TR 43 / Section 6.10.6 Minimum un-tensioned reinforcement

Note: This section is not used for post-tensioned beams or one-way slabs that are primarily bonded. Refer to "Determination of Bonded vs. Unbonded Cross Sections" for discussion.

For post-tensioned beams and one-way slabs the requirements of 3.12.5 and 3.12.11.2 are also applied. (Note that "Table 3.27" in TR 43 refers to the 1985 BS 8110 - this table has been renumbered 3.25 in the 1997 edition). This interpretation is somewhat more conservative than a literal reading of the code requirements.

For post-tensioned two-way slabs with bonded or unbonded tendons, un-tensioned reinforcement is provided in support regions as follows:

A_s = 0.00075A_c.

For span segment strips, this criteria is only applied to the first cross section at a support if the span ratio is less than 0.2.

For design sections, this criteria is applied when the span ratio is less than 0.2.

The 300mm spacing requirement is not checked.

The recommendations for slab edge reinforcement are not implemented.

User defined reinforcement that is at an angle to the cross section will only have the component perpendicular to the cross section considered.