Final Report
for the LITRE project
Web Based Observation and Control of an
Undergraduate Civil Engineering Laboratory Experiment
Submitted by
Vernon Matzen, Jim Nau and Abhinav Gupta
Department of Civil, Construction and Environmental Engineering
July 20, 2006
The project description contained the following items:
 An existing experiment in CE 324, Structural Behavior Measurements, will be
modified so that it can be controlled and observed remotely using web based
tools.
 In the web-based setup, a controller with a stepper motor will be used to operate
the screw actuator and the strains will be monitored, recorded and displayed using
a PC-based data acquisition system.
 The research will investigate appropriate ways to
o protect the experiment from overloading and internet / PC malfunctions
o set up procedures for scheduling, access and security.
 The write-up in the lab manual for this experiment will be
o modified to describe the web-based operation and then
o posted online so that the students will have a complete web-based
experience.
 The TAs will be trained in the remote operation of the experiment so that they can
give assistance as needed
Two related projects were going on concurrently with the LITRE project. Here is
how they were related, as well as a list of other funding sources:
 The NSF project dealt with the conversion of two laboratory experiments - a
shake table experiment and a soil consolidation test – to a web based format. The
original scope of the project included the wide flange experiment that was the
focus of this LITRE project, but the NSF budget was cut, and this experiment was
deleted from that project.
 The DELTA project included enhancements to the shake table experiment to
include web security and web based scheduling.
 In addition, we obtained some funding from the Engineering Online program,
from the Civil Engineering Department’s Education and Technology Funds
(ETF), and from other Departmental accounts.
Tasks completed as of June 30, 2006:
 Supported RA Jerry Bridges ($ 4,824)
 Purchased the following equipment (total of $3,176)
o Stepper motor ($825 from LITRE)
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o National Instruments data acquisition hardware ($6,426 from various nonLITRE funds)
o Computer to act as a proxy server ($1675 from LITRE, $1617 from nonLITRE funds)
o High speed Basler digital video camera ($11,451 from non-LITRE funds)
o Lens for digital video camera ($676 from LITRE, $2522 from non-LITRE
funds)
o Heavy duty tripod and pan-tilt tripod head ($2300 from non-LITRE funds)
o Lighting for video camera ($645 from non-LITRE funds)
Modified the wide flange beam experiment for web-based operation (modify the
screw actuator so it could be actuated by the stepper motor rather then by hand;
change the data recording procedure from manual strain indicators to data
acquisition modules.)
Modified the lab manual for web-based experiment. APPENDICES I
(introduction), II (original write-up), III (new write-up)
Beta tested the experiment with a group of visiting students in the Summer of
2005.
Completed web based scheduling, access and security procedures.
Ported lab write up to the web for the Spring 2006 lab offering.
Develop assessment questions for the experiment.
o What could be done to improve the online lab to make it a better teaching
tool?
o Are the instructions adequate, and the lab theory understandable and
clear?
o Is the remote experimentation a good alternative to use in the lab, or is in
class better suited for laboratory learning? Please explain.
Trained two new instructors in the web-based approach (TA Preston Royer and
faculty member Abhinav Gupta)
Implement the web based experiment in the CE 324 lab in the Fall of 2005 (shake
down runs) and the Spring of 2006 (half of each section performed the experiment
remotely).
Performed assessment in the Spring of 2006. The full results are given in
APPENDIX IV, and the results (22 responses) are summarized below:
o What could be done to improve the online lab to make it a better teaching
tool?
 7 students said that web access was a problem (some thought that
signing up 24 hours in advance was too long; others had difficulty
with the access)
 5 students said that a better written/web explanation was needed
since a TA was not available.
 3 students said they had difficulty with or didn’t understand the
EXCEL data sheet.
 2 students each had the following comments: It would be useful if
there were one or more graphics to illustrate the loading and set up
and labeling the components;

2 students each had the following comments: An online forum
would be useful; The experiment was slow and boring; It would be
useful to run the experiment both in class and remotely.
o Are the instructions adequate, and the lab theory understandable and
clear?
 21 students said that the instructions were adequate (although
several said that the theory was not as well explained.) One of
these students said that it would help to be able to see the entire set
up.
 1 student said that the instructions were not clear.
o Is the remote experimentation a good alternative to use in the lab, or is in
class better suited for laboratory learning? Please explain.
 18 students said that the in class lab experience is preferred.
 4 students said they preferred the web based version

