Calculation parameters

Defines the maximum numbers of steps, used to find the state of equilibrium in a section.

Defines the numerical precision in percentages.

As,tot or 0 (As, tot for As,req > 0 and 0 for As,req = 0)

The total area of reinforcement is used for the calculation on condition that the design function has been already run and that the program has already calculated the required area of reinforcement. Otherwise, zero value is used (even if the user has manually inserted some reinforcement bars).

The total area of reinforcement is the sum of the user-defined reinforcement (through basic reinforcement, through reinforcement zones/regions or through free bars) and calculated additional required reinforcement. The additional required reinforcement may be zero, if the user has already inputted enough user-defined reinforcement.

IMPORTANT: Keep in mind, that the function calculating the required areas of reinforcement MUST HAVE BEEN run before. Otherwise, the user-defined reinforcement is ignored and ZERO value is used.

As, user

The user-defined reinforcement is used for the calculation. The term user-defined reinforcement covers the basic reinforcement specified in member data, reinforcement bars inputted through reinforcement templates in reinforcement zones (1D members) or regions (2D members), and free bars of reinforcement.

In order: [ As, user ]; [ As,tot or  0]

If there is any user-defined reinforcement, it is used, otherwise, the total reinforcement is used (which in fact means the calculated required area of reinforcement). Remember, that for the second option, the design function must have been already run.

In order: [ As,tot or  0]; [ As, user]

If the design of reinforcement has been already performed and the required area of reinforcement has been already calculated, it is used. Otherwise, the user-defined reinforcement is used.

If this option is ON, the calculation procedure takes account of the defined reinforcement percentage for longitudinal reinforcement.

If this option is ON, the calculation procedure takes account of the defined shear reinforcement – number of legs, link diameter, spacing of the links, and minimal percentage of reinforcement.

This parameter can simplify the input for those users who calculate simple problems and need to adjust just a few basic parameters.

If ON, all the items in the column setup part are available.

If OFF, only the basic parameters are available. The less-common parameters are disabled.

The following cross-sections are supported: rectangular, L-section, T-section, I-section.

The bars are designed only in corners of the cross-section. The calculation is iterative and diameter or area of reinforcement in corner is increased until the check  is satisfied.

The user may determine that the design of reinforcement is carried out in the foot and head of the column. Otherwise, the calculation is carried out in all intermediate sections as well, which may be time consuming and bring no profit in terms of accuracy. The subsequent check of the designed reinforcement is performed in all sections.

The option activates a pseudo-linear calculation of buckling for 1D member (the genuine 2nd order analysis is the non-linear one, i.e. using the Timoshenko or Newton-Raphson iteration). If this option is ON, a special algorithm is started on the background that evaluates bar imperfections and 1st + 2nd order deflections which leads to an approximation of the 1st order bending moments by increased 2nd order moments.

DIN 1045-1 introduces for this situation the concept of "Model column method" and ÖNORM calls it "Spare bar method". Each national standard implemented in SCIA Engineer uses its analysis path that takes into account the stipulations of the particular standard.

If ON, the number of bars in the cross-section is optimised to achieve the minimum number of bars with the cross-section still passing the check.

The largest of bending moments My, Mz will be taken into consideration. The smaller one will be ignored.

Both My and Mz are taken into account. The design is carried out using interaction formula

(My/Myu)x + (Mz/Mzu)x < 1

where x is the safety factor (see below).

If the ratio of one bending moment to the other along the whole beam length is smaller than the input value, then the beam is considered to be subject to uni-axial bending. Otherwise, if at least one cross-section is found where the ratio is greater than the input value, the biaxial approach is applied.

Specifies the safety factor used in the interaction formula above.

Default value = 1.4.

real area of reinforcement

If this option is ON, the reinforcement is calculated from the real sectional area of individual bars.

delta area of reinforcement

If this option is ON, the reinforcement is calculated using the user defined area (delta).

If the option is ON, the number on bars in section is minimised so that their minimal number is used.

automatic

If ON, the ratio of y-reinforcement to z-reinforcement is determined automatically.

manual

If ON, the user specifies the ratio of reinforcement in y-direction to reinforcement in z-direction.

The effect of creep and shrinkage is given by

The strain is to be defined by the user. It could also be calculated by the program but this would imply even more additional input. Moreover, using a fixed value gives already pretty good results. So it is left out for now.

More accurate calculation could be done by recalculating the c factor, but this will be available in future versions.

If ON, the relative compression zone height ksi = x/d is limited. See Ultimate limit state

If the compression reinforcement is necessary, check this box to provide for its calculation.

There is a condition limiting the maximal force in the reinforcement that prevents the concrete from crushing.

The condition Fs<=1/2 Nc is obsolete; nevertheless it is kept in the program for "user compatibility". It is inactive by default.

Bending moment diagram may be "shifted" in supports in order to provide for reduction of support bending moments. The reduction depends on the type of support. For supports of Column type, the support dimension is calculated from the column’s cross-section. For standard supports the user must input the support size (see the chapter dealing with point supports in the main reference manual).