Structural Systems

CM 105

Precast Concrete Framing

• Offer exceptional strength and resistance to seismic stresses and high degree of fire safety

• Concrete framing plans can be divided into: column, beam, wall, floor and roof plans

• Walls are located to their edges, column to centers

Concrete Tilt-up Plans• Plans must show the location and size of each panel• Panels are dimensioned from edge to edge

Cast-in-place Concrete

Floor and Roof Decking• Other materials, such as the precast

concrete hollow core planks shown here, can also be used to create the floor and roof decks.

Fundamentals of Building Construction, Materials & Methods, 5th Edition

Copyright © 2009 J. Iano. All rights reserved.

Concrete Units and Stone

http://www.virginiaplaces.org/geology/buildingstones.html

http://www.vt.edu/about/2011-11-11-hokie-stone.pdf

Stone cladding

Stone Masonry• Rubble: Unsquared stone blocks• Random: Laid without continuous

horizontal joints• Coursed: Laid with continuous

horizontal joints

Fundamentals of Building Construction, Materials & Methods, 5th Edition

Copyright © 2009 J. Iano. All rights reserved.

Stone Masonry• Ashlar: Squared blocks• Random: Laid without

continuous horizontal joints• Coursed: Laid with

continuous horizontal joints

Fundamentals of Building Construction, Materials & Methods, 5th Edition

Copyright © 2009 J. Iano. All rights reserved.

Concrete Masonry Units (CMUs):• Can be manufactured in a great variety of shapes and

sizes

Fundamentals of Building Construction, Materials & Methods, 5th Edition

Copyright © 2009 J. Iano. All rights reserved.

Laying CMU• Mortar is

identical to that used for brick masonry.

• Corner leads are laid first.

• String lines and levels are used to keep walls straight, plumb, and level.

• Joints are tooled and the face of the blocks cleaned as work progresses.

Fundamentals of Building Construction, Materials & Methods, 5th Edition

Copyright © 2009 J. Iano. All rights reserved.

Wood Floor Framing – Sill Plate & Girders

Floor Framing – Floor Joists

Floor Framing Plan Example

Roof Framing Plan Example

Heavy Timber Framing

Courtesy Ryan Wall

Light Gauge Steel

Steel Framing

• Division 5 Metals, Section 05 40 00—Cold-Formed Metal Framing– Structural, loadbearing framing– Exterior wall framing (subject to

wind loads)

• Division 9 FinishesSection 09 22 16—Non-Structural Metal Framing– Interior nonloadbearing framing

Fundamentals of Building Construction, Materials & Methods, 5th Edition

Copyright © 2009 J. Iano. All rights reserved.

Light Gauge Steel Compared to Light Wood Framing

• Advantages– Like wood light framing:

versatile, flexible, simple to construct

– Noncombustible and immune to insect attack

– Dimensionally stable, with consistent material properties

– Lighter weight• Disadvantages

– Members require more frequent bracing

– Readily conducts heat and requires extra attention to eliminating thermal bridging effects

– Susceptible to corrosion

Fundamentals of Building Construction, Materials & Methods, 5th Edition

Copyright © 2009 J. Iano. All rights reserved.

Steel

Steel

Steel Alloys• Traditional mild steel

– ASTM A36– Minimum 36 ksi (36,000 lb

per sq. in.) yield strength• Contemporary high-

strength, low alloy steels– ASTM A992: W shapes– ASTM A572: other shapes– Produced economically in

mini-mills– Minimum yield strength

50 to 65 ksi• Use of stronger steel

allows savings in weight and reductions in the size of structural elements, reducing overall costs.

ASTM A992 steel columns lay stacked in a fabricator yard. Note the holes predrilled for connections that will be completed in the field.

More Steel Alloys• Weathering steel ASTM

A588– Surface rust adheres to base

metal, limiting further rusting

– Mostly used in highway and bridge structures, eliminating the need for a protective coating

– Right: 365-ft span highway arch bridge made principally of weathering steel

– Cor-Ten steel (a proprietary trade name for weathering steel)

• Stainless steel ASTM A240, A276– Added nickel and chromium– Forms self-protecting oxide

layer that provides long lasting protection against corrosion

Fundamentals of Building Construction, Materials &

Methods, 5th EditionCopyright © 2009 J. Iano. All rights reserved.

Question?

In a fire, without fire protection a steel beam is less able to withstand the heat than a timber.

WHY?