REVIEW LECTURE #1
KNOWLEDGE BASE REQUIRED:
STRENGTH OF MATERIALS
STEEL DESIGN
TIMBER DESIGN
SOIL MECHANICS
WE COVERED:
AREA AND CENTER OF GRAVITY
Itotxx = Ixx + Ay2
SECTION MODULUS
RADIUS OF GYRATION
SOLVED ONE PROBLEM
MECHANICS OF
MATERIAL BEHAVIOR:
WE REVIEWED STATICS:
DEFLECTION COMPUTATIONS
SOLVED DEFLECTION PROBLEM
•DUE TO LOAD
•DUE TO THERMAL EXPANSION
WE REVIEWED FLEXURE:
f
b
M

S
REVIEW OF STATICS (CONT’D)
MOMENT -SHEAR DIAGRAMS
SAMPLE PROBLEM
12000#
2'
16000#
18000#
6'
4'
14000#
SOLUTION
4000LB
-14000LB
56000 FT-LB
32000FT-LB
SIMPLE SUPPORT
CANTILEVER
OVERHANGING
CONTINUOUS
IN FORMING AND BRACING DESIGN MANY OF
THE MEMBERS HAVE MULTIPLE SUPPORTS.
WHAT IS THE DIFFERENCE
BETWEEN A CONTINOUS MEMBER
AND A SIMPLE SPAN??
Will the loads be higher for the
simple span or the continuous span??
Will the Shear be higher for the
simple span or the continuous span??
Will the Moments be higher for the
simple span or the continuous span??
IN FORMING AND BRACING DESIGN MANY OF
THE MEMBERS HAVE MULTIPLE SUPPORTS.
ASSUME A SPAN OF 10 FT. AT 1K/FT:
wl
A
B
C
D
SIMPLE SPAN SOLUTION
w=1k/ft
A=5k
.5wl
B=10k
.5wl
Vmax=.5wl=5K
Mmax=12.5 K-FT
C
.5wl
D
CONTINUOUS BEAMS - THREE SPANS
CONTINUOUS SPAN SOLUTION
w=1k/ft
A=4k
.4wl
B=11k
.5wl
C
.6wl
.4wl
Vmax=.6wl=6K
Mmax=10K-FT
D
.4wl
CONCLUSION:
NOTE:
•A Continuous Span will have:
 10% more load on its interior
supports than a simple span
20% less load on the exterior
support than a simple span
•Shear is greater in the continuous span solution 6K > 5K
•The maximum moment is greater in the
simple span solution 12.5 k-ft > 10 k-ft
CONCLUSION CONTINUED:
• The length of the Wood member would have to span
over all of the supports of the beam as one piece,
because it is difficult to splice different member together
effectively to achieve continuity!!
•Steel members would have to be the length of the full
member because you can splice the pieces together, but
welds and bolts are not sufficient enough to prevent stress
concentrations across the connections!!