# Topic: Uncategorized

## Question 24

The continuous  two span footbridge has a uniform EI  (100,000kNm^2) and carries a total load of 12kN/m over its entire length Following a recent flood both the left hand (A) and inner  support (B) sink by 25mm.  Using  any method determine the moment  over  support B.

HINT 1: Think about the relative  movement of each support.

## Question 23

3-D Bending moment and torsion diagrams are never easy, so practice makes perfect.

Having sketched the bending moment and torsion diagram for the structure above determine the moments and torsion acting on the base of the structure

Submit your answers here <CLICK> remember to state which axis the moments are acting about!

## A quick question to make you think

You are sitting in a rowing boat in a small pond, you have an unopened  can of baked beans with you. If you throw the  can (which sinks)  into the pond what happens to the level of the water in the pond

www.amsterdamology.com

This question was  plagiarized from Prof Peter Goodhew, thanks Mark

SOLUTION:  The  water level goes down!  In the boat the mass of the can displaces its own  mass of  water (which is a lot of  water as the beans are  dense) when the  can of beans  sinks to the  bottom of the pond they  only  displace  their own  volume which is   small ( as they  are  dense) hence the water  level goes  down! Don't worry  a  beautiful illustration of the solution is coming  soon.

## Structures 2 Students: read this!

Dear All

I will be teaching  you AR20389 Structures 2 from week  4- 11. I will cover several methods of  structural  analysis that  you  need to use in later  courses  in order to  determine  moments and  forces developed in a  structure  due to the  actions put upon it.

All of my notes are available through Moodle,  this blog is a little added extra providing  you with a weekly question based on the work  covered in class its not  compulsory but it  will certainly  help you understand the subject in time for the exam in Jan 2015!

See you in class on tuesday.

mark

## Question 21

For the statically determinate truss shown above determine the displacement at the point E (in mm).

Assume all members have the same EA= 10^5 kN and L=4m

You can solve this simple problem using virtual work. Firstly you must determine the forces in the truss (its determinate so just use statics once you have the reactions). Then find the forces in the truss  caused by a unit load placed at the posit where ewe want to know the deflection (E).

Multiple the two set of forces together for each member (L/EA) and sum! You should get a displacement at E of 2.1mm - SOLUTION

# For the statically determinate truss shown above determine the displacement at the point E (in mm).Assume all members have the same EA.You can solve this simple problem using virtual work. Firstly you must determine the forces in the truss (its determinate so just use statics once you have the reactions). Then find the forces in the truss  caused by a unit load placed at the posit where ewe want to know the deflection (E).Multiple the two set of forces together for each member (L/EA) and sum!

## Start of teaching 2013

Hi everyone,  its that  time of  year  again.   I will be   uploading  weekly  questions  for you all  to attempt.  These are not  assessed  but  they  will prepare you  for the  exam  in January.   If you are   stuck on a  certain question have look through  the  past 21  questions and the solutions !

Each  week  there  will be a  £5 prize   for the randomly selected  correct answer! This is open to anyone not just  Bath students.

Mark

## Revision questions coming up soon.

To help those  students who are  resisting  Structures 1A and Structures 2 in August/Sept I will be  uploading a question for each  course on a regular basis .

## Christmas and New year holiday

Happy new year to everyone.  The weekly blog questions will start again ready for Semester 2.  In the mean time I hope you are all outside enjoying the snow. Why not try to build an ice sculpture.

For more inspiring ice structures check out this link to Hienz Isler's work.

## Question 9

The top and bottom chord of the long truss shown below are CHS sections, and each has I = 31x106 mm4 and A = 6300 mm2. Take Esteel = 200 GPa. All members have the same length of 1m.  Determine the approximate deflection at  mid-span.
The correct answer is 26mm. The truss can be approximated to a beam. The second moment of Area of the 'beam' can be determined using parallel axis theorem allowing standard beam deflection equations applied for an approximate answer.

## Question 4

Something a bit harder this week to keep you all on your toes!

What diameter of steel cable is required such that the mid-span deflection of the timber beam is only 50% of the mid-span deflection of the beam without the cable?

Click the link below for the solution-->
MPS-6E4-02_4201_001