US 2534311 A
Description (OCR text may contain errors)
Dec. 19, 1950 SMITH 2,534,311
METALLIC PLATE (FONSTRUCTION I Filed Oct. 29, 1945 awe/144101" Fig. 2. ALBERT A. SMITH Patented Dec. 19, 1950 UNITED STATES PATENT OFFICE 2 ()laims.
This invention relates to a steel plate construction. It relates further to a steel plate construction adapted to be used as side walls of buildings, tanks, ship hulls, decks, platforms and bulkheads; and in particular the invention relates to a construction comprising a seam strap of substantially H shape in cross-section which is placed between the edges of abutting plates.
Heretofore, in steel ship construction, it has been customary to use steel plates, either riveted or welded, for the hull, bulkheads, decks and platforms. Theoretically this type of construction should be very strong and efficient. But in many cases the contrary has proven to be true. Welded ships have broken in two, i. e. they have cracked circumferentially. Many theories have been advanced as to the cause of this defect. The most probable one is that when the strakes of the hull are welded both longitudinally and vertically, the tremendous stresses which are locked up therein by the welding are of themselves of large value. When a stress raiser is present, the amount of normal working stress the plating can carry is lessened by the amount of the locked up stress. The failures usually Start in the extreme fibre of the girder, deck, or wall and progress across or around the structure. This is most evident in a ship structure when subject to wave action inducing tension in the extreme fibre of the ship girder which is either the deck or bottom plating of the hull.
This defect is not observable in wooden hulls where the strakes are independent. The horizontal shearing stresses are carried by the cross frames to which the strakes are'attached. No stress can be carried from strake to strake through the caulking.
The progressive failure is prevented by the type of construction disclosed by this invention in that there is no continuity of material to transmit the failure from plate to plate.
With this defect in view it is therefore an object of this invention to provide a steel plate construction in which the courses of the plates are independent of each other.
A further object of this invention is to provide a steel plate construction in which the welding of the longitudinal seams iseliminated.
Another object of this invention is to provide a steel plate construction in which the longitudinal adjacent edges of the plates are supported in a seam strap of approximately H shape in cross section.
Another object of this invention is to provide a construction which is water tight and in which amended April 30, 1928; 3'70 0. G. 757) the shearing stress in one course of plates is not transmitted to the adjacent courses.
Still another object of this invention is to pro- .vide a construction which is strong and durable and which is economical to produce.
With these objects in view reference is now made to the drawings which illustrate a preferred embodiment of the invention and in which:
Figure l is an isometric view showing the relationship of the seam strap to the shell plating of a ship, transverse framing, bulkheads etc.
Figure 2 is a transverse section through a longitudinal plate joint taken on line 22 Figure 1, showing the relationship of the seam strap to the plates.
In the figures of the drawing the same reference numerals are used to refer to the same elements wherever applicable. It! represents the seam strap which is substantially H-shaped in transverse cross-section as shown in Figure 2 and which is shown supporting shell plates [2 and I4. These plates and the seam strap are shown welded to various types of transverse framing supports or ribs l6, l3 and 20 as at ll, l9 and 2|. In Figure 2, the caulking of the seam strap to the shell plates is shown at 22. 24 represents a conventional water stop compound which may be placed in the seam strap prior to placing it on the plate or the abutting plate therein. 26 represents a joint in each course of plates.
The process of construction is rather obvious. A course of plates a strake in hull construction) is placed in position with respect to the transverse framing. The seam strap is placed thereon over the horizontal edge of the strake and the assembly is then welded or otherwise attached to the transverse or supporting framing. After two adjacent strakes have been placed in the seam strap and welded to the cross frames, the seam strap may then be caulked to the plates by the conventional caulking method. A structure is produced by this method which has no longitudinally welded seams. It is watertight and the strakes or courses of plates are relatively independent of each other. The structure is not unitary and the effect of stresses which are locked up within the strakes by the Welding of the longitudinal seams is nullified.
The plating of the hull structure is relieved of the function of carrying shear at the longitudinal seams, these forces being carried by the transverse framing members as frames, bulkheads, etc. and so the structure as applied to hull construction is better able to resist the forces occasioned by the conditions of loading and the bending occasioned by the action of waves in that the strakes are relativel free to act independently of each other.
While the above description has been drawn to ship construction, it is not desired to be strictly limited thereto as obviously this type of construction is applicable to any construction which is composed of adjacent plates. Furthermore, it is not desired to be limited to a seam strap of a specific H-shaped cross-section as any recessed element capable of receiving the edges of adjacent plates to which it may be caulked is included within the scope of this invention to the extent as defined by the herewith appended claims.
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
What is claimed is:
1. A metallic plate assembly adapted for use in construction of ships, buildings, tanks and the like, comprising adjacent courses of structural plates, seam straps with edge recesses positioned between said courses with each strap recess receiving a course edge and caulked thereto to form a water-tight but slidable joint, and transverse support ribs rigidly secured to said straps and the intervening courses.
2. A metallic plate assembly adapted for use in construction of ships and the like, comprising adjacent courses of metallic plates with intervening seams between courses, metallic seam straps having edge recesses positioned in said course seams with each recess receiving an adjacent course edge, water-proofing material in said recesses, and spaced transverse metallic ribs overlying said seam straps and the adjacent course plates and welded thereto, the outer edges of the seam straps being caulked on the plate edges to form therewith water-tight but slidable joints.
ALBERT A. SMITH.
REFERENCES CITED UNITED STATES PATENTS Name Date Hohl Mar. 9, 1937 Number