Civil Engineering
CE121 – Structural Engineering I- Lab
Fall Quarter – 3rd Year (Required)
IMPORTANT LAB SAFETY RULES:
Read and understand all the Material Safety Data Sheets of the Structures Lab (MSDS sheets are
outside the lab door).
Never work in the lab alone and without supervision from a Cooper Union Technician or a
Professor.
You are not allowed to operate or build something in the lab without direct supervision of a
faculty member or a technician.
Be careful with your steps. There are tripping hazards in the Lab.
Weekly Laboratory Schedule:
Form groups of four, with documented division of responsibility.
Survey the Lab and draw a floor plan of it. Produce a typical architectural drawing
with dimensions in feet-inches, equipment table, scale and title box. Do not show
details less than 6”. Include the First-Aid kits (inside the lab) and the MSDS box
outside the lab door. Read the Material Data Safety Sheets (MSDS) and write a report
about the MSDS materials and their most important PRECAUTIONS (one report per
student). Submit a drawing of the Lab (one per group).
Prepare for next week’s experiment (see below). Make sure that you can setup a way
to measure the very small deflections of the tension specimen during the experiment
(Talk to the Lab Technician about it).
Plan for Welding lessons in the next 8 weeks.
Week #1
Tensile Strength of standard metal specimens.
The goal is to plot the experimental stress-strain relationship and compare it with the
theoretical. Plot on the SAME diagram BOTH the experimental and the theoretical
curves. Then obtain the Proportional Limit, the Yield strength at 0.1% and 0.5%
offset, the Ultimate tensile strength, and the Modulus of Elasticity. Load to yield and
then unload. Measure the permanent deformation. Reload to failure.
Comment on the type of failure. Explain any discrepancies.
Draw plan and front view of the equipment and specimen tested.
Week #2
Setup next week’s experiment: Each group should select a different bar (length and/or
x-section) to test in compression. Then all groups will share the data to plot Stress v.s.
(L/r) AND COMPARE with the theoretical curve. Check the theory of buckling in the
last chapter of your Solid Mechanics textbook and include ALL deravations.
Euler buckling of slender bars (aluminum and steel).
Draw plan and front view of the equipment and buckled specimen.
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Week #3
Vibration of bars and frames. Define and compare the shapes of the fundamental, 2nd
(or 3rd mode) and corresponding resonance frequencies of vibration. Compare theory
with experimental data. Define and calculate the damping ratio for your specimen.
Week #4
Prepare for next week: Find out how to mix Cement, Water, Sand and Aggregates, in
order to fill a 6" diameter cylinder with a 12" height. (Make some extra concrete, so
that you will have enough to fill the cylinder.)
Go to the library and search textbooks and articles for ways to mix concrete using
formulas and charts to achieve your assigned strength. Do not just use a web link
with suggested quantities as in http://chadronconcreteandblock.com/concreteprod.aspx
A concrete mix is specified by indicating the weight (lbs) of water, cement, sand,
coarse aggregate, and any admixture per cubic yard of mixed concrete. Compare your
mix with the empirical formula 1:2:3 of cement:sand:aggregates, and a water to
cement ratio (w/c) of w/c=0.40 to produce fc’=4.3ksi or a w/c=0.5 for fc’=3.5ksi and
a w/c=0.65 for an fc’=2.4 ksi.
Come in the Lab next week, with the exact amount of the 4 materials needed to
produce the cylinder. Required concrete compressive strengths are: Group#1
fc’=2.5ksi, Group#2 fc’=3ksi, Group#3 fc’=3.5ksi, Group#4 fc’=4ksi, Group#5
fc’=4.5ksi, Group#6 fc’=5ksi
Schedule your concrete mix with Luis. Make sure that the concrete slump is 3 to 4
inches. Mix the wet concrete very well and make sure that you have no dry patches in
it.
SAFETY RULES:
Use gloves and eye protection when handling wet concrete:
Exposure of sufficient duration to wet portland cement can cause serious, potentially
irreversible tissue (skin or eye) destruction in the form of chemical (caustic) burns.
The same type of tissue destruction can occur if wet or moist areas of the body are
exposed for sufficient duration to dry portland cement.
Use dust masks and eye protection when mixing concrete:
Exposure to airborne dust may cause immediate or delayed irritation or inflammation.
Eye contact by large amounts of dry powder or splashes of wet portland cement may
cause effects ranging from moderate eye irritation to chemical burns or blindness.
Such exposures require immediate first aid (see MSDS Section 4) and medical
attention to prevent significant damage to the eye.
------No report is due next week, but prepare it for Week#9 when you test your cylinder.
Setup next week’s experiment: Each group should select a different bar. Find the
theory about the vibration of single and multi-degree of freedom systems. Then
concentrate on how to obtain the first 3 natural frequencies and modes of vibration for
a cantilevered beam with uniformly distributed mass.
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Week #5
Bridge project definition and ideas building. Submit individual sketches of your
designs by next week. Provide a Side view, top view and typical x-section in sketches
on a graph paper using the same scale in the horizontal and vertical direction. The xsection scale can be larger than the top and side view. Use pencil. If you prefer, you
can also try a 3-D sketching software. Save your sketch to include it in the final report!
