US3514918A - Method of pre-stressing a column - Google Patents

Description

June 2, 1970 B. ARCHER ET 3,

METHOD OF PRE-STRESSING A COLUMN Filed Sept. 25, 1969 2 Sheets-Sheet 1 w M%M INVENTORS June 2, 1970 B. ARCHER ET AL 3,514,918

METHOD OF FEE-STRESSING A COLUMN 7 Filed Sept. 25, 1969 2 Sheets-Sheet 2 INVENTORS SM/,4? 4 12 74/4 07. 44 2 United States Patent Office US. Cl. 52741 9 Claims ABSTRACT OF THE DISCLOSURE Method for pre-stressing a concrete column or utility pole of the type developed by pumping concrete into one of several aligned and interlocking telescoping sections. As the concrete is pumped, the sections vertically extend from a rigid base. Prior to setting of the concrete, a tension is drawn from one or more vertically spaced points at the top of the column and laterally away from the column, so as to bend said column away from its vertical axis as a pre-stress against anticipated lateral load upon the column.

CROSS-REFERENCES TO RELATED APPLICATIONS A continuation in part of applicants earlier filed applications: Method for Developing a Column, Ser. No. 676,- 286, filed Oct. 18, 1967, now Pat. No. 3,471,980, Method for Pumping a Column, Ser. No. 702,406, filed Feb. 1, 1968, now Pat. No. 3,469,358.

The parent applications concerned developing different types of rigid columns by pumping fluid concrete into a plurality of longitudinally aligned interlocking telescoping sections. As the concrete sets, the columns are permanently rigidized in a mode of vertical extension. The present application is directed to the improvement of prestressing such a column by drawing a stressing line from one or more points at the top of the column downwardly towards a point laterally spaced from the base thereof so as to bend the column laterally away from its vertical axis. As the concrete sets, the stressing line may be removed. The lateral load, when placed upon the column, returns the column to its vertical axis.

BACKGROUND OF THE INVENTION (1) Field of the invention According to the present invention, utility poles of the type supporting an eccentric load are stressed reciprocably away from the anticipated eccentric load. For example, utility poles used in supporting power lines having a line angle converging at the pole, a dead end utility pole, or a utility pole supporting a long span adjacent to a short span are pre-stressed reciprocably away from the anticipated load. As the concrete sets, the stressing lines are removed and the pole is positioned for vertical support of the anticipated eccentric load, eliminating the necessity for conventional guide wires or lateral supporting struts and the like.

(2) Description of the prior art Prior inventors have considered the possibility of using metallic, vertically aligned forms for the pouring and setting of concrete as columns. However, the forms were bolted to a rigid base and were not necessarily interlocking. The prior art does not show developing a vertical column by pumping of concrete into interlocking, longitudinally aligned sections, then drawing a tension away from the top section so as to pre-stress the developed 3,514,918 Patented June 2, 1970 column. The most pertinent prior art is Sweden 212,189 (1966) which shows a column pumped vertically downwardly, the sections being neither sealed nor interlocking with respect to each other.

SUMMARY OF THE INVENTION According to the present invention, a column is pre stressed by anchoring a column form in a rigid base, then pumping fluid concrete into the form 'above the base, maintaining fluid pressure within the form so as to rigidize the base and pre-stressing the column by drawing tension laterally away from the column, so as to bend the column apart from its vertical axis reciprocably to the anticipated eccentric load.

BRIEF DESCRIPTION OF THE. DRAWINGS FIG. 1 is a side elevation of a telescoping column, partially in section, showing the pre-stressing load in phantom;

FIG. 2 is a like vertical section, showing a modification of invention wherein a tapered column is pre-stressed;

FIG. 3 is a side elevation, partially in section, showing another modification wherein the column is a cylinder;

FIG. 4 is a schematic top plan, showing the stressing of a pole supporting a converging line angle high tension mm;

FIG. 5 is a schematic top plan showing the stressing of a pole positioned inter-mediate a short wire span and a long wire span;

FIG. 6 is a schematic top plan, showing pre-stressing of a dead-end utility pole;

FIG. 7 is a transverse section taken along section line 77 of FIG. 1 and showing a laterally extending support arm for the eccentric load; and

FIG. 8 is a transverse section, taken along section line 88 of FIG. 1, showing the pumping gate elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, there is illustrated a pre-stressed pole 10 of the type made of steel, aluminum, plastic, or like interlocking sections 12, 14, 16, and 18. Each of the sections 'has a top ring 24 and a bottom ring 26, serving to align and seal the sections with respect to each other. Bottom section 12 includes a hydraulic coupling 42 and a pumping gate 44 which is closed as the concrete pumping is completed. Top section 18 may include a top 20 with air vents 22 therein.

