CIVL2201 STRUCTURAL MECHANICS 2022:
VIRTUAL LABORATORY INSTRUCTIONS – BENDING OF A STEEL CHANNEL SECTION
SUBMISSION DETAILS
Submit both your report (PDF or DOC) and your excel file separately online via canvas
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Due: 23:59 pm (Sydney time), Friday 27 May, Monday 30 May, 2022.
OBTAINING RESULTS – ON CAMPUS STUDENTS VS REMOTE STUDENTS
Remote students will not perform a physical experiment. They will use a spreadsheet that generates
random (but valid) results. On campus students will perform an experiment.
VIRTUAL LAB ADJUSTMENTS (FOR REMOTE STUDENTS)
Remote students are unable to perform the experiment in person.
There will be a short video explaining what you would have done in person.
We will provide you with a set of randomised results to use for your calculations and report. Everyone will get slightly different numbers but they will be valid. The results you will get will include:
The dimensions of the steel beam length and cross section
Tabular set of loads and deflections at various points
The calculation and report requires minimal interaction between each of you, but you will be expected to have an online group meeting to discuss the various issues amongst yourselves.
SCHOOL OF CIVIL ENGINEERING
OBTAINING YOUR VIRTUAL DATA (REMOTE STUDENTS ONLY)
ON CAMPUS STUDENTS DO A REAL EXPERIMENT TO OBTAIN THEIR DATA
Download the data spreadsheet from canvas
Enter the student numbers of the members of your team
The data will change depending on the student numbers
Use the data based on your student numbers
Include a PDF or screen shot of your data generation spreadsheet as an appendix in your written
report where you would normally place your raw measured data.
Enter the student ID numbers for your team
Use the data generated in the spreadsheet as your data (don’t use the data in this picture!)
Only look at the “student input” sheet
IN PERSON EXPERIMENT INSTRUCTIONS
Students are required to perform three small experiments with a common theme during the semester. This gives students the opportunity to experience some structural behaviour at close hand. The results of the experiments will be compared with the theory developed in lectures and tutorials. The experimental sessions are designed to be “self- serve” and performed without supervision.
The laboratory sessions are to be performed at a time of the students’ convenience and should take approximately 1 hr. The laboratory location is Room 379, in the structures lab mezzanine. To get to this room head towards the Civil Engineering Drawing Office, but just before the set of 4 stairs leading to the Drawing Office, take the long corridor on the right and Room 379 is the last door on the left.
Visit to book a time to do the lab.
Students are to form groups of three of their own choosing.
There are two beam set ups that students can use in the mezzanine lab. Students may use either. Students may need to share some equipment with the other group if both beams are being used at the same time.
The laboratory is open from approximately 8.30 am to 4.30 pm. Students will not be able to commence a session after 3.30 pm. Students should allocate approximately 30 minutes for their session.
There are 3 experiments/reports and 3 people in the group.
Each student picks one different report and writes that one report and submits that one report only.
o Across the group of 3, one student writes report 1, one student writes report 2, one student writes report 3.
o You should be familiar with the content and calculations that each member did – there could be an exam question related to the report.
Reports are graded individually.
The analysis of the results and preparation of the report might take 5-6 hours, so students should plan to
perform the experiment well before the due date.
There is a separate instruction sheet on the requirements and marking scheme for the laboratory report. There may be an exam question related to the experimental work.
GROUPWORK EXPECTATIONS
While students are (predominately) assessed on the quality of their individual reports, all students are expected to contribute actively to the collective activities of the experiment by:
Responding to an agreed communication method amongst group members
Being pro-active in finding a time of mutual acceptance, and then participating in, group meetings or activities
Supply any calculations or results required by other team members in a timely manner (well before the
reports are due).
If a group member is not participating, in the first instance, other members are encouraged to make multiple polite approaches to the student. If unsuccessful, please escalate to Tim. If the co-ordinator is satisfied a group member has not contributed appropriately, the final grade for the report will be adjusted to account for the lack of contribution.
ACADEMIC HONESTY
This report should be your own work, and the electronic submission will be checked using Turnitin.
Directly copying parts of this information sheet (such as the experimental method) is not permitted in the
report. The report should be in the student’s own words.
