Title:
Response of Externally Post-Tensioned Continuous Members
Author(s):
Mohamed H. Harajli, Mounir E. Mabsout, and Jack A. Al-Hajj
Publication:
Structural Journal
Volume:
99
Issue:
5
Appears on pages(s):
671-680
Keywords:
continuous beam; moment; strength; stress; tendon; unbonded tendon
DOI:
10.14359/12307
Date:
9/1/2002
Abstract:
The results of experimental and analytical evaluations of the behavior and strength characteristics of continuous concrete beams prestressed using external tendons are presented. The test variables included the areas of the external prestressing steel and the ordinary bonded reinforcement, configuration of the deviators, and the profile of the external tendons. Similarly to beams with internal unbonded tendons, the stresses in the prestressing steel at nominal flexural strength were below or slightly exceeded yield. As a result of the change in tendon eccentricity with increasing beam deflection (second-order effects), specimens with undeviated tendons mobilized relatively smaller load capacities and post-elastic deformations. Increasing the area of internal bonded reinforcement resulted in better crack distribution and, consequently, a more ductile mode of flexural failure. A comprehensive analytical model based on the concept of plastic hinge length was developed to predict the flexural response characteristics of continuous concrete members post-tensioned with external or internal unbonded tendons, with due consideration to the influence of the second-order effects and the rotational capacity in the plastic region. The important parameters that affect the behavior are evaluated and discussed.