Floor Systems and Structural Support Quiz

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Questions and Answers

What do floor systems primarily do?

Transfer loads horizontally to beams, columns, or loadbearing walls (correct)

Support only live loads like people and furniture

Transfer loads vertically to the foundation

Transfer loads solely to the walls of a structure

Which of the following is considered a live load supported by floor systems?

Weight of construction materials

Fixed installations like HVAC systems

Weight of the floor itself

People and movable equipment (correct)

What is the role of stirrups in concrete beams?

Provide additional weight to the beam structure

Connect beams to the loadbearing walls

Resist vertical components of diagonal tension (correct)

Support horizontal reinforcement bars

What are top bars in concrete beams used for?

As tension reinforcement in sections under upward bending Signup and view all the answers

Which type of concrete slab is primarily used to span structural bays in one or both directions?

Reinforced concrete slab Signup and view all the answers

What does the term 'dead loads' refer to regarding floor systems?

Weight from the structural components like floors and ceilings Signup and view all the answers

What is the purpose of using hooks at the end of tension bars in concrete beams?

Develop necessary embedment length for anchorage Signup and view all the answers

Which material is typically used to support steel decking within floor systems?

Steel beams Signup and view all the answers

What must wood light framing rely on due to its combustibility?

Finish flooring and ceiling materials Signup and view all the answers

What is the common rule of thumb for estimating joist depth?

Span/16 Signup and view all the answers

What is the maximum allowable deflection for joists as a fraction of the span?

1/360 Signup and view all the answers

What is the purpose of bridging in joist framing?

To provide crossbracing Signup and view all the answers

In balloon framing, how do the studs behave compared to platform framing?

They extend the full height of the building Signup and view all the answers

What defines a beam pocket in construction?

A recessed area for a beam to fit Signup and view all the answers

What does the stiffness of joist framing under stress influence?

The load-bearing capacity Signup and view all the answers

What do joist hangers specifically do in construction?

Anchor wooden beams or joists Signup and view all the answers

What distinguishes LH and DLH series joists from K series joists?

They are designed for increased loads with heavier webs and chord members. Signup and view all the answers

What is the primary function of Form Decking?

To serve as temporary support until the slab can support itself and live loads. Signup and view all the answers

Which type of decking is designed to provide textile reinforcement to bonded concrete slabs?

Composite Decking Signup and view all the answers

What is a characteristic feature of Cellular Decking?

It includes perforated cells that function as acoustic ceilings. Signup and view all the answers

What is a notable advantage of Light-Gauge Steel Joists?

They can span longer distances while being lighter. Signup and view all the answers

What is the primary use of wooden beams in construction?

For structural support Signup and view all the answers

Which material often serves as the core structure in residential wood frame construction?

Wood Joists Signup and view all the answers

What is a critical design feature of Metal Decking aimed at improving its structural integrity?

A corrugated pattern for added stiffness. Signup and view all the answers

What is a characteristic of non-bearing partitions?

They only support their own weight Signup and view all the answers

Which type of decking is NOT typically associated with a concrete fill application?

Wood Planking Signup and view all the answers

How do bearing walls differ from partition walls?

Bearing walls also support part of the house Signup and view all the answers

Which of the following describes the function of a steel beam?

It redirects loads applied along its axis Signup and view all the answers

What type of wall is designed to divide space without supporting any vertical weight?

Non-bearing partition Signup and view all the answers

Bearing partitions must be supported by which of the following structures?

Beams, girders, or walls Signup and view all the answers

Which statement about wooden beams is true?

They can have both structural and decorative purposes Signup and view all the answers

What is a key advantage of using steel beams in construction?

Provides excellent load direction capabilities Signup and view all the answers

What is the primary purpose of subflooring?

To serve as a working platform during construction Signup and view all the answers

What advantage do prefabricated wood joists and trusses have over dimension lumber?

They are generally lighter and more dimensionally accurate Signup and view all the answers

What do glued combined subfloor underlayment panels achieve when attached to joists?

They form integral tee beam units with the joists Signup and view all the answers

What is a characteristic of solid-sawn lumber as used in post and beam construction?

It is oversized softwood lumber with cross-sectional dimensions over 6 inches Signup and view all the answers

Which of the following describes non-bearing partitions in relation to joists?

They are built parallel to the joists and do not extend above Signup and view all the answers

The term 'I-Joists' refers to which of the following?

Prefabricated wooden elements designed for framing purposes Signup and view all the answers

What is a disadvantage of using solid sawn lumber compared to prefabricated options?

It is generally heavier and less dimensionally stable Signup and view all the answers

How does the presence of a floor opening length relate to joists?

It creates additional stress on the joists if not properly managed Signup and view all the answers

What factors should be considered when selecting a wood beam?

Lumber species and modulus of elasticity Signup and view all the answers

What is glue-laminated timber primarily made from?

Laminating stress-grade lumber with adhesive Signup and view all the answers

What is Parallel Strand Lumber (PSL) primarily produced using?

Bonding long, narrow wood strands under heat and pressure Signup and view all the answers

What must be considered regarding bolt connections in beam structures?

