J1 - Building Science - LT #1

Question 1

Explain how concrete can be a live load and then a dead load.

Answer 1

Concrete is cast - Live
After curing - Dead load

Question 2

What is a Live load?

Answer 2

Variable, non-permanent load that acts on a building structure. Live Load may be static, repetitive, or dynamic. Human-caused or environmental.

Question 3

What is a Static Load? (LIVE)

Answer 3

External forced is applied and held in a fixed position for a period of time.

EX: Static load caused by gravity is the weight of a piece of furniture. Due to being movable or replaced.

Question 4

What is a repetitive load?

Answer 4

Repeating Load caused by gravity or the momentum of an object.

EX: Cars crossing a bridge place temporary gravitational load on bridge

Question 5

What is dynamic load?

Answer 5

Load that can be changed over time

EX: Repetitive action of cars braking and accelerating on a bridge.

Question 6

Wind creates what kind of load on a building?

Answer 6

Both static and dynamic live loads.

EX: Strong gusts of wind place dynamic loads on a building but a steady breeze puts a static live load.

Question 7

Wind loads create what kind of pressure?

Answer 7

Differential loads across a building draw heated air out of it and rain water into it.

Question 8

What kind of load do rain and snow create?

Answer 8

Static Live load.

EXL Rain has a greater effect when snow is on the roof, as the snow absorbs the weight and load on the roof.

Question 9

Specified Snow Load Formula:

Answer 9

S (Cb x Ss) + Sr

Question 10

Regardless of snow load, no roof may be designed to support less than:

Answer 10

1 kPa

Question 11

Occupant live loads include:

Answer 11

Furnishings, equipment and people.

Question 12

What is an example of a dynamic load?

Answer 12

Earthquake.

Question 13

What is a dead load?

Answer 13

Caused by gravity acting on all the building materials.

Question 14

Dead loads in a typ. wood framed house include:

Answer 14

Wood framing members, concrete foundation, windows & doors, interior and exterior finish materials and siding and all permanent fixtures.

Question 15

Dead loads in a wood frame are treated as:

Answer 15

0.5 KPA (10 LB)

Question 16

Four common stresses acting on a building are:

Answer 16

Compression
Tension
Torsion
Shear

Question 17

What is compression stress?

Answer 17

Force acting to SQUASH

Question 18

What is tension stress?

Answer 18

Tension - pulling force

EX Rope used to hoist is under stress

Question 19

In a joint or beam, the top is under compression and the bottom is under:

Answer 19

Tension

Question 20

Forces of tension and compression are greates at which part of the beam?

Answer 20

Closest to the edge.

Question 21

What is a stress of torsion?

Answer 21

Torsion is the force caused when one or both ends of an object are twisted (Torqued).

EX: Extreme winds can result in torsion

Question 22

How can a bulding reduce effects of torsion stress?

Answer 22

Symmetry

Question 23

What is shear stress?

Answer 23

When loaded components try to slide. Pushing or pulling forces act in opposite directions on a solid component.

Can be horizontal, vertical or diagonal.

Question 24

Vertical shear occurs where?

Answer 24

Vertical shear occurs where there are loads, such as those in a beam acting on a supporting member such as a column.

Question 25

Building components that are under both horizontal and vertical shear stress experience:

Answer 25

Diagonal shear.

Question 26

Gravity is the force that gives objects what?

Answer 26

Weight

Question 27

Flat roof can be affected by wind uplift when the wind hits a large wall and has to:

Answer 27

Change directions upward

Question 28

Hurricane ties connect:

Answer 28

Trusses to top plates, helping to anchor down the roof.

Question 29

Soil that can be squeezed into a ball and retains shape is:

Answer 29

Cohesive soil