Understanding Primary and Secondary Members in Steel Structures

 In Steel structures, what are primary members and secondary members?

1. Primary Members: Also known as main components, these are elements whose failure will lead to the failure of related components and endanger the functioning of the load-bearing structural system. In hull structures, primary members include deck beams, girders, and outer plating.

2. Secondary Members: These are non-load-bearing masonry or small concrete components that are added after the main structure is completed and before the decoration works begin in building construction. 

 Additional Information:

1. Longitudinal Members:

    Deck Longitudinals: These are strong longitudinal components arranged along the length of the ship in the deck structure, often made from large composite T-shaped sections. Deck longitudinals serve as support points for beams, ensuring the deck's longitudinal strength and force transmission.

    Deck Longitudinal Girders: These longitudinal components used in the longitudinal framing deck structure are usually made from bulb flats or unequal angle steel. Deck longitudinal girders contribute to overall longitudinal strength, increase deck plate stability, and bear transverse loads on the deck.  

2. Transverse Members:

    The transverse members in the deck structure are collectively referred to as beams. Beams support the deck and bear the weight of cargo, machinery, and equipment on the deck, as well as water pressure when waves hit. They also support the sides of the ship and, together with ribs and shell plates, form a transverse framework to resist transverse deformation of the hull.