Externallypost-tensioned steel tendons have long been an attractive option for increasing the design loads or correcting strength and serviceability problems in bridge and building structures. More recently, alternative solutions have been developed and implemented that use straight post-tensionedcarbon fiber reinforced polymer (CFRP) tendons, ideally enlisting their high-strength to failure, small relaxation, corrosion resistance, and light weight. In this paper, a novel CFRP system for external post-tensioning is presented. The solution consists of unbonded CFRP bars connected to dead- and live-end steel anchors by means of couplers that allow the bar to develop the full tensile strength. Intermediate deviators can be extended vertically to impart additional post-tensioning (PT) force and achieve a profiled bar configuration. The required uplift forces for deflectioncontrol of a flexural member are provided by modifying the number, position and extended height of the deviators, similarly to commercially available systems that use steel wire strands. The structural efficiency of such approach in controlling deflection is analyzed and discussed for single-span one-way members on the basis of a parametric study that considers the influence of member geometry, flexural stiffness, boundary conditions, and PT system layout. A design example is also provided.
Externally Post-Tensioned Carbon FRP Bar System for Deflection Control / F., Matta; Nanni, Antonio; A., Abdelrazaq; D., Gremel; R., Koch. - In: CONSTRUCTION AND BUILDING MATERIALS. - ISSN 0950-0618. - STAMPA. - 23:4(2009), pp. 1628-1639. [10.1016/j.conbuildmat.2007.08.002]
Externally Post-Tensioned Carbon FRP Bar System for Deflection Control
NANNI, ANTONIO;
2009
Abstract
Externallypost-tensioned steel tendons have long been an attractive option for increasing the design loads or correcting strength and serviceability problems in bridge and building structures. More recently, alternative solutions have been developed and implemented that use straight post-tensionedcarbon fiber reinforced polymer (CFRP) tendons, ideally enlisting their high-strength to failure, small relaxation, corrosion resistance, and light weight. In this paper, a novel CFRP system for external post-tensioning is presented. The solution consists of unbonded CFRP bars connected to dead- and live-end steel anchors by means of couplers that allow the bar to develop the full tensile strength. Intermediate deviators can be extended vertically to impart additional post-tensioning (PT) force and achieve a profiled bar configuration. The required uplift forces for deflectioncontrol of a flexural member are provided by modifying the number, position and extended height of the deviators, similarly to commercially available systems that use steel wire strands. The structural efficiency of such approach in controlling deflection is analyzed and discussed for single-span one-way members on the basis of a parametric study that considers the influence of member geometry, flexural stiffness, boundary conditions, and PT system layout. A design example is also provided.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
