In the previous post in this series I looked at the results available from the EStress function in the RC Design Functions spreadsheet.  Three associated functions are:

• EstressCap
• PLCurve
• TStiff

EStressCap finds the maximum bending moment for a specified axial load, either using the stress limits specified in AS 3600 or AS 5100, or an input stress limit.

EStressCap Output

The function input is similar to the EStress function:

EstressCap(input range, axial load, output column index, output row index, Allowstress, MSign, prestress, code, depth)
Function arguments in italics are optional

If the optional AllowStress argument is omitted the stress limit specified in AS 3600 is used if Code = 1 or is omitted, or the lower stress specified in AS 5100 for dead load only if Code = 2.  If AllowStress   > 0 then this value is used as the stress limit, and the Code value is ignored.

The other two functions are alternative methods of evaluating the tension stiffening effect. PLCurve uses a fictitious pre-compression strain applied to the reinforcement to model the effect of concrete shrinkage and creep strains, and the Eurocode 2 provisions for tension stiffening.  TStiff uses a concrete tensile stress block to model the effect of tension stiffening; see Tension Stiffening for more details.

PLCurve and TStiff output

PLCurve either requires creep and shrinkage data (to AS 3600 or Eurocode 2) to be input, or the fictitious prestress may be input directly.

TStiff requires details of the tensile stress block, or default values may be used.  See Tension Stiffening for details.

Additional input for PLCurve and TStiff