Section 4.3.4.3 Flexural tension stresses in concrete
The interaction of the BS 8110 requirements, the TR 43 requirements, the different classes and the use of bonded and unbonded tendons makes describing the service tensile stress limits and requirements in text form very confusing. In some circumstances, BS 8110 and TR 43 conflict, while in other circumstances neither one explicitly considers a particular configuration.
Our implementation of these requirements is detailed in the table below. For each combination of tendon type, structure type and class, two limit stresses and a reinforcement calculation are listed. The first limit stress is the maximum stress allowed if no supplemental un-tensioned reinforcement is used. The second limit stress is the absolute maximum stress allowed. The reinforcement calculation details how to calculate the required supplemental reinforcement when stresses exceed the first stress limit.
Tendons | Member Type | Class | Tension limit without supplementary reinforcement | Absolute tension limit | Reinforcement calculation |
---|---|---|---|---|---|
Bonded | Beam | 1 | 0 | 0 | 4.3.4.3 (c) |
Bonded | Beam | 2 | 4.3.4.3 (c) | ||
Bonded | Beam | 3 / 0.1 mm | Tables 4.2 / 4.3 | 0.25fcu | 4.3.4.3 (c) |
Bonded | Beam | 3 / 0.2 mm | Tables 4.2 / 4.3 | 0.25fcu | 4.3.4.3 (c) |
Bonded | One-way | 1 | 0 | 0 | 4.3.4.3 (c) |
Bonded | One-way | 2 | 4.3.4.3 (c) | ||
Bonded | One-way | 3 / 0.1 mm | Tables 4.2 / 4.3 | 0.25fcu | 4.3.4.3 (c) |
Bonded | One-way | 3 / 0.2 mm | Tables 4.2 / 4.3 | 0.25fcu | 4.3.4.3 (c) |
Bonded | Two-way | All | TR 43 Table 2 | TR 43 Table 2 | TR 43, 6.10.5 |
Unbonded | Beam | 1 | 0 | 0 | TR 43, 6.10.5 |
Unbonded | Beam | 2 | 0 | TR 43, 6.10.5 | |
Unbonded | Beam | 3 / 0.1 mm | 0 | Tables 4.2 / 4.3* | TR 43, 6.10.5 |
Unbonded | Beam | 3 / 0.2 mm | 0 | Tables 4.2 / 4.3* | TR 43, 6.10.5 |
Unbonded | One-way | 1 | 0 | 0 | TR 43, 6.10.5 |
Unbonded | One-way | 2 | 0 | TR 43, 6.10.5 | |
Unbonded | One-way | 3 / 0.1 mm | 0 | Tables 4.2 / 4.3* | TR 43, 6.10.5 |
Unbonded | One-way | 3 / 0.2 mm | 0 | Tables 4.2 / 4.3* | TR 43, 6.10.5 |
Unbonded | Two-way | All | TR 43 Table 2 | TR 43 Table 2 | TR 43, 6.10.5 |