Ch 1-2

Question 1

The term emergency traffic is used for:

Answer 1

Emergency traffic means to clear the air of radio traffic to issue an evacuation order. Generally used for a collapse or potential collapse

Question 2

A step beyond a prefire plan is to perform a

Answer 2

Prefire analysis.

Analysis goes further and than a plan and involves studying the information of the prefire plan to gather specific occupancy and construction issues or concerns

Question 3

Buildings codes establish what level of safety?

Answer 3

Minimum levels of safety provided for new buildings

Question 4

The greatest enemy of all firefighters is

Answer 4

Gravity

Question 5

Relying on experience, a loan is not sufficient for today’s firefighters; they must also be aware of

Answer 5

The theories and principles involved in building construction.

Question 6

Definition – all of the structural elements and the connections that support and transfer the loads in a building

Answer 6

The gravity resistance system

Question 7

The basic meaning behind fire resistance buildings is

Answer 7

To some degree, the building will resist fire caused collapse.

Question 8

Generally speaking, 4 types of forces can be applied to a structural member:

Answer 8

Compression
Tension
Torsion - twisting or turning
Shear - opposing forces within the member

Question 9

The result of forces applied to a structural member are known as

Answer 9

Stress – the force per unit area that produces a deformation. Psf or psi

Strain – the actual percentage of elongation or deformation that occurs when a material is stressed. Fractions of an inch.

Question 10

NFPA 5000 refers to any force or other action, the results from the weight of all the billing materials, occupant, and their possessions, environmental effects, differential movement, and restrained dimensional changes. This is known as:

Answer 10

Any Load.

Question 11

The weight of a building itself, and any equipment permanently attached to it or built-in to it. Also known as self weight.

Answer 11

Dead load

Question 12

Fire resistance is closely related to ?

Answer 12

Mass.
Any element with less mass is inherently less fire resistant

Question 13

A lightweight steel trust is also known as a

Answer 13

A bar joist

Question 14

Any load in a building other than a dead load is considered to be

Answer 14

Live load.

Dead loads can be accurately calculated, but live loads are indeterminant.

Billing codes specify minimum live floor load designs for specific building types

Question 15

Uniform live loads, refer to loads distributed over the entire area in PSF, but a concentrated load…

Answer 15

Refers to a load applied to specific large objects, such as a safe.

Question 16

Added live loads can include

Answer 16

Trapped water on a roof and snow 

Question 17

A three-dimensional pyramid like truss is known as a

Answer 17

A spaceframe

Question 18

A load is delivered in a short period of time is known as

Answer 18

An impact load

There’s no such thing as a no-impact load, no matter how softly personnel or equipment are placed on a structure. There is a substantial increase in the stress on that structure momentarily.

Question 19

A lateral impact load such as from an explosion can be delivered how?

Answer 19

From a direction that has a little or no stress resistance

Walls are designed for vertical compressive loads, but are not typically designed to resist lateral loads from the sides

Question 20

The safety factor built 10 to ordinary buildings is not enough to prevent progressive collapse after the first impact load.
Progressive collapse is particularly hazardous in which construction?

Answer 20

In the construction of concrete frame buildings.

Back drafts or CO explosions can occur and blow the building apart

Question 21

Static loads and repeated loads are known as

Answer 21

A static load is applied slowly and remain constant. A heavy safe is an example of a live static load.

A repeated load is applied intermittently. A rolling bridge crane in an industrial occupancy applies repeated loads to each column as it passes.

Question 22

A shear wall is installed in a building to resist lateral loads from:

Answer 22

Wind loads and earthquakes.

Shear walls provide shear strength, creating stiffness and a strong enclosure.

Question 23

2 closely related structural frames used in buildings to resist lateral wind and earthquake loads are

Answer 23

Braced frames - Uses diagonal members for bracing purposes

Moment frames - uses moment, connections between columns and beams that resist rotation.

Question 24

As opposed to gravity connections, hurricane bracing provides:

Answer 24

Metal straps to hold roofs in place, and bolts to hold the frame to the foundation.

