Truss: maximum load

Error

There was an error loading the page.

Contributors

William Haynes

Feedback

From users who are members of Engineering Statics :

William Haynes

said

Ready to use

5 years, 4 months ago

History

○

William Haynes 5 years, 4 months ago

Gave some feedback: Ready to use

○

William Haynes 5 years, 4 months ago

Gave some feedback: Ready to use

○

William Haynes 5 years, 4 months ago

Published this.

○

William Haynes 5 years, 4 months ago

Created this.

There is only one version of this question that you have access to.

There is one other version that you do not have access to.

Question statement

Determine the maximum mass $m$ which may be applied to the truss without exceeding {tmax} kN in tension or {cmax} kN in compression in any member.

Give any introductory information the student needs.

			Name	Type	Generated Value

cmax	integer	80
tmax	integer	105
max1	number	5770
max2	number	10700
answer	quantity	quantity(5770, "kg")

Automatically regenerate variables?

Name

Data type

Value

xxxxxxxxxx
 
random(50..100#5)
​

JME function reference

Description

Describe what this variable represents, and list any assumptions made about its value.

Can an exam override the value of this variable?

Generated value: `integer`

→ Used by:

max1
tmax

Statement
Advice

Parts

Maximum Load Gap-fill
1. Gap Max Load Engineering Accuracy with units
  Add

Gap-fill

Ask the student a question, and give any hints about how they should answer this part.

$m_{max} = $ Max Load

Advice

Note that members $AE$, $DF$ and $AF$ are zero force members, that $AD = DC$ and $BE = EF = FC$, and that angle $\beta = 45°$

Let $T$ be the weight of the load which has a mass $m$. $T = m g$.

Joint C

Draw a FBD of joint $C$. The tensile forces on the pulley are equivalent to forces acting on the pin $C$.

The two tension forces acting on joint $C$ resolve to a single force $T' = \sqrt{2} T$ acting down and to the left at a 45° angle. Redraw the FBD to this.

By inspection you can conclude:

$DC = 0$

$FC = T'$ (compression).

Joint B

Draw a free body diagram of joint $B$.

From $\Sigma F_y = 0 $ you conclude that

$AB = T' \sin{45°} = T$ (tension).

Apply Design Conditions

Since we have two design constraints, you will need to check them both.

For Compression

$FC = T' = \sqrt{2} T=\sqrt{2} m g $

$FC < \var{cmax}$ kN

$\sqrt{2} m g < \var{cmax * 1000} $ N

$m < \frac{\var{1000 cmax}}{\sqrt{2} g} = \var{max1}$ kg

For Tension

$AB = T = m g $

$AB < \var{tmax}$ kN

$ m g < \var{1000 tmax} $ N

$m < \frac{\var{1000 tmax}}{g} = \var{max2}$ kg

Solution

The maximum mass will be the smaller of these two values.

$m_{max} = \var{answer}$

Give a worked solution to the whole question.

URL

Text alternative
URL

Text alternative
URL

Text alternative
URL

Text alternative
URL

Text alternative

Use this tab to check that this question works as expected.

There was an error which means the tests can't run:

Part	Test	Passed?
Gap-fill
Gap-fill		Hasn't run yet
Engineering Accuracy with units
Engineering Accuracy with units		Hasn't run yet

This question is used in the following exams:

My First Exam by Sergio Blanco in Sergio's workspace.
Chapter 06 Exercises by Michael Proudman in Engineering Statics.
29. Special Loading Conditions by Michael Proudman in Engineering Statics.
29. Special Loading Conditions by William Haynes in Engineering Statics.
Chapter 6 Exercises by William Haynes in Engineering Statics.

Loading...

Error

Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

William Haynes 5 years, 4 months ago

William Haynes 5 years, 4 months ago

William Haynes 5 years, 4 months ago

William Haynes 5 years, 4 months ago

Error in variable testing condition

Error

Warning

Generated value: `integer`

Parts

Gap-fill

Loading...

Error

Truss: maximum load

Metadata

Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

Contributors

Feedback

History

Comment

Checkpoint description

William Haynes 5 years, 4 months ago

William Haynes 5 years, 4 months ago

William Haynes 5 years, 4 months ago

William Haynes 5 years, 4 months ago

Error in variable testing condition

Error

Warning

Generated value: integer

Parts

Gap-fill

Generated value: `integer`