The effective width can either be entered manually, or be calculated automatically either as a one time process or each time a design is performed.

To manually enter the effective width:

To calculate the effective width automatically as a one time process:

1. First select Calculate effective width in the properties.
2. Then click the [...] box that appears next to Calculate.
3. The calculated value is reported in the effective width property.

Tekla Structural Designer will calculate the effective width of the compression flange, be for each composite beam as per Section I3.1a (360-05/-10).

For each side of the beam, it is taken as the smaller of:

• beam span/8 – span taken as the center to center of supports
• one half of the distance to the center line of the adjacent beam
• the distance to the edge of the slab

Although the program calculates b_e, it is your responsibility to accept the calculated figure or alternatively to adjust it. Engineering judgment may sometimes be required.

For example consider the beam highlighted below:

The program calculates the effective width as the sum of:

• to the right of the beam, b_e(right) = beam span/8
• to the left of the beam, b_e(left) = one half of the shortest distance to the center line of the adjacent diagonal beam

To the left of the beam, some engineers might prefer to use one half of the mean distance to the adjacent beam. To do so you would need to manually adjust the calculated value via the Floor construction page of the Beam Properties.

To automatically calculate the effective width each time a design is performed:

To combat the possibility of model edits and the need to recalculate the effective width for individual beams it is possible to automatically perform the Calculate process discussed above automatically to all beams prior to a Design command.

The effective width can either be entered manually, or be calculated automatically either as a one time process or each time a design is performed.

To manually enter the effective width:

To calculate the effective width automatically as a one time process:

1. First select Calculate effective width in the properties.
2. Then click the [...] box that appears next to Calculate.
3. The calculated value is reported in the effective width property.

Tekla Structural Designer will calculate the effective width of the compression flange, b_eff, for each composite beam as per Clause 5.4.1.2 of EC4.

Unless hollowcore units are used, it is taken as the smaller of:

• Secondary beams: the spacing of the beams, or beam span/4
• Primary beams (conservatively): 80% of the spacing of beams, or beam span/4
• Edge beams: half of above values, as appropriate, plus any projection of the slab beyond the centerline of the beam.

For hollowcore precast plank units only, we calculate the effective width for each side of the beam as the minimum of:

• Assumed concrete fill (500 mm) + recommended gap
• beam span/8 – span taken as the center to center of supports
• one half of the distance to the center line of the adjacent beam
• the distance to the edge of the slab

These effective breadths are used in both strength and serviceability calculations.

Although the program calculates b_eff, it is your responsibility to accept the calculated figure or alternatively to adjust it. Engineering judgment may sometimes be required.

For example consider the beam highlighted below:

The program calculates the effective width as the sum of:

• to the right of the beam, b_eff(right) = beam span/8
• to the left of the beam, b_eff(left) = one half of the shortest distance to the center line of the adjacent diagonal beam

To the left of the beam, some engineers might prefer to use one half of the mean distance to the adjacent beam. To do so you would need to manually adjust the calculated value via the Floor construction page of the Beam Properties.

To automatically calculate the effective width each time a design is performed:

To combat the possibility of model edits and the need to recalculate the effective width for individual beams it is possible to automatically perform the Calculate process discussed above automatically to all beams prior to a Design command.

The effective width can either be entered manually, or be calculated automatically either as a one time process or each time a design is performed.

To manually enter the effective width:

To calculate the effective width automatically as a one time process:

1. First select Calculate effective width in the properties.
2. Then click the [...] box that appears next to Calculate.
3. The calculated value is reported in the effective width property.

Tekla Structural Designer will calculate the effective width of the compression flange, b_e, for each composite beam as per section 4.6 of BS 5950 : Part 3 : Section 3.1 : 1990.

For each side of the beam, it is taken as the smaller of:

• beam span/8 – span taken as the centre to centre of supports
• one half of the distance to the centre line of the adjacent beam (for slabs spanning perpendicular)
• 40% of the distance to the centre line of the adjacent beam (for slabs spanning parallel)
• the distance to the edge of the slab

Although the program calculates b_e, it is your responsibility to accept the calculated figure or alternatively to adjust it. Engineering judgment may sometimes be required.

For example consider the beam highlighted below:

The program calculates the effective width as the sum of:

• to the right of the beam, b_e(right) = beam span/8
• to the left of the beam, b_e(left) = one half of the shortest distance to the centre line of the adjacent diagonal beam

To the left of the beam, some engineers might prefer to use one half of the mean distance to the adjacent beam. To do so you would need to manually adjust the calculated value via the Floor construction page of the Beam Properties.

To automatically calculate the effective width each time a design is performed:

To combat the possibility of model edits and the need to recalculate the effective width for individual beams it is possible to automatically perform the Calculate process discussed above automatically to all beams prior to a Design command.