IMPROVEMENTS IN CONSTRUCTING THE SUPER- STRUCTURE AND FOUNDATION OF BRIDGES
Year: 1873

page_text: LETTERS PATENT to William Edward Newton, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Civil Engineer,
for the Invention of " IMPROVEMENTS IN CONSTRUCTING THE SUPER-
STRUCTURE AND FOUNDATION OF BRIDGES."-A communication from
abroad by James Buchanan Eads, of St. Louis, in the State of
Missouri, United States of America.
Sealed the 3rd March 1874, and dated the 10th September 1873.
PROVISIONAL
SPECIFICATION left by the said William Edward
Newton at the Office of the Commissioners of Patents, with his
Petition, on the 10th September 1873.
I, WILLIAM EDWARD NEWTON, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Civil Engineer, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN CONSTRUCTING THE
SUPERSTRUCTURE AND FOUNDATION OF BRIDGES," to be as follows :—
This Invention relates to various improvements in the manner and
form of construction of the foundation and superstructure of arched
bridges, and applies more particularly to iron bridges.

page_text: The first part of the Invention relates to novel methods of constructing
and trussing or stiffening the arches of bridges, so as to enable them to
resist the changes of form induced by unequal loading, and to bear the
changes of temperature without being strained.
The second part of the Invention relates to a less expensive method
than that heretofore employed for constructing the foundations for arched
bridges, and consists in the use of metallic posts or piles secured in the
masonry or screwed into the river bank or bottom, whereby the requisite
stability of the piers and abutments may be obtained with greater
economy of material.
The third part of the Invention relates to a new method of erecting
the arches of bridges, whereby it is practicable to erect very long spans
without the aid of expensive temporary works beneath them, and with
the use of little or no material or devices save those which constitute
part of the permanent structure. This is effected by constructing the
halves of each arch on vertical pivots connected with the abutments, so
that if it requires two, three, or more arches to form a span of suitable
breadth, each of these arches will be divided at the centre, and its inner
or shore ends will be hung on the vertical pivots above mentioned, so
that when these halves of arches are completed they may be swung
round horizontally like a pair of gates are made to turn on their hinges,
and meet in the centre. When the halves of the arches are brought
into this position they are connected and secured together at the crown
so as to form a complete arch.
It is known to engineers that resistance to deflection in a suspension
bridge can be obtained by means of a very light girder, because the
centre of the catenary or cable furnishes a central support for it, whereby
the girder virtually forms two continuous girders of half the length. If
this girder were divided into two independent beams, each of half the
length of the catenary or inverted arch, they would be deflected only
one-eighth as much with a given load per foot as they would be if they
formed one single girder without the support at the centre, but when
joined in a continuous girder and supported about the middle by the
arch, if one-half have its part of the load imposed it will only deflect
one-sixteenth as much, because to bend that half down necessitates the
bending up of the unloaded half, and this requires an equal additional
force. This economic result however of a continuous girder cannot be

page_text: obtained if the centre of the arch rises and falls from the extensions and
contractions of its length resulting from temperature, as the girder then
suffers a corresponding distortion and consequent straining.
It must be evident that if any given suspended arch were inverted
with all its weights, and the curve of the arch remained unaltered, the
tensile strains that were in it before would be simply converted into
compressive strains of exactly the same intensity, and that if the cables,
instead of being of solid section, were made tubular to prevent buckling,
the same sectional area of metal would suffice in the arches in one form
as well as in the other if made of material capable of resisting in equal
degree tensile or compressive strains.
If we assume that the reversal of the suspended arch could be accom-
plished and its form maintained intact without additional bracing it will
be seen that a much cheaper bridge would be obtained than by the
suspension method, as we could then dispense with the high towers,
back chains, and anchorages needed by the catenary, because the thrust
of the upright arch could be received near the bases of the towers, and
the back chains and anchorages of the suspension bridge would then be
avoided, and the high towers be unnecessary.
Now if we imagine an arch thus altered and reversed from its suspen-
sion form, and converted into an upright arch, with its light truss over
it, and secured to the arch by struts from each joint of the arch, it is
evident that the same truss will have equally as great power to resist
distortion in the arch as before. It will be likewise evident that if the
arch be jointed at the middle and at the abutments, and the girder be
separated at the middle over the central joint, that it will still possess in
a great degree the value of the continuous girder, because if one-half of
the arch be loaded the girder over that half cannot be bent down without
bending the other half up, the effect of the load being to force up the
unloaded half of the arch.
The essential features of the Invention are,-

