Determine the force in members E H and G I of the truss shown. (Hint: Use section aa.)

Name: Problem 63, Chapter 6: Vector Mechanics for Engineers: Statics and Dynamics
Uploaded: 2020-07-06T21:46:39-08:00
Duration: 3 min 21 s
Channel: Eric Mockensturm
Description: Determine the force in members E H and G I of the truss shown. (Hint: Use section aa.)

step 1 In problem 63 and 64 we're given another truss that looks like this. And we have some external l

Determine the force in members E H and G I of the truss...

Key Concepts

Method of Sections

The method of sections is a structural analysis technique used to determine the forces in specific members of a truss. By conceptualizing a ‘cut’ through the structure, the method allows for the isolation of a section of the truss and the application of equilibrium equations to that section to solve for unknown internal forces.

Equilibrium Equations

Equilibrium equations, which state that the sum of forces and moments acting on a static system must be zero, are fundamental in truss analysis. These equations ensure that all components are in balance and allow for the systematic solving of unknown forces within the structure.

Free-Body Diagrams

Free-body diagrams are critical tools in engineering analysis that simplify complex structures by isolating a section and representing all forces acting on it. They provide a clear visualization of the forces and moments, facilitating the proper application of the method of sections and equilibrium equations.

Internal Member Forces

Internal member forces refer to the forces that develop within the individual members of a truss as it responds to external loads. Understanding these forces—whether tensile or compressive—is essential for assessing the structural integrity and performance of the truss.

Transcript

00:01 In problem 63 and 64 we're given another truss that looks like this.

00:10 And we have some external loads acting on it and some reaction forces here.

00:17 And we have a pin joint here but because there's no horizontal external loads acting, the horizontal component of that reaction will be zero.

00:27 These won't be equal because these loads are off.

00:30 Set but we can do a force and moment balance and figure out what these two loads are so in the y direction the force balance is this these things both all have 12 kips and then we can use the distances that we were given each one of these sections is 15 feet and make do our moment balance about point a here and then we solve these two equations and two unknowns and we get that this reaction is 24 kips and this one is 12 kips.

01:06 Now what we're asked to do is find first we want to do h, let's see here, eh and gi.

01:20 So eh is this guy and ei is this guy.

01:26 So we're going to take a cut like this just like we did in the previous problem.

01:30 And again we'll be able to find the loads in these members but we won't be able to find the loads the absolute loads in these members but we'll be able to find the difference so i would make that cut and we expose those these loads over here feh fgi and fef and fgf and we can some forces and moments in the this time i'm not going to use vectors because everything is either has an is in either the x or the y direction.

02:06 So in the horizontal direction, we know that these two things have to sum to zero, so they have to be equal to opposite.

02:13 In the vertical direction, we get that the difference of these two must equal faa...

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