Results from the final exam:
o Question pertaining to this experiment:
 Web based group
 Section 1: 17.8 out of 25 points
 Section 2: 18.1 out of 25 points
 In class group
 Section 1: 19.2 out of 25 points
 Section 2: 19.5 out of 25 points
o Overall exam averages
 Web based group
 68.3%
 In class group
 75.0%
Summary and conclusions:
All of the tasks associated with this LITRE project were completed: One
experiment in the CE 324 lab was converted to a web based environment; access,
scheduling and security software was written and implemented; the instructions for this
experiment were modified for web usage; instructors were trained; the experiment was
implemented partially in the Fall of 2005 and more fully in the Spring of 2006; and an
assessment was made of the effectiveness of the web based experiment.
The results of the assessment were not a surprise. The responses to the first
question about improvements that could be made pointed out that we still need to
improve the web access and the data spreadsheet. The lab manual can also be made
clearer. The online forum is an interesting idea and one we will consider implementing.
This may be useful for the in class experiments, also.
The responses to the question about the clarity of the manual show that, while the
instructions on conducting the lab were clear enough, the write up on the theory was not.
The responses to the last question are the most interesting and, perhaps, indicate
that we need to modify the write up for distance to clearly indicate the subtle difference
in objectives between the remotely conducted lab and the one done in the lab itself. We
apparently didn’t make it clear that the rationale for conducting the lab remotely was not
just to save us all from having to spend 3 hours in the lab, but to illustrate that the remote
technology does work, and that the results can be just as good as those obtained during
the hands-on version of the lab.
The results from the final exam are a bit disappointing. We had hoped that the
students performing the experiment remotely would learn as much as those performing it
in the lab while, at the same time, learning how to use modern technology to conduct
experiments remotely. Even though the differences in grades are not great, we believe
they should be much lower; i.e. there should be little difference if any between the
students performing the experiment remotely and those performing it in the lab.
Future work:
We will modify the lab write-up in accordance with the comments above, and
implement this remote experiment again in the Fall. We will reduce the sign up wait
period from 24 hours to some smaller number. We will modify the assessment questions
to better reflect the actual objectives of the experiment.
APPENDIX I
Introduction to the lab manual
Lab Introduction
I.
II.
III.
IV.
V.
Objectives…………………………………………………………………2
Lab Policies………………………………………………………….........2
Safety……………………………………………………………………...3
Laboratory Equipment and Instrumentation………………………………3
A. Transduction…………………………………………………………7
B. Measurement and Recording Devices……………………………….8
Frequently Asked Questions………………………………………………13
Experiments
1. Strain and Deflection Measurements in a Cantilever Beam
2. Elastic Buckling
3. Torsion Test of a Hollow Tube
4. Free and Forced Vibrations of a Single Story Shear
5. Indeterminate Beam Behavior
6. Normal and Shearing Strains in a Wide-Flange Beam
I. OBJECTIVES
1. Provide the student with a “feel” of the response quantities such as
displacements, strains, forces etc. as observed in actual physical behavior
of structural members such as beams, columns etc.
2. Compare response quantities from actual physical behavior of structural
elements with those obtained from theory.
3. Learn to use modern instrumentation to measure the response quantities
and understand the principles of its working.
4. Prepare technical reports to describe the nature of the experiment and its
outcome.
The objective of this Lab course is to make the student familiar with the real
behavior of structural elements as observed in field of work. It will also provide
an insight into the order of magnitude for different response quantities, thus
enabling the student to verify theoretical results and the assumptions of the
theory.
II.
LAB POLICIES
1. DO NOT WEAR OPEN TOED SHOES! You will be asked to leave
the lab and you may not be able to make up the missed lab.
2. Attendance of ALL labs is required in order to receive a grade in this
course.
3. If you must miss a lab due to an excused absence, you will need to
reschedule the missed lab to coincide with another session (if you are a
section “B” student then rescheduling for the section “A” time of the
previous week will be necessary!).
4. The lab reports are to be turned in within one week of the period in which
the experiment was performed.
5. The penalty for late reports is 10% per school day, up to a maximum of
50% with a maximum of 10 days to turn the lab in. After 10 days you will
receive a zero.
6. The NCSU honor code will be followed in both letter and spirit.
http://www2.ncsu.edu/prr/student_services/student_conduct/POL445.00.1.htm
Although you will work in pairs during lab, you are expected to do your
own work for the report. This policy applies to everything included in
your reports. DO NOT copy someone else’s work! Any breach of this
policy will result in severe penalties.
7. Reasonable accommodations will be made for students with verifiable
disabilities. In order to take advantage of available accommodations,
students must register with Disability Services for students at 1900
Student health Center, Campus Box 7509, 515-7563.
http://www.ncsu.edu/provost/offices/affirm_action/dss/ For more
information on NC State’s policy on working with students with
disabilities, please see
http://www.ncsu.edu/provost/hat/current/appendix/appen_k.html
III. SAFETY
1.
2.
3.
4.
Absolutely no horseplay.
No bare feet, sandals, flip-flops, or other abbreviated footwear.
Exercise appropriate caution in use of electrical equipment.
Fire alarm procedure: turn off equipment; gather up personal valuables;
exit calmly but promptly. Exit route: turn left, then right, exit at the back
door at the southeast corner of Mann Hall. Gather at the planter just
outside the door for further instructions.
5. Be careful with the weights that you will be using to conduct the
experiment.
6. No food or drinks.
7. No smoking or use of other tobacco products.
8. Keep work area neat. Leave personal items on shelf or hooks near door.
9. Notify the lab instructor immediately in the event of an accident.
10. Refer to the lab safety manual for further questions.
SAFETY TRAINING OUTLINE
IN CASE OF EMERGENCY CALL PUBLIC SAFETY AT 515-3333
Safety training will be conducted by the Principal Investigator or their designate(s) prior
to the use of the lab. Following is a list and brief description of the main topics to be
covered in safety training:
1.
2.
3.
4.
5.
6.
Appropriate Clothing and Personal Items
Eye Protection
Housekeeping Rules
Electrical Hazards
Fire Extinguishers
First Aid
This training must be documented in writing using the form following the next page.
This document will be archived in the Department Personnel File.
1.
Appropriate Clothing and Personal Items:
Shoes that cover the entire foot must be worn whenever in the laboratory. Sandals,
flip-flops, or other abbreviated footwear is not allowed. While hazards in the lab are
few, individuals are urged to wear clothing which protects as much of the body as
possible. It is recommended that older, expendable clothing be worn while in the lab,
since grease (from the screw actuators) and other substance might stain or otherwise
cause unsightly damage to new clothing.
2.
Eye Protection:
In CE 324 lab, conditions do not warrant the use of safety glasses, and hence they are
not required. However, safety glasses are required for the application of strain gages,
which may be necessary in research activities. Strain gage application is the only
procedure in this laboratory which warrants and requires the use of eye protection.
3.
Housekeeping Rules:
There will be no eating or drinking in the laboratory.
There will be no smoking or consumption of other tobacco products in the laboratory.
Horseplay of any kind is never permitted in the laboratory.
Safety clothing and other protective devices are generally nor required in the lab.
However, eye protection is required for the application of strain gages (see Eye
Protection). Open-toed shoes and sandals are not permitted, nor are bare feet,
because of the potential danger posed by objects (especially slotted weights) which
may fall if not handled and applied carefully.
Ties, scarves, and loose clothing should be removed or secured with appropriate
fasteners. Loose or hanging jewelry should also be removed. Long hair should be
carefully restrained (see Clothing and Personal Items).
Bench tops should be kept clear of any personal items, devices, or materials not
directly involved in the experiment in progress. This minimizes the chances of an
accident and diminishes the severity of any accident which might occur.
4.
Electrical Hazards
No significant electrical hazards exist in the lab. Most of the frequently used
electrical equipment is battery-operated. Some instrumentation requires 120volt AC
power, which is provided in the lab with grounded electrical outlets. The instruments
using this power are equipped with a three-pronged plug. The condition of the
wiring, plugs, cords, and related equipment is periodically inspected for electrical
hazards.
5.
Fire Extinguishers
One dry-chemical fire extinguisher is located on the wall in Room 112, as shown on
the Evacuation Plan Map. Should additional equipment be required, the Evacuation
Plan Map shows the location of larger dry-chemical extinguishers in the hallway
outside the lab. Fire extinguishers should only be used by those who feel competent
and comfortable given their formal training and previous experience. Even in the
case of a small fire, the pull alarm in the main hallway outside the lab should be
activated immediately, since a timely response by fire fighters is critical to ensure the
safety of all occupants of the building.
6.
First Aid
A basic first-aid kit containing bandages is provided in the laboratory. Following any
first aid, a nurse of physician at the nearest medical facility should provide further
examination and treatment, if warranted. Someone knowledgeable about the accident
should always accompany the injured person.
On _______________________________, I ____________________________ was
dates of instruction
printed full name
instructed by ______________________________________________ on the hazards
printed name(s) of Instructor(s)
present in Rooms 112 and 112D Mann Hall, and the proper safety procedures to
follow when working there as outlined in the Safety Plan for that area.
I understand these hazards and accept them as a necessary part of my work.
I will follow the proper safety procedures in my work in this area at all times.
___________________________
Student’s Signature
__________________________
Date
Attested by Instructor:
___________________________
Instructor’s Signature
__________________________
Date
IV. LABORATORY EQUIPMENT AND INSTRUMENTATION
A.
TRANSDUCTION
One of the most important concepts in instrumentation is transduction, which is
the process of converting one variable which is difficult to measure into another
which is more easily read. Fore example tire pressure is usually measured with a
dial gage. The pressure has been converted into the mechanical response of a
gauge needle.
1. Displacements: Displacement is always measured relative to some
reference frame. Magnitudes of displacements can be determined in only
two ways:
a. By direct comparison, e.g. with a ruler. But how was the ruler
calibrated? By comparing its length to a known standard.
b. By “transduction”, for example by relating the displacement to the
rotation of a dial gage needle. But, how was the dial gage calibrated?
Again, by using a known standard.
In both cases, a standard length must be used. In high quality devices, the
standard is traceable to the National Institute of Standards and Technology
(NIST).
2. Strain: Engineering strain is defined as a change in length over the
original length. In most applications, the change in length is too small to
measure directly. There are several practical ways of measuring strain,
but the most common is to use a bonded electrical resistance strain gage.
The gage is bonded to the surface of the specimen and is configured so
that as the strain in the gage strains, its resistance changes by a predictable
amount. The ratio of the change in resistance to the strain is defined as the
Gage Factor. That is
R R
G.F.  R  R
L

