High School STRUCTURAL DESIGN AND ENGINEERING
2016 PROBLEM STATEMENT
BACKGROUND
Structural engineers design and analyze structures that support or resist loads, such as
buildings, large non-building structures, machinery, medical equipment, vehicles, or any item
for which structural integrity affects function or safety. Structural engineering work is based on
physical laws and practical knowledge about the performance of different materials and
geometries.
Structural engineers use a number of simple structure elements to build complex structural
systems. Through structural analysis (a key component in the structural design and engineering
process), engineers determine the effects of loads on structures and their components. Applied
mechanics and mathematics, and materials science are used in structural analysis to help
compute a structure's deformations, internal forces, stresses, support reactions, accelerations,
and stability. Analysis results help to verify a structure's fitness for use and, in many cases, can
eliminate the need for actual physical tests.
CHALLENGE
Research light rail transit systems, and then develop a design for a box girder support beam and
rail bed for a light rail system.
Consider the following:
1. Aesthetics
2. Height requirements
3. Rail width requirements
4. Maximum allowable span between vertical supports
5. Dead load of a single span
6. Live load of a single span
7. Minimalist design and engineering concepts
8. Materials
9. Off-site pre-built or pre-fabricated components
10. Utilities
The submitted structure will be tested using a TSA-designated testing instrument. The center of
the structure must maintain a one-inch (1") hole and clearance so that a rod can be passed
through the structure for testing.
Balsa wood is the designated construction material; participants may choose their own glue
type. The box beam girder must remain open at each end so that judges are able to view the
interior design and layout. Only the exterior surface area of the box beam girder may be
covered (with dimensional sheet balsa wood). The railway support structure should be attached
to the top of the box beam girder; the test block will rest upon this surface.
SIZE CONSTRAINTS
Beam structure
Length: 16"
Width: 3 ¾"
Height: 2 ½"
MATERIALS
Box girder beam structure
Balsa wood strips
five pieces, 1/16" x 1/16" x 24"
five pieces, 1/8" x 1/8" x 24"
five pieces, 1/8"x ½" x 24"
Rail structure
Length: 16"
Width: 4 ¾"
Height: ¼"
Railway gauge inner spacing: 3 ½"
Railway structure
Balsa wood strips
five pieces, 1/8" x 1/8" x 24"
Balsa wood sheets
two pieces, 1/32" x 3" x 24"
Standard card stock (65 lb.)
one piece, 8 ½" x 11"
DESIGN CONSTRAINTS
1. Teams should design and construct the strongest box girder beam possible, applying the
principles of engineering and using the least amount of materials. The design should serve as a
modular component in a light rail system.
2. At check-in, teams must present a simple, full size, three-view drawing (all views on one side of
an appropriate sized sheet) that show each structural member of their design.
3. Identified materials may not all be needed to design and build a winning structure; the use of
too many materials may be a negative factor in calculating the efficiency of the structure after
testing.
CONSTRUCTION CONSTRAINTS
1. Substructures are not allowed.
2. For this event, lamination refers to the combining of two or more pieces of material with the
grain running in the same direction; laminating pieces of same size balsa materials is not
allowed for this event; laminating of card stock also is not allowed.
3. Lap joints are allowed and involve gluing two pieces of balsa material with the grain pattern
normally at right angles; however, any lap joint less than 10° or greater than 170° would
circumvent the lamination guidelines and be ruled unacceptable.
4. The 1/32" balsa wood sheets should be used as the outside covering of the box beam girder;
pieces of these sheets also may be used to create internal construction components (combined
with the other materials), as long as the lamination guidelines are followed; pieces of these
sheets may not be laminated together.
5. The card stock may be used to create a watershed/covering for the beam underneath the rail
bed; it also may be used as gusset material to connect/reinforce butt and end joints of
materials; cardstock may not be laminated between structural members.
6. No hot glue may be used, and the use of glue for coating structural components is not
allowed.
7. The dimensions noted for the rail bed portion of the design are fixed in terms of
minimum/maximum widths and heights.
8. The beam and rail structure lengths are fixed.
9. The total height of the entry (which includes the rail bed) where it rests on the abutments, must
be 2 ¾".
10. All other dimensions for the box girder beam section of the entry may be below the maximum
dimensions noted.
TESTING
1. A PITSCO structure testing instrument will be used for stress testing.
2. Testing block: ¾" thick x 3 ¾" wide x 12" long hardwood stock, with a piece of 1/16" thick x
3 5/8" wide x 12" long stock glued centered side to side.
3. During testing, 1" at each end of the structure will rest on the two testing instruments vertical
supports.
4. Failure of a structure occurs when the testing instrument records structural failure.
REQUIREMENTS FOR CHECK-IN
1. Completed model structure
2. Three-view drawing
3. Verification form (page 321, 2015 & 2016 HS Competitive Events Guide)
4. Assessment form
ILLUSTRATIONS/PHOTOS
The illustrations and photos that follow provide example information about the box girder beam.
Although the configuration illustration shows a rectangular shape for the box girder beam, this is not a
requirement for a team’s design.
Basic configuration
Lamination
Examples of beam supports and configurations