page_text: 3rd. A metallic bridge, pier, or abutment firmly anchored in the
masonry or earth.
4th. A bridge, abutment, or pier composed of columns inclined
together in pairs, and jointed at the apex, which latter is located in the
line of the thrust of the arch.
5th. The combination of the bridge, abutments, piers, towers, or
vertical struts, with half spans or ribs of a bridge, and pivoted connec-
tions to connect the same together, for the purpose of facilitating the
construction of the bridge by enabling the half ribs to be swung around
in detail on a vertical pivot, and there joined to corresponding half ribs
(forming the other half of the span), so that when the two halves are
brought together and joined they will form a complete arch, and when
two or more of such arches are thus formed parallel to each other, and
properly braced against lateral flexure they will form a complete span.
It will be understood from the foregoing that this improved method
of constructing bridges gives an equally cheap construction as to that
part of the suspension bridge which is between the towers as any of the
methods hitherto adopted, while it avoids the expensive features of that
system.
It also avoids spandrel bracing and the ribbed arch, and the strains of
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Edward Newton in the Great Seal Patent
Office on the 10th March 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of September, in the
year of our Lord One thousand eight hundred and seventy-three, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Edward Newton, Her special

page_text: The third part of the Invention relates to a new method of crecting
the arches of bridges, whereby it is practicable to erect very long spans
without the aid of temporary works beneath them, and with the use of
little or no material or devices save those which constitute part of the
permanent structure.
It is known to engineers that resistance to deflection in a suspension
bridge can be obtained by means of a very light girder, because the
centre of the catenary or cable furnishes a central support for it, whereby
the girder virtually forms two continuous girders of half the length. If
this girder were divided into two independent beams, each of half the
length of the catenary or inverted arch, they would be deflected only
one-eighth as much with a given load per foot as they would be if they
formed one single girder without the support at the centre, but when
joined in a continuous girder, and supported at about the middle by the
arch, if one-half have its part of the load imposed, it will only deflect
one-sixteenth as much, because to bend that half down necessitates the
bending of the unloaded half up, and this requires an equal additional
force. This economic result however of a continuous girder cannot be
obtained if the centre of the arch rises and falls from the extensions and
contractions of its length resulting from temperature, as the girder then
suffers a corresponding distortion and consequent straining.
It must be evident that if any given suspended arch were inverted
with all its weights, and the curve of the arch remained unaltered, the
tensile strains that were on it before would be simply converted into
compressive strains of exactly the same intensity, and that if the cable
instead of being of solid section were made tubular to prevent buckling,
the same sectional area of metal would suffice in the arches in one form
as well as in the other, if made of material capable of resisting in equal
degree tensile or compressive strains.
If we assume that the reversal of the suspended arch could be accom-
plished, and its form maintained intact without additional bracing, it will
be seen that a much cheaper bridge would be obtained than by the
suspension method, as we could then dispense with the high towers,
back chains, and anchorages needed by the centenary, because the thrust
of the upright arch could be received near the bases of the towers, and
the back chains and anchorages of the suspension bridge would then be
avoided, and the high towers be unnecessary.

page_text: The last two Figures, as also Figures 5 to 13 inclusive, illustrate the
third part of the Invention.
The object of the improved construction of girder is to stiffen an arch
jointed at the middle, whose two halves, unless thus trussed, would be
flexible.
The voussoirs, segments, or members, composing the arch should be
in straight sections between the points where the vertical struts are
attached to them, and the supporting connections between the arch and
girders should be solely by vertical members. Lateral diagonal bracing
between these verticals and between the arches and girders for resisting
storms or side movement can of course be used as requisite.
The sectional form and depth of the girders used can be such as may
be deemed most economical and desirable by the engineer.
The joints at the centre and the abutments are to prevent the straining
of the arch when it expands and contracts. The joints themselves thus
located are not claimed as novel except when in combination with said
half-span girders above mentioned.
A, A, (see Figures 1, 2, &c.,) represent straight tubes forming sections
or lengths of the arches B, C, which are combined to form a compound
arch, the sections being abutted or joined together by collars D, and
secured in relative position by stays and struts shewn at E and F; G is
a pier or abutment%; H, the skew back; and I, a tower or upward
extension of the pier or abutment for the support of the outer ends of
the girders, which latter may consist of upper and lower chords K and L
and intermediate bracework M, or may be wholly of plate iron, as in
Fig. 12, but should in any case be made so as to resist both tension
and compression in each of its chords. N, N, are struts or uprights
connecting the arches B, C, to the girders.
The arches may or may not stand in a vertical plane. They may be
inclined at top, as shewn in Fig. 2, the ends of the arches inclining out-
wards at the abutments, and secured to them so as to brace the bridge
against transverse strain or lateral vibration. Where the span is not
great, or where two or more rails or roadways are carried, the spreading
of the arches at the abutments will not probably be requisite for stability
against lateral strains.