L
(2)
Modern strain indicators measure (∆R/R) very accurately and incorporate
a user specified Gage Factor to compute and display strain. The reading is
in micro (10-6) inches per inch, often called microstrain and denoted µε.
Stain gage manufacturers provide gage factors which have been
determined by applying known strains to sample gages. The known
strains are referenced to standards which are traceable to the NIST
3. Force: As with displacements, the magnitude of force can be measured in
two ways:
a. by comparison, e.g. using a pan balance
b. by transduction, e.g. using a spring cable
But again, the question remains: how is the balance or the scale calibrated?
In this lab you will use two methods to apply loads: (a) calibrated weights
(with calibrated 1pound weight hanger), and (b) a screw actuator with a
device called a “load cell”. The load cell is a stiff spring element that is
inserted between the loading mechanism and the structure. It has four or more
strain gages attached to it, and the indicated strain output can be related to the
applied load. The load cell is calibrated using a precision resister.
B.
MEASUREMENT AND RECORDING DEVICES
1. Digital Multi-Meter (DMM). Digital Multi-Meters give digital readouts of
AC voltage, DC voltage, amperage, and resistance. They are battery
operated, so turn them off when they are not in use. Directions on how to
use the DMMs will be provided in the lab. See figure 1 below .
Figure 1 Digital Multimeter
2. Digital Strain Indicator. When a strain gage is wired to a Digital Strain
Indicator (DSI), the DSI measures a change in voltage across a
Wheatstone bridge induced by a change in resistance in that gage. By
varying the gage factor, this change in voltage can be converted into a
change in resistance (G.F. = 1.000), strain (G.F. from manufacturer, 2.080
for example), stress, load, moment, and so on. We use this concept when
calibrating the load cells.
.
Figure 2 P-3500 Digital Strain Indicator
The DSIs that we use in this course are the model P-3500 (see figure 2 on
the previous page) from the Instruments Division of the Measurements
Group, Inc., Wendell, NC. The instructions for use are on the inside of the
lid and are self explanatory (quarter bridges assume a 3-lead wire method
which we always use in this lab).
3. Switch and Balance Unit. These units, Measurements Group Model SB10, enable up to ten strain gages to be connected to a single P-3500 digital
strain indicator. Each gage can be balanced and the strain displayed by
selecting the appropriate channel via the selector knob.
4. Digital Outside Micrometer Caliper. These micrometers (see figure 3)
measure outside distances up to one inch with a readability of one tenthousandth of an inch (0.0001”). Micrometers are very fragile. Never lay
one down near an edge where it may be knocked onto the floor.
Vernier
Thimble
Sleeve
Figure 3 Micrometer
Vernier, 0.0001 inches
20
10
15
5
0
0
10
1
2
3
Reading on sleeve
Reading on thimble
Reading on vernier
0.400 inches
0.003 inches
0.0005 inches
Final Reading
0.4035 inches
4
5
0
Sleeve, 0.025 inches
Thimble, 0.001 inches
Figure 4 Reading a Micrometer
5. Vernier Caliper. The vernier calipers can measure inside and outside
distances up to 6” to a readability of one one-thousandth of an inch
(0.001”) or one one-fiftieth of a millimeter (0.02 mm). These, too, are
fragile instruments so treat them with great care. Figure 5, shows a typical
vernier caliper and figure 6 shows how to read the caliper vernier scale.
Locking Screw
Inside Calipers
Vernier Scale
0.001 inches
Beam Scale
0.025 inches
Outside Calipers
Figure 5 Vernier Caliper
Reading on beam scale
Reading on vernier Scale
0.950 inches
0.008 inches
Final Reading
0.958 inches
Figure 6 Reading a Vernier Caliper
6. Linear Variable Differential Transformer. An LVDT is an
electromechanical device that produces an electrical output proportional to
the displacement of a separate movable core. It consists of a primary coil
and two secondary coils symmetrically spaced on a cylindrical form. A
free-moving rod-shaped magnetic core inside the coil assembly provides a
path for the magnetic flux linking the coils. The LVDTs we have are
made by TRANS-TEK, INCORPORATED Ellington, CT and are actually
DC-DC LVDTs, that is both the input and output voltages are DC. The
relationship between the voltage output and the displacement of the core is
found through calibration. You will learn how to calibrate LVDT as part
of one of the experiments. Figure 7 shows a photo of both the power
supply and the LVDT. Figure 8 on the next page shows how to connect
the LVDT wires to power supply and to the DMM.
Figure 7 Power Supply and LVDT
The LVDTs are held in place for an experiment with a MAGNETIC
BASE and a wooden holder. The magnetic bases can be placed at
different heights from the table using the steel risers with threaded rods.
They can be attached to the aluminum reaction fame using special steel
plates. Be very careful with the core when the LVDT is in the vertical
position. If you are moving the specimen, either remove the core or rotate
the LVDT into the horizontal position. The testing tables are quite stiff,
but they are not rigid. When using an LVDT be careful not to stand on the
table or touch the specimen.
On/Off
-V
DMM
Com
Power
Supply
+V
Black (-)
Red (+)
Red (+input)
Black (-input)
Blue (+output)
Green (-output)
LVDT
Figure 8 Wiring an LVDT into the Power Supply and DMM
7. Accelerometer. There are many types of accelerometers commercially
available. We will use a piezoelectric type on the vibration experiment. It
gives a voltage output that is proportional to the acceleration. The relation
between the acceleration and the voltage is called the calibration constant.
It will be provided.
8. Oscilloscope. We will use a Digital Storage Oscilloscope (DSO) software
package with a PC-based data acquisition system as the readout device for
accelerometers.
V.
FREQUENTLY ASKED QUESTIONS
How can I get an A in this lab course? The obvious answer is to do well on
the lab reports, study sheets and on the final. To do this, we recommend the
following: Read this introduction carefully to find out what you are supposed
to learn in the lab. Read each lab write-up before you come to lab so that,
when you arrive, you will know what you are supposed to be doing and what
questions to ask. Complete the study sheet associated with that days lab.
Review the theory related to the experiment you will be working. Ask enough
questions in lab so that you know what is happening and why.
Is this Manual the only textbook? Yes. However, you will probably want to
refer to your textbooks from Solids, Structures, or Dynamics (as appropriate)
while you are in lab. Assumptions, theory, and equations are not repeated in
this manual, but reference is made to the appropriate material in one of these
other textbooks.
Will there be a lecture before each lab? Yes, but it will be short. The first lab
will be conducted as a group, with the instructor demonstrating each step
before the students attempt it. There will be ample time for questions and
discussion, and suggestions will be given on how lab reports should be
written. For the other experiments, there will be a brief explanation of the
procedure at the beginning, and then the groups will work independently.
There will, of course, be an instructor available to assist you in all of the labs.
