Primary vs Secondary Structure


I just started in architecture school and I am trying to understand the difference between Primary vs Secondary structure in a structural system.

As far as I can tell, primary probably means all loadbearing elements but what is secondary? Also, is there tertiary structure?

Oct 3, 16 10:21 am
Non Sequitur

Structure is structure.

I've never heard of 1st vs 2nd.

Oct 3, 16 11:14 am  · 
Primary - everything without which the building won't stand up. Typically this means columns, braces and beams in steel construction. In concrete add shear walls and slabs. In some super tall or non standards geometry buildings floor slabs are also "activated" meaning they provide diaphragm action, whereas in much other construction they merely rest on primary elements.

Secondary - everything that holds something up (provides "structure") but isn't crucial to the buildings structural integrity. Example of this is facade steel like mullions and transoms or other arrangements to hold cladding, or various structural elements that hold up secondary elements like canopies, ceilings and decorative screens etc.

Tertiary systems come in to play sometimes, especially in large projects, for instance where the module of primary structure is vastly different in pure size from the module of for instance a cladding panel that attaches to it. Think a long span roof with parallel trusses every 30' and a 3x10' roof cladding element: then the secondary grid might create spans of say 10x10' bays and then there's the tertiary following the cladding module.

Oct 3, 16 5:32 pm  · 
1  · 


Feb 13, 19 12:18 pm  · 

Other examples of secondary structure would be the lintels in masonry walls, the shelf angles that support finishes when they span over a window or other opening and there are other odd and ends that provide support or stabilization such as cross bracing in steel bar joist or structural elements used during the construction of the building.

Feb 13, 19 1:39 pm  · 

I know this is necrothreading a bit, but I thought it important for future people who may find this... Primary structure vs Secondary structure is defined as terms in IBC.  Read them.  They have fireproofing implications.

Feb 13, 19 11:34 am  · 

Interesting - mind telling the section? (I'm reviewing for exams currently)

Feb 13, 19 2:00 pm  · 

704, but again it depends on your construction type.

Feb 13, 19 2:20 pm  · 

Well, as mentioned, this conversation is based on construction type, and other things, but all the definitions for elements of your building can be found in Chapter 2 of the corresponding code. They're in alphabetical order.

Feb 13, 19 4:20 pm  · 


Feb 13, 19 2:24 pm  · 

The secondary structure is used to stabilize the building, not the main structure for load-bearing

Sep 11, 20 10:07 pm  · 

'sup bot?

Sep 11, 20 10:52 pm  · 

look up the definition of secondary members in the building code. 

Sep 12, 20 6:39 am  · 

The Primary structural members are what hold up the structure and resist loads that the structure is subjected to. If you remove any of them, they structure my collapse or fold up.

 Secondary structural members serve some other useful function that are not related to the strength or stability of the structure.

Mar 19, 21 8:35 am  · 

Would a CONCRETE staircase within a concrete structure be a primary, secondary or tertiary component?

Aug 4, 21 4:16 am  · 

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