Basalt is a dark-colored, fine-grained, igneous volcanic rock which is hard and dense. Individual mineral crystals are typically hard to see with the naked eye, although some kinds can contain larger crystals, or it may have holes that are empty (bubbles) or filled with other minerals.  Basalts are generally black or dark grey and polish well.  As a result, they are not easily scratched by metal objects. Basalt is often used for paving and ocasionally for wall construction.

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Stone masonry building - walls are likely to be a mix of basalt and trachyte stones with variation in block size and colour (J. Bothara)

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A stone masonry building built in 1920s in Christchurch, New Zealand; exterior stonework is Halswell basalt with Oamaru limestone facings (W. Clark)

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A 19th century stone masonry construction: exterior wall wythe is fine grained grey Halswell basalt, with facing stones and base course of pinkish-brown Port Hills trachyte and string courses of speckled Hoon Hay basalt; Canterbury Provincial Buildings complex, Christchurch, New Zealand (W. Clark)

Structural steel or timber members are bolted together with steel bolts and nuts.


Bolted connection of three steel members joined at a column, Canada *S. Brzev)

A more detailed occupancy description than the Building occupancy class - general

A framework of beams and columns in which inclined, often diagonal, structural members brace the building and provide strength and rigidity. The bracing can take a variety of forms. If diagonal members are stocky they resist both tension and compression forces. However if slender, they resist tension forces only. Usually, braced frame members are triangulated and meet at joints (similar to a vertical truss). Eccentrically Braced Frames are the exception - their inclined members are deliberately offset at joints in order to create ductile fuse regions in the steel beams. Braced Frames may or may not be infilled.


A simplified drawing of a typical cross-braced frame structure (A. Charleson, Seismic Design for Architects, Architectural Press 2008, p. 64, Fig. 5.2).


Examples of different types of braced frames (A. Charleson, Seismic Design for Architects, Architectural Press 2008, p. 77, Fig. 5.23).


Exterior braced frame as a retrofit scheme for a reinforced concrete building, Mexico (C. Scawthorn)


Braced frame (Chevron braces), Seattle, USA (S. Brzev)

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Eccentrically braced steel frame under construction, New Zealand (A. Charleson)


Concentrically braced steel frame under construction, Canada (S. Brzev)

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Concentrically braced frame, India (A. Charleson)

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Braced frame, Iran (A. Charleson)








Steel braced frame, Seattle, USA (S. Brzev)

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Exterior steel braced frame as a retrofit solution, University Hall, University of Berkeley, California (S. Brzev)


Birds Nest Stadium in Beijing, China has a 3-D braced frame structural system (S. Brzev)

The main overall type of occupancy