How long will each lab take? You will usually be in the lab the full 2 hours
and 50 minutes. You won’t necessarily be performing the experiment the
entire time – of the time will be spent reducing data and making typical
calculations. By knowing how your results turn out before you leave the lab,
you can catch any problems you may have with your data, and you will find
that your lab reports are easier to write and take less time.
Can I use old lab reports? No. The cliché “You only get out something what
you put into it” is true in this lab. The more work you do on your own and the
more thought you give to the experiments, the more you will get out of the
lab. And, of course, there is the final. We will not intentionally make it
difficult, but we will try to find out if you understood what was going on in
the six experiments.
Can I quote the lab manual in my lab report? Quotation is permitted, but
plagiarism is not. The objective of writing a lab report is not to rewrite the lab
manual but to attain a working understanding of the theories tested. From this
understanding, you will be able to make quality conclusive lab reports.
Is there a final lab exam? Yes, there will be one on Thursday evening on the
last week of classes. The questions will be related to the fundamental
concepts covered during the semester (state of stress at a point, relationship
between stress and strain, transduction, calibration, and so on).
Tips on reading the Vernier calipers
-Place object snugly between the jaws, do not squeeze the jaws too tightly on the
specimen as it may yield an inappropriate reading and/or damage the device.
-Identify the beam and Vernier scales
-Remember the smallest division on the beam scale is 0.025 inch and the smallest
division on the Vernier scale is 0.001 inch.
-Note the value on the beam scale which just precedes the zero mark on the Verniew, say
X.
-Note the value (say Y) on the Vernier scale which precisely (not very close, but
PRECISELY) aligns with a division on the beam scale.
-Add X to the product of the Y time 0.001 inch for the final measurement.
Tips on reading the Micrometer Calipers
-Place object snugly between the spindle, do not overtighten the micrometer on the
specimen as it may damage this expensive device.
-Identify the sleeve scale value which just precedes the edge of the thimble (say A).
-Identify the value on the thimble which just precedes the horizontal mark on sleeve (say
B).
-Identify the value on the Vernier scale which most closely aligns with a horizontal
division on the sleeve (say C).
-Multiply B by 0.001 inch and C by 0.0001 inch and add these products to A to yield the
final reading.
Setting up a ±0.5 inch Linear Voltage Differential Transformer for
the deflection measurement
1) The first step is to calibrate the LVDT as instructed by the
instructor. When this is done, DO NOT disconnect the
wires!
2) Determine the section of the structural element where the
displacement needs to be measured.
3) Secure the magnetic base on the steel table such that the
LVDT can be aligned vertically over the specimen.
4) Readjust the LVDT, with the core in place, in the clamp until
the voltage displayed on the DMM is between +17 and -17
Volts. Unless a good deal of displacement is expected, it is
usually convenient to start at close to zero volts.
5) Check to insure that the LVDT is secure in its clamp.
6) Check that the LVDT is acting correctly by gently depressing
the member up and down.
7) Begin your experiment and take readings as instructed.
8) Compare your displacements with the theoretical predictions
(if possible) and make certain nothing unseemly has
occurred. Get the instructor to verify your results once you
are satisfied.
9) Carefully disconnect the LVDT and place it back in the kit.
Setting up a P-3500 Digital Strain Indicator to read
strains from a single gage
1. Depress the amp zero switch and adjust it to zero with
the appropriate knob. It will very likely be at zero and
require no adjustment.
2. Set the unit to a quarter-bridge setting, if not already set,
using the far right hand switch.
3. Hook up the gage wires to the correct terminals.
Connect the red wire to the P+ terminal, the white wire to
the D-120 terminal and the black wire to the S- terminal.
4. Depress the gage factor switch and adjust as necessary
according to the gage in use (usually around 2.0 to 2.1).
5. Depress the run switch and adjust the balance knob until
the reading is zero.
Steps to Calibrating a 2-kip Load Cell with a P-3500
Strain Indicator
1) Find the appropriate calibration certificate for your load cell
and copy down the value of the compressive load, which
coincides with the 60kΩ resistance.
2) Plug the load cell into the P-3500.
3) Turn on the P-3500 and adjust the amp to zero.
4) Set the P-3500 to a FULL bridge setting.
5) Set the P-3500 to RUN mode and balance the unit to zero.
6) Place the 60kΩ resistor across the P+ and S- terminals.
7) While in RUN mode adjust the Gage Factor knob until the
display matches the compression load from the calibration
certificate. NOTE: The G.F. may need to be in the 2.3 to 4.5
range to do this.
8) Remove the resistor from the P+ and S- terminals, balance to
zero and apply a test load.
APPENDIX II
Lab manual for the Wide Flange Beam Experiment
Experiment #6 Study Sheet
All questions relate to the T-section below
1500 lb
A
5.00”
1.00”
4.00”
48”
32”
1.00”
A
E = 10.0 x 106 psi
V = 0.32
1.
Find the normal strain (in microstrains) at the top and bottom of the beam at
section A-A.
2.
Calculate the shearing strains (in microstrains) at the following points.
a.
at the top of the flange,
b.
at the bottom of the flange,
c.
at the top of the web,
d.
at the neutral axis, and
e.
at the bottom of the web.
3.
Sketch both the normal and shearing strain distribution over the cross section at
A-A.
4.
Is the one-dimensional form of Hooke’s Law for normal strain applicable for
converting normal stress to normal strain in this beam? Explain.
Department of Civil Engineering
North Carolina State University
Raleigh, North Carolina
CE324
STRUCTURAL BEHAVIOR MEASUREMENTS LABORATORY
EXPERIMENT NUMBER 6:
NORMAL AND SHEARING STRAINS IN A WIDE FLANGE BEAM
NAME___________________________
OTHER MEMBERS OF GROUP:
__________________________
__________________________
__________________________
SECTION_________GROUP________
DATE EXPERIMENT PERFORMED_____________________________
DATE REPORT TURNED IN______________________________
I.
Reference:
CE 313 textbook
II.
Objective: To find the normal and shearing strain distribution in the web of a
cantilevered wide-flange beam.
III.
Specimen:
A five foot long 5 x 5 wide flange aluminum beam is welded to a base plate
which is in turn bolted to the column of a test frame. Vertical loading is applied with a
screw actuator to the end of the beam. Five rectangular rosette strain gages are mounted
across the web in a vertical line approximately halfway between the load and the support.
A single uniaxial strain gage is mounted on the top of the flange in line with the rosette
gages.
IV.
Background:
One of the assumptions of Bernoulli-Euler beam theory is that the beam is under
pure bending, that is, no shear. Under these conditions, the normal stress is related to the
bending moment through the equation:
 ( y) 
My
I
(1)
The normal strain can be obtained using the one-dimensional form of Hooke’s
law as in lab 1.
 ( y) 
 ( y)
E

