tailieunhanh - Calculation of loading induced tendon slip in beams prestressed with extern al tendons

This study consists of two parts, in which both experimental and numerical studies on externally prestressed concrete beams were investigated. In Part I, three identical beams of Tshaped section prestressed with external tendons have been tested to failure to investigate the effects of geometry of the applied load on flexural behavior of externally prestressed concrete beams. The tendon slip at deviators was also monitored in order to examine the evolution of stress in the external tendons. | Vietnam Journal of Mechanics, VAST , Vol. 28, No. 3 (2006), pp. 165- 175 CALCULATION OF LOADING-INDUCED TENDON SLIP IN BEAMS PRESTRESSED WITH EXTER N AL TENDONS PART I: EXPERIMENT Bur KHAC DIEP' LAM Huu QUANG Department of Bridge 8 Tunnel Engineering, Institute of Transport Science 8 Technology Abstract. This study consists of two parts, in which both experimental and numerical studies on externally prestressed concrete beams were investigated. In Part I, three identical beams of Tshaped section prestressed with external tendons have been tested to failure to investigate the effects of geometry of the applied load on flexural behavior of externally prestressed concrete beams. The tendon slip at deviators was also monitored in order to examine the evolution of stress in the external tendons. Test results were presented with emphasis on the effects of geometry of applied load and tendon slip at deviators. 1. INTRODUCTION Recently, external prestressing is commonly used for construction of new bridges because of its ease and cost saving. However, as the external tendons have no bond with concrete, the deformation of the external tendons is totally different from the deformation in concrete at the tendons level, ., the conventional compatibility of deformation between the prestressing tendons and concrete for beams with bonded tendons cannot be directly used to evaluate the stress in the external tendons. Therefore, it is rather difficult to determine the stress in the external tendons under the applied load since it depends on many parameters. Indeed, the stress increase in the external tendons under the applied load, unlike bonded tendons, is member-dependent instead of section-dependent. Thus the stress in the external tendons depends on the deformation of the entire member, and is uniform within the tendon segment between the deviator points, Further more, the stress increase in the external tendons might be likely the same over t he entire its length, or be