It is academic dishonesty to copy and paste either word or excel data from a current or former student into
your report or calculation spreadsheet. It is academic dishonesty to allow a student to copy your work.
It is academic dishonesty to fabricate data (ie make up fake results that you did not personally observe –
note that using the “virtual results” providing in during COVID by your spreadsheet is acceptable).
SPECIAL INSTRUCTIONS FOR REPEATING STUDENTS
You are expected to perform the experiment this year.
Your report must be from a different section from the past (e.g. you wrote deflection report last year; you
may not write deflection report this year).
You must use experimental data obtained this year. You may not recycle data from last year.
You may recycle text from your previous reports if it is relevant for this year, however given your overall mark
last year, is re-using parts of a previous assignment going to improve your mark this year?
DIAGRAMMATIC REPRESENTATION OF THE TEST SET UP
Steel Channel section
Strain gauge at midpsan
Loading hook 1
Support frame
Loading hook 2
Loading hook 3
EQUIPMENT LIST
300 mm steel rules
1 m wooden rule
Micrometer & vernier
3 × dial gauges for measuring deflection plus magnetic stands Electronic strain gauge reader
BEFORE YOU START
Section A-A
Is the beam correctly centred between the supports?
Do the results seem logical and consistent?
Is linear elastic behaviour expected? Since the load is being increased/decreased by a constant increment,
how should the displacement and strain measurements change each time?
The beam clearly deflects more as more load is applied, and hence the strain must be changing. If the strain
gauge readings do not change notably between increments that would suggest that either the strain gauges
are not connected properly, or the battery is low or dead in the strain gauge box.
Take great care not to damage the strain gauge wires.
MEASURING THE DIMENSIONS
Use the wooden ruler to measure the distance between the supports, and the distance between the load points.
Use the micrometer to measure the thickness of the section
Use the vernier to measure the depth of the web and the width of the flanges.
Record your measurements on the booking sheet at the end of these notes.
HOW TO USE A MICROMETER (TO MEASURE THE THICKNESS OF THE SPECIMEN)
Take readings from the barrel
Coarse adjustment
Fine adjustment
(rotate until the ratchet clicks once)
(Image taken from http://www.mitutoyo.com/)
(taken from http://cghintra1.glan-hafren.ac.uk/open/quilt/engineering/reading_a_metric_micrometer_scal.htm)
HOW TO USE A VERNIER (TO MEASURE THE WIDTH AND DEPTH)
Do not trust the dimension shown on these pictures!!!
WHAT IS THE ZERO READING (RELATIVE VALUES)?
The beginning of the experiment is normally the benchmark against which other measurements are compared. However, at the start of the experiment the instruments do not always give a reading of zero. For example, at the beginning the dial gauge may show a deflection of 10.1 mm. This is known as the zero reading. All measurements are then relative to this. So if the next reading is 11.2 mm, then the actual deflection is 1.1 mm. A similar situation exists for the strain gauge readings.
HOW TO USE A DIAL GAUGE TO MEASURE DEFLECTION
Ensure the dial gauge is vertical.
The large dial is in increments of 0.01 mm, and one revolution is 1 mm. The small dial shows the
millimetres. This gauge reads 25.02 mm.
HOW TO MEASURE THE CORNER RADIUS OF A CHANNEL SECTION
1 – Place a flat edge on the flange (eg a ruler)
2 – Use a ruler to measure from where the corner starts to the flat edge
PREWORK – EACH STUDENT NEEDS TO DO THESE CALCULATIONS AND INCLUDE IT IN THEIR REPORT
Tabulate the measured dimensions from your virtual results spreadsheet.
Consider two scenarios
o Assumingperfectlysquarecorners(Icalc-square).
o Usingtherealroundedcornergeometry(Icalc-round).
Calculate the position of the centroid and I twice
o Firstlybyassumingperfectlysquarecorners(Icalc-square).
o Firstlybyusingtherealroundedcornergeometry(Icalc-round).
Working out the I value based on round corners is going to be a bit tricky!
EXPERIMENT 1: STIFFNESS & EXPERIMENT 2: STRAIN OUTLINE & THEORY
Two different experiments are combined into one. The first part involves examining the stiffness of the beam through two types of deformation – deflection and curvature. The second part calculates the strain in several ways.