A lateral strut 30, having insulator 32 or bracket, may be provided for supporting an eccentric load on top sec tion 18. Tensioning wire 34 extends from eye 28 in the top section downwardly and laterally away from the base 46 to an anchor 36 supported in ground 50. Additional and identical tensioning :wires 38 and 40 may be also employed to pre-stress the entire column to the mode illustrated in phantom in FIG. 1. As the concrete sets in this pre-stressed condition, lines 34, 38, and 40 may be removed, the column remaining in compression on the near side and in tension on the far side.

It is anticipated that the actual design load when applied will neutralize the stressed compression and tension on the near and far sides respectively, allowing a considerable reduction of material required by pre-stressing in a direction opposite to the actual applied load. One or more such loads may be applied by identical strut 30.

In FIG. 2, there is illustrated a modification of invention where a tapered column 10' is employed and has a plurality of laterally extending struts 30', 52, and 54. As the concrete is pumped through coupling 42', gate 44' is shut, and tension may be pulled along lines 34, 38', and 40' to anchor 36'.

FIG. 3, also, illustrates a further modification of the invention, a cyclindrical column being similarly prestressed.

FIGS. 4-6 illustrate varying situations in which the eccentric load may be applied to the pre-stressed column.

In FIG. 4, there is a line angle or convergence of a power line towards the pre-stressed pole, the stress being drawn at the apex of the line convergence and away from the eccentric load.

In FIG. 5, the pre-stressed pole is supported intermediate a short span pole 62 and long span pole 64, the stress being drawn in parallel with or reciprocably away from the long span 68 between pole 10 and pole 64.

In FIG. 6, dead-end pole 10 is pre-stressed away from the line load 70 and pole 72.

In FIG. 7, there is illustrated the top section 18 having eye 38 for supporting the tension wire as well as lateral strut or arm 30 and insulator or like element 32.

FIG. 8 further illustrates positioning of the bottommost section 12 within concrete or compacted base 48 and surrounding ground 50.

It is believed that the present invention will have particular acceptability where line angle changes in power transmission lines are made, conventionally necessitating guy wires. By pre-stressing according to the present invention to conventional guide wire strength requirements and removal of the stressing lines after setting of the concrete, a reduction in rights of way for power lines may be made since the guide wire space is eliminated. Simultaneously, of course, the structural capacity of the pole is increased.

We claim:

1. Method for pre-stressing a column comprising:

(A) anchoring a telescoping form of the type including a plurality of longitudinally aligned, interlocking sections to a rigid base;

(B) pumping fluid concrete into said sections, so as to longitudinally extend said sections above said base;

(C) maintaining fluid concrete pressure within said sections so as to rigidize said sections with respect to each other; and

(D) pre-stressing said column by drawing a tension from one of said exetnded sections away from said column, so as to bend said column away from its vertical axis.

2. Method for pre-stressing a column as in claim 1,

wherein said pre-stressing includes drawing said tension from a plurality of vertically spaced points on said column laterally away from said column.

3. Method for pre-stressing a column as in claim 2, including converging drawing of said tension from a plurality of vertically spaced points on said column to an anchor secured in said base laterally apart from said column.

4. Method for pre-stressing a column as in claim 3, including drawing said tension equal in force to the anticipated lateral load to be placed upon said column.

5. Method for pre-stressing a column as in claim 1, wherein said column supports a converging line and said tension is drawn away from the convergence of said line.

6. Method for pre-stressing a column as in claim 1, wherein said column supports a longitudinal line and said tension is drawn in parallel with said longitudinal line.

7. Method for pre-stressing a column comprising:

(A) anchoring a column of the type having a closed top, an open bottom, and a pumping gate extending through its side, said column being secured in a rigid base beneath said pumping gate;

(B) pumping fluid concrete into said column so that said concrete extends into said base and above said pumping gate substantially throughout said column;

(C) maintaining fluid pressure within said column so as to rigidize said column;

(D) pre-stressing said column by drawing a tension from a point above said pumping gate laterally away from said column, so as to bend said column away from its vertical axis.

8. Method of pre-stressing a column as in claim 7,

wherein said column is cylindrical.

9. Method of pre-stressing a column as in claim 7, wherein said column is tapered.

References Cited UNITED STATES PATENTS 989,069 4/1911 Siewert 52632 1,568,596 1/1926 Frost 52146 1,684,663 9/1928 Dill 264228 2,660,049 11/1953 Maney 264-228 X FOREIGN PATENTS 212,189 5/1966 Sweden.

PRICE C. PAW, JR., Primary Examiner U.S. Cl. X.R.

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