US1574657A

US1574657A - Steel-trussed structure

Info

Publication number: US1574657A
Application number: US8234A
Authority: US
Inventors: Jackson John Grant
Original assignee: Individual
Current assignee: Individual
Priority date: 1925-02-10
Filing date: 1925-02-10
Publication date: 1926-02-23
Anticipated expiration: 1943-02-23

Description

Feb. 23 1926.

J. G. JACKSON STEEL TRUSSED STRUCTURE Filed Feb. 10, 1925 llll I My alii lph.

Illl l l I l l III. giiiii! I II Patented Feb. 23, 192.6.

UNETEE 4S tries.

:STEEL-TRUSSED STRUCTURE.

Application filedFebruary 10, 1925. Serial No. 8,234.

To all commit may cancer-n:

Be 1t known that I, JOHN GRANT JACK- soN, a subject of the King of Great Britain,

and a resident of the city of Chatham, in thecountyofKent, in .the Province of Ontario, Canada, have invented certain new and useful Improvements in Steel-Trussed Structures, of which the following is .the specification.

My invention relates to improvements in steel trussed structures .and the object .of the invention is to devisea steel structure stiffened and reinforced bya cementitious material in such a manner as to increase the strength of the structure under compression strains to be at least equal to the tensile strength of the steel.

A further object is to construct a cement reinforced steel structure which will have less tendency to deflect or buckle under compression due to transverse or bending stresses {as a result-of the greater spacing of the active elements and consequently greater moment of inertia of the cross section and at the same time being of such nature as to resist more effectively such compression strains by virtue of the greater cross seotional area of the compression resisting material.

A still further object is to .devise a cement reinforced steel trussed structure that can be readily constructed :and which will be 7 comparatively light in weight for its size and strength.

Another object is to devise a trussed structure which will lend itself to being nested during manufacture, transportation and storage, and yet another object is to devise a structure in which several units can be .built up into a complete trussed structure either during manufacture or erection.

My invention consists of a cement reinforced steel structure constructed and arranged all as hereinafter more particularly described and illustrated in the accompanying drawing in which a Fig. 1 represents a front elevational view of my preferred construction, showing the same in the form of a pole.

Fig. 2 is a side elevation thereof.

Fig. 3 is a crosssectional View taken on the line 3-3 Figure 1.

Fig. t is an enlarged cross sectional view on the line 4 4i Figurel.

Like characters-of reference indicate corresponding parts in the different views.

'1 are the longitudinal steel members of the structure, each consistingpreferably of,

a plurality of spaced apart steel rod members disposed as .is shown inthe cross sectional views and of sufficient s'trengthto take care of .the tensile stresses required, when taken together with the relatively small longitudinally extending auxiliary steel members 2 which surround'the 'members-1 and are adapted to retain the cement filler 3 in position, it being-understood that the

steel members

1 and 2 are'embe'dde-din Portland cement or other.cementitiousmaterial of the requisite consistency to reinforce them under compression strains. The indtependent longitudinal members "1 and the auxiliary members 2 which preferably consist of wire mesh and the cement filler 3 are tied together by means of suitably spaced lateral steel members 4, which are embedded or encased in the-lateral cement members 5.

The cement portion of the unit -structure is preferably cast about the members 1, "2 and 4 so that the .lateral cementmembers 5 will be homogeneously united to thegoement fillers 3.

In the form of pole illustrated, the unit is of substantially V-shaped cross section, being provided with opposed longitudinal flange portions 6. Reinforcing cement ribs encasing steel reinforcing and tieing members 8 are provided for increasingthe resistance against distortion at thejunction of the-flange members with the legs of the V-shaped portion. 7 I

9 are cross straps constructed of-meta'l or cementitious material, either reinforced or not as the case may be, said straps extending across the opposite faces of the flanges 6 to the faces provided with the ribs 7 and adapted .to be secured to such flanges by means ofthe bolts 10 which extend therethrough. v

The straps time provided forpreventing the distortion of the legs of the pole due to excessive spreading stresses. The straps 9 are not applied to the pole until the same is about to be erected, and consequently my poles, which are of V shaped crosssection, will nest togethervd'uring stor'age or transportatiom as indicated in dotted lines in Figure 3. i

Where desired, two of my poles of V- shaped cross section can be erected in opposed relation to one another and joined together by lateral members, thus making up a much stronger structure. Used singly, they are particularly applicable for use as trolley or electric light poles.