My
EI
(2)
In most applications, however, shearing forces are present. For beams that are
long and slender, say the length is more than three to four times the depth, the effect of
shear on the overall deformation will be small. Thus Bernoulli-Euler beam theory is
considered to be valid to engineering accuracy. Using this theory it can be shown that the
distribution of shearing stresses has the form:
 ( y) 
VQ( y )
It ( y )
where,
(y) is the shearing stress at a distance y from the neutral axis,
V is the shearing force at the cross section,
Q(y) is the first moment of area above y about the neutral axis,
I is the moment of inertia of the entire cross section about the neutral axis, and
t(y) is the width of the section a distance y from the neutral axis.
(3)
The shearing strain can be obtained using the shear modulus, G, as follows:
 ( y) 
VQ( y )
GIt ( y )
(4)
where G is related to E through the equation:
E
2(1   )
G
(5)
If the cross section is rectangular, the shearing strain distribution is parabolic as
shown in figure 1. The normal strain is linear for every cross section as long as the beam
closely satisfies the Bernoulli-Euler beam assumptions.
y

y
h

b
e
Figure 1. Strain Distributions in a beam with Rectangular Cross Section
In this case the shearing stress equation is found as follows:
h

A( y )    y b;
2

y
1 h
 
2 2

y ;

I
bh 3
;
12
2

h
 1 h
 b  h 
Q( y )  A( y ) y    y b   y      y 2 ;
2
 2 2
 2  2 

V
VQ( y )
 ( y) 

It ( y )
2

b  h 
2
   y 
2  2 

bh3
b
12
6V
 3
bh
 h  2

2
   y 
 2 

t(y) = b
(6)
(7)
(8)
The shearing stress is zero at the extreme fibers and a maximum at the neutral axis. For
the rectangular cross section, the maximum shearing stress is:
 max 
3V 3
  avg
2A 2
(9)
where A = bh, the entire area of the rectangular cross section.
Since the thickness of the cross section is not uniform for the wide flange cross
section, the vertical shearing stress (and hence the shearing strain) distribution will not be
parabolic. Considering only the thickness, it is clear that the thickness of the web is
much smaller than the thickness of the flange (meaning the flange width) and, hence, the
shearing stress will be much smaller in the flange than in the web. The contribution of
the vertical shearing stress resultant in the two flanges is small compared to the total
vertical shearing force and hence, to engineering accuracy, it is usually neglected. The
normal stress distribution remains linear. Figure 2 shows the distribution of both
shearing and normal strains in the wide flange section.


Figure 2. Shearing and Normal Strain Distributions in a Wide Flange Beam.
V.
Experimental Background
Strain measurement: Normal strains in the x-direction can be measured directly
by using a gage that is aligned with that axis. Shearing strains, on the other hand, cannot
be measured directly with strain gages. A rosette gage, has three strain gages, describes
completely the state of strain at a point and hence the shearing strains can be found by
using the information gathered from the uniaxial strains measured by the three elements.
Mohr’s circle for strain provides a convenient way to do this. The rosette gage we use is
in a rectangular pattern, meaning that the three elements are 45o apart. Figure 3 shows a
rectangular rosette strain gage (greatly enlarged) in the orientation we use. Notice that
the middle gages, B is aligned with the x-axis. To derive the equation for the shearing
strain, look first at the stress block in figure 3 which, in this case, is above the neutral
axis. Mohr’s circle for the state of strain corresponding to this state of stress can now be
drawn. The notation used here for shearing strain is that the shearing stress shown in
figure 3 is positive and, hence, the shearing strain is positive. The primary difference
between Mohr’s circle for stress and strain is that, for strain, the vertical axis (for
shearing strain) is half that of the horizontal axis (for normal strain). Notice, also, that
the positive shearing strain axis is down.
P
yx
x
C
x
xy
B
A
y = -x
x = Ex
y = -x
Figure 3. Stress Block and Strain Gage Rosette on a Cantilever Beam
Points A, B, and C on the Mohr’s circle in figure 4 correspond to elements A, B, and C in
figure 3. Since the elements on the rosettes gage are 45o apart, the points on the Mohr’s
circle are 90o apart. The coordinates of B, which locates the x-axis on the circle, are (x,
xy/2). The geometric proof given below provides the relationship between the normal
strains at A and C (which can be measured) and the shearing strains (which cannot be
measured).
C
D
E
90o

