CONCRETE STRUCTURES

Multiple-Choice:

Clearly mark only one correct answer for each question:

Each correct answer is worth 2 points

1. Exposure A classifies which of the following cases ? ( 2 points)

xa. high-rise structures

b. urban & suburban areas

c. open terrain

d. coastal areas

2. Who invented Portland Cement? ( 2 points)

a. The Romans

xb. Joseph Aspdin

c. Frost & Parker

d. The Egyptians

3. The general wind speed for the state of Oklahoma is? ( 2 points)

a. 60 mph

xb. 75 mph

c. 90 mph

d. 100 mph

4. What is the standard weight of a sack of Portland cement? ( 2 points)

a. 20 lbs

b. 50 lbs

xc. 94 lbs

d. 100 lbs

Student Name:_______________________

5. What is the Monroe Effect ? ( 2 points)

a. chill factor for windows

b. rain water suction

c. wind from right only (from left under British code)

xd. wind turbulence (uplift) in between high-rise structures

6. What is the diameter of #10 rebar? ( 2 points).

a. 1/8"

b. 1/2"

xc. 1-1/4"

d. 1"

7. Single Family homes fall under what occupancy category?

xa. I

b. II

c. III

d. IV

8. What is the weight of reinforced normal weight concrete? ( 2 points)

a. 115 pcf

xb. 150 pcf

c. 175 pcf

d. 380 pcf

9. What seismic zone is the City of Los Angeles in?

a. 1

b. 2

c. 3

xd. 4

10. What is type I Portland cement? ( 2 points)

a. Sulfite-resistant Portland cement

xb. Normal Portland cement

c. Low-heat Portland cement

d. Modified Portland cement

11. What is a Shear Wall as defined by BOCA? (2 points)

a. any concrete wall

b. two pieces of steel forming a diagonal

xc. a wall designed to resist lateral forces parallel to the wall

d. a 8'x4' sheet of 1/8" plywood nailed to studs 24" O.C.

12. What is the purpose of adding retarders to the concrete mix? ( 2 points)

a. increase strength of concrete

b. increase frost resistance of concrete

c. make the concrete fire-retardened

xd. slow down the setting time of concrete

Student Name:_______________________

13. What is the typical width of a concrete foundation wall? ( 2points)

a. 4"

b. 6"

xc. 8"

d. 1'

14. What is the minimum bearing for wood joists on top of foundation walls? ( 2 points)

a. 2"

xb. 3"

c. 4"

d. 6"

15. What is the recommended minimum slope for an exterior slab? ( 2 points)

a. 1/16" / ft

xb. 1/8" / ft

c. 1/4" / ft

d. 1/2" / ft

16. Too much water causes the concrete to? (2 points)

a. harden faster

b. be liquified

c. expand after curing

d. reach a lower strength

Short Answer Questions:

17. Name the Design Methods used to account for Wind forces (4 points)

Method 1 = Normal Force Method

simultaneous pressure on all surfaces

Method 2 = Projected Area Method

single pressure for structures <200 ft

18. Identify 4 historically important concrete structures. (4 points)

a. Notre-Dame du Haut Ronchamp, Arcosanti Cordes Junction, Tunnel, Goetheanum

b. Marina City, Hoover Dam, Center Point, Americana Hotel, Bennett Bay Bridge,

c. Fiat-Lingotto, Schwandbach Bridge Bern, Fallingwater, Casa Mila Gaudi, Pantheon

Palazetto della Sport, Sidney Opera House, Colosseum, Guggenheim Museum,

Chapel of the Holly Cross, Dulles Airport, Carpenter Center, St. John's Abey, Habitat

19. Name 4 elements which Lateraly stabilize a building. (4 points)

shear wall

rigid horizontal diaphragm

braced frame

rigid frame

Student Name:_______________________

20. Name the components in a concrete mix. (3 points + 1 bonus point)

binder (cement) 1 point

water 1

aggregates (fine & coarse) 1

admixtures optional

21. Name 3 admixtures (3 points)

accelerators pozzolanic powder

air-entraining retarders

latex plasticizing agents

pigments

22. What are some of the benefits of air-entrained concrete? (3 points)

improved workability

improved durability

improved freeze-thaw performance

decreases bleeding and aggregate segregation.

