{{Short description|Engineering concept}} {{distinguish|living hinge}} thumb|300px|Diagram of a structure featuring plastic hinges In the structural engineering beam theory, '''plastic hinge''' is the deformation of a section of a beam where plastic bending occurs.<ref>{{Cite book | edition = 2 | publisher = Butterworth-Heinemann | isbn = 0-7506-6221-2 | last = Megson | first = T.H.G. | title = Structural and Stress Analysis, Second Edition | date = 2005-04-29 }}</ref> In earthquake engineering plastic hinge is also a type of energy damping device allowing plastic rotation [deformation] of an otherwise rigid column connection.<ref>[http://mceer.buffalo.edu/education/reu/04Proceedings/12Long_Bergad.pdf Analysis of Rotational Column with Plastic Hinge] Michael Long and Corey Bergad, retrieved November 5, 2006</ref>
==Plastic behaviour== In plastic limit analysis of structural members subjected to bending, it is assumed that an abrupt transition from elastic to ideally plastic behaviour occurs at a certain value of moment, known as plastic moment (M<sub>p</sub>). Member behaviour between M<sub>yp</sub> and M<sub>p</sub> is considered to be elastic. When M<sub>p</sub> is reached, a plastic hinge is formed in the member. In contrast to a frictionless hinge permitting free rotation, it is postulated that the plastic hinge allows large rotations to occur at constant plastic moment M<sub>p</sub>.
Plastic hinges extend along short lengths of beams. Actual values of these lengths depend on cross-sections and load distributions.<ref>{{cite journal |last1=Megalooikonomou |first1=Konstantinos G. |last2=Tastani |first2=Souzana P. |last3=Pantazopoulou |first3=Stavroula J.|author3-link=Stavroula Pantazopoulou |title=Effect of Yield Penetration on Column Plastic Hinge Length |journal=Engineering Structures |year=2018 |volume=156 |pages=161–174 |doi= 10.1016/j.engstruct.2017.11.003|bibcode=2018EngSt.156..161M }}</ref> But detailed analyses have shown that it is sufficiently accurate to consider beams rigid-plastic, with plasticity confined to plastic hinges at points. While this assumption is sufficient for limit state analysis, finite element formulations are available to account for the spread of plasticity along plastic hinge lengths.<ref>{{cite journal | doi = 10.1061/(ASCE)0733-9445(2006)132:2(244) | volume=132 | title=Plastic Hinge Integration Methods for Force-Based Beam–Column Elements | year=2006 | journal=Journal of Structural Engineering | pages=244–252 | last1 = Scott | first1 = Michael H. | last2 = Fenves | first2 = Gregory L.| issue=2 }}</ref>
By inserting a plastic hinge at a plastic limit load into a statically determinate beam, a kinematic mechanism permitting an unbounded displacement of the system can be formed. It is known as the collapse mechanism. For each degree of static indeterminacy of the beam, an additional plastic hinge must be added to form a collapse mechanism.{{cn|date=August 2024}}
==References== <references/>
Category:Building engineering Category:Structural engineering