Name: beam shear force diagram
Uploaded: 2025-05-22T09:06:03.000Z
Duration: 1 min 27 s
Channel: JoVE

Le diagramme de cisaillement est une représentation graphique de la distribution des forces de cisaillement le long de la longueur de la poutre.
Considérons une poutre AB soutenue à deux extrémités et soumise à des charges perpendiculaires. Construisez son diagramme de cisaillement.
Dessinez le schéma du corps libre de la poutre. À l’aide des équations d’équilibre de la force et du moment, les forces de réaction à chaque support peuvent être calculées.
Appliquez la méthode de section à la poutre.
Ensuite, considérez une distance arbitraire du point A dans la région AP. Dessinez un schéma de corps libre de la section. Dans la condition d’équilibre, la force de cisaillement dans la section est égale à la force de réaction au niveau du support.
De même, considérons un point arbitraire dans la région PQ. En dessinant le schéma du corps libre et en utilisant l’équation d’équilibre, le cisaillement dans la section peut être déterminé.
Enfin, le point arbitraire est considéré dans la section QB. En dessinant le diagramme du corps libre et en rappelant l'équation d'équilibre, il est possible de déterminer le cisaillement de la section, qui reste constant jusqu'à la fin de la poutre et finit par tomber à zéro pour maintenir l'équilibre.

<ol>
	<li>Hibbeler, R.C. (2016). Génie mécanique \u2012 Statique et dynamique. Hoboken, New Jersey : Pearson Prentice Hall. p. 361.</li>
	<li>Bière, F.P. ; Johnston, E.R. ; Mazurek, D.F ; Cromwell, P.J. et Self, B.P. (2019). Mécanique vectorielle pour les ingénieurs \u2012 Statique et dynamique. New York : McGraw-Hill. Pages 381.</li>
</ol>

diagramme des forces tranchantes

Dans l'étude de la mécanique des poutres, les diagrammes des forces tranchantes jouent un rôle crucial dans la compréhension de la répartition des forces tranchantes le long de la poutre. Considérons une poutre AB qui est soutenue aux deux extrémités et soumise à des charges perpendiculaires. Tout d'abord, un diagramme des forces extérieures et des réactions internes agissant sur la poutre est dessiné. On peut calculer les forces de réaction à chaque support en utilisant les équations d'équilibre des forces et des moments. La composante verticale des forces de réaction aux points A et B pour la poutre donnée est de 24 kN et 18 kN, respectivement.

<img alt="Figure 1" src="/files/ftp_upload/14301/14301_PT_Figure_1v2.svg" style="text-align: center; height: 300px;"> 

Un diagramme des forces tranchantes est une représentation graphique qui illustre la répartition des forces tranchantes le long de la poutre. Pour créer ce diagramme, la méthode des sections est appliquée à la poutre. Ensuite, une distance arbitraire à partir du point A à l'intérieur de la région AP est considérée. Un diagramme des forces de cette section est dessiné pour analyser les forces qui y agissent. Sous la condition d'équilibre, la force tranchante dans la section est égale à la force de réaction au support, qui est V1 = 24 kN. De même, un point arbitraire à l'intérieur de la région PQ est considéré. En dessinant un diagramme des forces de cette section et en utilisant l'équation d'équilibre, la force tranchante, V2, peut être déterminée. <img alt="Equation 1" src="/files/ftp_upload/14301/14301_Equation_1v2.svg" style="text-align: center; height: 13px;"> Finalement, un point arbitraire est considéré à l'intérieur de la section QB. Un diagramme des forces est dessiné pour cette section, et l'équation d'équilibre est rappelée pour déterminer la force tranchante, V3, dans la section. <img alt="Equation 2" src="/files/ftp_upload/14301/14301_Equation_2v2.svg" style="text-align: center; height: 13px;"> Cette force tranchante reste constante jusqu'à la fin de la poutre, allant finalement à zéro pour maintenir l'équilibre.

Diagramme des forces tranchantes

Dans l’étude de la mécanique des poutres, les diagrammes de cisaillement jouent un rôle crucial dans la compréhension de la distribution des forces de cisaillement sur la longueur d’une poutre. Considérer...

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Shear Diagram

beam shear force diagram

Beam shear force diagrams show how shear changes along the length of a supported beam. In beam mechanics, they help students track the internal shear force caused by perpendicular loads. The beam AB in this example is supported at both ends, so the first step is to draw a free-body diagram that shows the external forces and internal reactions.

The reaction forces at supports A and B are found with equilibrium equations for force and moment. For the beam shown, the vertical reaction at A is 24 kN and the vertical reaction at B is 18 kN. These values become the starting point for building the shear diagram.

To form the shear diagram, the method of sections is used. A point is chosen at an arbitrary distance from A in the region AP, and a free-body diagram of that section is drawn. From equilibrium, the shear force in that section is V1 = 24 kN.

The same process is repeated in the region PQ. An arbitrary point is selected, the section is isolated, and the equilibrium equation is applied to find V2. A third section is then taken in the region QB. Its free-body diagram gives V3, which stays constant until the end of the beam and then goes to zero so the beam remains in equilibrium.

Beam Shear Force Diagram

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shear diagram

Beam shear force diagrams show how shear changes along the length of a supported beam. In beam mechanics, they help students track the internal shear force caused by perpendicular loads. The beam AB in this example is supported at both ends, so the first step is to draw a free-body diagram that shows the external forces and internal reactions. The reaction forces at supports A and B are found with equilibrium equations for force and moment. For the beam shown, the vertical reaction at A is 24...

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key terms and concepts

Learn how to build a beam shear force diagram using free-body diagrams, reaction forces, and the method of sections for a supported beam.

Beam Shear Force Diagram | JoVE K12

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Beam Shear Force Diagram

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