9 Steel Construction

Question 1

Basic properties of steel

Answer 1

Strongest building material
Non rotting, resistant to aging, dimensionally stable
Consistent
Relatively expensive but strength and variety allows for less quantity to be used

Question 2

Ductile

Answer 2

Capable of being bent shaped or drawn out

Question 3

Lower carbon content of steel compared to iron allows it to

Answer 3

Be shaped due to it being less brittle and more ductile

Question 4

Cold rolled steel is used for members that

Answer 4

Have a thin cross section, such as floor decking and wall studs

Question 5

Two disadvantages of steel

Answer 5

Rusts

Loses strength when heated by fire

Question 6

At 1200 degrees f steel loses what percent of strength

Answer 6

Appx 72%

Question 7

Amount of expansion when heated for slender steel members such as columns and beams, can be determined by a property known as

Answer 7

The linear coefficient of thermal expansion

Question 8

Linear coefficient of thermal expansion, unrestrained steel beam 20’ long is heated from 70 to 1000 degrees uniformly, it would expand

Answer 8

1.4 inches, if restrained it would expand less

Question 9

Heating of steel members is not uniform in fires, therefor the expansion is

Answer 9

Not uniform

Question 10

Cast iron fronts were used in old buildings cast iron cracks from impact load rather than yielding like steel. It’s concerning because

Answer 10

A crack could cause collapse of cast iron building front

Question 11

Steel Beams and columns are connected on two ways

Answer 11

Welding or bolting, riveting was once used but not practical any more.

Question 12

Beam and girder steel frames can be classified as

Answer 12

Rigid, simple, or semi rigid.

Question 13

Rigid frame steel building

Answer 13

Connections between beams and columns designed to resist bending forces from load and lateral force

Question 14

Girder

Answer 14

Large horizontal member used to support joists and beams at isolated points along their length

Question 15

Simple steel frame

Answer 15

Joints designed primarily to support vertical force. Beams and trusses frequently supports by masonry

Question 16

Semi rigid

Answer 16

Possess enough rigidity to provide some diagonal support. May use sheer walls or diagonal bracing

Question 17

Steel trusses provide a structural member that can carry loads

Answer 17

Across a greater distance than beams

Question 18

In three dimensional space frames, steel stresses are known as

Answer 18

Delta trusses because they resemble the triangular Greek delta

Question 19

Two common applications of basic trusses

Answer 19

Open web joist and joist girder

Question 20

Bar joist

Answer 20

Open web truss entirely of steel with steel bars as web members

Question 21

Open web joists are available on what range of size

Answer 21

Depth up to 6 ft and span up to 144’, more frequently depth of less than 2’ and span of 40’

Question 22

Steel rigid frame building with gabled roof is widely used for

Answer 22

One story industrial, farm buildings spanning 40-00 ft

Question 23

Steel arches are used for large unobstructed interior flor space requirements spanning in excess of

Answer 23

300 ft

Question 24

Girder arch

Answer 24

Solid arch built from angles and webs

Question 25

Trusses arch

Answer 25

two halves of the arch are made of trusses and are pinned in the middle

Question 26

Slenderness of steel members can cause what when used as columns

Answer 26

Bucking and is a function of the length of the column

Question 27

Columns for structural support should not have a slenderness ratio greater than

Answer 27

120

Question 28

Three methods of supporting floors in steel buildings

Answer 28

Open web joist (bar joist) or trusses Steel beams Light gauge steel joists

Question 29

Open web joists are commonly used to support floors of

Answer 29

Concrete minimum 2" over metal deck, supported by steel beams or masonry walls at ends

Question 30

Steel joists are produced with depths of, and can be spaced up to

Answer 30

Depth of 6-12" and spaced 16-48" apart

Question 31

Mass of steel reduced failure rate in fires, therefore, beam and girder type rigid connections

Answer 31

Are less prone to failure

Question 32

Gusset plates

Answer 32

Metal or weeded plate used to connect and strengthen intersections of meal or wooden truss components

Question 33

Gusset plate also increases what at the connection

Answer 33

Mass, therefore decreasing the possibility of failure

Question 34

In gabled rigid frame what is the strongest part of the roof and wall

Answer 34

Knee joint, last to fail

Question 35

On older buildings, steel framework was encased in brick or concrete. Steel column encased in 3 inches of concrete with siliceous aggregate would have a fire rating of

Answer 35

4 hrs

Question 36

In modern applications the most common used insulation, or fire resistance, is

Answer 36

Gypsum, sprayed materials, and intumescent coatings

Question 37

Some fire resistance is applied by spraying and are known collectively as

Answer 37

Spray applied fire resistant materials SFRMs

Question 38

A type of gypsum with additives like glass fibers to increase fire resistance used where specific requirements are needed

Answer 38

Type x gypsum.

Question 39

Fire resistance value of gypsum is from

Answer 39

It's worse content, 21%

Question 40

Most common forms of SFRMs are

Answer 40

Mineral fiber | expanded aggregate coatings such as vermiculite and perlite

Question 41

Spray on fire resistance is based on type and thickness of material, applied proofing can rage from what thickness and fire rating

Answer 41

7/8- 1 7/8" with fire rating of 1-4 hrs

Question 42

Cementitious

Answer 42

Containing or composed of cement, with cement like characteristics

Question 43

Cementitious ingredients can include

Answer 43

Portland cement, gypsum, perlite, and vermiculite Some manufacturers use magnesium oxychloride, oxysulfste, calcium aluminate, phosphate , or ammonium sulfate Density ranging from 15-50 lb/cubic ft

Question 44

Intumescent coating

Answer 44

Coating or paint like products that chars, foams, and expands when exposed to heat creating insulating barrier. Expanding 15-30 times

Question 45

Mastic coating reacts similar to

Answer 45

Intumescent coatings, but are complex and organic

Question 46

Intumescent coatings have a thickness of

Answer 46

0.03 to 0.4"

Question 47

Membrane ceiling

Answer 47

Suspended insulating tile ceilings to provide fire resistance of 1-3 hrs as a rated ceiling assembly

Question 48

Ceiling assemblies aren't rated individually but rather as part of a floor and ceiling assembly, penetration of the ceiling can

Answer 48

Severely reduce or eliminate the fire rating

Question 49

Reduction in fire code requirements examples

Answer 49

Eliminating fire resistance requirements for roof members 20 ft or higher over floor Allowing reduction in fire resistance when building is sprinklered when not normally required.

Question 50

In IBC building type ratings, the letter designation afterward indicates fire resistance, type II A vs type II B, which is more resistant

Answer 50

Type a is more resistant than type b

Question 51

Fire resistance of steel depends on

Answer 51

Mass of steel and degree of fire resistance provided