Question 25

Portal bracing is the practice of

Answer 25

Using heavy rivets between girders and columns from the top to the bottom of the frame

Question 26

A diaphragm floor is designed to stiffen the building against

Answer 26

Wind and other lateral loads, such as earthquakes

Question 27

Bracing of high-rise buildings our examples of these three types of construction

Answer 27

Tube construction, externally braced buildings Core construction, internally braced Vierendeel truss, rectangular trust with very rigid corner, bracing, formed by exterior box, columns, and spandrels.

Question 28

Very heavy loads, located at one point in a building, such as a steel beam resting on a masonry wall, is

Answer 28

A concentrated load. A concentrated load can either be a dead load or a live load

Question 29

If you try to breach a wall and find it to be stronger than normal, you may be in a

Answer 29

Wall column, or under a concentrated load. Try somewhere else.

Question 30

Loads are classified according to their orientation (or imposition) placed on the structure. They can be classified as (2)

Answer 30

Axial – passing through the centroid of the section Eccentric – perpendicular to the plane of the section, but not passing through the center

Question 31

A fire load represents the potential fuel available to a fire. The building itself may be included in the fire load if it is combustible. The fire load represents:

Answer 31

The total amount of potential energy (heat) in the fuel. The heat release rate HRR, indicates the rate of available energy released. These two are distinct values based on the type, shape, and orientation of the fuel. 

Question 32

The fire loading of a building is assessed in pounds of fuel per square foot. This requires a calculation of three pieces of information:

Answer 32

The weight of the combustible material The caloric value of the material The floor area.

Question 33

The basic measurement of caloric value is the BTU. This is:

Answer 33

The amount of heat required to raise a pound of water 1°F. Class A materials are estimated at 8000 BTU/lb Plastics and class B liquids are estimated at 16,000 BTU/lb.

Question 34

Putting it all together, a fire load of 80,000 BTU psf, or 10 pounds of class A psf is approximately equivalent to what in the ASTM E-119

Answer 34

A 1- hour exposure in the standard for endurance test or the ASTM E-119 16,000 BTU psf is equal to a 2- hour exposure

Question 35

A suspended load is a load hanging from a beam from an overhead structure, typically using:

Answer 35

A slender rod or other tensile member. This is similar to a tensile column with much less mass or fire resistance. A tie rod from wall to wall in an older timber building is also a type of suspended load

Question 36

A safety factor represents the ratio of strength of a material just before failure to the safe working stress. The design load is only a fraction of the test of strength. Therefore.

Answer 36

If the design load is 1/10 of the tested strength, the safety factor will equal 10. Steel has a safety factor of 2. Masonry constructed in place might have a safety factor of 10.

Question 37

The safety factor of steel used in a temporary location, such as excavation bracing is allowed to have a safety factor of:

Answer 37

Half of what would be permitted in a structure. In other words, the permitted load is doubled while the building is under construction. The steel will fail much sooner.

Question 38

In a composite material, all elements most react together so there’s no failure. Examples of a composite material is.

Answer 38

Reinforced concrete. Studs welded to steel beams and then embedded in a concrete of floor produces a diaphragm floor.

Question 39

Sandwiching a piece of steel between two wooden beams is called a

Answer 39

Flitch plate girder This may also be made with plywood between two wooden beams

Question 40

Composite construction, which is different from composite elements, is used to describe buildings in which:

Answer 40

Two different materials carry structural loads. An example is a concrete building having a top floor of lightweight steel

Question 41

The oldest structural member Transmits forces in a direction perpendicular to such forces to the reaction points.

Answer 41

A beam. A beam can be either vertical or horizontal and orientation or attitude.

Question 42

When a beam is loaded, it deflects or bends downward. The initial load is its own dead weight. Any load placed on a beam is known as

Answer 42

It’s superimposed load. A beam may have a slight camber or upward rise to deflect the superimposed load, causing it to be nearly horizontal.

Question 43

When a beam is deflected, the top and the bottom are: The middle is:

Answer 43

The top of the beam is in compression, the bottom is in tension. The central line is termed the neutral axis or plane.

Question 44

An ideal beam is a cable. This is because.

Answer 44

The cable is fully in tension, and makes the most economical use of its available material.

