US1186109A - Bridge. - Google Patents

Description

www0/awo mLm/LJMM- MWMQWW D. B. LUTEN.

BRIDGE.

APPLICATION FILED MAR. 8| 1909.

Patented J une A6, 1916.

Danie! B, Liften.

Hovnmd DANIEL B. LUTEN, OF INDIANAPOLIES, INDIANA BRIDGE.

Original application led November 1, 1906, Serial No. 341,605.

Specication of Letters Patent.

Patented June 6, 1916.

Divided and this application filed March 8,

1909. Serial No. 481,961.

To all whomy t may concern.'

Be it known that I, DANIEL B. LUTEN, a citizen of the United States, residing at indianapolis. in the county of Marion and State of Indiana, have invented certain new and useful Improvements in Bridges, of which the following is a specification.

My invention relates to concrete structures comprising bridges or arches in series balanced upon piers between the spans, and the object of my invention is to so apply myv improved construction to bridges or other arched structures that arches having unequal horizontal thrusts, or of unequal iengths, may be balanced against each other upon the saine pier.

This application is plication tiled by me No. 341,605.

The accompanying drawings illustrate my invention.

Figure l is an elevation of a brldge constructed in' accordance with my presentanvention; Fir. 2 is a longitudinal yertical section; an( Fig. 3 a detail Showing the manner of balancing arches of difierent iengths.

lu a bridge consisting of several spans it is highly desirable for the sake of appearance, that the middle span should be the longest span; for otherwise, to one stand ing at one end of the structure, the nearest span will appear the dominating span, due to an optical illusion, thus apparently destroying the symmetry and dignity of the structure. Moreover the main span in the middle of the structure makes better p'rovision for floods. And with spans decreasing in length toward the abutments, the thrust on the abutment is decreased and the efiiciency ot' the structure thus doubly increased. The balancing oi unequal arch spans upon their intermediate piers has hitherto been accomplished by giving to the longer spans an increased rise, thus reducing the thrust of the longer span; but this can be of but limited application, for in order to maintain a division of an ap- Nov. 1, i906, Serial the thrusts at a constant value, the increase in the rise must be made greater proportionately, than the increase in span, and since a bridge floor must be made substantially level, no great variation oi' span can be permitted. Moreover even a. slight variation of span results in a considerable elevation of the crown of the main span over those of the end spans. lf then the structure were to be submerged in iood to a point near the crowns of the short arches, the thrusts of the short arches 'would be greatly reduced by the buoyancy of the Water and the main arch, not yet submerged, would exercise a much greater thrust on the pier, tending to overturn it in the direction of the shorter submerged arch. My im proved construction enables me to balance arches of unequal spaii upon slender piers Without increasing the rise o the longer span.

As a means for balancing unequal arches upon the pier, I find it desirable to arrange the arches as shown particularly in Fig. 1. In order to accomplish this result, instead of making the shorter span Hatter than the longer one, as has heretofore been the custom, the thrusts may be balanced by raising the end of the shorter span to meet the pienI at a higher point than the longer spanas shown in detail in Fig. Where the line of thrust E of the short span meets the line of thrust D of the longer span, upon the` long span side of the central pier, the force D however, being greater than the force E, the resultant F will be deflected to cross the center line of the pier and this line F may be made to emerge from the base of the pier Within the middle third, although, it' the pier be reinforced along its face as later described, this is not absolutely essential. It becomes immediately apparent that by this means al level bridge Without camber may be readily produced, as illustrated in Fig. 1, Where the spans gradually increase in length, the adjacent end of each shorter span rising upon the adjacent end of the next', fgllowing longer span. This inclination in the end 3112112 (lf the SQI'QS Will alSO Save material in the abutmentat the end of the bridge, since it lowers the spriiglng llne, and this may be exaggerated for that purpose. For the salie of appearance the ap` parent springings may 'oe maintained at an actual level on the piers by distortion of the curves, While the virtual springings are alternately elevated. This method ofbalancing the arches provides for the equahzmgof the thrusts due to the fixed load by the introduction ot a bending moment in the pier. Ifthe pier is very slender, so that the resultant F may pass outside of the middle third, I reinforce the pier against this moment by providing reinforcing members 40,

reinforcing members may be, if desired, downward extensions from reinforcing members 41 which extend through the arch either adjacent the intradosal or ythe extradosal surfaces being preferably extensions of the extradosal members.

Since the moving loads, on arches supported upon an intermediate pier, do not balance, their thrusts also will be unequal and are resisted by the reinforcing members thus embedded near each face of the pier.

The super-elevation required in the shorter arch above the longer arch, may be determined by equating the moments of their respective thrusts at their intersection with the center line of the pier, taken about the base of the pier as a center.

I claim as my invention l. In combinati0n,'two arches of unequal span, and an intermediate pier upon wh'ich such arches meet, the pier being so slender that if either 'arch is removed the line of thrust due to the other arch on the pier emerges from the pier outside of the middle third of the pier base so that the pier is incapable of supporting one of said arches 'with the other removed, the center line of the arch-rib of the shorter span meeting the center line of the pier at a point farther removed from the base of the pier than is the intersection of the center line of the archrib of the longer span with the center line of the pier.

In combination, two arches of unequal span, and an intermediate pier upon which such arches meet, the pier being so slender that if either arch is removed the line of thrust due to the other arch on the pier emerges from the pier outside of the middle third of the pier base so that the pier is incapable of supporting one of said arches with the other removed, and the outer surfaces of the two arches intersecting each other on that side of the center line of the pier toward the longer span.

3. The combination of a series of arches of span decreasing toward the end, each arch of shorter span having its two virtual springings at dierent heights and its higher virtual springing toward the adjacent arch of longer span and higher than the adjacent springing of said adjacent arch of longer span.

. 4. The combination of a plurality of arches of unequal span, and a pier supporting the adjacent ends of two such arches, that end of the shorter arch which is supported by said pier being elevated above that end of the longer arch which is so supported and also above the other end of the shorter arch.

5. The combination of a series of arches,

an intermediate arch of the series being longer than the two adjacent arches an having its two virtual springings atv substantially the same height, and each of said two adjacent arches having its two virtual springings at different heights and its higher virtual springing toward the intermediate arch and higher than the adjacent springing of said intermediate arch.

YIn witness whereof, I have hereunto set my hand and seal at Indianapolis, Indiana, this fifth day of March, A. D. one thousand nine hundred and nine.

' DANIEL B. LUTEN. [11. 5.]

Witnesses:

C. H. KNIGHT, J. P. COOK.

(topics nt this patent may be obtained tor avc centi each, by addressing the Commissioner ol Patenti,

Wilmington, n. c."

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