Principle design procedure

The principal design procedure for structural design shall not commence until the technical description of design work and the conceptual sketch (drawing) have been approved by  public client.

The procedure reduces risks during acceptance control at review with public client. A thorough PM reduces these risks.

Recommended stages of design work is illustrated below.

Structural design work is not recommended to proceed between stages without approval from responsible design manager (AK).

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1.       Design workflow

Design workflow seen below is recommended:

• Establish Calculation Assumptions (Part A).
• Internal review of Part A against the approved PM.
• Upon approval of Part A by AK, work on FEM modell may commence.
• Internal review of Input Receipt associated to FEM modell against Part A.
• Upon approval of the Input Receipt by AK, work on Foundation (Part B) and related production drawings may commence.
• Internal review of Part B and foundation drawings.
• Upon approval by AK, work on substructure (Part C) and related production drawings may commence.
• Internal review of Part C and substructure drawings.
• Upon approval by AK, work on superstructure (Part D) and related production drawings may commence.
• Internal review of Part D and superstructure drawings.
• Upon approval of Part D and associated drawings by AK, internal quality assurance is completed.

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2.       Report size and disposition

A calculation section submitted to design manager (AK) for quality assurance is recommended not to exceed the size of one A4 binder (approximately 500 pages).

If this limit is exceeded, the calculation is recommeded to be subdivided into additional parts. The standard parts division (A–D) shall be expanded as necessary (e.g., A–AX) to maintain clarity and manageability.

The reason for this division is several. It allows several designers to work in parallel on different parts and reduces the workload for the design manager (AK) if a maximum of 500 pages is received at a time. Also advantageous for time impact and costs to consider views from design manager (AK).

FEM modelling shall be performed using FEM software, preferably capable of handling both 3D and 2D analyses. The latter is generally used to ensure the reasonableness of the 3D analysis.

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3.       FEM modelling

If the selected FEM software cannot perform both types of analysis, supplementary calculations shall be carried out using a separate 2D FEM program.

A documented reasonableness check shall always be included as part of the calculation to verify the accuracy and reliability of the results.

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4.      System analysis

System analysis shall be carried out in a manner that generates appendices for Input Receipt and Results.

4.1     Input Receipt

The Input Receipt shall contain all information entered into the calculation tool. This enables quality assurance to be performed without requiring access to the specific software used. The reviewer shall not need to open the software to understand what the designer has applied in the model.

The Input Receipt shall also include sufficient information to allow the calculation to be reproduced in the future using the same or alternative software.

Geometry (following shall be included):

• Definition of Points with a coordinate table
• Definition of Lines, including a table indicating start and end Points
• Definition of Surfaces, including a table indicating the enclosing Lines
• Definition of Volumes, including a table indicating the enclosing Surfaces

Loads (following shall be included):

• Magnitude
• Direction and sign convention
• Position relative to the defined geometry

Load Combinations:

• All load combinations and envelopes shall be defined.

4.2     Results

The Results shall present load effects in a clear and verifiable manner to facilitate review.

Load effects (following shall be included):

• Tabular form
• Diagram form (to facilitate interpretation and verification)
• Contour plots (to ensure that selected design sections are representative)

General Requirements (following shall be included):

• Clearly indicate the load case or load combination
• Clearly indicate the structural component
• Include units and position/reference location
• Include the applicable sign convention

Load Cases and Combinations (following shall be included, as minmum):

• Design load combinations for Ultimate Limit State (ULS)
• Design load combinations for Serviceability Limit State (SLS)
• Main load cases (typically including self-weight and traffic loads)

4.3     Importance of user and theory manuals

Access to user and theory manuals, preferably in PDF format, is very important to enable design managers (AK) to carry out reviews. Also important for being able to reuse calculation reports in the future.

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5.      Code check

If suitable commercial program is available, it should be used. If such software is not available, custom programs may sometimes need to be developed by designer.

5.1     Commersial programs

All commercial programs shall be listed in a common register accessible to all employees.

When purchasing new programs, verification shall always be carried out by the design company in an appropriate manner. This is particularly important when the software provider states in the agreement or documentation that the user bears full responsibility for the application of results.

Every commercial program ust have an accompanying manual, preferably in PDF format, to enable safe use by designer and review by the design manager (AK).

Each commercial program shall have a designated superuser (manager) with responsibilities:

• Provide support to other users within the design company
• Maintain high knowledge of the program
• Propose improvements to program supplier

5.2     In-house programs

Minimum requirements on In-house programs are listed below.

The program shall include:

• Date
• Version number
• Program designation/name

Transparency requirements:

• All formulas shall be visible
• References for all formulas shall be provided
• All variables shall be clearly defined

Documentation requirements:

• Page numbering shall be included
• The program shall be structured and easy to follow