][ STEEL STRUCTURES ][
][ STEEL STRUCTURES ][
Student Name: __________________________________
SS#: __________________________________
ARCH 5023/ ARCH 4333 - ARCHITECTURAL STRUCTURES I
][STEEL STRUCTURES][
UNIVERSITY OF OKLAHOMA - COLLEGE OF ARCHITECTURE
EXAM 2
Friday 10.03.97
Please print clearly.
Show all work.
Include units of measurement.
Closed Notes
Manual of Steel Construction allowed
Simplified Engineering for Architects and Builders allowed
2 (8 1/2"x11") Summary pages allowed.
Multiple-Choice:
Clearly mark only one correct answer for each question:
Each correct answer is worth 2 points
1. What is the advantage of S shapes over W shapes for beam applications? ( 2 points)
a. thinner web
b. thinner flange
c. x thicker web
d. thicker flange
2. When are I beams used instead of bearing plates? ( 2 points).
a. when you switch from two single 8' garage doors to one 16'-0" door
b. when window openings exceed the overall wall length
c. x when the length of the bearing plate becomes excessive
d. when federal building codes override local ordinances
3. What is the primary concern in the design of a steel beam? ( 2 points)
a. shear
b. lateral support
c. x bending strength and deflection
d. web crippling
4. What determines the width of a beam bearing plate? ( 2 points)
a. x width of wall
b. cost of steel
c. grade of steel
d. laterally unsupported overall critical length of ASTM specified radius of gyration
5. What is the maximum allowable bending stress for braced A36 steel beams? ( 2 points)
a. 10 ksi
b. 14.5 ksi
c. 17.4 ksi
d. x 24 ksi P&A 267
6. What is the maximum allowable shear stress for un-reduced A36 steel beams? ( 2 points)
a. 10 ksi
b. x 14.5 ksi P&A 266
c. 17.4 ksi
d. 24 ksi
7. What is the maximum acceptable live load deflection for a steel beam according to AISC? (2p)
a. L / 240
b. L / 300
c. x L / 360
d. L / 480
8. What is the k distance in inches for a W 18 x 35 ? ( 2 points)
a. 5.56"
b. 2.81"
c. 2.00"
d. x 1.13 P&A 171
9. What is the Web Thickness for a W 36 x 300 ? (2 points)
a. 0.360 "
b. 0.500 "
c. x 0.945 " P&A 170
d. 3.000 "
10. What is weight per linear foot of a ASTM A36 W 8 x 24? (2 points)
a. 8 lb/ft
b. 16 lb/ft
c. x 24 lb/ft
d. 36 lb/ft
11. What material can be sprayed on for fireproofing of steel beams? ( 2 points)
a. masonry
b. concrete
c. lath
d. x fibrous and cementatious coatings
12. What is minimum yield stress for ASTM A36 steel beams? ( 2 points)
a. 19 ksi
b. 22 ksi
c. 29 ksi
d. x 36 ksi P&A 266
14. Which force rarely governs the design of steel beams? ( 2 points)
a. deflection
b. x shear
c. bending moment
d. section modulus
15. What is the allowable bearing pressure for a steel beam bearing on the full area
of 3000 psi concrete? ( 2 points)
a. 225 psi
b. 500 psi
c. x 750 psi P&A 295
d. 1125 psi
16. What is the actual depth of a ASTM A36 W 21 x 147 ? (2 points)
a. 2.1"
b. 14.7"
c. 21"
d.x 22.06"
17. What is the maximum width N of the beam bearing plate, if the steel beam is supported on a
standard width concrete block basement wall. ( 2 points)
a. 4"
b. 6"
c. x 8"
d. 12"
Short Answer Questions:
18. Name three (3) ways to determine deflection (1 point each, 3 points total)
1. Formula D = 5/384 x Wx(LxLxL) / EI (actual formula not required to earn point)
2. Deflection graph (P&A 280)
3. Safe load tables (P&A 282 -284)
19. Sketch a W 8 x 24 and Identify the following dimensions on the drawing. (1 point each + 1 point for sketch = 4points total)
web thickness 0.245"
depth 7.93"
flange width 6.495"
20. Sketch a bearing plate and identify the three (3) critical dimensions on the drawing. (1 point each, + 1 point for sketch = 4 points total)
B, N, t
21. What can be done to prevent crippling of a steel beam web if the maximum interior load has been exceeded, indicate on sketch ? (1 point each + 1 point for sketch = 4 points total)
1. reinforce web with web stiffener
2. increase length of bearing plate
3. select beam with thicker web.
22. How can the fire rating of the I-beam below be increased? (1 point each = 4 points total)
a. masonry enclosure
b. concrete enclosure
c. lath enclosure
d. gypsum board
e. fibrous and cementatious coatings
f. special paint
g. water cooled
23. Sketch a horizontal steel member to span 20' (2D or 3D) and identify the material? ( 4poitns)
=================
v v
20'-0"
I-beam 12" deep
steel Truss
steel Joist
built-up member
c-chanel
24. Sketch the end support of an I beam resting on a concrete basement wall? ( 4 points)
(and label the sketch)
beam
plate
poured concrete
25. You are the construction manager for Manhattan and need to order an I-beam from
WW-steel what information do you need to fax to them? ( 3 points)
W 21 x 93
30'-0" long
redoxide
spray-on fire protection
bolted connection - hole locations
stiffner plate locations
26. You can optimize a steel beam based on which (2) factors? ( 1.5 points each = 3 total)
headroom
weight
Calculations:
Indicate what is given, asked, graph and what your solution is underline your answers.