23. What is Hydration? (3 points)

hydration is the chemical reaction between water & cement

1 point 1 point 1 point

setting = process of hardening

24. Sketch the USA and indicate the 5 major code regions by name? (5 points)

BOCA

UBC State Codes, NY, NJ

SBC

South Florida

25. Sketch a Concrete Foundation System ( 4 points)

Student Name:_______________________

Calculations:

26. Problem: ( 5 points)

You are working on a hill side construction project in Hawaii. Given a wind speed of 100 mph.

What is the wind stagnation pressure under UBC code?

Show all formulas and calculation steps!

A. Given: V = 100 mph

Code = UBC

B. Asked: Wind Stagnation Pressure (qs)

C. Calculation:

UBC Code:

Wind Stagnation Pressure (qs)

qs = 0.00256 (V*V)

given 100 mph

qs = 0.00256 (100*100)

qs = 0.00256 (10,000)

qs = 25.6 psf

qs = 26 psf rounded

D. Answer:

The Wind Stagnation Pressure (qs) amount to 26 psf for

a wind speed of 100 mph under UBC code.

Student Name:_______________________

27. Problem: (15 points)

You are designing a 150'x100', 15 story, flat-roof, concrete office building, with 10' finished floor to finished floor ceiling height, on gravel, at the corner of Sunset Blvd & Vine Street in Hollywood,CA under UBC building code.

Determine the design pressure in determining the wind loads for the main windforce-resisting system.

A. Given: 150' x100'

15 story

flat roof

concrete structure

10' finished floor heights

soil = gravel

UBC code

you may also solve the problem under BOCA code

students to provide the appropriate tables

B. Asked: V = Shear Force acting on the structure

C. Solution:

UBC Code:

Wind Stagnation Pressure (qs)

qs = 0.00256 (V*V)

Example 100 mph

qs = 0.00256 (100*100)

qs = 0.00256 (10,000)

qs = 25.6 psf

qs = 26 psf rounded

Design Wind Pressure (p)

p = Ce Cq qs I

Ce = combined height, exposure and gust factor coefficient UBC 23-G

Cq = pressure coefficient for the structure or portion of structure under consideration UBC 23-H

qs = wind stagnation pressure at 30 ft given in UBC Table 23-F

I = Importance Factor

BOCA

Pd = Pe x I x I x Cp

Pd = Design pressure

Pe = effective velocity pressure

including gust effect

For Buildings & Structures

Exposure B

lower 9

Exposure C

higher 15

I = Importance Factor

Classification of Buildings

Nature of Occupancy Category

Single Family I

with more than 300 people II

Essential Facilities (Hospitals) III

low hazard to humans (Storage) IV

Importance Factor

Category 100 miles f. Ocean Ocean

I 1.00 1.05

II 1.07 1.11

III 1.07 1.11

IV 0.95 1.00

Cp = external pressure coefficient

Wall Pressure

Windward Wall 0.8

Leeward Wall - 0.5

Side Walls - 0.7

Roof Pressure

Wind Direction Angle

Normal to ridge

Parallel to ridge

Student Name:_______________________

28. Problem: ( 15 points)

You are designing a 150'x100', 15 story, flat-roof, concrete office building, with 10' finished floor to finished floor ceiling height, on gravel, at the corner of Santa Monica Blvd. & Ocean Avenue in Santa Monica under UBC building code.

Determine the seismic shear force acting on the structure.

A. Given: 150' x100'

15 story

flat roof

concrete structure

10' finished floor heights

soil = gravel

UBC code

you may also solve the problem under BOCA code

students to provide the appropriate tables

B. Asked: V = Shear Force acting on the structure

C. Solution:

EARTHQUAKE DESIGN under BOCA

V = 2.5 * Av * I *K * C * S * W

V = Total Lateral Force Shear at the Base

Av = Peak velocity related Acceleration

0.40 = Seismic 4 0.40 selected

0.30 = Seismic 3

0.20 = Seismic 2

0.10 = Seismic 1

0.05 = Seismic 0

0.15 = State of Oklahoma

I = Occupancy importance

1.5 = hospital

1.25 = over 300 people 1.25 selected

1.0 = residential

k= Horizontal Force Factor

k = 4.0 masonry shear wall in zone 2

k = 2.5 tanks

k = 2.0 none-buildings

k = 1.5 concrete 1.5 selected

k = 1.0 steel

k = 0.87 special frames

k = 0.8 moment frames

C= Coefficient

c = 1 / 15 x T

T = duration of vibration in seconds

S= Soil Factor

S1 = 1.0 = rock, gravel 1.0 selected

S2 = 1.2 = stiff clay > 200'

S3 = 1.5 = clay > 30'