page_text: It may sometimes be found desirable for the arches to rise as high as
the top chord of the stiffening girders or even above it. In such cases
the girders must possess extra lateral stiffness to secure the arches
against lateral flexure if the horizontal bracing between the arches be
omitted through the girders on account of the passage of traffic through
the girders.
The expansion of the girders will be in the direction of their length,
and may
be relieved at each end of the span on the abutments or towers
in slip joints.
The expansion of the arches will simply cause a proportionate rise at
the middle.
Where the girder is neither wholly above the arch nor wholly below
it, but is placed as in Fig. 3, it will be desirable to make the connection
between the arch and girder where they come side by side, so that the
expansion of the arch will not be interfered with by the girder. This
can be easily accomplished in various ways by any experienced
engineer.
•
The chief merit of the improved system of construction, and onc
cause of its great economy is in totally avoiding strains of temperature.
Hence the vertical attachments between the girder and arch must be
long enough to oscillate and accommodate their positions to the expand-
ing and contracting of the girder. These attachments (struts and
suspenders) must be secured to the arch at the junction of its various,
segments, and to the chords of the girders at its various joints.
When the corresponding points of attachment are too close together.
to use a strut or suspender the girder should be secured at such points to
the arch by a slotted or slip joint to allow the free horizontal movement.
of the girder under change of temperature, and yet prevent any vertical.
movement of the arch independently of the girder.
As I claim no novelty in the method of bracing together laterally the
several ribs or arches, girders, and struts composing a span, I describe no
particular method of doing so, as any of the systems in general use are
applicable to the present Invention.
The second part of the Invention consists in the manner of constructing
the foundations.

page_text: In Fig. 4 the joint P connects the end of the arch B to a diagonal
brace Q, extending in the direction of the thrust of the arch, the other
end of this brace being secured to the apex of the abutment structure.
This brace Q really constitutes an extension of the arch B. The abut
ment structure has two inclined pillars or supports R, R, for each rib of
the arch, which pillars are securely joined together at top, and spread
out downward like two sides of the letter A. These pillars or legs R, R,
may be secured to vertical pillars S, S, supported in masonry T, and.
having collars U, U, to give a firmer hold upon the masonry, or the
legs R, R, may extend down to the solid rock or other foundation V, as
shewn. The legs R, R, especially in the latter form, should have
suitable bracing W to keep them in proper relative position. These
pairs of "A" shaped columns R, R, are to be supported against the
current or other lateral force by bracing between each two or more pairs
forming a pier or abutment. X, X, are vertical struts extending from
the joint P to the abutment or pier to prevent the joint P from moving
vertically; Y, Y, are horizontal struts extending from the joint P of one
arch to the same joint of the arch next adjoining, or to some other fixed
point of the abutment, to prevent horizontal movement of the joint P.
The vertical struts X, X, and horizontal ones Y, Y, may be omitted by
securing the end of the arch B directly to the apex of the abutment, but
in this case the clear span between the opposite ends of the arches will
be limited by the amount occupied by the stride of the abutment columns
at the water line.
In Figures 5 and 6, which show part of the bridge in side elevation,
and the abutment and pier in vertical section, iron pillars, anchor plates,
and braces are securely embedded in the masonry or concrete to supply
the necessary weight to resist the strains of the arches, and to resist
vertical pressure.
In Figures 5 and 6 the weight of the arch is supported on a pillar Z,
and its thrust taken by a diagonal b. The pillars Z, Z, stand in a line
transverse to the bridge, and are secured together by suitable connections.
c is a horizontal strap connecting each pillar Z to the lower end of its
diagonal b; d is an anchor plate bearing against the front of the
masonry T, and secured by the strap e to the foot of the pillar Z.
In Fig. 7 the arrangement is similar, and the anchor structure has
struts and anchor collars U to give firm bearing in the concrete or other
masonry T.