In this experiment the simply supported beam will be loaded as follows. From Example 3.3.4 in the Lecture Notes, it is known that in the central region of the beam, the bending moment is constant. This implies that the curvature must be constant as well. Every point between hooks 1 & 3 will have the same curvature, or “bendiness”, as calculated by the equation below.
The curvature, κ, in the middle zone can be calculated as follows.
2 4g2 rc
Constant moment and curvature in
central region between
loading points
Constant radius,
when curvature is
Length of beam in constant moment
: Difference between
mid-span deflection and
deflection under loading
For remote students, all the dimensions and recordings below will be given to you in your individualised spreadsheet
Before placing any loads on the steel beam,
o Measuretheappropriatecross-sectiondimensions
o Recordtheinitialvalueofthedialgaugeatpoints1,2&3,andusetheelectronicmultimeter
to give to the initial value of the strain on the strain gauge. o Thesewillbecomethezeroreadings.
Loading and unloading the beam
o Place10lbsoneachofhook1andhook3.
Record the dial gauge deflection readings at hooks 1, 2 & 3
Record the strain gauge reading.
o Repeattheprocessofloadingandtakingreadingswithloadsof20lbs,30lbs,40lbs,50lbs. o Unloadthebeam10lbsatatime,andrecordthereadingsat40lbs,30lbs,20lbs,10lbs,0
Analysis results: (Experiment 1: Stiffness)
Include the prework results for (Icalc-round) & (Icalc-square)
Your aim is to show the relationship between moment and curvature.
The following will help you think about how you can calculate and show the results:
o Whatisthedeflectionateachpoint(1,2,3)foreachvalueofload(loadinganddownloading)? How can you best show these results in your report?
o ForeachvalueofP,whatisthemomentinthemiddleofthebeam? o ForeachvalueofP,usedeflectionstocalculatethecurvature.
What diagrams or calculations might you need to include in your report to demonstrate this?
o GivenM=EIκ,howcanyouusetheseresultstogiveyouasinglevalueofIexp? o
Analysis results: (Experiment 2: Strain)
Include the prework results for (Icalc-round) & (Icalc-square)
Your aim to the compare the strain measured by the strain gauge (εgauge) and the strain obtained from
the deformation (εdef)
For each value of P (loading and unloading):
o Whatisthestrain-directlyfromthestraingauge(εgauge)
o Whatisthecurvature(useprocessexplainedabove)
o What is the strain based on the deflected shape, 𝜀defl 𝜅 𝑥 (where x is the distance from
the centroid to the strain gauge)
What diagrams, tables or calculations might you need to include in your report to demonstrate this?
REPORT (experiment 1 – stiffness)
Your report should use the template we used for lab report 1. One person out of your group of three should write this report.
Introduction
Your report should include some basic background information about the relationship between moment and curvature.
When writing your report, you should write as if you really did go into the lab and did the measurements, and loaded the beam, as written in these discussions. Avoid quoting my words directly. A method should include some type of diagram. Your method should include the following as the very first sentence “Due to the COVID crisis, this experiment was not performed in person. The method described below was demonstrated by video, and the results provided randomly and differently to each student. Nonetheless, this report has been written as if it was carried out in reality.”
Your results should be presented in an appropriate “report format manner”. They should include the following:
The dimensions of the beam and cross section
The calculated values of (Icalc-round) and (Icalc-square). Detailed calculations should be in an appendix.
The results and calculated values of deflection, moment & curvature
The relationship between M and κ, and how you have calculated Iexp?
In the appendix, include your raw results:
o Remote students – A PDF of your “random results spreadsheet” showing your “raw virtual experimental results”
o On campus students – A scan of the data recording sheet with your observed values
Discussion:
Your key aim is to compare the 3 values of I, (Icalc-round), (Icalc-square) and (Iexp). Hence your discussion ought to contain:
What type of behaviour was demonstrated by your results?
A comparison of these values of I.
Comment on any differences and any possible reasons for the difference.
Which of the three values ought to be the best?
What assumptions have been made in these calculations that may not be strictly true? Discuss
Discuss any other relevant points.
A paragraph of approximately 100 words may be sufficient to address each point.
