CEE 4606 - Capstone II Structural Engineering

transcript

Villanova UniversityDept. of Civil & Environmental Engineering

CEE 4606 - Capstone IIStructural Engineering

Lecture 2 Design Considerations in the Third-World

and an Introduction to Building Codes

Design Constraints and Considerations

• Construction– Equipment– Material Availability– Processes

• Material Testing– Concrete– Steel

• Testing Results

Construction Equipment• Have:

– Electricity (with occasional power loss)– Portable generator – Welding rig– 1 Concrete vibrator– Drills (with some bits)– Circular saw, table saw, hand saws– Hand tools (hammers, tape measures,

shovels, etc.)

Construction Equipment

• Do Not Have:– Concrete Mixer– Lifting Crane

Formwork and Other Heavy Objects Must be Carried by Hand

Construction Equipment

• Do Not Have:– Concrete Mixer– Lifting Crane– Backhoe– or Concrete Trucks

Materials must be carried by hand ...

… or by wheelbarrow

Construction Materials

• Wood– Plywood not readily available– Structural lumber very expensive – Some on site– Most lumber is cut by hand from trees

on site

Hand-cut Lumber

Scaffolding and Formwork Must be Built by Hand

• Steel– Access to sheet metal, light gauge

tubes, bars, ties, etc.– Rebar available, but sizes are limited– All bars and stirrups must be bent by

Rebar is Cleaned, Bent, and …

… Cut by Hand

• Concrete– Portland cement available (Type I)– Aggregates taken from nearby river

Oxcart Used to Haul Aggregates From Nearby River

• Concrete– Portland cement available (Type I)– Aggregates taken from nearby river– Concrete mixed by hand using

shovels

Concrete is Hand-mixed with Shovels

A pile of dirt, cement, and a little water

Lots of shovels

Get the buckets

Construction Schedule• Keep this is mind

when you are developing a construction schedule

• Talk to past trip participants for approximate rates of “production”

• Concrete– Portland cement available (Type I)– Aggregates taken from nearby river– Concrete mixed by hand using

shovels– No quality control/quality assurance

(QC/QA) program

Concrete Mix Design

• 3 wheelbarrows of sand• 3 wheelbarrows of aggregate• 2 bags of cement (94 lbs/bag)• 2 - 3+ five gallon buckets of water

Note: 1 wheelbarrow = 2.5 bags of cement

Recommendations on the Cement Bag

Concrete Cylinders - ASTM Protocol?

Questionable Cylinders in 2000?

Quality Cylinders in 2002

2000 - Cross Project Material Testing - Concrete

• 3 cylinders were tested prior to trip (non-ASTM procedure)

• 12 cylinders were taken from the cross pour

• 3 cylinders tested at 7 days• 4 cylinders tested at 14 days• 3 cylinders tested at 21 days• 2 cylinders tested at 28 days

2001 - Chapel Foundations Material Testing - Concrete

• 3 cylinders remaining from the cross project were tested at 325 days

• 15 cylinders were made from the many footing pours

• 6 were tested at 14 days• 9 were tested at 28 days

2000 and 2001 Concrete Test DataYear 1 Cylinder Strength

Trip Age (psi)1 7 1230

2 7 1660

3 7 960

4 14 1750

5 14 1530

6 14 1830

7 14 1650

8 21 1490

9 21 1760

10 21 1590

11 28 1450

12 28 1620

13 325 1780

14 325 1360

15 325 1650

Year 2 Cylinder StrengthTrip Age (psi)

1 14 820

2 14 910

3 14 800

4 14 960

5 14 1130

6 14 1310

7 28 2130

8 28 1970

9 28 1610

10 28 1770

11 28 1790

12 28 1850

13 28 1070

14 28 1110

15 28 680

Document The Construction Process

This was the batch that the 680 psi cylinder came from

Dr. Gross says “no more water”

2002 – 7 day breaks

Year 3 Cylinder Strength AggregateTrip Age (psi) Size

1 7 2540 Large2 7 2430 "3 7 2390 "4 7 2380 "5 7 2050 Small6 7 1970 "

2002 – 28 day breaksYear 3 Cylinder Strength Aggregate

Trip Age (psi) Size7 28 3640 Large8 28 3930 "9 28 3380 "10 28 3180 "11 28 2270 Small12 28 2110 "13 28 2820 "14 28 2820 "15 28 1390 Footing16 28 1010 Footing

Material Testing - Steel

• 2 samples of rebar were tested• Tested in tension to failure• Data collected

– Bar Sizes– Yield Load– Ultimate Load

Bar Yield Load Ultimate LoadSize (lbs) (lbs)#6 23500 37600

8 mm 3825 5600

Steel Test Data

• Develop a plan on what material (steel and concrete) samples you want your site representative to bring back

How good can this steel be ...

#16 bar!

Labor• The workers at the orphanage take

pride in their work• High quality of construction

Shoddy American Work, and ...

… Work Ethic

Posas Verdes, Honduras• Governing Code?• Any other information?• What are the next steps?

– You’ve started looking at load paths – We need load types– We need to determine load combinations – Therefore, we need to decide on a code

Building Codes in the United States

• SBC, BOCA, UBC, and IBC• UBC is primarily used in areas of

high seismicity (Western US)• UBC vs. BOCA

– Better information on seismic design– Excellent design aids– BOCA will be covered in CASE (?)

International Building Code, 2000• UBC, 1997 will not be updated again• Move of the industry is away from

the three different codes to one, IBC• Seismic provisions primarily based

off of UBC requirements• We will use IBC, 2000 along with

any information you can find– (handouts)

Chapter 16 – Structural Design

1602 – Definitions1603 – Construction Documents

(you’ll want to make sure your drawings comply with this section)

1604 – General Design Requirements (LRFD vs. ASD vs. strength)

1604 – General Design Requirements

1604.2 – Strength1604.3 – Serviceability

– Deflection– Table 1604.3 – and/or Appropriate Code (ACI, AISC)

1604.5 – Importance Factors – (Table 1604.5)

1604.8 – Anchorage (roof designs)

Load Types

• Dead Load• Live Load• Wind Load • Seismic (Earthquake) Load

Are there any special considerations due to the location of our site?

1605 – Load Combinations• LRFD

– 6 combinations– Exceptions and other loads

• ASD – 6 combinations– Exceptions and load reduction

• Alternate combinations 1605.3.2• Special seismic combinations

Section 1606 - Dead Loads

• What are the dead loads that you must consider for this structure?– Roof and trusses– Masonry walls– Concrete beams, columns, and slabs– Stairs– Any other permanent fixtures

Section 1607 - Live Loads

• Considerations include– Occupancy category Table 1607.1

• Uniformily distributed loads• Concentrated loads

– Distribution of floor loads– Roof loads– Live load reduction (1607.9)– Construction loads

Division III - Wind Design• What do we need to consider to

determine wind pressures?– Building type– Building geometry and effective wind

area– Importance factor– Exposure – Type of resisting system– Wind speed

Pressure Distribution

Hurricanes for the 1998 season

Hurricane Mitch

Chapter 16 continued

1610 – Soil Lateral Load1611 – Rain Load

– Rainy season impact ?1612 – Flood Load

– Proximity to river or creek?1613 – Earthquake Load (next time)

Current Tasks• Fill out the survey if you haven’t

already• Determine the DL and LL on your

structure • Start researching wind and

earthquake history of Honduras• Determine your design wind speed

Lecture 3

• Introduction to Seismology• Review of Seismology of Central

America• International Building Code, 2002

seismic requirements• Roof Design

The Enforcer