They are in fact reinforced steel structures in which the reinforcement is cementitious material such as Portland cement. The principle involved is entirely distinct from reinforced cement structures in which the reinforcing steel is provided for reinforcing the cement against tensile stresses whereas in my structures the cement is provided for reinforcing the steel against compressive strains, which experience has shown to be the limiting strain in the design of steel truss poles. or tower structures.

Itis particularly noticeable by all engineers using steel trussed poles and towers that such structures are relatively weak in the members subjected to compressive strains due to the tendency to deform or buckle under stresses substantially less than tensile stresses which such members resist.

A pole contructed according to my invention overcomes this ditficulty by the use of a plurality of independent members tied together by suitably disposed transverse members, each member as above stated comprising longitudinally disposed steel members which are provided with compression reinforcement of cementitious material such as Portland cement.

The complete pole whether in the case of unit construction or built up form is capable of resisting compressive strains better than a steel structure of equal steel cross sectional area and further, such a pole will'be substantially. equal in weight to a structure composed solely of steel of the same strength and will be much lighter than a reinforced concrete pole of the same size and strength. It will moreover lend itself much more readily to being transported due to its light weight and adaptability to nesting, as well as effecting a considerable saving in material and labour in construction. 7

In providing the ribs 7, I do so to increase the resistance of the angle portions to lateral stresses which might tend to spread the flanges 6. This is particularly desirable as a means for resisting the ground pressure upon the outwardly extending flanges 6 in the case of a pole embedded in the'soil and subjected to lateral strains.

On referring to the drawing, it will be noted that the transverse members 5 are of deep cross section below the ground line of the poles in order to act as ground anchors for, lateral stresses. 1

WVhat I'claim as my invention is 2.

1. 'A cement reinforced steel structure comprising independent longitudinal steel members, suitably spaced transverse steel members connecting the respective longitudinal steel members together, said longitudinal and transverse members encased in cementitious material, opposed longitudinal flanges on the sides of the structure, and tieing means extending between the opposed flanges.

2. A cement reinforced steel structure comprising independent longitudinal steel members, suitably spaced transverse steel members connecting the respective longitudinal steel members together, said longitudinal and transverse members encased in cementitious material, opposed longitudinal flanges on the sides of the structure, and transverse straps extending between the opposed flanges and secured thereto.

3. A cement reinforced steel structure comprising independent longitudinal steel members, suitably spaced transverse steel members connecting the respective longitudinal steel members together, said longitudinal and transverse members encased in cementitious material, opposed longitudinal flanges on the sides of the structure, and reinforcing means between the flanges and main portion of the structure for reinforcing the junction of the flanges and the main portion against fracture or distortion.

4. A cement reinforced steel structure comprising independent longitudinal steel members, suitably spaced transverse steel members connecting the respective longitutudinalsteel members together, said longitudinal and transverse members encased in cementitious material, opposed longitudinal flanges on the sides of the structure, laterally extending spaced ribs of cementitious material between the flanges and the main portion of the structure, and reinforcing and tieing metal members in the ribs secured at their ends to the longitudinal steel members.

5. A cement reinforced steel structure comprising independent longitudinal steel members, suitably spaced transverse steel members connecting the respective longitudinal steel members together, said longitudinal and transverse members encased in cementitious material, and opposed longitudinal flanges on the sides of the struc ture, the structure being V-shape in cross section for enabling one structure to be nested within another.

7 6. A cement reinforced steel structure comprising independent longitudinal steel members, suitably spaced transverse steel members connecting the respective longitudinal steel members together, said longitu dinal and transverse members encased in cementitious material, and opposed longitudinal flanges on the sides of the structure, the structure being V-shape in cross section for enabling one structure to be nested within another, and the main portion of the structure between transverse members having orifices extending through the cementitious material.

7. A cement reinforced steel structure members arranged so that when encased in comprising independent longitudinal steel the cementitious material the resultant members, suitably spaced transverse steel structure Will be V-shape in cross section 10 members connecting the respective l0ngitu-' With orifices extending through the legs of 5 dinal steel members together, said longituthe structure between the spaced transverse dinal and transverse members encased in members. cementitious material, the longitudinal JOHN GRANT JACKSON,