8.1mec PRINCIPLES OF CONSTRUCTION

Question 1

C1 - Soil testing is needed for what kinds of buildings?

Answer 1

All buildings except single family dwellings

Question 2

C2 - Describe the function of and difference between test pits and boring.

Answer 2

The geotech Engineer generates a soil profile to show the strata (horizons) of varied soil types.

Test Pit (<3)

Boring (>3)

Question 3

C3 - Describe the 2 broad classes of soil.

Answer 3

1. coarse grain (particles visible to naked eye)
   
   • gravel
   • sand
2. fine grain
   
   • silt
   • clay

Question 4

C4 - How does ASTME define soil types. (4)

Answer 4

1 - description (ex: silty gravel)

2 - bearing capacity (ex: 5000 psf)

3 - susceptibility slight (ex: slight)

4 - permeability + drainage (ex: poor)

Question 5

C5 - Define ALLOWABLE BEARING CAPACITY.

Answer 5

Max unit pressure a foundation is permitted to impose VERTICALLY or LATERALLY on soil mass.

Question 6

C6 - Define a standard penetration test.

Answer 6

Measures density of granular soils by recording the number of blows required to advance a standard soil sampler

Question 7

C7 - Describe the shearing strength of cohesive and granular soils when unconfined.

Answer 7

1. Cohesive - maintain strength when unconfined
2. Granular - require a confining force for their shear resistance

Question 8

C8 - Describe 6 potential soil problems.

Answer 8

1 - SETTLEMENT - dead load causes structure to compact soil and ‘settle’

2 - DIFFERENTIAL settlement causes cracks

3 - FROST action heaving during freeze thaw = stress on footing .: footing must be 12” below frost line

4 - EARTH MVMT prevalent w clay soils .: footings lower than 5’ subject to less mvmt

5 - soil DRAINAGE moisture content impacts bearing capacity .:must know water level & drain properly

6 - WATER TABLE foundation must be well above water table to avoid • hydrostatic pressure • capillary action

Question 9

C9 - Describe 5 potential soil interventions.

Answer 9

1 - SOIL MODIFICATION - to improve consitancy/bearing etc.

2 - INCREASE BEARING CAPACITY - deepening of footing - increase bearing area of footing

3 - IMPROVE DRAINAGE - increase bearing capacity

4 - REMOVE/REPLACE UNSUITABLE SUBSOIL - typ. replaced w compacted granular engineered mix

5 - COMPACTION - w rollers

Question 10

C10 - Describe 4 types of earthwork in order of execution.

Answer 10

1 - ROUGH GRADING - permanently filled slopes stable @<2:1

2 - EXCAVATION - removal of existing - permanently cut slopes are stable @ <1.5:1

3 - BACKFILL - earth replaced around foundations + footings - deposit in 6-12” layers - tamp to avoid settlement

4 - FINISH GRADING - final distribution of earth @ conclusion of construction - accurate win 1”

Question 11

C11 - If soils are not adequately dense for a foundation to bear upon, what can be done?

Answer 11

The soil may need compaction in order to achieve optimum density or soaking to achieve optimum moisture content.

Question 12

C12 - Silt and sandy soils are typically _____ and susceptible to _____.

Answer 12

• impervious
• frost

Question 13

C13 - Ideal soil type for construction?

Answer 13

Clean (no silt or clay) sand or gravel

Question 14

C14 - Which soil types have either very poor or unsuitable bearing capacity.

Answer 14

All organic soils:

• Organic silt-clay
• Organic clay and silt
• Peat (highly organic = unsuitable)

Question 15

M1 - WHAT IS THE WATER PRESSURE IN CITY SUPPLY SYSTEMS AND HOW MANY STOREYS CAN BE SUPPLIED WITHOUT A PUMP?

Answer 15

50 PSI - 6 STOREYS

Question 16

M2 - HOW IS WATER SUPPLIED ABOVE 6 STOREYS?

Answer 16

THE WATER IS PUMPED UP TO A ROOFTOP RESERVOIR & GRAVITY DOWNFEED

Question 17

M3 - LIST THE SEQUENCE FROM SUPPLY MAIN TO WATER FIXTURE

Answer 17

1 - WATER MAIN

2 - CURB BOX

3 - WATER METER

4 - PAST SHUT OFF VALVE

5 - HOT WATER TANK

6 - RISERS

7 - BRANCHES

8 - FIXTURES

Question 18

M4 - MINIMUM SLOPE OF A SANITARY DRAIN

Answer 18

1-2%

Question 19

M5 - FUNCTION OF A VENT IN A SANITARY SYSTEM

Answer 19

• ALLOW SEPTIC GAS TO ESCAPE
• PREVENT VACUUM SIPHONING

Question 20

M6 - FUNCTION OF A TRAP IN A SANITARY SYSTEM

Answer 20

• SEAL SEWER GASSES SO THEY CANNOT ESCAPE THE FIXTURE

Question 21

M07 - Describe Heat Loss and Heat Gain.

Answer 21

Heat Loss

• heat loss to exterior in cold weather
• convection / radiation / conduction

Heat Gain

• heat gained within the building
• latent heat / lighting / occupants

Question 22

M08 - Describe a radiator and a fin-tube convector.

Answer 22

Radiator

• series /coil of pipes w steam or hot water inside
• heats space by radiating heat

Fin-Tube Convector (baseboard)

• series of thin vertical tubes spaced closely to max heat transfer to air
• cool air drawn in from below by convection, and heated by contact with fins and discharged out the top

Question 23

M09 - List the 6 main Fuel/Power Sources for heating and cooling systems.

Answer 23

1. Natural Gas
   
   • burns clean / no storage rqrd
2. Propane
   
   • burns clean / >$ natural gas
3. Oil
   
   • efficient and rqrs delivery /storage tanks
4. Coal
   
   • rarely used in residential and only sometimes in commercial
5. Electricity
   
   • clean /compact /costly
6. Properly harvested wood
   
   • sustainable energy source
   • causes poor IAQ and air pollution