RMS Titanic - Construction - Framing
Source: ANATOMY OF THE TITANIC - Tom McCluskie
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Rising up from the double-bottom at each side of the hull were the side frames or ribs to which the outside shell or skin was attached. If we imagine the keel as the spine of a human body, these frames or ribs perform an identical function to the ribs in a human skeleton. These frames extended from the double-bottom upwards to the base of the Deck bridge, which was the eight deck from the inner bottom. Each frame had a height of 66ft and was spaced apart at 3ft intervals, except at the bow and stern where the frame spacing was 2ft at the bow and 2ft 3in at the stern.
The frames were constructed in a channel section, 10in deep amidships, with angle and reverse bars at the frame end of 45 degrees. I addition to the frames themselves, at frequent intervals in the structure there were heavy web frames for greater strength. Increased strength was also ensured in the machinery spaces by the addition of web frames placed at closer intervals with especially heavy bracket plates connecting the frames to the wing tanks, and wing brackets to provide maximum hull stiffness in heavy seas.
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The framing extended past each deck level. Attached to each frame were the deck beams; these were also of 10in deep channel section up to the lower deck level and of smaller section above this for stability purposes. Each deck beam was located in accordance with the frame spacing and was attached to its respective frames by strong support brackets.
As the hull construction proceeded, transverse or cross beams were added and placed at each deck level. These beams were also of 10in channel section at the lower deck and, as previously for the deck beams, they were of smaller section above this deck. Each transverse beam was attached to the side frames by thick bracket plates reinforced with angle bars for additional strength.
To complete the structure four longitudinal girders ran the length of the ship, each girder being constructed of plates with deep angles at the top and bottom. Because of the width of the compartments required in the machinery spaces, these girders were not continuous in construction. To compensate for this, the girders in the engine and turbine compartments were provided with a special cranked or angled arrangement. Each of these cranked girders had the equivalent collective sectional area to that of the four main longitudinal girders in the other part of the vessel. Stanchions or upright columns were erected and fitted at intervals below these girders up to and including the middle deck or third deck level above the double bottom.
Each stanchion was constructed from solid steel columns. Above the third deck level the stanchions were replaced with solid steel pillars of smaller diameter. This unusual arrangement was a design feature incorporated by Thomas Andrews to allow him to place the pillars at more frequent intervals thus providing greater hull strength. The deck plates were also increased in thickness to ensure that hull strength and integrity was maintained throughout the structure.
This general description of the internal structure of Titanic indicates the considerable lengths to which Harland & Wolff went in ensuring the hull had the greatest possible strength. Titanic was intended to be the largest vessel in the world, and it was therefore of vital importance that the hull had the maximum degree of stiffness in order for Titanic to operate safely and comfortably in heavy seas.