Show all work, include formulas, units of measurement and page number of table used.
27. Problem: (12 points)
A W 21 x 57 beam of A 36 steel has an end reaction of 40 kips
that is developed in bearing over a length of N = 8 inches
Check the beam for web crippling.
A. GIVEN: 2 points
W 24 x 84
A 36 steel
R 40 kips end reaction
N = 8 inches
B. ASKED: 1 point
Is web cribbling critical?
C. GRAPH: 3 points
_________________ k = distance from flange
_________________ to web toe
N= 8" W 24 x 84
R1 = 40 kips
D. CALCULATION:
1. P&A 170 Table 4.1
k = distance from outer face of flange to
web toe
k = 1.56 in 1point
2. P&A 170 Table 4.1
t = thickness of the beam web, in inches
t = 0.470 in
3. Maximum end reaction
(OVER SUPPORT)
R = End Reaction over support
t = thickness of the beam web, in inches
N = length of bearing in inches
k = distance from outer face of flange to web toe
R = 0.75 Fy x t x (N + k) 1 point
R = 0.75 x 36 ksi x 0.47" x ( 8" + 1.56")
R = 27 ksi x 0.47" x (9.56")
R = 12.69 ksi" x 9.56"
R = 121.3164
R = 121 kips 1 point
4. Actual End Reaction
R1 = 40 kips
5. 121 kips > 40 kips
R > R1 1 point
o.k.
crippling is not critical
E. ANSWER 1 point
The maximum allowable end reaction
is greater than the actual reaction.
The beam therefor is NOT CRITICAL
with regard to web crippling
Calculations:
Indicate what is given, asked, graph and what your solution is underline your answers.
Show all work, include formulas, units of measurement and page number of table used.
28. Problem: (10 points)
A W 21 x 57 member of A36 Steel transfers an end reaction of 50 kips (196 KN)
to a wall built of 2000 psi poured concrete by means of a bearing plate of A36 steel, resting on the full wall thickness of 8 in.
Design the bearing plate
A. Given:
A W 21 x 57 member
of A36 Steel
transfers an end reaction of 50 kips
to a wall built of 2000 psi conrete
by means of a bearing plate of A36 steel.
resting on the entire wall
wall thickness 8" = N
B. Asked: 1 point
Design the bearing plate
N
B
t
C. Diagram: 1 point
D. SOLUTION:
1. End Reaction to be supported
R = 50 kips = 50,000 p 1 point
2. Allowable bearing Pressure
see Table 9.3 page 295
given:
2000 psi
concrete bearing on full area
Fp = 500 psi from table 9.3 1 point
3. Preselected Area of Plate
A = R / Fp
A = 50,000 p / 500 p/sqin
A = 100 sq inch 1 point
4. Depth N of Plate:
N = 8 inch given
(usually limited by the thickness of the wall)
(concrete block = 8" wide)
5. Length B of Plate:
B = A / L
B = 100 sq in / 8 in
Step 3 Step 4
B = 12.5 inch
which is rounded off to 13 inch 1 point
6. With the true dimensions of the plate
(8 in x 13 in) we now compute the thickness
of the plate.
7. Actual Area of the Plate
A = N x B
A = 8 in x 13 in
A = 104 in 1 point
8. Actual Bearing Pressure:
fp = R / A
fp = 50,000 p / 104 in
fp = 480.76923 psi
fp = 481psi 1 point
9. Compare to allowable unit stress Bearing Fp
Fp = 500 psi Table 9.3 P&A 295
10. Actual Stress to be smaller than allowable
481 psi < 500 psi
fp < Fp o.k. 1 point
11. Distance k1 for Wide Flange (W) Shape
Note: Table 4.1 P&A 170 does not show k1
ASD Manual of Steel Construction 1-20
for
W 21 x 57
k1 = 7/8"
k1 = 0.875" 1 point
12. Determine n:
n = B/2 - k1
n = 13 / 2 - 0.875
step 7 step 10
n = 6.5 - 0.875
n = 5.325 inch 1 point
13. Fb = Allowable Bending Stress in the plate
Table 8.1 P&A
Fb = 0.75 x Fy
Fb = 0.75 x 36
Fb = 27 ksi 1 point
14. Thickness t of Plate:
Formula P&A 295
due to the limitations of the word processor
the following symbol
----------
v
stands for the square root
which includes the nominator and denominator
-------------------
t = V 3 fp x n x n
---------------
Fb
-------------------
t = V 3 fp x n x n 1 point
---------------
Fb
------------------------------------------------
t = V 3 x 481 psi x 5.325 in x 5.325 in
----------------------------------------------
27,000 psi
-----------------------------------
t = V 1443 psi x 28.3556 sqin
-----------------------------------
27,000 psi
-----------------------
t = V 40917.13
------------------------
27,000
------------
t = V 1.5154
t = 1.23 in 1 point
========
E. Answer:
15. The bearing plate design is:
N = 8 inches
B = 13 inches
t = 1.23 inches = 1 1/4 inch
1 point
Calculations:
Indicate what is given, asked, graph and what your solution is underline your answers.
Show all work, include formulas, units of measurement and page number of table used.
29. Problem: (6 points)
The College of Architecture will be expanded in the comming year, we will add another set of
class rooms to the south side of the building for this a 24'-0" long W 12 x 22 member of A36 Steel will be connected to the existing concrete structure. The beam is braced every 4'-0"
What is the allowable load for the selected beam?
P&A 282
W 12 x 22
span 24'
= 16.9 kips
Please click on the speaker for immediate feedback! 
©Dr. Gruenwald 1996, 1997
