CHECK OF WORKING STRESSES AND MAXIMUM CRACK WIDTH ACCORDING TO BS8110-85 FOR DOUBLY REINFORCED SECTION

To check the working stresses and maximum crack width for a doubly reinforced section according to BS8110-85 (British Standard Code of Practice for the Structural Use of Concrete), you can follow these steps:

Determine the Applied Loads:

Identify the applied loads on the doubly reinforced section, including dead loads, live loads, and other relevant loads.
Calculate the Bending Moment:

Determine the design bending moment (M) at the critical section of the doubly reinforced section.
Consider the effects of applied loads, span length, and support conditions.
Calculate the Compressive Force in Concrete:

Determine the compressive force (C) in the concrete at the critical section using the equation:
C = M / (d – x)
Calculate the Tensile Force in Steel Reinforcement:

Determine the tensile force (T) in the steel reinforcement at the critical section using the equation:
T = M – C * (d – x’) / (d’ – x’)
Check Working Stresses:

Calculate the working stresses in the concrete and steel reinforcement.
Verify that the working stress in the concrete (σ_c) is within the permissible limits specified by BS8110-85.
Verify that the working stress in the steel reinforcement (σ_s) is within the permissible limits specified by BS8110-85.
Check Maximum Crack Width:

Calculate the maximum crack width (w) based on the tensile strain in the steel reinforcement.
Verify that the calculated crack width is within the permissible limits specified by BS8110-85.
Consider factors such as cover requirements, bar diameter, and environmental conditions.
Modify Reinforcement if Required:

If the working stresses or maximum crack width exceed the permissible limits, adjust the reinforcement to meet the requirements.
Modify the reinforcement distribution, bar sizes, or concrete cover to achieve the desired results.