Question 45

The principles of a beam and carrying capacity factors:

Answer 45

The load carrying capacity or strength of a beam increases as the square of the depth, but increases only in direct proportion to increases in width In other words, the increase is only based on the beam remaining the same orientation. As the length of the beam increases, the safe load capacity decreases in direct proportion. (Double the length, half the capacity). A uniformly distributed load, has twice the capacity of an equal concentrated load in the center of the beam

Question 46

Different terms are used for various types of beams:

Answer 46

Simple beam - supported at 2 points Continuous beam – supported at 3 or more points Fixed beam – supported two points and rigidly held in position Overhanging beam – not a cantilever Girder- a beam that supports other beams Spandrel girder – a beam from the top of one window to the bottom the next A Lintel Grillage – series of closely spaced beams Cantilever beam— rigidly fixed at one end and projected out from the other Suspended beam – a simple beam suspended on attention member Transfer beam – moves loads laterally when it is not convenient to arrange columns one above the other.

Question 47

In a cantilever or overhanging beam, the tension and compression forces are reversed when

Answer 47

The beam is projected beyond the support point.

Question 48

Beam loading refers to the distribution of loads along the beam. Concentrated loads or distributed loads or loads over a cantilever are not equal. This is a particular concern when:

Answer 48

Buildings are under construction, partially constructed, or under demolition. Excessive loads can be found concentrated in different areas, such as stacks of bricks or other construction materials.

Question 49

The reaction of a beam is the result of the force exerted by the weight of the beam and it’s load on:

Answer 49

The supports of the beam, (columns or girder).

Question 50

The load that will bend or break a beam, which includes the factor of the position of the load, is the

Answer 50

The bending moment. Heavy loads should be placed directly over or very close to the point of Support to reduce the bending moment

Question 51

A type of beam as a frame structure, consisting of a triangle or a group of triangles, arranged in a single plane is

Answer 51

A truss Trusses are designed to support axial loads, but not rotational forces.

Question 52

A type of beam that is a framed structure, consisting of a triangle or a group of triangles, arranged in a single plane is

Answer 52

A truss Trusses are designed to support axial loads, but not rotational forces.

Question 53

The parts or members that make up the web of a truss are:

Answer 53

Top and bottom chords, Top in compression, bottoming tension Struts are the compressive connecting members making up the triangles Panel points are the connections.

Question 54

Trusses are named or described by their overall appearance. Examples are.

Answer 54

A parallel – chord truss A triangular truss A bow string truss Pratt truss Inverted King post – upside down triangle Inverted queen post – upside down quadrilateral Vierendeel truss - the only rectangular rose

Question 55

In sketching of a truss, the members are shown as

Answer 55

Thick lines are compressive loads Thin lines are tensile loads

Question 56

The difference between a king post and a queen post truss is

Answer 56

The King post has 1compression member and the queen post has 2 compression members

Question 57

The weakness or problem with trusses is that trusses can fail in a variety of ways. This includes:

Answer 57

If they are tied together for stability, one truss failure can cause multiple truss failures The failure of one element of a truss can cause the entire web to fail Gussett plates are a major weakness in lightweight wood trusses

Question 58

A structural member that transmit a compressive force along a straight path in the direction of the member

Answer 58

A column Columns can be vertical or horizontal, but have to be impressively loaded Non-vertical columns may be called struts or rakers A line of columns in any direction is called a bent A pillar is a freestanding masonry load carrying column

Question 59

The load carrying capacity of a column is a factor of:

Answer 59

Columns, lose strength by the square of the change in length. Example, a 12’ column can only carry 1/4 of the load of a 6’ column of the same cross section and material

Question 60

The most efficient shape of a column is closest to a complete circle. But most columns need to be square or rectangular for designs, plans, and connections. The most efficient non-circular column for a compressive load is

Answer 60

One with a cross section of a square such as a 4”x4” or an H I shapes are used for beams

Question 62

There are 3 types of columns that are differentiated by the manner in which they generally fail:

Answer 62

Piers are short, squatty columns, which fail by crushing Long, slender columns, fail by buckling such as an S shape Intermediate columns can fail either way

Question 63

Euler’s law columns are long thin columns. Based on Euler’s law formula for these columns, load carrying capacity can increase because:

Answer 63

If the columns are braced in the middle, the load carrying capacity is 4 times the initial amount. This is because the column has become two columns, each half the original length. If the bracing fails, the load carrying capacity decreases to 25% or 1/4.

