SCHOOL OF CIVIL ENGINEERING



CIVL2201 STRUCTURAL MECHANICS 2021: ASSIGNMENT 2

SUBMISSION REQUIREMENTS
 Assignment is due electronically 23:59 Thursday 13 May 2021 (Sydney time)
 It is intended that you attempt the questions with hand calculations and a hand drawing (with a ruler) on
a piece of paper, and you submit a scanned version of your pages. If you use a tablet and stylus, you
may submit an "electronically generated hand drawing" converted into Word or PDF. You can either:
o Scan pages individually and insert as images into Microsoft Word. The scanned images should
be as close to A4 size as possible. You can either submit the Word docx file, or convert to PDF.
o Scan directly into a multipage PDF file. The hard copy of the assignment should include your
working and answers for questions 1 & 2, plus a printout of your answer to question 3. Please
submit stapled sheets without any manila folders or slip in sheet protectors etc, and include the
assignment cover sheet.
 Q3 is to be typewritten but you should have a scanned hand-sketch of your supporting diagram.
ACADEMIC HONESTY
 Students are always encouraged to help each other with studying, however copying solutions from
anyone, where you have little or no academic input is not acceptable.
 Any form of copying and pasting electronic data for question 3 is not acceptable.


1) A timber column will be strengthened by wrapping with CFRP (carbon fibre reinforced polymer) where the
two materials act compositely.

 The timber column is square with cross sectional dimensions D x D.
 The CRFP wrapping provides additional thickness t around the perimeter
 Material properties are Etimber = 12 GPa ECRFP = 80 GPa, and both materials experience linearly
elastic behaviour.

























D
t
L

Typical column cross-section
The design engineer wants to ensure that the stress in the timber or CRFP remain does not exceed
a certain value (as per the table below), and that the maximum axial strain of the column does not
exceed 0.1%.



Group 
D 
(mm) 
t 
(mm) 
  L (mm)  ftimber, max 
(MPa) 
fCRFP max 
(MPa) 
2A  200  4    3500  40  100 
2B  225  3    3500  35  200 
2C  250  5    3500  38  500 
2E  225  4    2500  50  250 
2F  200  2.5    3500  30  200 
2G             
             
11A  200  3    3500  42  800 
11B  175  5    3500  48  620 
11C  200  6    3500  37  375 
11E  175  8    2500  45  210 
11F  225  4    3500  41  600 
11G  250  2    3000  33  150 
             





 What maximum axial load P that can be applied whilst ensuring that all criteria are satisfied? 
 Your final answer should then clearly state the stress in the materials, and the axial shortening, for
calculated value of P.
 Your answer should show appropriate working and explanation.




2) A reinforced concrete beam has rectangular cross section (h × 2h). It is oriented such that the horizontal
axis is the stiffer axis. There are 4 steel reinforcing bars (each of diameter ds), 1 in each corner of the cross-
section.

The vertical distance from the centre of the bar to top (or bottom) edge of the section, or the horizontal
distance from the centre of the bar to the side edge is called the cover. The cover is initially set at 50 mm.

The beam can be considered as a simply supported beam of length L where L is based on the given span to
depth ratio of the beam. The beam experiences a vertically downwards UDL along its entire length of
magnitude w.

You may assume that both materials exhibit linear elastic behaviour, with specific properties as given in the
table. Use Econc = 30000 MPa and Esteel = 210000 MPa.

Increasing the depth of concrete cover can improve the fire performance and the durability resistance
against steel corrosion, so the engineer decides to move the steel reinforcing bars so that the cover
becomes 75 mm.

How does this increase in cover affect the maximum UDL w the beam can hold before the concrete cracks
due to tensile bending stress? You can assume that the concrete does not fail in compression, nor does the
steel fail in either tension or compression.


How to answer this question:

This question is intentionally vague. This is still an assignment, rather than a written report. You are
expected to provide a numerical answer. But you are also trying to communicate not just “the answer”, but
also the problem, your thought and calculation process, and how the change of cover impacts the relevant
response to another engineer.

You need to consider
• What calculations you need to do and how you might explain why you are doing them
• What answers you might need to present and in what form(s)/style(s)

You should be guided by the types of issues we discuss in the lectures. Higher grades ara awarded to
submissions that explain the process well.









Group  h (mm)  ds (mm) 
fcrack 
(MPa) 
Span/depth 
2A  275  20  3  20 
2B  305  24  3.5  22 
2C  315  20  4  24 
2E  320  24  5  20 
2F  330  20  4.5  22 
2F         
         
11A  280  24  3.5  22 
11B  290  20  4  24 
11C  300  24  5  20 
11E  330  20  6  22 
11F  340  24  4.5  24 
11G  350  20  5  20 
         





3) Read all of Chapter 2 of the ASCE / FEMA World Trade Center Building Performance Study which
can be downloaded from the Canvas eLearning site.

Identify a portion of the report which in your opinion relates to any issue you have studied in your
degree so far (it does not have to be in Structural Mechanics).

Write approximately 300 words plus a (scanned) hand drawn diagram explaining how this issue
relates to what you have studied. You must specifically state the unit of study and the particular
issue/theory/case study.

Directly copying from the report is not acceptable – you must specifically relate the World Trade
Center issue to something you have studied so far in your degree.

If you are a repeating student, you are required to write about a different portion of the report than
any previous submission.

This is not an email to Prof Smith.

Submission:
 An electronic copy of your 300 words in a .doc or .docx file to Turnitin / Canvas


Tim Wilkinson
Tim Wilkinson
School of Civil Engineering
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