Anisotropic Curvature and Damage of Unbonded Post-tensioned Concrete Slabs During Fire Testing
2017 (English)In: Fire technology, ISSN 0015-2684, E-ISSN 1572-8099, Vol. 53, no 3, p. 1333-1351Article in journal (Refereed) Published
Abstract [en]
Two furnace tests, using two different fire exposures, on unbonded post-tensioned concrete slabs (1700 × 1200 mm) are reported. Local curvature is measured along two lines approximately in the middle of the slabs both parallel (longitudinal) and orthogonal (transverse) to the prestressing direction. More pronounced curvature in the transverse direction is accompanied by the formation of cracks running predominantly in the longitudinal direction. While the transverse curvature relaxes back to the original state after the cooling phase the curvature in the longitudinal direction ultimately exhibits upward deflection due to the hogging moment caused by the prestress in the tendons acting on a cross section with temperature reduced mechanical properties at the fire exposed side. The effect on crack formation due to the prestressing can additionally be detected by ultrasonic pulse velocity measurements in the different directions through the depth of the slab, where a reduction of 5–25% is observed in the transverse direction compared to the longitudinal direction. The phenomenological mechanical behaviour of the slabs is captured in a finite element model which describes the evolution of stress in the prestressing tendons. This model additionally suggests that the curvature in the transverse direction is independent of the prestressing in the longitudinal direction. © 2016 Springer Science+Business Media New York
Place, publisher, year, edition, pages
2017. Vol. 53, no 3, p. 1333-1351
Keywords [en]
Concrete slab, Crack formation, Deflection, Fire, Hydrocarbon fire curve, Post-tension, Standard fire curve, Ultrasonic pulse velocity, Concrete slabs, Concrete testing, Concretes, Crack initiation, Cracks, Deflection (structures), Finite element method, Flammability testing, Light velocity, Prestressing, Stresses, Hydrocarbon fire, Longitudinal direction, Mechanical behaviour, Post-tensioned concrete slabs, Standard fire, Transverse curvature, Fires
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:ri:diva-27581DOI: 10.1007/s10694-016-0637-8Scopus ID: 2-s2.0-85001105673OAI: oai:DiVA.org:ri-27581DiVA, id: diva2:1058278
2016-12-202016-12-192023-06-07Bibliographically approved