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1. Forging new generations of engineers

2. BEAMS AND COLUMNS

3. A “good” design?
 The building dead load is the only known
load. All other forces will vary in
magnitude, duration and location.
 The building is designed for design load
possibilities that may never occur.
 The structural efficiency of a building is
measured as the ratio of dead to live
load.The building designer strives to keep
the ratio low.

4. Beam Design
• Beams are used in floors and roofs.
• Maybe called floor joists, stringers, floor
beams or girders.
• Loads on beams are either concentrated
or distributed (uniform loads)
• Designed for Shear, Moment (bending)
and Deflection

5. Beams
• Beams are sized appropriately to safely support
the loads a structure will carry.
• Beams are primarily subjected to bending and
shear.
• Deflection and deformation can be calculated.
• Beams are sized to provide the maximum result
with the minimum materials. A factor of safety is
included in the design.

6. Beam Deflection
• Limit Deflection to
– L/240 of total load (whereas L=length in inches)
– L/300 of total load
– L/360 of total load (building use throughout life is
unknown) Preferred
• WHY??
– Ceiling cracks in plaster
– Roof ponding (flat roofs)
– Visual or psychological reasons
– Designer’s judgment

7. Beam Types
• Simple
• Continuous
• Cantilever
Moment
(fixed at one end)

8. Beam Types
• Fixed
Moments at each end
• Propped- Fixed at one end supported at other
• Overhang

9. Forces and Supports
Supports are translated into forces and moments in a
free body diagrams. The following are three common
supports and the forces and moments used to
replace them.
Roller:
Pin
Connection:
Fixed
Support:
Fy
Fy
Fx
Fx
Fy
Mo

10. Columns
• Columns carry primary Axial Loads and
therefore are designed for compression.
• Additional loads from snow, wind or other
horizontal forces can cause bending in the
columns.
• Columns then need to be designed for
Axial Load and Bending.

11. Forces
F (External)
WCOL (External)
R1 (Internal)
R2 (Internal)
RSoil (External)
WFTG (External)
R2 (Internal)
WFTG (External)
R4(Internal)
Footing
F (External)
WCOL (External)
R3 (Internal)
Column

12. Reference Sources
– Jefferis, A., & Madsen, D. A. (2001). Architectural Drafting and
Design. Albany, NY: Delmar, a division of Thomson Learning.
– Kane, K., & Onouye, B., (2002). Statics and Strength of
Materials for Architecture and Building Construction.(2nd
ed.).
Saddle River, NJ: Pearson Education, Inc
– Shaeffer, R. E., (2002). Elementary Structures for Architects and
Builders (4th
ed.). Columbus, OH: Prentice Hall.
– http://www.concretenetwork.com/concrete/footing_fundamentals/
why_soils_matter.htm
– http://www.emporis.com/en/
– http://www.pbs.org/wgbh/buildingbig/lab/forces.html