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3.1.5
STRUCTURAL
EFFICIENCY
HAROLD HYTE
TJ HOLASKA
LOGAN BOSTIC
PROJECT
INTRODUCTION
Structural engineers face the challenge of designing structures
that can support not only the weight of the structure itself but
other loads as well, such as forces caused by people, furniture,
snow, wind, and earthquakes. The structural framing system
should be designed to carry these loads in an efficient manner.
Because the cost of construction materials used to build a
structural system is often based on the weight of the materials,
it is cost effective to use the least amount of material necessary
to provide a structure that can safely carry the applied loads.
The most efficient structures are strong and lightweight.
One measure of the cost effectiveness of a structure is
structural efficiency. Although structural efficiency can be
defined in many ways, in this activity we will define structural
efficiency rating as the ratio of the load applied to the structure
to the weight of the structure itself.
Structural
efficiency =
41.23%
2lbs /
.048501lbs
STRUCTURE IMAGE
This was our original structure. After this we decided to put the
three struts in a conical shape to increase it’s strength.
IN THIS PROJECT YOU WILL WORK IN A TEAM OF
THREE TO DESIGN AND CONSTRUCT AN
EFFICIENT STRUCTURAL FRAME (USE PLAYING
CARDS AND MASKING TAPE) TO SUPPORT A
MAXIMUM DESIGN LOAD OF FIVE POUNDS.
PROJECT
OBJECTIVE
COMPETITION
RESULTS
Team
Weight of
Structure
(lbs)
Load
Supported
(lbs)
Structural
Efficiency
Knea
Carsen
.0485017
5
103.05%
Lee
Regan
.061729
8
129.6%
Nathan
Justin
Chandler
.061729
6½
Harold
TJ
Logan B.
.048501
2
41.23%
Logan H.
Aaron
Noah
.044092
3
68.09%
105.29%
Our structure was
able to hold .048501
lbs and supported 2
lbs of weight. This
gives it a structural
efficiency of
41.25%.
Structural efficiency
is calculated as
load applied /
weight of structure.
PROJECT
CONCLUSION
1.What factors could affect the choice of materials for the structural frame of a
building?
The purpose of the building means it will have a different load it is required to support, and as
such sometimes an extremely strong material is not required. The strength of whatever
material is going to be used can also effect the material selection.
2. Is it advisable to compare the Structural Efficiency Rating for two different proposed
framing systems for a building if one system uses structural steel framing and the other
uses cast-in-place concrete? Why or why not? If not, what would be a better
comparison to determine efficiency?
Yes, because while they would have a different weight and would also be able to support a
different amount of load, you’re comparing their efficiency to support the load for the amount
of weight they have, so it is exactly what you want.
3.Why would a structural engineer be more interested in the Structural Efficiency Rating
using the maximum design load than the efficiency determined by using the maximum
load capacity of the structure?
The maximum design load is used supposed to be a safety precaution to prevent the structure
being destroyed under the maximum load.

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