 3.1.1-1, we determine the reactions and sketch the shear diagrams. Then we compute the values of maximum vertical shear V and maximum positive bending moment M. Sufficient reinforcement should be provided at all sections to resist the envelope of the acting tensile force, including the effect of inclined cracks in webs and flanges. The area of steel provided over supports with little or no end fixity assumed in design, should be at least 25% of the area of steel provided in the span. Where a beam is supported by a beam instead of a wall or column, reinforcement should be provided and designed to resist the mutual reaction. This reinforcement is in addition to that required for other reasons. This rule also applies to a slab not supported at the top of a beam.
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3.1-1 Continuous beams - VŠVU · 2017-12-12 · symmetrical T-beams shall not exceed 0.40 of the span length of a simply supported beam or 0.25 of the span length of a continuous
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Sabah Shawkat Cabinet of Structural Engineering 2017
3.1-1 Continuous beams
Every building, whether it is large or small, must have a structural system capable of
carrying all kinds of loads - vertical, horizontal, temperature, etc. In principle, the entire
resisting system of the building should be equally active under all types of loading. In other
words, the structure resisting horizontal loads should be able to resist vertical loads as well, and
many individual elements should be common to both types of systems.
A beam may be determinate or indeterminate
Statically determinate beams are those beams in which the reactions of the supports
may be determined by the use of the equations of static equilibrium.
If the number of reactions exerted upon a beam exceeds the number of equations in static
equilibrium, the beam is said to be statically indeterminate. In order to solve the reactions of
the beam, the static equations must be supplemented by equations based upon the elastic
deformations of the beam.
The degree of indeterminacy is taken as the difference between the number of reactions to the
number of equations in static equilibrium that can be applied.
The degree of indeterminacy is taken as the difference between the number of reactions
to the number of equations in static equilibrium that can be applied.
Continuous beams are those that rest over three or more supports, thereby having one
or more redundant support reactions. According to figure 3.1.1-1, we determine the reactions
and sketch the shear diagrams. Then we compute the values of maximum vertical shear V and
maximum positive bending moment M.
Sufficient reinforcement should be provided at all sections to resist the envelope of the
acting tensile force, including the effect of inclined cracks in webs and flanges.
The area of steel provided over supports with little or no end fixity assumed in design, should
be at least 25% of the area of steel provided in the span.
Where a beam is supported by a beam instead of a wall or column, reinforcement
should be provided and designed to resist the mutual reaction. This reinforcement is in
addition to that required for other reasons. This rule also applies to a slab not supported at the
top of a beam.
Sabah Shawkat Cabinet of Structural Engineering 2017
Figure 3.1.1-1
A continuous beam carries a uniform load over two equal spans as shown in figure 3.1.1-1.
A beam carrying the loads shown in figure 3.1.1-2 is composed of four spans. It is supported
by five vertical reactions. We determine the values of the bending moments over supports as
follows.
Figure 3.1.1-2
Sabah Shawkat Cabinet of Structural Engineering 2017
A uniform load is carried over three equal spans as shown in figure 3.1.1-3.
Figure 3.1.1-3: equal spans of continuous beam
A uniform load is carried over the more than 3 equal spans with different shapes of cross-
section as shown in figure 3.1.1-4, figure 3.1.1-5.
Figure 3.1.1-4: four spans continuous beam
Figure 3.1.1-5
Sabah Shawkat Cabinet of Structural Engineering 2017