US2370940A - Composite ship construction - Google Patents

Description

March 6. 1945. c. P. CUENI 2,370,94

v COMPOSITE SHIP CONSTRUCTION Filed Jan. 21, 1942 4 She'ets-Sheet 1 k WI/0mm Z Z 5 Z 5 l IN V EN TOR. (lfMf/vr 312/1 Cl/[A/l March 6, 1945. c. P. CUENI 2,370,940

COMPOSITE SHIP CONSTRUCTION.

F'iled Jan. 21, 1942 4 Sheets-Sheet 2 March 6, 1945. c. P. CUENI COMPOSITE SHIP CONSTRUCTION 4 Sheets-Sheet 3 Filed Jan. 21, 1942 INVENTOR. fMi/vr fiw/ CuE/V/ March 6, 1945. c. P. CUENI COMPOSITE SHIP CONSTRUCTION 4 Sheets-Sheet 4 Filed Jan. 21, 1942 N w W (a f Mm /./10//AV////4 m m 3 I 0 J W 3 IN VEN TOR. (ZL Mm/r 840/ Caz/w Patented Mar. a, 1945 Olement Paul Cueni, Arlingtom'N. J., assignor to Porete Manufacturing Company, Arlington,

N. J., a corporation of New Jersey Application January 21, 1942 SerialNo. 427,648

14 Claims.

-The present invention relates to reinforced concrete ships, barges and floating docks.

The idea of using reinforced concrete instead of steel in the construction of ships and barges is not new. About thirty years ago the first concret shipwas built and during the first World War a great numberof seagoing concrete ships were constructed in various countries. Though .these ships proved to have a number of advantages against steel ships they did not fulfill the expectations of the designers.

Concrete ships built according to the heretofore used methods were too heavy and therefore could not carry as much heavy cargo as a steel ship of the same size. The bending and placing of. the reinforcing bars and keeping them in the I right placeflduring pouring and setting of the concrete wa too complicated and ',required too much time. Therefore the introduction of the reinforcing bars in place was quite expensive and the time of construction was too long. Concrete is a brittle material and cannot as well withstand local blows and scratches resulting from rough handling, or accidents as steel can. Therefore,

puncturing of the shell with resulting leakages occurred too frequently and made expensive layoffs for repair necessary.

It is among the objects of the present invention to eliminate the above mentioned disadvantages of concrete ships, concrete barges or concrete docks.

It is also among the objects of the present invention to provide a new design in which the keelsons, frames and beams, composed of structural steel shapes forming together a rigid steelskeleton, are connected by shear reinforcements to the concrete" hull, or to the concrete deck slab or both, in such a manner that the concrete slab with the members of the steel skeleton form composite sections. H

, Itis another object of the present invention to provide means for facilitating the placing of theforms, theplacing of the reinforcing bars and holding them in place during pouring and setting of the concrete.

It is another object of the present invention to provide a frame design wherein square panels are formed by the ribs, making possible the design of a hull shell, which takes advantage of a two way reinforcement.

It is still another object of the preserit invention to provide a flexible concrete hull not subject to shrinkage cracks, and having a much higher resistance against localv blows, by prestressing the reinforcing bars'.

It is a further object of the present invention to provide a' rigid skeleton serving as ribs for the concrete shell and connected thereto by an effective shear reinforcement, the skeleton being designed to withstand the forces produced by 'prestressing the steel wires used for reinforcement of the concrete shell.

It is a still further object of the present invention to provide a rigid skeleton upon which precast concrete slabs are fastened in such a way that the labs, forming the hull shell, or the deck, form a composite section with the members of the skeleton to which they are fastened.

' "It is not new to use a rigid steel skeleton in the construction of concrete ships. Itwas realized'long ago that the placing ,of the reinforcing bars without the help of such a skeleton was too complicated and took-too much time and required to o accurate a bending of the bars and therefore .wasexpensive. But the member of the skeleton were not designed as composite sections together withthe concrete hull, and so adisadvantage was eliminated at'a high cost. More steel wa required, and the dead loadincreased.

