# Support articles

### Tilt-up wall panel design (ACI318): How is maximum moment calculated during lifting?

Explanation
As the wall is tilted, the direct bending moment due to the self weight of the panel decreases because the effective span will decrease. However, as the wall is tilted the axial compression in the wall due to its self weight increases from zero (when at zero degrees) to a maximum (when at 90 degrees). As tilt-up wall panels are generally very slender, the additional bending moments caused by the combination of the panel deflection due to self weight bending and the axial compression have to be considered with the total moment being equal to the direct bending moment plus the

September 6, 2016

by Tekla User Assistance Team

### Masonry wall panel design (BS5628): Why can I not have a panel supported by adjacent sides only?

The masonry wall panel calculation gives you a lot of variations of supporting sides however it doesn't cover a situation where only adjacent sides are supporting, i.e. bottom and left.
Solution
This is a limitation of the yield line approach used in the calculation. It is used to determine the moments in the wall and requires at least one pair of opposing supports. Note: This is not just a limitation of the Tedds calculation but is also not covered by the tables used in BS5628 or Eurocode.

September 6, 2016

by Tekla User Assistance Team

### Vibration of Floors (SCI-P-354): Comparing response factors

The most significant changes in P354 are in
The evaluation of modal mass
The ability to use VDV analysis to justify floor systems which fail analysis
P354 gives results that seem to be more conservative but more consistent primarily due to the fact that the step changes in the calculation of the modal mass have been smoothed out and the massive differences across the boundary conditions returned by P076 are no longer apparent.
For P076 Cases 1 & 2 (secondary mode)
Long span secondary beams and shorter span primary beams means that the secondary beam mode deflection governs the floor

September 6, 2016

by Tekla User Assistance Team

### Steel Column Design (EN1993): Classification of columns subject to compression only

The Tedds calculation for the classification of web in a column is exactly the same as that adopted by CSC Fastrak and the 'Part subject to bending and compression' column of Table 5.2 (sheet 1 of 3) of EC3 is always used even if there is no moment applied to the column (which in reality would be unlikely).Using the Tedds approach, say alpha is found to be 0.75 i.e. 3/4 of web is in compression then this apparently gives you a 'better' i.e. higher limit for say a Class 1 section than if the 'Part subject to compression' column is used so the section could be Class 1 to Tedds but Class 2 using

September 6, 2016

by Tekla User Assistance Team

### Strip footing analysis & design (BS8110) - 300mm minimum depth limit for unreinforced footings.

The 300mm limit is taken from the ICE little green book, cl.4.10.5.1, page 53.

September 6, 2016

by Tekla User Assistance Team

### RC pile cap design (BS8110): Anchorage of Tension Steel - no check performed

If bar anchorage is selected the calculation determines the minimum anchorage length required which the user can use in the detailing of the reinforcement - there isn't supposed to be a pass/fail statement.

September 6, 2016

by Tekla User Assistance Team

### Masonry wall panel design (EN1996): Moment coefficient for wall supported left, right & bottom

If the ratio of ‘height to length’ falls within the upper and lower limit the Tedds calculation will use the yield line method to determine the bending moment coefficient. If your height to length ratio is outside of the specified limits Tedds will use simple elastic analysis (one way spanning) to determine the coefficient.This works correctly for a wall supported on all 4 edges. However, if a panel is supported left, right and bottom and h/L <0.3. The panel can't span top to bottom because there is no support at the top and so a yield line analysis is carried out.

September 6, 2016

by Tekla User Assistance Team

### Base plate design (CSA-S16): A_req calculated but not checked against area provided

Problem
Area of steel required for base plate is calculated, but is not compared to Area of steel provided. In the attached example Areq = 226244 mm2 and the area of the base plate is only 202500mm2 but Tedds does not return a fail.
Solution
The calculation of A_req is only there to determine whether or not the column is lightly or normally loaded i.e. to determine whether t_req1 or t_req2 is to be adopted for the plate thickness. The actual check on the concrete bearing strength (and hence the size of the base plate) is contained in the section titled 'Design bearing strength'. This allows

September 6, 2016

by Tekla User Assistance Team

### Steel beam analysis & design (EN1993) - How is kc calculated from Table 6.6?

Deriving k_c
Slenderness correction factor, k_c, is based on the values in Table 6.6 but this table does not give much information. Table 6.6 is in fact based on the values in BS5950: Part 1:1985 - Table 15 and this is the data Tedds uses..
Advanced
The calc item can be viewed in Tedds for Word by opening the library and selecting 'Tedds Calcs and Components > Steel member design (EC3) > Steel beam analysis & design (EN1993-1) > Components > General > Calculate correction factors kc'

September 6, 2016

by Tekla User Assistance Team

### Crane gantry girder design (BS5950) - How is the stiff bearing length calculated?

In this calculation the beam web bearing and buckling checks (cl 4.5.2.1 & 4.5.3.1) both refer to the stiff bearing length, b1. In BS5950 this refers to cl.4.5.1.3 which relates to Figure 13 and shows four methods of calculating b1 using various combinations of t, T, r, s and g. TEDDS simply takes b1 = hr.The check being carried out here is the web bearing/buckling under the wheel load. The gantry girder bearing onto the support check is not within the scope of the calculation. The wheel load is taken to be applied as a point load to the top of the rail, which is probably slightly

September 6, 2016

by Tekla User Assistance Team

### Timber beam analysis & design (EN 1995): Vibration Checks

The vibration check given in EC5 is geared entirely towards floor vibration so doesn't really fit in the timber beam calculation, even if the timber beam is supporting a floor, the calculation simply doesn't have access to the variables required to run the vibration calculation. Therefore the vibration check should be undertaken as a completely separate calculation.