F
G
90o
B
A
xy
Figure 4. Mohr’s Circle for Strain
point G = B = x
point D =A
point F =C
distance GB = xy/2
triangle ADE = triangle CFE = triangle EGB
therefore DE = EF = GB
DF = C – A = 2GB = 2(xy/2)
therefore xy = C - A
VI.
Experimental Procedure
Calculating the moment of inertia, I, using section measurements.
Because of the shape of the section, it is clear that we will not be able to use a simplified
equation to calculate the moment of inertia. We will need to divide the section into
discrete pieces for which a moment of inertia can be readily calculated using the parallel
axis theorem. Then we will combine these values to generate a moment of inertia for
your composite section. The most important thing to remember is to generate a
discretization that will be simply solved. For instance, consider figure 5 which is a
representation of a T-section with tapered flanges. Figure 6 represents two possible
methods of discretization. Both are perfectly allowable, but the one on the right is much
simpler to calculate and is only slightly less accurate.
11 pieces
Figure 5
Figure 6
2 pieces
For our purposes, we will divide the wide flange section in a fashion to the simpler
example of figure 6. Thus, our section will be comprised of 3 pieces. An approximation
of this shape can be observed in figure 7 below.
b1
bavg
t2
t3
t1
tavg
t4
w1
d1
d2
w2
davg
wavg
w3
t5
t8
t6
tavg
t7
bavg
b2
Figure 7. Wide Flange Approximation
Upon measurement of the appropriate dimensions, calculate the contribution of each
piece to the moment of inertia and sum them all to obtain the total composite moment of
inertia. Remember that the parallel axis theorem states that the contribution of each piece
should be equal to
I cgi  Ai d i
2
(10)
where
Icgi is the moment of inertia about that segments centroid,
Ai is the area of that segment, and
di is the distance from the section’s centroid to the segment’s centroid.
thus the total moment of inertia from the three pieces should be equal to
 I
3
1
cgi
 Ai d i
2

(11)
The normal strain due to bending can be readily calculated using equation 2 assuming the
other necessary parameters are known.
Calculation of Q(y) for the composite section to calculate shearing strain
The calculation of Q(y) must be completed for each rosette gage location. Using the
composite section, this should be a relatively simple process. The equation for the first
moment of area states that
Q( y )   yda
(12)
For this section, we can simplify the equation to
n
Q ( y )   Ai d i
(13)
1
where di is the distance from the centroid to the center of that segment.
For our purposes this calculation of Q would normally need to be done five times, but
from symmetry we can show that the two outer gages and the inner two gages are
equivalent. Thus, only three calculations will need to be made here. Upon completion of
these calculations, the shearing strain may be calculated using equation 4, assuming the
other parameters have been determined.
Measurement of normal and shearing strains
Because of the complexity of this procedure, only one specimen will be used for the
entire lab. The necessary measurements and gage locations will be given during the
course of the exercise. See figure 8 for a photo of the specimen and gage layout..
Rosette Gage Layout
Strain Gage Locations
“Fixed End”
Specimen
2-kip Load Cell
SB-10’s and P3500’s
Figure 8. Specimen and Rosette Gage Photo
There are a total of sixteen individual strain gages which will be measured. Three on
each of the five rosettes and a single uniaxial gage mounted on top of the beam in line
with the rosettes. The rosettes have been symmetrically mounted to simplify the
calculation procedure. Each gage is wired into an SB-10 terminal as in lab 3. Each SB10 is in turn wired into a P-3500. The individual gage measurements can be observed by
selecting the appropriate channel on the SB-10. In addition, there is a 2-kip load cell
which is also plugged into a P-3500. Using these devices, the appropriate measurements
can be taken during the loading process. For this exercise, an ultimate load of 1000 lbs
will be applied. The load will be applied with no intermediary steps.
Linearity will be checked by monitoring the top-mounted uniaxial gage through a second
loading and unloading cycle to 1000 lbs in 500 lb increments.
The shearing strains can be approximately checked by back-calculating the shear stress
and then back-calculating the shear force.
VII.
Report
a) Plot the normal strain distribution (Exp and theoretical) (Strain on x-axis and distance
from neutral axis on the y-axis)
b) Plot shearing strains distributions (Exp and theoretical) (Strain on x-axis and distance
from neutral axis on the y-axis)
These plots should resemble the sketches on figure 2. Plot the theoretical values
connected with a line and experimental as discreet points. Be sure to scale the shear
strain plot such that the strain axis goes all the way to zero i.e. x-axis starts from
zero. Otherwise EXCEL will likely choose a scale that greatly exaggerates the curvature
of the plot.
c) Plot the linearity check from the uniaxial gage data.
A single experimental sketch will suffice, but include sub-sketches of the gage locations.
Include in your discussion of results: What do you think a test of deflection for this wide
flange beam would have resulted in, if loads were to be applied at the end of the beam to
obtain deflection and then compared using theoretical equation of PL3/3EI and why.
Some interesting simple checks of the data may be performed if you are interested. For
instance, you may check the approximate shear in the section by back calculating the
shear stress and then calculating the resultant shear force in each region by multiplying
this stress by the area over which it acts. By summing these values over the five regions
you can get an estimate of the total shear force. Also, you can do a “better” job of
calculating the moment of inertia of the section by dividing the flanges into rectangles
and triangles (for the tapered portion). The moment of inertia and centroid of a triangle
can be found using the appendix of your mechanics text. All of these “checks” can be
done very quickly using EXCEL.
DATA SHEETS
Specimen measurements and predicted strains
Material
6061 T6 Aluminum
Young’s Modulus:
Poisson’s Ratio:
Shear Modulus
psi
psi
Dimensions (Refer Fig. 7)
t1
(in)
w1
(in)
d1
(in)
t2
(in)
w2
(in)
d2
(in)
t3
(in)
w3
(in)
t4
(in)
t5
(in)
t6
(in)
t7
(in)
b1
(in)
t8
(in)
b2
(in)
Average measurements
tavg
(in)
wavg
(in)
davg
(in)
bavg
(in)
Moment of inertia calculations (Eq’s 10 & 11)
Icg
Ipa
I1
(in4)
(in4)
I2
(in4)
(in4)
I3
(in4)
(in4)
Itotal
(in4)
First moment of area calculations, Q (Eq. 13)
Distance between gages
Q5
(in3)
Q4
(in3)
Q3
(in3)
Q2
(in3)
Q1
(in3)
(in)
Distance from load to rosette gages
(in)
Theoretical strains at 1000 lbs
Gage
x ()
xy ()
A ()
B ()
C ()
x ()
xy ()
A ()
B ()
C ()
x ()
xy ()
y (in)
Uniaxial
5
4
3
2
1
Experimental Strains
Zero pounds
uniaxial
5
4
3
2
1
1000 pounds
uniaxial
5
4
3
2
1
Zero pounds
A ()
uniaxial
5
4
3
2
1
Uniaxial Gage Linearity Check
Load(lb)
0
500
1000
500
0
Strain()
B ()
C ()
x ()
xy ()
APPENDIX III
Instructions for the web based lab
Procedure for Running Remote Experiment
1.) Read over the lab sheets. Understanding the mechanics behind the
experiment is most important. The discussion is very straight forward
and not at all complicated. For reference during the experiment see
“Mechanics of Materials”, by James Gere. This is as good a reference
that can be found on the subject of mechanics. Refer to section 1.6, 5.15.5, 5.8, and 5.10, also the discussion of Mohr’s circle in chapter 7 is
excellent especially if you do not understand the proof given in the lab
sheets as to how the rossette gages can be used to determine shearing
strain.
2.) Calculate the moment of inertia and first moment of area (Q) from the
cross sectional dimensions given in the data sheets. For help with these
calculations see chapter 12 in Gere. In the data sheets Icg refers to the
inertia of the individual pieces about their centroid (i.e. bh3/12) while IPA
refers to the inertia calculated with the parallel axis theorem, or
transformed moment of inertia. Also there are examples in chapter 5 on
calculating the first moment (Q).
3.) Calculate the theoretical values from Bernoulli-Euler beam theory that
you will compare your experimental findings to.
 ( y) 
 ( y)
E