According to the present invention the concrete ribs' of a reinforced concrete 'ship are simply replacedby plain steel ribs forming a composite section together with the concrete'hull. Such a section has by necessity the same section modulus as the reinforced concrete T section and the same moment of inertia or a greater one.

' Compared with a rib of a steel ship of equal section modulus it has a much higher moment of inertia and therefore is stiffer.

The advantages of aplain steel rib forming composite section with the concrete hull are substantial; All the concrete in the ribs is elimi nated and the dead weight reduced. The rib concrete in; a ship built according to the heretofore used method amountsto from 30% to 50% of'thejtotal concrete used. The reduction in dead weight is therefore considerable.

In the heretofore used method the formwork was complicated andhad to be supported by falsework. In a ship built according to the present in'vention'the formwork is much'simpler, as

noforms for ribs are required, and at least the inside forms are supported by the rigid skeleton.

'The forms can be placed much faster. 4

In the heretofore used method much time was required to .bend and place the reinforcing bars.

With the new method according to the present invention less reinforcing bars are required,'since 'there are no rib bars, and the bending and the placing of the remaining'bars is much easier.

-The bars do not have to be bent accurately to the shape of the hull because they can be fastened to the shar reinforcement welded to the steel skeleton, which will hold themin the right position during the pouring and setting of the concrete.

To use two-way reinforcement in square or almost square concrete, slab panels is not new but in the construction or concrete ships advan tage of the two-way reinforcement could not be taken because cross ribs would further compil cate the formwork and the advantage gained in the shell itself is lost by the addition of heavy cross ribs. being plain steel, add verydiafitle to dead weight and make possible a reduction in the Fre inforcement or thickness of the shell. I

Probably the greatest disadvantage of concrete ships or barges is the brittleness of the boncrete.

In ships built according to the heretofore used method ,punctured s'hells occurred too, often and made frequent lay-ofis necessary i'for, repairs. Sometimes the apparent damageto the shell from With composite design the cross ribs,

slight blows was small, butiupon careful "exam'ination the concrete was .f'ound't'o be cracked, and leakage resulted, making lrepa'ir necessary. .In ships built according .to the present inven'tion this disadvantage and also the forming of shrinkage cracks is eliminated, and at the same time the.

amount of reinforcing in the shell is reduced by 40% to %.,thus reducing Jfalrther'theldead weight. I By using highstrengt'h'istel wires with small diameter and prestressing them .to .a degree design stress, taking, into consideration shrinkage and plastic flow of concrete, will produce .any tensile stresses in the concrete, a new reinforced concrete is formed which has almost the same elastic properties as steel or wood.

Instead of using high tensile steel wires intermediate grade reinforcing bars prestretched zbe- .yond the ,yield point before being placemlcan also be used. Such a concrete slab can be bent considerably by an external force without getting;

tension cranks and after the external force .isremoved .the slab will zinove vback to its original position. But-even if the external force is strong .en-oughto produce bending in such a degree that tension cracks appear, it does not necessarily? mean permanent damage to the concrete slab. If the stresses in the steel wires are still below the ultimate yield point when the external force is removed, the slab will move back -to almost.

.its original :position and tension cranks in the concrete will be closed hermetically by the inter-1 nal forces introduced into the slab by highly prestressing the wires. 7

I'he ,prestressing of the reinforcing bars in one,

direction is enough since by releasing thepre-.; I

prestressing can be so designed that .i-ttis efiec- ,ti-ve enough to make impossible any-formation of shrinkage :cracks. It would provide the con- -'crete slab with more flexibility than possessed-byj aconventional concrete slab.- .By prestressing :the reinforcing bars,

for in stance the longitudinal bars of the hull, lateral forces are produced, due to the curved shape of;

"including the concrete deckslab; 1

the hull. Some frame has to be provided to take care of these lateral stresses. ton, members of which are designed to formthe ribs for the reinforced concrete hull, can well serve for this purpose, so that no special frame is required. After the external force, producingthe prestressing, is released the prestres'sed reinforcement will produce stresses some mem-- bars of the rigid skeleton'whichgbeing of opposite sign than the stresses produced by the normal forces acting upon the structure, may be used to reduce the required section modulus of such members.

