Section 1 Introduction
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 1 Ship Structures - Part 7 Enhanced Structural Assessment (Provisional) - Chapter 3 Total Load Assessment, TLA - Section 1 Introduction

Section 1 Introduction

Parent topic: Chapter 3 Total Load Assessment, TLA

1.1 General

1.1.1 The Total Load Assessment, TLA, procedure is an optional procedure that is applied on a voluntary basis when an Owner or designer who seeks to increase confidence levels in the structural integrity of a ship. The TLA procedure is illustrated in Figure 3.1.1 Overview of the Total Load Assessment, TLA Procedure

Figure 3.1.1 Overview of the Total Load Assessment, TLA Procedure

1.1.2 The TLA procedure is based on the following concepts:

  1. Derive the total design loads acting on each structural member.

  2. Derive the structural resistance of each structural member.

  3. Derive the load utilisation factors.

  4. Ensure the load utilisation factors are less than the required design factors.

1.1.3 This Chapter gives the simplified stress analysis methods to be used for the TLA procedure. Direct calculations or alternative proven methods of analysis which are more rigorous will be accepted.

1.1.4 The design loads for the TLA procedure are given in Vol 1, Pt 7, Ch 2 Total Design Loads, Total Design Loads.

1.1.5 The structural design factors are given in Vol 1, Pt 7, Ch 3, 4 Structural design factors and utilise the design criteria in Vol 1, Pt 6, Ch 5 Structural Design Factors

1.1.6 The simplified stress analysis techniques predict the total stresses acting in the structure as a consequence of the total loads. These techniques cover the assessment of stresses in the following:

  • Primary structure.
  • Primary/secondary plating systems.
  • Grillage plating systems.

1.1.7 The resulting stresses are then checked against a set of design factors, which include stress, deflection and buckling requirements.

1.1.8 The TLA procedure is in addition to the normal Rule structural design approval requirements specified within Vol 1, Pt 6, Ch 3 Scantling Determination.

1.2 Structural design

1.2.1 The TLA procedure only forms part of the structural design process, TLA covers the structural design of the ship in the sea environment only. There are many other structural requirements as a consequence of other loads and good structural design practices that need to be incorporated. These include:

  • bow flare impact and bottom slamming loads;
  • ice requirements;
  • design requirements to cover other strength issues, for example helicopter or vehicle decks;
  • military requirements such as fragmentation protection;
  • local impact loadings due to tugs, docks;
  • supporting structure for machinery, cranes and lifting devices; and
  • corrosion margins.

1.2.2 The structural design should clearly exhibit good structural continuity and smooth transition of scantlings between adjacent plating areas. In general, the TLA derived maximum scantlings for each structural member at any section within 0,3L R to 0,7L R are to be maintained over the central region.

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