CONCLUSION
The report should contain any conclusions that can be derived from the results of the experiment. Refer to the general instruction sheet on lab report writing for guidance on how to write a report. The underlying question that should be asked when writing a report is “Would another engineering student from another university be able to understand this report and replicate the experiment?”
REPORT (experiment 2 – strain)
Your report should use the template we used for lab report 1. One person out of your group of three should write this report.
Introduction
Your report should include some basic background information about the relationship between strain and curvature on a cross section.
When writing your report, you should write as if you really did go into the lab and did the measurements, and loaded the beam, as written in these discussions. Avoid quoting my words directly. A method should include some type of diagram. Your method should include the following as the very first sentence “Due to the COVID crisis, this experiment was not performed in person. The method described below was demonstrated by video, and the results provided randomly and differently to each student. Nonetheless, this report has been written as if it was carried out in reality.”
Your results should be presented in an appropriate “report format manner”. They should include the following:
The dimensions of the beam and cross section
From your prework- The calculated values of (Icalc-round) and (Icalc-square). Detailed calculations should be in
an appendix.
The calculated values of (εgauge), and (εdefl). Detailed calculations should be in an appendix.
The relationship between the two sets of values?
In the appendix, include your raw results:
o Remote students – A PDF of your “random results spreadsheet” showing your “raw virtual experimental results”
o On campus students – A scan of the data recording sheet with your observed values
Discussion:
Your key aim is to compare the 2 sets of values of ε: (εgauge), and (εdefl). Hence your discussion ought to contain:
What type of behaviour was demonstrated by your results?
A comparison of these values of ε.
Comment on any differences and any possible reasons for the difference.
Which of the two values ought to be the best?
What assumptions have been made in these calculations that may not be strictly true? Discuss
Discuss any other relevant points.
A paragraph of approximately 100 words may be sufficient to address each point.
CONCLUSION
The report should contain any conclusions that can be derived from the results of the experiment. Refer to the general instruction sheet on lab report writing for guidance on how to write a report. The underlying question that should be asked when writing a report is “Would another engineering student from another university be able to understand this report and replicate the experiment?”
EXPERIMENT 3: DEFLECTIONS OUTLINE
This experiment investigates the deflections of beams. The experimental deflections are compared to those predicted by theory. The deflection will be measured in two places.
Loads are placed on hanger #1 only, and the deflection is to be measured at hooks # 1, 2 & 3. The online instruction video may show the load on a different hook. The load is applied to hook 1, and your virtual results are based on loading on point 1.
(VIRTUAL) METHOD
Due to COVID-19 restrictions, all the dimensions and recordings below will be given to you in your individualised spreadsheet
Before placing any loads on the steel beam,
o Measuretheappropriatecross-sectiondimensions
o Recordtheinitialvalueofthedialgaugeatpoints1,2&3,andusetheelectronicmultimeter
to give to the initial value of the strain on the strain gauge. o Thesewillbecomethezeroreadings.
Loading and unloading the beam
o Place10lbsoneachofhook1only.
Record the dial gauge deflection readings at hooks 1, 2 & 3
Record the strain gauge reading.
o Repeattheprocessofloadingandtakingreadingswithloadsof20lbs,30lbs,40lbs,50lbs. o Unloadthebeam10lbsatatime,andrecordthereadingsat40lbs,30lbs,20lbs,10lbs,0
Analysis results: (Experiment 3: Deflections)
Include the prework results for (Icalc-round) & (Icalc-square)
Draw the BMD for the general case of a load P.
Tabulate the experimental results showing the load, and the values of deflections at the three points.
Plot the load deflection results from all three points on the same load v deflection graph.
Write an expression for the bending moment using Macauley bracket notation.
Determine the boundary conditions, and hence use the theory developed in lectures to establish a
general algebraic equation for the deflection at any point z in terms of P and EI. (This equation might be similar (but not the same) as the equation for v about 2/3 down the page on page 9-10)
Substitute in z = a, to obtain the algebraic equation for the deflection at the very specific point of hook 1. (This equation might be similar (but not the same) as the equation for the mid span deflection on the top of page 9-11).
Using the value of Icalc-square and each value for P, calculate the set of theoretical deflections at hook 1
Compare the experimental/measured results for the deflection at point 1 for load P, with the theoretical
deflections.
Ignoring the applied l
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