page_text: Figures 8, 9, and 10 shew a modification intended more especially for
bridges of lighter and cheaper construction.
Figures 8 and 9 are side views of portions of arches shewing respec-
tively the arrangement of piles for an abutment and for a pier. Fig. 10
a top view of the arrangement shewn in Fig. 9. In this arrangement
the ends of the arch are secured to a suitably formed skew back or
abutment plate f, supported by metallic screw piles g, g, screwed into
the river bank or bottom (as the case may be), and properly secured to
the skew back plate. The pillars or uprights Z in this case may pass
vertically through the skew back plate, and the lower end may consti-
tute one of the screw piles, as shewn, or the pillar may end in the skew
back, its lower end being secured thereto or secured to it by nuts above
and below the arch and skew back, as shewn in Figures 8, 9, and 10.
The third part of the Invention relates to the manner of erecting the
arches. In this the arches constituting the skeleton of the proposed
structure are to be erected in half spans on the opposite banks of the
stream, with the arches jointed to the abutments in such manner as to
admit of swinging the half arches around and across the stream until
they are joined at the centre of the span in place just as an opening.
would be closed by the swinging together of two gates each of half the
width of the opening, and hung on opposite posts.
c
To form a span for a bridge in this manner, instead of two posts and
two swinging members, four posts and four swinging members or half.
ribs of the two arches forming the span would be needed. When these.
four members are thus swung around to their proper positions, and
joined at the centre of the span, they will be ready to receive the lateral
bracing to hold them afterward against wind pressure. Other ribs.
similarly formed may then be swung into place alongside those already
in place in like manner to obtain the requisite strength of structure.
In this method of erection the top hinge will be formed at the end of
the girder.
Figures 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14 illustrate this method of
erection with different forms of abutments. In light bridges the posts Z
may form the pivot of the upper and lower hinges, and the tops of these
posts may be sustained by permanent iron towers, the tops of which may
constitute parts of the roadway, as at I, I, Figures 11 and 12, or they
(the posts) may be temporarily held by guys in the same manner that

page_text: derrick masts are held. In Figures 11 and 12 the bases of the metallic
towers are shewn in dotted lines, the portion of the arch and the abut-
ment being in side elevation in these Figures.
Figures 13 and 14 illustrate the details of the lower hinges shewn in
side elevation on a smaller scale in Figures 11 and 12. These hinges &
are arranged in the abutment so as to permit the provision of additional
ribs by the sides of the first two in place and also to provide for the
vertical movement of the arch at this point from expansion and
contraction.
Fig. 14 represents a top view of the hinge for horizontal motion, the 1
rib B being swung to its permanent position, and the rib C being along-
side of the bank and at right angles to the other, where it is supported
during erection on temporary trestling.
The dotted lines h in Fig. 13 shew the hinge socket for allowing the
arch to rise and fall by the influence of temperature when in its proper 1
position, and the dotted lines i in the same Figure shew the outlines of
the pivot or hinge on which it is swung into position. j in the same
Figure shews the bracket portion of the skew back to receive the thrust
of the arch.
To prevent sagging before the centre connection of the arch is made 2
the upper hinge / should be arranged to be moved in a direction
transverse to the stream, so as to elevate the rib at the centre of the
span, and likewise in a direction with the stream, so as to aid in lifting
the weight of the rib off the trestling at the shore before swinging it.
This movement of the hinge is easily accomplished by screw or 2
hydrostatic jacks, where large spans are erected, or by the temporary
guys aforesaid.
It is not necessary to explain it in detail.
The design of the half span rib shewn in Fig. 11 is not claimed as
novel, nor inclining the sides of the ribs from a vertical plane, as shewn
in Fig. 2. The novelty it is intended to illustrate consists in the method 30
of swinging and erecting it.
Having now described the Invention which has been communicated
to me by my foreign correspondent, and having explained the manner of
carrying the same into effect, I claim as the Invention secured to me by
Letters Patent as aforesaid,-
First. The combination of the horizontal girder K, L, M, with an
36

page_text: upright flexible jointed arch B or B, C, giving mutual support, as and
for the purpose set forth.
Second. The combination of two independent half-span girders, with
an arch pivotted at the centre, for the purpose of preserving the form of
the arch when unequally loaded, as set forth.
Third. The mode herein set forth of constructing the metallic bridge,
pier, or abutment so that it may be firmly anchored in the masonry or
earth, as shewn and described.
。
Fourth. Constructing bridge abutments or piers of columns inclined
together in pairs and joined at the apex, which latter is located in the
line of the thrust of the arch, as herein set forth.
Fifth. The combination of the bridge abutments, piers, towers, or
vertical struts, with half spans or ribs of a bridge and pivotted connec-
tions to connect the same together for the purpose of facilitating the
construction of the bridge by enabling the half ribs to be constructed on
shore, and then swung around in detail, and joined to corresponding half
ribs forming the other half of the span, as herein set forth.
In witness whereof, I, the said William Edward Newton, have here-
unto set my hand and seal, the Tenth day of March, in the
year of our Lord One thousand eight hundred and seventy-four.
W T NEWTON (T. 0 )