Week #6
Installation of strain gages. Schedule your installation with Luis. No report is due this Week #7
week, but prepare theory of strain gauges (explain what is a Wheatstone bridge, etc.) to
include in next week’s report. Show your individual bridge sketches to the Professor
and select a design to represent your group.
Bending stresses and strains. Compare actual stress measured, with the theoretical
ones. Comment on any discrepancies. Write a report in the standard format, including
strain gauge installation and theory. Draw your final group Bridge design in a 3-D
software and start the structural Analysis.
Week #8
Compression strength of standard concrete cylinders. Write a report about your
Week #9
concrete mixing 4 weeks ago, and explain any differences between your assigned fc’
and the experimental one.
Finalize x=sectional design and show analysis and design calculations to the Professor.
ORDER materials.
Draw bridge members and connections in detail .Produce construction drawings and
Week #10
use them to cut members and drill/weld connections. When ordering wood members, it
is better to order the actual x-sections instead of a larger x-section that needs to be cut.
Start building the Bridge.
Week #11
Equipment use and safety. Start building the Bridge. Cut members to exact length,
Week#12
drill holes and or weld members. Schedule with the Lab technician the times when you
are going to build your bridge, so that you can be directly supervised. No student is
allowed to work alone or unsupervised. For your safety, there will be serious
consequences if this rule is violated!
Welding lecture. Bridge Building
Week#13
Bridge Testing
Week #14
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Written report is due.
Submit the final (bound) report with the same sections as the normal weekly reports.
Week #15
The final report should include at a minimum: All preliminary sketches with your
individual name, title and scale. Your calculations and how you arrived at the
geometry and the size of the x-sections.
After loading the bridge to nonlinear deflections and then unloading and reloading to
failure, plot loading and unloading curves and comment on any differences from linear
behavior. Comment on the mode of failure and explain why it failed that way. Include
a picture of the failed bridge with comments. Write about lessons learned from
designing and building your bridge. In a separate page, calculate your bridge score (be
honest about construction time). Submit representative Finite Element input and
output data (not more than 20 pages) and ALL your Excel and hand calculations.
Highlight important data on the computer output, type the units and explain what they
mean. Provide side view, top view and a connection detail of your bridge. Give
addresses and phone numbers of your suppliers on a separate page.
Report Format for CE121 Lab
Cover page: Giving title, group members, dates etc.
Table of Contents: Listing of the following sections and figures.
1. Objective
What the experiment was about.
How it was conducted
Where it was conducted
2. Experiment
Apparatus and procedure.
Draw engineering plans and sections of equipment and materials used in the experiment.
3. Theory
Clearly describe theory of Test equations etc. (Stress, strain as a function of shape and material,
etc.).
Sample calculations.
4. Results
Clearly describe all your graphs, neatly prepare all tables, graphs, etc. Show calculations.
5. Conclusions
Important findings, equations, etc. You will be required to do some research for a good
conclusion.
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6. References
By number and refer to these references in your report.
7. Appendix
Lab notes, data sheet, sketches.
Make sure to label and number all figures and tables. Refer to them by
the same number in the body of your report.
Have all the variables and their units clearly listed in your figures and tables. Be consistent with
significant figures and decimal places.
Note: All images and diagrams borrowed from outside sources must be clear and properly cited.
All engineering plans must have a proper title box, date, and scale per drawing. Units and
conversions must be consistent.
Your written report will be graded based on:
1. Presentation
a. Appearance (binding, typescript, uniformity, titles, pagination, etc …)
b. Mechanical organization (title page, table of contents, appendices, bibliography,
etc)
c. Illustrations (quality, quantity, relevance)
d. Logical organization (Introduction, development, conclusions, etc)
2. Language
a. Tone and pitch to intended audience
b. Legibility and persuasiveness
c. Quality of thought, logic tightness and articulation of argument
d. Grammar
e. Style
Administration and Organization of Laboratory work
1
The class is divided into groups of four
2 A project leader and a recorder are elected from among and by the group members. They
will begin the initial meeting of the group, organize it and oversee the overall development of the
project. The function of the recorder is to keep the minutes of the meetings and to centralize the
information gathering. This documentation is kept in the group folder which must be brought to
class every time and is to be submitted to the instructor along with the final report.
3 The class is divided into several experiments, lasting approximately one week each and a
final bridge building experiment that lasts 4 weeks. A new leader and a new recorder will be
elected for each new phase.
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4 Class time (scheduled hours) is used for experiments, group discussion and decision-making
process. Research, analysis, design and development work is mostly conducted outside of class
hours.
5 The instructor serves as a consultant to the group and interact through the project leader
as well as directly with the group.
6 For the Bridge Project, each leader makes a brief two-minute oral presentation, in the
presence of the instructor and other groups, of the work completed thus far, the problems
encountered and the solutions obtained, and the anticipated work for the next phase
7 A formal, type-written report, professionally prepared, with proper illustrations, figures
and supporting documentation, is due at the completion of the project.