Ehe use of precast slabs in the construction of concrete ships has several advantages. Precast slabs :can be made at less cost and of higher ultimate strength concrete thana hull poured in. place. The prestressing of precast slabs also is :easier than the prestressing of a hull poured in place. The, precast slabs can .be poured in, advance during the Tabri'ca'ting'and assembly of the skeleton, and the fastening of them "to the steel frames "will take less time than the pouring of the entire hull. Therefore, the construction' of a ship with precastlslabs will require the 'slflip ways fora shorter time than a ship'p'our'eil in place. If the hull'is damagedrepair is simpler with precast :units, The daima'ged'slab's are'siinfply replaced by new ones andno sensitive joints of old and new concrete "are result of such repair. e e

A prerequisite for the speedy erection j 'cf the precastslabs is a rigid skeleton to which the slabs can easily be fastened. rouse a'r'ig'id steelfranie for thatpurpose not new, but it is new. to fasten the precast reinforced .concrete.'slabs in such a "way :that slabs and steel ribs iorm one statical unit and are (:lesigned a'ssuch.

The precast slabs are provided with alight steel frame on all four sides, "facilitatin gthe handling and erection of the slabs and, which ,frame is are welded to the steel ribs, thus making .Figjz is .a longitudinal section through the fioor of the ship near the keelson;

Fig. 3 is a cross section ofthe-keelson;

Fig. 4 is a crossfvsectiongof ,a floorbeam; I

Fig. .5 is a cross s'ect'ion of a side frame;

'Fig. 6 is a plan of'a frame panel;

,Fig. 6 is a cross section through-such a. panel; Fig. .'7 is .aplan view of. the bottom of -.a ship;

.l ig. :8 is a cross section of a frame showin 7 the connection of precast slabs;

Fig.8 is a. plan view of such a .joint, and

9 is a cross sectionof a .frame showing a joint of a precast slab with concrete poured in .place. I v I l-n-Eig. 1 there is shown :therigid steel skeleton composed of keelson I, floor beam 2,, side frame 3, deck beam 4, cross frames 5, a concrete shell 6 and deck slab 1. The steel skeleton is .one unit, all members .l 1205- being riveted or welded'tc .gether. The concrete shell 6 andldec k s'lablare connected to the members 'I, .to'il'ro f theskeleton by a steel shear spiral 8 or ther'errecuve shear The steel skeler reinforcement insuch a way-that the members i to Set the steel'skeleton form composite sec- "tions with the reinforced concrete "shell 5 orthe deck slab 1, respectively. 'l'hefl shear reinforcement must be designed to transmit the shear'bejtween the steel rib "and the concrete-slab, in' a similar way as the "rivets connecting the steel "rib with'the steel shell in' a plain steel' ship.

' The main frames-in such a shipmay be cross frames, as shown in Fig. under z; 3 and 4 or" they may be longitudinal frames running" parallel to the keelson, like the crossframes 5, in Fig. 1.

The frames2, 3 and 4 cross frames.

are then reduced to lighter The steel skeleton may be" e qcse -jor a n welded sections, riveted 'sectionsforrolledqsections. All-welded sectionsrequire less steel than riveted or rolled sections andjare moreeco'nomical, except maybe for lig ht member's, where rolled sections probably are asfeconomical aswelded' i ones, for instance for the cross frames The concrete shell or deck slab may consist; of

"plain reinforced concrete, the-inain" reinforcement running in one or twoidirections, perpendicularor diagonal to thefframe's, orof-a pe'rstressedreinforced concreteiyhere part or all of the main reinforcement is pr'e'stressed. In the longitudinal section Fig.2, I; shows the keelson, '2 the cross section through the I floor beams, 5 the cross frames, G'the reinforced con-" crete shell of the hottom of the'ship adds the shearspiral. H H The spacing of the frames is a matter of design and depends on the type and size'of the ship, on the thickness and reinforcement of the ..concrete slab, and the properties of, th'econcrete and reinforcing steel.