My
EI
 ( y) 
VQ( y )
GIt ( y )
4.) Make sure your default web browser is microsoft internet explorer.
Then select the labview link to download the viewer so you can run the
experiment.
5.) Next select the link to run the experiment, you will see the experiment
page as shown below.
6.) You will need to log in with your unity ID and password, and you will
probably have to run through several pop-ups, but do not cancel any of
these. Navigate through the menu’s. If you have not scheduled a
timeslot to control the experiment you need to do so at least 24 hours
before you plan on running the experiment. Select the menu to schedule
a time to control and follow the instructions given. Come back to the
website at the time you have scheduled to control the experiment.
7.) The following page will be displayed when you enter the experiment to
control it.
1.) Press Run button
2.) Press to turn on lights
View video below, may
need to resize window to
view
3.) Select load from pull down menu
4.) Read strains and load from the
boxes labeled at the left
You will first need to hit the run button at the top of the picture. Then
you will turn on the lights by pressing the button that says lights. Next
use the drop down scroll bar to select the load to apply to the beam.
Once the load has been reached read off the strains for each gage and
record in your data sheet. Once you are done loading make sure you
unload the beam and remember to turn off the light before you hit the
stop button that is located at the top to the page. Once this has been
done you can simply close your web page.
APPENDIX IV
Assessment questionnaire and responses
1) What could be done to improve the online lab to make it a better
teaching tool?
• One thing that could be done is to maybe somehow find a way to put
something up to show how the load acts and how the beam deflects more
accurately. Besides that, materially, it is explained very well, and the
study sheet really helps you prepare adequately for the actual experiment.
• One thing that could be done to improve the online lab would include
fixing the excel data sheet (that is sent to the user’s email account) so
that it is properly labeled. I had a hard time figuring out what the
values represented.
• To improve the online lab the excel spreadsheet could be made easier to
understand or maybe a legend with it to explain the columns.
• The only thing I thought that could have been improved to make this lab
better would be to allow you to do the lab even if you did not sign up to
24 hours in advance. If a time was open and no one was performing the
experiment then I did not see why you could not just log in and do the lab
right then.
• To improve the online laboratory I would first work out all the bugs to
make sure it would let everyone in. I heard form several classmates that
they were unable to get in and actually do the lab. Also, an online forum
might make it easier for classmates to chat and discuss concepts, which
would make it similar to a lab setting in which they can interact and even
the instructor could be present.
• This lab could be improved by making it easier to access. I know that I
had trouble getting on the website and having to make it work for me. I
ended up having to go up to a TA’s computer to do the experiment.
Otherwise, it was pretty straightforward and just required time. There’s
nothing we could have done in terms of errors or mistakes, so there wasn’t
much difference between just being given the numbers or running this
experiment and watching it give you the numbers.
• Explain a little better what exactly needs to be included in the lab
report.
• The internet did not work properly for some people in my group. If you
could make the lab compatible with other browsers it would be better.
• The actual loading of the specimen took an extremely long amount of
time. It was actually very boring to watch the load increase. I lost my
interest by the time it reached 1000 lbs. Is there anyway to load it
faster.
• The online lab could be improved by making the data which I emailed to
myself more interpretable and useful. I received 17 columns and almost
17000 rows of unlabeled numbers and it took me some time to realize what
any of them meant. In the end, I did not make any use of them.
• One thing that could improve the online lab would be to do the lab in
teams with a TA or professor available. Some things are not easily
understood without a TA present.
• I feel that the lab could be improved in several ways. I think that
students should have more access to the labs than having to sign up a day
in advance then go through multiple sign in problems. Most students have
a hard enough time as it is finding time to set aside to do it but may be
able to just decide to sit down and do it.
• I think that more class discussion of the aspects of the lab would have
made the online lab more helpful.
• The online lab could be a better teaching tool if the T.A. was ore
directly involved in the process, to field questions in determining values
and utilizing data obtained from the experiment.
• I think that you need to find an undisturbed place where the camera and
equipment can be setup and not be touched until the experiment time is
over.
• Need a couple of in class sessions to explain the methodology of using
the tools, also inclusion of the ability to do the lab online and hands on
to better understand.
• I think that having a labeled diagram of the items that are being
recorded during the lab would be helpful in understanding the lab.
• The lab is adequate, but a shorter signup time would be helpful.
• By completing the lab over the internet, I found it more difficult to
complete and understand the lab. While the convenience of not coming to
campus for lab was nice, the absence of an instructor and the tangible
learning experience made it more challenging.
• The main problem with the online lab was that it gave technical
difficulties. If those could be worked out then it would be a great way
to conduct a lab.
• One thing that could improve the online lab would be to have it done in
teams rather than doing it individually.
• The online lab seems to be a good teaching tool. As long as the students
give themselves enough time to become acclimated to the procedure, it is
easy to understand and run the experiment.
2) Are the instructions adequate, and the lab theory understandable and
clear?
• The instructions are adequate because they are laid out before you very
directly, step by step. The theory, for the most part, is understandable,
except that there are so many equations, and it seems like some of them
don’t have a very good explanation (i.e. equations 6, 7, and 8). There
probably shouldn’t be more of a write up about them, but possibly just a
little more explanation in the lab. However, it isn’t extremely
necessary, as long as you take a good look at it.
• Yes, the instructions seem to be adequate. It was easy to download the
software needed and to carry out the experiment.
• The instructions are pretty clear and the lab theory is understandable.
• I think the instructions were adequate and very easy to follow.
• The instructions are clear and adequate but the theory is not completely
clear, which I feel the online forum, as suggested above, could help with
the understanding.
• The instructions were clear and it was easy to follow. There were no
tricks that were hidden that you may have had to know. I think that
anyone could have run the experiment.
• The instructions are clear, but the theory was not fully described.
• The theory was not as clear as it could be. Without the TA present, we
got confused.
• I believe that the instructions for the lab were very adequate. The
only other thing that might have been interesting to see, would be how the
actual instrumentation was set up, seeing that we were not actually in the
laboratory to set it up.
• The instructions were adequate and the lab theory was understandable and
clear.