Thickness of members and direction of loads Signup and view all the answers

What is the main benefit of using larger, fewer structural members in wood plank-and-beam systems?

Potential savings in material and labor costs Signup and view all the answers

What benefit do shear plate or split-ring connectors provide?

Greater stresses per unit bearing capacity Signup and view all the answers

Why is it essential to integrate the supporting grid of beams with interior partitions?

For both structural and visual reasons Signup and view all the answers

What is Laminated Veneer Lumber (LVL) made from?

Bonding layers of wood veneers under heat and pressure Signup and view all the answers

Study Notes

Flooring Systems

Floor systems transfer loads horizontally to beams, columns, or load-bearing walls.
Live loads include people, furnishings, and movable equipment.
Dead loads include the weight of the floor construction itself.

Key Materials in Floor Systems

Concrete: Precast concrete planks may be supported by beams or load-bearing walls.
Steel: Steel beams support steel decking or precast concrete planks.
Wood: Wood beams support structural planking or decking.

What are Concrete Beams?

Reinforced concrete beams work together with longitudinal and web reinforcement to resist applied forces.

Reinforcing Bars in Concrete Beams

Reinforcing bars extend into and down column support for structural continuity to develop required embedment length for anchorage.

Types of Reinforcing Bars in Concrete Beams

Top Bar: Longitudinal bar serving as tension reinforcement in the section of a concrete beam subject to upward bending of a negative moment.
Bottom Bar: Also longitudinal bar serving as tension reinforcement; but in a different section of a concrete beam than the top bar.
Bent Bars: Longitudinal bars bent to an angle of 30° or more with the axis of a concrete beam, perpendicular to and intersecting the cracking that could occur from diagonal tension.
Stirrups: U-shaped or closed-loop bars placed perpendicular to the longitudinal reinforcement of a concrete beam to resist the vertical component of diagonal tension.
Hooks: Bends in the end of tension bars to develop equivalent embedment length for anchorage (90°, 135°, or 180° bend).

What are Concrete Slabs?

Concrete slabs are plate structures reinforced to span either one or both directions of a structural bay.

Types of Concrete Slabs

One-Way Slab: Uniformly thick, reinforced in one direction, and cast integrally with parallel supporting beams.
One-Way Joist Slab: Cast integrally with a series of closely spaced joists, supported by a parallel set of beams.
Two-Way Slab and Beam: Uniform thickness reinforced in two directions and cast integrally with supporting beams and columns on all four sides of square bays.
Two-Way Waffle Slab: Two-way concrete slab reinforced by ribs in two directions; can carry heavier loads and span longer distances than flat slabs.
Two-Way Flat Plate: Concrete slab of uniform thickness reinforced in two or more directions and supported directly by columns without beams or girders.
Two-Way Flat Slab: A flat plate thickened at its column supports to increase shear strength and moment-resisting capacity.

What is Prestressed Concrete?

Reinforced by pre-tensioning or post-tensioning high-strength steel tendons within their elastic limit.

Two Types of Prestressing Techniques

Pre-Tensioning: Pre-stresses a concrete member by stretching the reinforcing tendons before the concrete is cast.
Post-Tensioning: Pre-stresses a concrete member by tensioning the reinforcing tendons after the concrete has set.

Pre-tensioning Process

Steel tendons are first stretched across the casting bed until a predetermined tensile force is developed.
Concrete is cast in formwork around the stretched tendons and fully cured.
Tendons are placed eccentrically to reduce maximum compressive stress to that produced by bending alone.
When the tendons are cut or released, the tensile stresses are transferred to the concrete through bond stresses. This produces a slight upward curvature or camber in the member.
Deflection of the member under loading tends to equalize its upward curvature.

Post-tensioning Process

Unstressed steel tendons, draped inside the beam or slab form, are coated or sheathed to prevent bonding while the concrete is cast.
After the concrete has cured, the tendons are clamped on one end and jacked against the concrete on the other end until the required force is developed.
Tendons are securely anchored on the jacking end and the jack is removed.
Steel tendons may be left unbonded, or they may be bonded to the surrounding concrete by injecting grout.
Deflection of the member under loading tends to equalize its upward curvature.

What are Precast Concrete Floor Systems?

Involve units that are cast and steam-cured in a plant off-site, transported to the construction site, and set in place as rigid components with cranes.

Precast Concrete Units

Solid Flat Slabs: Dimensions given.
Hollow Core Slabs: Dimensions given.
Single Tees: Dimensions given.
Double Tees: Dimensions given, noting that temporary supports might not be required.
Rectangular Beams: Dimensions given.
L-Shaped Beams: Dimensions given.
Inverted Tee Beams: Dimensions given.
AASHTO Girders: Dimensions given and noting use in bridge design.

What is Structural Steel Framing?

Structural steel girders, beams, and columns are used to construct a skeleton frame for structures ranging in size from one-story buildings to skyscrapers.

Types of Beams Systems

One-Way Beam System: Suitable for long, narrow buildings, especially when column-free space is desired; each pair of external columns supports a long-spanning beam or girder.
Two-Way Beam System: Increases floor depth but provides more space for mechanical services.
Triple Beam System: Long spanning plate girders or trusses are used to carry the primary beam, which supports a layer of secondary beams.