September 6, 2016

by Tekla User Assistance Team

### Timber frame racking panel design (BS5268): Additional contribution value of secondary panel

When the secondary panel is Category 3 or 4 the additional contribution value appears to be incorrect and the value used is greater then that stated in table 2 of BS56268-6.1
Solution
In this instance the calculation is following the guidance from note 9 in table 2:"NOTE 9, For both category 3 & 4 board materials, if the fixing specification for each plasterboard layer is changed to 2.65 mm diameter plasterboard nails at 150 mm spacing, then their basic racking resistances, both as primary board or as secondary board, may be increased by 50%"Please be aware that this is not advised

September 6, 2016

by Tekla User Assistance Team

### Retaining wall analysis & design (AS4678) - Expression error: undefined variable '_LocaleFile'

Attempting to re-run an old calculation that references the generic System Library results in the error message: undefined variable '_LocaleFile'.
To resolve the problem either:
Insert a new calculation in a new document. Open the variable manager in the original document and use Select All > Copy. In the new document open the variable manager and use Paste to populate with the copied variables. Calculate the new document.
Delete the old calculation field, re-insert the calculation in a new field and then re-calculate. The first time the calc is re-run may result in other errors; these can

September 6, 2016

by Tekla User Assistance Team

### Steel beam torsion design (SCI-P-057): Units of total applied torque

If the load type is set to full UDL, why in the input for total applied torque are the units kNm and not kNm/m ?Solution
The total applied torque Tq that the guide method (and hence the Tedds calc) requires and you input is just a torque – i.e. has units of kNm. The calculation does not ask for the loading (that gives rise to Tq) and then calculates Tq for you. Hence you are required to enter directly the Tq required by the design guide method, which is the total torque (regardless of the arrangement of loading that gives rise to this). The calculation requires the description of arrangement

September 6, 2016

by Tekla User Assistance Team

### Retaining wall analysis & design (BS8002): Base resistance to sliding

The base resistance to sliding is in accordance with cl4.2.2.3 of 8002 which states you can either use the total stress (c_b - base adhesion) or the effective stress (delta_b - angle of base friction given in degrees), however this calculation only uses the base friction approach. Given that you know the plasticity index of the soil, Clause 3.2.6 gives you a way of calculating delta given phi and phi can be estimated via table 2 from the soil plasticity index.
It is our recommendation the above approach be checked against the code and verified as a suitable approach by the user

September 6, 2016

by Tekla User Assistance Team

### Snow loading (BS6399): Why is the site snow load reduced for altitudes < 100m?

BS6399-3 cl 6.2 states "Note: for simplicity the calculation it is assumed that the same value for the basic snow load on the ground should apply for altitudes between 0-100m. If preferred the equation for altitudes greater than 100m may be used for altitudes between 0-100m; in these cases the correction term; S_alt (A-100)/100 will automatically be negative."
i.e. You should increase the basic snow load for altitudes >100m but for altitudes < 100m you can either use the default s_b value or opt to use the formula to reduce the site snow load.Tedds implements the latter option and use

September 6, 2016

by Tekla User Assistance Team

### Pad footing analysis and design (BS8110): Unreinforced pad base

Tick the "Analysis Only" option on the first page of the interface (under the sketch)

September 6, 2016

by Tekla User Assistance Team

### Cold formed sections (BS5950) - Section is subject to torsional or torsional flexural buckling

What the code says:
When designing a section which is subjected to axial load and major axis bending, combined bending and compression checks are required in accordance with section 6.4 of BS5950-5. Under clause 6.4.1 of this section it says that the checks apply to members 'which are not subject to torsional or torsional flexural buckling.' The torsional and torsional flexural buckling capacities ie P_{T} and P_{TF} are calculated in accordance with section 6.3 and then compared to the elastic flexural buckling capacity P_{E} which is min(P_{Ex},P_{Ey}). If P_{T} or P_{TF} is less than P_{E

September 6, 2016

by Tekla User Assistance Team

### How can I allow the Update Service to operate through a firewall?

The Tekla Structural Update Service will check to make sure that your Tekla Tedds and Tekla Structural Designer software is up to date but you may need to allow it to operate through your firewall.
Solution
There are two aspects to the Update Service - the first aspect is communication with our Update Service Server which holds the information about which updates are available for each version of the software. Secondly there is where the update files themselves are hosted.
Update Service Server
The Update Service Server is hosted on https://updates.tekla.com/ therefore your firewall needs to

September 6, 2016

by Tekla User Assistance Team

### Tekla Structural Update Service update June 2016

Tekla Structural Update Service
Minor updates and new Update Service endpoint, https://updates.tekla.com

September 6, 2016

by Tedds Development Team