• The instructions are adequate, but the theory is a little hard to
understand. It is hard to compare the formulas in the theory to the lab
data sheet we are provided.
• I think that the lab theory was very understandable and clear to what we
were doing. Going over the basic principles in class definitely helped.
The instructions and all the different links on the website were a little
confusing at first, but as long as you read them all it is very easy to
understand.
• I believed the instructions on how to run the lab were very
understandable and clear.
• The instructions are adequate, and the lab theory did make sense,
although there were a few points where some of the wording in the text is
vague, with regard to equations.
• The instructions and theory are both very understandable. I understood
what I was supposed to be doing and what I was supposed to learn.
• The instructions were adequate when explained by the TA thoroughly. The
lab theory however was difficult to grasp with just handouts. A time to
come in and discuss questions would be good to include as an optional
event.
• The instructions were helpful in understanding how to conduct the lab
and the lab theory was understandable.
• It is understandable, but I think it would work better if the class
could get in front of computers and do the lab together. That way, we
still get the online experience, but it is easier to have questions
answered. The process is hard to remember when you have only a small
presentation of how to do everything.
• The instructions were enough to complete the lab, although probably not
enough to fully understand it.
• Yes, the instructions were clear. I would spend a few more minutes in
class explaining exactly what is needed.
• The instructions are adequate, but the theory is a little hard to
understand. It is hard to compare the formulas in the theory to the lab
data sheet we are provided.
• The instructions are very clear and lead you through the lab in a timely
manner.
3) Is remote experimentation a good alternative to use in the lab, or is
in class better suited for laboratory learning? Please explain.
• First off, in class is always the best way to learn in the lab, just
because it truly is “hands on.” However, remote experimentation is very
interesting, and it does provide another way to learn the material, but
it’s not as good of an option as actual in class experimentation. In
class experimentation makes everything easy to see, in comparison to
remote experimentation, partly because group work is encouraged more in
class experiments as well.
• I think for this lab, the remote experiment is a good alternative to
being in the classroom. The lab itself is very easy to explain and carry
out and with the remote application the experiment can be performed at
anytime as many times needed.
• I think remote experimentation is a good alternative to use in the lab.
I would like the option of attending a lab if I really didn’t understand
the material.
• I think the remote experiment was a great experience and a neat way to
do a lab which I had never done before. It was also good because it gave
you the flexibility to perform the experiment whenever you wanted to.
• I feel that in its current setup, I would prefer an in person lab,
mostly because I would have an instructor and classmates to ask questions
to and help get a full grasp of everything. But I can definitely see the
online lab being a better alternative in the future, because of its
convenience to a time schedule.
• I like the lab setup better just because of the variation in numbers and
actually doing something manually, rather than watching it on a computer
screen. I just feel like I get more out of it when I can see what is
going on and being a part of it.
• It’s interesting and all, but I feel that I learn more about the subject
at hand when we meet to do the lab.
• I think maybe individual teams working on the lab with the TA would work
better.
• I believe that this takes away from the laboratory experience. Sure, it
was nice to not have to stay in the lab for an hour or so, but you lose
something when the answer is just a click away. There’s no setup, no
group work, and there’s nothing to compare your results to. In the lab,
we usually are able to compare our results to other groups, where here, we
have nothing but our own work to compare to. I believe that the online
system turns a lab experiment into something like a homework problem. You
might as well have gave us the numbers and told us to write a report on
it.
• I think, in general, in class labs are better for learning the material,
by doing the entire lab hands on. Having the experience of doing a lab
remotely once was also useful, but I think I would have learned a lot less
if all or most of the labs had been performed remotely.
• I do not think there is anything really wrong with the remote
experiment. However, I think an in class lab is better suited for
learning. The lab would be easier to understand if you are working with
others and you have the lab TA there to help you through any problems that
may arise.
• I think that all labs are always better suited in the classroom. This
lab was very easy to perform and it was very useful to know how to
remotely control the experiment, but the classroom allows you hands on and
the ability to learn more and ask questions.
• Personally I prefer the in class lab, because I like to have a hands on
feel and like to be able to speak to the instructor if I have any
questions.
• I definitely believe in class is the preferred alternative for
laboratory leaning, for the value of working had on with a project, and
having someone there who can field questions regarding the lab.
• I think that in class is the better way to learn because I like to
actually have hands on experience with my peers when doing these labs. It
is just a learning preference for me but online labs were effective in a
minimal way.
• I believe the in class experience is good to continue to do because it
will allow you to visibly see what is going on and how the things work.
In addition, you will be able to see where you sources of error can come
from. However, more complex computer oriented labs are better suited
online. I believe the inclusion of both in the curriculum is the best
option for laboratory learning.
• I do not think that remote experimentation is a good alternative, but I definitely think it is a
useful tool that should be used in conjunction with the lab. For easier labs such as this one,
where the actual conducting of the lab report is not so difficult, the remote alternative saves
everyone time and effort.
• I like in lab learning better.
• I feel that the remote experimentation is not a good alternate to the in class lab. It seems the
online actions take away from the whole purpose of the laboratory classes hands on experience.
• Remote experimenting is a good way to implement a lab. The theory was nothing out of the
ordinary and it really made it an easy lab to complete, while still getting the same learning
effect and understanding of what’s going on.
• I think an in class lab is better suited for learning because you are
working with others and you have the lab TA there to help you through
misunderstandings.
• In my opinion, I prefer labs that are run in the class setting.
Questions may come up that can be answered right away and it is easier to understand exactly
how the experiment is set up.
Exam Questions
Prestons Lab
Points missed on question pertaining to remote lab: Remote group: -7.2/25
Non-remote group: -5.8/25
Average Exam grade: Remote group: 66.25
Non-remote group: 64.25
Jerrys Lab
Points missed on question pertaining to remote lab: Remote group: -6.9/25
Non-remote group: -5.5/25
Average Exam grade: Remote group: 68.3
Non-remote group: 75
Nothing very unusual, looks like the remote users did slightly worse on the question but
nothing significant. From both lab sections the non-remote group scored 1.4 points
better on the question than did the remote group.