In the cross sectionFig. 3; l is the keelson,

composed of three plates welded together into an 4 I shape, forming a composite section together '.with the concrete shell 8,2 is the floor beam,

framed into the keelsori, The top flange 9 of I- beam shape is much heavier than ithebotto-m flange l0, which is increased by 'theareayof the concrete slab 6 and its longitudinal reinforcement ll, l2, l3, I and IB.. The spiral shear reinforcefment 8, welded'to the flange (if the 'keelSon, l,

serves as a base to v which reinforcing bar I3 is welded, which. servesas a chair to'keep the ex-= terio-r cross reinforcement ll of the slab, in its right place during pouringandf setting'fof the concrete. In a similar way'the bars I 5 and l6. welded tothe spiral serve as a chair for the in terior cross reinforcement I! of the concrete slab.

Sis a side view of the spiral shear reinforcement,

welded to the floor beam 2, audit! is an'additional interior cross reinforcementj fori the con- .crete haunch.

together with the concrete'shellw. The shear spiral, the chair bar and the slab reinforcement is the same as shownin Fig; ll-The bar 22' is the concrete haunchreinforcem'ent also sh'ownin different shapein Figs. 3 and 4. v

Bent in this shape and placed alternately, one

in this direction and the next in the other direc-.

tion; it provides a concrete haiznchfreinforcement and also additional negative reinforcement for the concrete shell over the frames The insideformwor k 23 supported "by the cross pieces 24 can' easily be attachedby the wedges 2'5 and lnserts 26 to the steel frames. It is obvious that after the steel skeleton is erected with the shear spirals welded to it, the placing of the reinforcing bars is facilitated and expedited considerably as compared with the heretofore used method of building concrete ships. The placing of the interior, formwork is simplified; no forms are needed for ribs and no scaffolding is necessary, since the forms are supported by the-steel skeleton as shown in Fig.5." I v cross frame, 3 a shear spiral and -6 the reinforced concrete shell. H and M show the exteriorslab reinforcing'running in both directions, l2and His theinterior slab reinforcement. 19,- and 21 are the reinforcingbars welded to the "spirals and serving as chairs for thejslab reinforcement.

22 isthe haunch reinforcement placed across the frames, Each panel is square or almost square, which will allow advantage to betaken of a twowayreinforcement. 'For the same thicknessof slab andthe same reinforcement a greater spacingof the frames will be possible. The slab" is also made stronger by heavy edges formed by "the haiinches on top of the frames, indicated by the dotted lines 21 and shown at 28 in cross/section, Fig. 6 If no advantage is taken-of twoway re nforcement the cross frames 5 can 'hereduced considerably-inhumber and size." 'How- ''ever, a heavier slab is'then required, and the fibor beams, side frames anddeck beamsmust be spaced closer together; 7

' Fig. 7, being the planet the bottom ofthe steel skeleton, shows the keelson |,'-the floor beams 2, the side frames" 3, the'cross frames-5, and the concrete shell 6. 1 1

29 is a bulkhead consisting of a concrete slab and steel frames. It may be-advisable to'o'mit the steel floor beam, side frame and deck beam where bulkheads are required, except where-lat- In the cross section Fig. 5,2 is' a fioor beam composed of three plates welded together into an .I-beam shape, forming a composite section together with. the concrete shell 8.."

' -The spiral shear, reinforcement 8, weldedto the floor beam 2 sup'portsfjbars l9 and 20 which serve as chairs, for the longitudinal interior reinforcing bars I2, and bar 2!, also welded to the I spiral 8,.serves as a chair forthe' exterior reinforcing bars H of theconcreteshell;

5 is a cross frame welded'to the floor beam 2.

