Sudden Collapse of Unbonded Underprestressed Structures


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Title: Sudden Collapse of Unbonded Underprestressed Structures

Author(s): G. I. N. Rozvany and J. F. Woods

Publication: Journal Proceedings

Volume: 66

Issue: 2

Appears on pages(s): 129-135

Keywords: beams (supports); concrete slabs;cracking (fracturing) ; dynamic loads; flat plates (concrete) ;flexural strength; live loads; prestressed concrete; research; stability; unbonded prestressing.

Date: 2/1/1969

Discusses the behavior of unbonded prestressed beams and slabs at flexural cracking, which is often accompanied by a sudden decrease of the load capacity. This instability phenomenon is of considerable importance because it can cause a sudden collapse of unbonded prestressed structures when they are subjected to excessive live loads or earthquake loads. A theoretical explanation of the foregoing problem is given, and it is concluded that sudden collapse can be avoided by making the average concrete prestress greater than the modulus of rupture. Experimental verifications of the foregoing proposition are presented. Two worked examples are included to illustrate the proposed method.