Editing Structure (section)

== Load-bearing ==
[[File:Sámi storehouse.jpg|thumb|left|A traditional [[Sami people|Sami]] food storage structure]]
[[File:Voûte de l'église Saint-Séverin à Paris.jpg|thumb|upright|Gothic quadripartite cross-ribbed vaults of the [[Saint-Séverin]] church in Paris]]
[[Building]]s, [[aircraft]], [[skeleton]]s, [[Ant colony|anthills]], [[beaver dam]]s, [[bridge]]s and [[salt dome]]s are all examples of [[Structural load|load]]-bearing structures. The results of [[construction]] are divided into [[building]]s and [[nonbuilding structure|non-building structure]]s, and make up the [[infrastructure]] of a human society. Built structures are broadly divided by their varying design approaches and standards, into [[Structural engineering#Specializations|categories]] including building structures, [[architectural structure]]s, civil engineering structures and mechanical structures.

The effects of loads on physical structures are determined through [[structural analysis]], which is one of the tasks of [[structural engineering]]. The [[Structural engineering#Structural elements|structural elements]] can be classified as one-dimensional ([[rope]]s, [[strut]]s, [[Beam (structure)|beams]], [[arch]]es), two-dimensional ([[membrane]]s, plates, [[Concrete slab|slab]], [[Shell (structure)|shells]], [[Vault (architecture)|vaults]]), or three-dimensional (solid masses).<ref name=Carpinter>{{cite book|last1=Carpinteri|first1=Alberto|title=Structural Mechanics: A unified approach|date=2002|publisher=CRC Press|isbn=9780203474952}}</ref>{{rp|2}} Three-dimensional elements were the main option available to early structures such as [[Chichen Itza]]. A one-dimensional element has one dimension much larger than the other two, so the other dimensions can be neglected in calculations; however, the ratio of the smaller dimensions and the composition can determine the [[Flexural rigidity|flexural]] and [[Compressive strength|compressive]] stiffness of the element. Two-dimensional elements with a thin third dimension have little of either but can resist biaxial traction.<ref name=Carpinter/>{{rp|2–3}}

The structure elements are combined in ''structural systems''. The majority of everyday load-bearing structures are ''section-active'' structures like frames, which are primarily composed of one-dimensional (bending) structures. Other types are ''Vector-active'' structures such as [[truss]]es, ''surface-active'' structures such as shells and folded plates, ''form-active'' structures such as cable or membrane structures, and hybrid structures.<ref>{{cite book|last1=Knippers|first1=Jan|last2=Cremers|first2=Jan|last3=Gabler|first3=Markus|last4=Lienhard|first4=Julian|title=Construction manual for polymers + membranes : materials, semi-finished products, form-finding design|date=2011|publisher=Institut für internationale Architektur-Dokumentation|location=München|isbn=9783034614702|edition=Engl. transl. of the 1. German}}</ref>{{rp|134–136}}

Load-bearing biological structures such as bones, teeth, shells, and tendons derive their strength from a multilevel hierarchy of structures employing biominerals and [[protein]]s, at the bottom of which are [[collagen|collagen fibrils]].<ref>{{cite journal|last1=Zhang|first1=Z.|last2=Zhang|first2=Y.-W.|last3=Gao|first3=H.|title=On optimal hierarchy of load-bearing biological materials|journal=Proceedings of the Royal Society B: Biological Sciences|date=1 September 2010|volume=278|issue=1705|pages=519–525|doi=10.1098/rspb.2010.1093|pmid=20810437|pmc=3025673}}</ref>