8 Use the Laboratory usage (Weekly Schedule) listed above to prepare for the Design of the
next experiment.
9 Each student must contribute to the setting of goals and the organization of tasks in the
group.
10 Each student must be able to critically apply corrective actions based upon feedback from
others.
11 Each student must participate, listen and cooperate with others, share information and
reconcile differences.
13. Each student should provide an overall (semester) rating (1 worst 10 best), for every
member of the team and include it on the final Bridge project.
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Bridge building Project
Build a 6 foot bridge, to simulate the ASCE steel bridge competition rules as close as possible.
Scale all the dimensions of the official ASCE bridge competition by a factor, such that the
longest span of the ASCE bridge will become 6’. Make sure that you preserve an unobstructed
5.5”x10” x-secction through the bridge, to simulate the vehicular traffic, or use an open top deck.
For safety reasons, your bridge should be designed to yield or buckle when the total vertical load
on the bridge reaches 400lbs. Your bridge should collapse or have large nonlinear deflections at a
load not more than 500lbs, when applied in the middle 2’ of your bridge.
Please note the maximum size of a member in the bridge is 14inches long (except for cables) and
not more than ½ inch thick for steel, (½” * 36ksi/Fy for other materials). If you need longer
members, connect two (or more) together.
Tip: If your calculated bridge member x-sections are too small, you may elongate them to
increase their buckling length, or you can reduce the height of the bridge to as low as 6 inches
(without impinging on traffic clearance). To minimize construction cost, reduce the number of
members and connections.
Try to design an innovative and aesthetically pleasing bridge. A beautiful design will give you as
much as 25% extra credit.
Start your bridge exploration with a sketch on the same horizontal and vertical scale using graph
paper. Draw the boundaries of the bridge first.
Bridge score sheet.
Aesthetics (see section 6.1 for criteria.)
Appearance: balance, proportion, elegance, finish.
AESTHETICS SCORE (A) (Best is 0, worst is 100) = _____________
Construction Speed
Time require to construct the bridge.
CONSTRUCTION TIME (T) =
_______Total minutes x NumberOf Builders / 3 = _____________
Weight
WEIGHT (W) =
_____________pounds x 5 = _____________
Stiffness
MAXIMUM DEFLECTION (D) =
_____inches x 20=____________
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Overall Performance
T_____ + W _____ + D_____ + A_______ =
____________
Lowest total wins. Aesthetics is the tie-breaker.
In addition, Each student should provide an overall rating (1 worst - 10 best), for every
member of the team.
Bridge Design References on the web
Bridge Slide Library http://www.eerc.berkeley.edu/godden/index.html
Bridge Clearinghouse http://www.iti.northwestern.edu/clear/bridge/
Structural Design and Bridges
http://www.struct.kth.se/research/bridges/index.html
West Point Bridge Designer (software)
http://bridgecontest.usma.edu/
AISC Steel Bridge Competition
http://www.aisc.org/education.asp?ar=20&co=31
Professor Tzavelis’s Lecture
http://www.cooper.edu/~tzavelis/classes/bridgeslecture
Steel suppliers we have used in the past:
Colonial Steel at 855 East 140th Street, Bronx NY 10454.
Tel. 718-9935500
Joseph T. Ryerson & Son Inc at Box 484, Jersey City, NJ 07303
Fax 201-4353434
Weinstock Fasteners on 358 West Street, Manhattan
212-9291500
www.McMaster-Carr.com
www.onlinemetals.com
800-70422157
Or any other that you might prefer.
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CE Departmental Lab Policy
1. No student or group of students, undergraduate or graduate, can work
in any of the CE labs, C-14 or non-C-14, unless a professor or a
technician is present in that particular lab at all times that the students
are working in that lab. This means that the buddy system is no longer
allowed.
2. For the single C-14 CE Lab (the environmental lab), a C-14 Professor
or a C-14 technician must be present in that lab at all times when the
students are working in that lab.
3. The CE Research Design Lab (Room 401) is exempt from the
requirements 1 & 2 above. CE juniors, seniors and graduate students will
be given ID Card-swipe access to Room 401 in the near future.
4. The CE Department will try to accommodate all reasonable requests
by CE students to work in the CE Labs but this will be permitted only
during 9AM-5PM workdays when we can assure that a professor or a
technician is present in the lab. A student must obtain prior approval
from the faculty advisor or the chairman at all times so we can assure
that arrangements have been made for a faculty member or a technician
to be present in the lab. Except for Room 401, students, undergraduate
or graduate, have not been provided programmed ID-Card swipe access
to any of the CE labs. This means that without prior approval, students
cannot gain access to any of the CE labs.
5.If a student wants to use the labs during off hours (other than 9-5
workdays), it is the student's responsibility to obtain prior approval of
the Chairman. This will be allowed only if the department is able to
assure that a faculty member or a technician has agreed to be present in
the lab during the off hours when the student will be working in the lab.
Since the Dean of Engineering has made it clear that payments to a
technician for off-hours work are not in the budget, this means that a
professor or a technician will have to volunteer their time for off-hours
work for a student to work in the lab.
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