What are Steel Beams?

The general objective is to use the lightest steel section that will resist bending and shear forces within allowable limits of stress and without excessive deflection for intended use.

Types of Steel Beams

More structurally efficient wide-flange (W) shapes have largely superseded the classic I-beam (S) shapes.
Beams may also be in the form of channel (C) sections, structural tubing, or composite sections.

What are Open-Web Steel Joists?

Lightweight, shop-fabricated steel members with a trussed web.

Types of Open-Web Steel Joists

K Series Joist: Web consists of a single bent bar running in a zigzag pattern between the upper and lower chords.
LH and DH Series Joist: Heavier web and chord members for increased loads and spans.

Floor Decks of Open-Web Joist Framing

Metal decking with concrete fill
Precast concrete planks
Plywood panels or wood planking

Metal Decking

Corrugated to increase stiffness and spanning capability.

Three Major Types of Metal Decking

Form decking
Composite decking
Cellular decking

What is Form Decking?

Serves as permanent formwork for a reinforced concrete slab until the slab can support itself and its live load.

What is Composite Deck?

Serves as tensile reinforcement for the concrete slab which it is bonded with embossed rib.

What is Cellular Decking?

Manufactured by welding corrugated sheet to a flat steel sheet.
Serves as an acoustic ceiling when a perforated cell are filled with fiberglass.

Light-Gauge Steel Joists

Manufactured by cold-forming steel sheets or strip steel.
Lighter, more stable, and can span longer distances.

Span Ranges for Light-Gauge Steel Joists

Dimensions given.

Light-Gauge Steel Joists - Overhangs and Floor Openings

Dimensions given.

Wood Joists

An essential subsystem of wood light-frame construction.
Because of wood light framing's combustibility, it must rely on finish flooring and ceiling materials.
Susceptibility to decay and insect infestation requires positive site drainage; adequate separation; appropriate pressured lumber.

Wood Joists - Spacing, Supporting, and Additional Support

Joists are spaced; cavities can accommodate services; joists may be concealed.
End joists may be doubled to provide additional support; some sheathing or subflooring may be needed.

Wood Joists - Span Ranges

Dimensions given.
Rule of thumb for estimating joist depth: span/16.
Joist deflection should not exceed 1/360th of span.

Wood Joists - Bridging

Consists of wood and metal crossbracing or full depth blocking; required if depth is 6 times its thickness.

What is Wood Joists Framing?

Utilizes a series of horizontal beams or joists to support a floor's weight.
Typically run from one side of the structure to the other or between beams or walls.

Platform Framing

A construction technique predominantly used in wood-frame buildings.
Each floor is framed separately with studs or support posts that run from the bottom of one floor to the top of the same floor.

Balloon Framing

In balloon framing, studs extend the full height of the building, typically two stories.

Beam Pocket

A recessed space designed to hold the end of an intersecting beam in a concrete wall, masonry wall, or a column.

Wood Beam with Joists Hanger

Used to anchor wooden beams or joists on floors, ceilings, and roofs.
Primarily used with well-seasoned lumber.

Steel Beam with Ledger

A structural element that opposes loads applied along the side to the beam's axis.
Primarily used to support heavier loads or to create a continuous support for joists.

Wood Beam with Spliced Joists

A method of joining long spans of wood members when space for a single piece is not practical.
Solid blocking between the joists is used during the assembly to maintain consistency.

Non-Bearing Partitions

A dividing wall that supports no vertical weight other than its own.

Bearing Partitions

Function as dividers and hold up part of the house.

Floor Projections, Planks, and Openings and more

Dimensions and engineering recommendations given.

Wood Subflooring

A structural material that spans across floor joists, serving as a construction platform.
Uses a variety of materials to maintain structural rigidity.

Prefabricated Joists and Trusses

Prefabricated pre-engineered wood joists and trusses are increasingly used in the place of dimension lumber due to being lighter and more dimensionally stable.

Solid Sawn Lumber

Solid-sawn heavy timber members are employed as the main structural components in post-and-beam construction.
Solid-sawn timber is oversized structural lumber that is six or more inches in its smallest cross-sectional dimension.

Glue-Laminated Timber

Laminated stress-grade lumber with adhesive under controlled conditions.

Parallel Strand Lumber (PSL)

Structural lumber product made by bonding narrow wood strands under heat and pressure using a water-proof adhesive.

Laminated Veneer Lumber (LVL)

Structural lumber made by bonding layers of wood veneers under heat and pressure with a waterproof adhesive.

Wood Beam Supports

Provides resistance to uplift and horizontal forces.
Provides sufficient clearance for construction access.

Wood Decking

Consists of plywood, lumber, or glued laminated members placed over structural members to provide structural rigidity.

Wood Decking - Types

Dimensions given.

Wood Decking - Surface Patterns

Different types of groove designs given.

Wood Decking - Type of Span

Simple Span
Double Span
Continuous Span

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Description

Test your knowledge on floor systems and their various components with this quiz. It covers important concepts such as live and dead loads, the role of beams and joists, and the materials used in structural framing. Perfect for students of construction and civil engineering.