Announcements: Day 9

Day 9: Announcements

Homework

Due Tuesday.
Questions?
Today's Assignment

Lab

NExt week is the BIG event....
5 pound weight available in 5-418 during "business hours"
AFTER you have completed the construction of the bridge, paint one "fassade" with a white wash or light spray of white. This is to enhance the visualization of the failure mode as it is filmed.

Today's outline......

Thursday walk-about

1. The Hallway in front of 3-133

Floor Loads

Tributary Area?
Dead Load
Cement Block 8" (55 psf of surface)
Terrazzo (12 psf per inch thickness)
RC Slab (1/30th) 15' est span = approx 6" (150 pcf)
Pipes & H₂O
Anything else?
Live Load
Occupancy
Auditorium (fixed seating)
Corridor
Office
Other live loads?
Furniture & Fixtures

HOMEWORK PROBLEM 1

2. The Stairway between 1 and 2.

Structural System?
what supports what?
Loads to consider?
DL?
LL?
Dynamic Loading? (JUMP)

3. The Hallway above the infinate corridor.

note the 4-12inch diameter cast iron pipes.
water hammer load
how does one account for this load?
what percentage is distributed to what beam?
how do we account for the loading changes that occur to a building?

4. Down the Hall towards Mass Ave.

note the expansion joint (separation joint) Secondary loads

Thermal expansion (Cement = 0.0000126 degrees C)(0.0000070oF)
- delta T (alpha)L = (60oF )(0.0000070)(180ft)(12in/ft) = 1.00 inches
- delta T (alpha)L = (120oF )(0.0000070)(180ft)(12in/ft) = 2.00 inches
Vibration of building parts
Settlement
Note the change in structural system..... why?
advantage or disadvantage? It depends....on what?

5. The Dome Lobby Balcony

The system?

the support types?
the beam -
single sided loading implications
torsion

Floor Load DL

Terrazzo (12 psf per 1")
Slab (150 pcf)
Beam (150 pcf)

Occpancy Load ?
Dynamic Load? (JUMP)
F=ma
MASS!!!!
effect on earthquake loading
note another expansion joint
a clue for change
destructuve or sacrificial joint
why is the terrazo cracked?

Good exam question
Determine the total load on the balcony. Draw the FBD and indicated the reactions.

6. Stairway downstairs by Rotch Library

(JUMP)

7. 77 Mass Ave railing

what is the system?

8. The Kresge Auditorium. (Eero Saarinen, 1955)

(from the student center)
System stability?
How do you draw the FBD?
Loading
DL

consider actual geometry - 1/8th of a sphere
Standing Seam copper (1 psf)
Underlayment (1 psf)
Shell assume 4" (150 pcf)

drawn as a horizontal projection
snow - Boston (40 - 60 psf)
wind - 100 mph = about 25 psf
value depends on the fassade - why? (shape, direction)
shape - what are the coefficients for this structure? (experimental, but probably about 1.4)
how is the fassade load resisted? ("tipping" of the shell)

(in the lobby)

note the connection to the earth
what forces are here?
what is the rest of the story?
note the fassade support system - vertical AND horizontal
what are the layers of the system?
what does the form and orientation of the elements mean?
what bears on what?
what does the form of the way the primary structure meets the ground mean?
what about the ceremic floor tiles?
note the auditorium seating support structure
how does it "work?"

Materials

glass (single pane) + sash (8 psf vertical surface)
Steel(490 pcf)

HOMEWORK PROBLEM 2