Understanding Reaction Forces in Pure Bending for Structural Resistance

[chetzread]

Homework Statement

to resist the bending, there must be reaction force(blue) act against the applied force(red), the reaction force that resist bending is the longitidunal normal force , right?
why the author stated it as longitidunal shear force, is it wrong?

Homework Equations

The Attempt at a Solution

longitidunal shear force is the green colour arrow, right? how could the force resist the bending?

 

[haruspex]

Homework Statement

to resist the bending, there must be reaction force(blue) act against the applied force(red), the reaction force that resist bending is the longitidunal normal force , right?
why the author stated it as longitidunal shear force, is it wrong?

Homework Equations

The Attempt at a Solution

longitidunal shear force is the green colour arrow, right? how could the force resist the bending?

Your own diagram is inaccurate in several ways.
The set-up is a beam fixed at one end, with a transverse load applied at the other, not in the middle. There is no source of a force to provide the support you show in blue.
You do not show any forces where the beam is fixed. These forces will consist of a vertically upward force to balance the load, plus a torque to balance the moment of the load. This torque is transmitted in the form of the longitudinal shear forces.