Question 64

Walls are basically a wide slender column. Walls are classified into two main divisions: Several examples of walls are:

Answer 64

Loadbearing wall - carries its own weight plus some part of the structure Non loadbearing wall - veneer wall, panel wall/curtain wall, and a partition wall are examples Other types of walls include: cross walls – perpendicular Composite wall – two or more masonry materials Party wall – loadbearing wall, two structures Firewall – should be able to contain a fire Partition wall – non-loadbearing that subdivide floor areas A knee wall – between the roof and the top floor of a wood frame home Demising wall – wall the bounce tent spaces Shear wall - designed to resist wind forces Cantilever wall - high freestanding wall, not supported at the top

Question 65

A veneer wall is usually a brick wall that depends on the underlying wall for stability, tied with metal ties and bedded in the mortar. The layout of the bricks are:

Answer 65

Stretchers – the bricks are all laid lengthwise. Also known as a running bond. Headers, which are turned on end to cross the wall and tied together.

Question 66

Walls can be braced or stiffened by several means, including:

Answer 66

A buttress – masonry structure built on the outside surface of a wall. Could be a flying buttress. A pilaster is a masonry column projecting from one or both faces of the wall in which they’re located Wall columns – columns of steel, reinforced concrete, or solid masonry in a block wall Cavity or hollow wall – 2 wythes separated by a space for rain, drainage or insulation.

Question 67

The Arch combines the function of the:

Answer 67

The beam and the column. The arch is under compression along its entire length. Many arches did not require adhesive when the stones were cut and placed perfectly Arches are usually braced by heavy masonry buttresses since they tend to push outward at the base The original stones that make up the arch are called voussoirs and the final stone is called the Keystone.

Question 68

The thrust of an arch is normally outward, unless the arch is tied. In which case the thrust of the arch is.

Answer 68

Downward. This is applicable because a bowstring truss roof is not an Arch. It is a beam and the thrust is straight down on the wall or column.

Question 69

The rigid frame is derived from the arch. Steel rigid frames are used for clear space industrial and commercial buildings. Wooden rigid frames are used often for churches The key to these rigid frames is that

Answer 69

The frames must be tied together at the bottom to resist the outward thrust of the arch. these ties are often made of steel reinforcing rods.

Question 70

Scheels and domes are categorized by construction and materials. Three examples are.

Answer 70

A shell is a thin curved plate made of concrete. An example is an eggshell. A dome is a shell that can be considered a three-dimensional arch A geodesic dome is formed by a large number of triangles of equal size

Question 71

An important concept of the manner in which a load is spread from the point of application to the ground is called

Answer 71

Transmission of loads. The rule is that all loads must be transmitted continuously to the ground from the point at which they are applied. Any failure of continuity will lead to a partial or total collapse. Ultimately, all loads are delivered to the ground through the foundation.

Question 72

Connections of the structural elements of a building include the following

Answer 72

Pinned connections – connected by simple connectors, such as bolts, rivets, or welded joints. Not usually strong enough to reroute forces if a member is removed. A shear connection – prevents the column and beam from sliding past each other (nonrigid). May only be bolted. A moment connection - more substantial - it also permits the beam and the column from rotating (rigid connection). Bolted and welded.

Question 73

Concrete building connections include

Answer 73

Monolithic concrete – includes successive poured castings. Becomes a rigid frame structure. A wet joint can make precast concrete buildings into monolithic concrete.

Question 74

plastic design is used in steel buildings, in which the connections:

Answer 74

The connections redirect overloads to other sections of the building in plastic design

Question 75

Steel Gussett plates also known as ?? Are used in lightweight wood trusses.

Answer 75

Steel Gussett plates are also known as a gang nail. These penetrate only about 3/8 of an inch.

Question 76

Unprotected steel failure is listed as:

Answer 76

Steel heated to 1000°F elongates 9.5 in./ 100 feet of length. Unprotected steel rod and cables can fail at 800°F The most vulnerable point in steel construction is the connection.

Question 77

Residential structures are usually designed for a floor load of about:

Answer 77

30 to 40 PSF, including an adequate built-in safety factor. 

Question 78

The proper way to breach a masonry wall is to make a

Answer 78

Triangular opening, because a parallel opening would only be supported by the mortar above the bricks