25.9.4 General Zone
(b) Linear stress analysis, including finite element analysis or equivalent
(c) Simplified equations in AASHTO LRFD Bridge Design Specifications, Article 188.8.131.52, except where restricted by 184.108.40.206.2
The design of general zones by other methods shall be permitted, provided that the specific procedures used for design result in prediction of strength in substantial agreement with results of comprehensive tests.
(a) Member cross sections are nonrectangular
(b) Discontinuities in or near the general zone cause deviations in the force flow path
(d) Multiple anchorage devices are used in other than one closely spaced group
(e) Centroid of the tendons is located outside the kern
(f) Angle of inclination of the tendon in the general zone is less than —5 degrees from the centerline of axis of the member, where the angle is negative if the anchor force points away from the centroid of the section
(g) Angle of inclination of the tendon in the general zone is greater than +20 degrees from the centerline of axis of the member, where the angle is positive if the anchor force points towards the centroid of the section
(a) Three-dimensional analysis procedures
(b) Approximated by considering the summation of effects for two orthogonal planes
(a) Two horizontal bars at least No. 4 in size shall be provided parallel to the slab edge. They shall be permitted to be in contact with the front face of the anchorage device and shall be within a distance of h/2 ahead of each device. Those bars shall extend at least 6 in. either side of the outer edges of each device.
(b) If the center-to-center spacing of anchorage devices is 12 in. or less, the anchorage devices shall be considered as a group. For each group of six or more anchorage devices, n + 1 hairpin bars or closed stirrups at least No. 3 in size shall be provided, where n is the number of anchorage devices. One hairpin bar or stirrup shall be placed between each anchorage device and one on each side of the group. The hairpin bars or stirrups shall be placed with the legs extending into the slab perpendicular to the edge. The center portion of the hairpin bars or stirrups shall be placed perpendicular to the plane of the slab from 3h/8 to h/2 ahead of the anchorage devices.
|Type of reinforcement||Maximum design tensile stress|
|Bonded, prestressed reinforcement||fpy|
|Unbonded, prestressed reinforcement||fse + 10,000|