Slab Reinforcement Rectangles Generation

1)Reinforcement Intensity Rectangle on Columns

Reinforcement demand is calculated according to intensity rectangle. To find the width of the yellow intensity rectangle in a certain direction,

Measure the linear center to center distance of the columns connected with stress lines in desired direction

Measure the linear center to center distance of the columns connected with stress lines in adjacent directions
25% of the shortest distance is the distance between the center of column and yellow rectangle in desired direction.

For example ;

Min (166.125”,281”,315.50”) = 166.125”
0.25*(166.125”) = 41.53125”

The distance between the face of column and yellow rectangle can not be less than 1.5 times the thickness of slab.

The average intensity of reinforcement is calculated according to this rectangle.

SAFE top slab reinforcement results are exported as XREF file to calculate the average reinforcement intensity.

Average intensity is calculated by dividing the sum of all maximum strip line values inside the yellow rectangle to the width(feet) of the yellow rectangle. However there are some exceptions for this calculation.

→ If design strip width extends beyond the yellow rectangle but strip line is still inside the rectangle, design strip value is multiplied by a factor which is a ratio of width in yellow rectangle to total strip width. To calculate the factor;

Measure the strip width remaining in the intensity rectangle
Divide it to total design strip width

For example ;

The strip line (red) is still in yellow rectangle but design strip width drawn by magenta color extends beyond the intensity rectangle.

Strip width remaining in the intensity rectangle = 6.75”
Total design strip width = 12”
Factor = 6.75/12=0.5625
Modified strip value = 0.3075*0.5625=0.17297

→ If design strip line is not inside the intensity rectangle, the strip value is ignored even if design strip width extends to the intensity rectangle.

→ If design strip line is not inside the intensity rectangle but the design width extends to the intensity rectangle, the sum of maximum strip values are divided by a modified rectangle width.

Modified rectangle width is calculated as follows ;

Measure the width of strip remaining within the intensity rectangle
Substract it from rectangle width

Average intensity of C53 column at 1st layer is calculated as follows;

→ The sum of maximum strip values : (0.3075*0.5625+0.4344+0.6622+1.1984+1.1007+0.5222+0.3456)=4.4365

→ Modified rectangle width in feet : 78.8750”/12=6.5729'

→ Average intensity = 4.4365/6.5729=0.67496

Rebar decision

Column Strip Top Rebar Decision

Rebar diameter and spacing is being decided from table according to the determined intensity.

Note : Column top rebar diameter can not be less than #5 .

Note : Column top rebar can not be less than minimum required rebar.

Middle Strip Top Rebar Decision

Reinforcement intensity for the span between two columns is the maximum strip value between the intensity rectangles of two columns.

Rebar diameter and spacing is being decided from the table according to the determined intensity.

Note : Middle strip top rebar can not be less than minimum required rebar.

Note : Minimum required rebar = 0.0018*Slab Thickness*12

Note : Maximum rebar = 0.01*(Slab Thickness-Clear cover)*12

Note : Maximum Rebar Spacing = min(2*Slab Thickness , 18”)

2) Distribution Rectangle

Top slab reinforcement is being distributed in certain areas. Distribution rectangle indicates in which area the reinforcement will be distributed. And the number of rebar is calculated according to this rectangle.

Distribution rectangle is drawn as follows;

→ Measure the linear center to center distance of columns connected with stress lines.

→ For direction1, positive direction width is 0.25*max(positive direction length, negative direction length)

→ For direction1, negative direction width is 0.25*max(positive direction length, negative direction length)

→ For direction2, positive direction width is 0.25*max(positive direction length, negative direction length)

→ For direction2, negative direction width is 0.25*max(positive direction length, negative direction length)

Distribution rectangle must be symmetrical.

Note : The distance between the face of column and distribution rectangle can not be less than 1.5*SlabThickness.

→ Number of column top rebar is calculated as follows;

Divide the distribution rectangle width in desired direction to rebar spacing
Add 1
Round the number to upper integer

Note : If slab edge is rotated, number of rebar is calculated according to longer distance.

→ Number of column bottom rebar is calculated as follows;

Generally bottom rebar is #4@14 for both directions for columns unless otherwise noted.

Note : Column bottom rebar can not be less than minimem required rebar.

→ Number of rebar is not specified for middle strip.