. 8" is a side view of theshear spiral welded to the cross frame 5. H is the, exterior cross reinforcement and I! the interior cross reinforcement.

In the cross section Fig. .5, 3 isthej side frame composed of three. plates welded together into an I-beam shape, forming a'com'posite section eral forces occur. The arrows 30 show these lateral forces produced by prestressing thejlongi tudinal reinforcing bars. These forces canbe take'nby the steel skeleton, "without any 'addi- I tional temporary frames.

In Fig. 8 3! represents "the cross section-pf one of the frames, floor beamsor the keelson. In

Figs. 8 and 8 8 is a'shear reinforcement in the "form of a spiral, 32 aprecast reinforced'concrete the precast slabs 32 are bent over the chair-bars ,4! and 42 and wired or welded thereto. reinforcing bars of the precast slabs also canbe The members form composite sections by union through said shear reinforcement, chair bars fastened to said shear reinforcement longitudinally thereof and adapted to hold in place the reinforcing of said members, the latter being made of poured-in-place concrete.

8. A marine vessel comprising a substantially rigid steel skeleton having panels of substantial length and width, shear reinforcement integrally secured to said skeleton, reinforced concrete outer members secured to said skeleton, said members being precast and fitting into said panels, the junction being such that said skeleton and members form composite sections, the reinforcing of said members extending beyond at least one end thereof and secured to the adjacent shear reinforcement.

9. A marine vessel comprising a substantially rigid steel skeleton having panels of substantial length and Width, shear reinforcement integrally secured to said skeleton, reinforced concrete outer members secured to said skeleton, said members being precast and fitting into said panels, the junction being such that said skeleton and members form composite sections, the reinforcing of said members extending beyond at least one end thereof and secured to the adjacent shear reinforcement, and poured-inplace concrete uniting the same.

10. A marine vessel comprising a substantially rigid steel skeleton having panels of substantial length and width, shear reinforcement integrally secured to said skeleton, reinforced concrete outer members secured to said skeleton, said members being precast and fitting into said panels, the junction being such that said skeleton and members form composite sections, said members having steel edge pieces permanently secured to said skeleton.

11. A marine vessel comprising a substantially rigid steel skeleton having panels of substantial length and width, shear reinforcement integrally secured to said skeleton, reinforced concrete outer members secured to said skeleton, said members being precast and fitting into said panels, the junction being such that said skeleton and members form composite sections, said members having steel edge pieces permanently secured to said skeleton by being welded to structural shapes thereof.

12. A marine vessel comprising a'substantially rigid steel skeleton having panels of substantial length and width, reinforced concrete outer members secured to said skeleton, said members being precast and fittinginto said'panels, the

, junction being such that said skeletonand members form composite sections and being linked by substantially continuous, relatively stiff shear reinforcement integral with said skeleton, said members having steel edge pieces permanently secured tosaid skeleton by being Welded to structural shapes thereof, at least one of said pieces being continuous and being welded along. its entire length to provide a water-tight joint, andby substantially continuous, relatively stiff shear reinforcement integral with said skeleton, said members having'steel edge pieces permanently secured to said skeleton, shear bars secured to said pieces and embedded in said members, and poured-in-place concrete between adjacent members, said concrete having embedded therein said shear reinforcements and, steel pieces.

14. A marine vessel comprising a substantially rigid steel skeleton having panels of substantial length and width, reinforced concrete outer members secured to said skeleton, said members bein precast and fitting into said panels, the junction being such that said skeleton and'members form composite sections and being linked by substantially continuous, relatively stiff shear reinforcement integral with said skeleton, said members having steel edge pieces permanently secured to said skeleton, said pieces being angular in cross-section and located at corners of said members, and poured-in-place concrete between adjacent members, said concrete having embedded therein said shear reinforcements and steel pieces.

CLEMENT P. CUENI.

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