Monolithic cast bridge

A monolithic cast bridge broadly includes a unitary, monolithic structure (12) having a pair of spaced haunches (14, 16) a span (18) having upper and lower surfaces (20, 22) and a pair of axially extending webs (24, 26). Haunches (14, 16) define support-engaging undersides (28, 30) which are provided for supporting the bridge above a support level (48). The lower surface (22) of the span (18) extends upwardly from each of the haunches (14, 16) to present a maximum rise relative to the haunch undersides (28, 30) at a midpoint (50) of the span (18). The webs (24, 26) are spaced and substantially parallel with respect to each other, and respectively include lower surfaces (52, 58). The lower surfaces (52, 58) are substantially flat and correspond to the haunch undersides (28, 30). A pair of reinforcement cables (64, 66) are advantageously positioned within respective webs (24, 26), and are configured for reinforcing the structure (12) along its longitudinal axis.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the construction of prefabricated cast 
arched structures. More particularly, the monolithic cast bridge hereof 
concerns a unitary structure including an arched span, and an axially 
extending load bearing web depending from the span. 
2. Description of the Prior Art 
Presently, in the construction of cast arched structures, such as bridges, 
it is known to provide an arched span which extends between and is 
supported at its ends by a pair of opposed support elements. Such a span 
also commonly includes a plurality of integral transverse webs depending 
from the span. 
In fabricating such a structure, a form is assembled at the construction 
site. Cast material, such as concrete, is poured into the form. Once the 
cast material is set, the form is dismantled, and the structure is coupled 
with the support elements, if necessary, and then is ready for use. 
The transverse webs depending from the arched span, however, do not support 
loads along the longitudinal axis of the structure. Therefore, 
reinforcement of such arched structures generally entails inserting sheets 
of rebar, or similar sheet-like reinforcing members, into the span before 
the cast material is poured. The combination of rebar and cast materials 
yield a structure having sufficient strength along its longitudinal axis 
so that it may serve as a bridge. 
Since rebar is relatively flat and sheet-like, it must be bent in order to 
conform to the shape of the arched span. As a result, rebar is relatively 
difficult and labor intensive to properly position within an arched form. 
This problem is amplified as the thickness of the arched span decreases. 
As cast materials are poured into forms, small air pockets develop. These 
pockets are virtually impossible to detect. Since these air pockets affect 
the integrity of the structure, they must be reduced or eliminated by 
compacting the material. 
One known method of compacting the material and eliminating air pockets 
involves the use of stirring devices. Such devices are commonly hand-held, 
and include an elongated shaft with a stirring tip. The tip is inserted 
into the material for agitation before the material has cured. In order to 
fully agitate the material, the stirring tip must come into close contact 
with the entire volume of the structure. As a result, using such devices 
is relatively time consuming, and labor intensive. 
There is accordingly a real and unsatisfied need in the art for an improved 
arched structure which eliminates the need for positioning rebar within 
the structure as a means for reinforcement, and which may be 
prefabricated, transported to the construction site, and set in place as a 
unitary body. There is also a need to provide a structure which may be 
constructed and compacted without using stirring devices as a means of 
reducing air pockets and other defects within the structure. 
SUMMARY OF THE INVENTION 
The present invention addresses the problems discussed above, and provides 
a significant advance in the art. More particularly, the monolithic 
structure hereof includes a load bearing axial web depending from an 
arched span, eliminating the need for positioning rebar within the 
structure. The structure may be fabricated, and transported to the 
construction site as a unitary body for placement. 
A prefabricated cast bridge broadly includes a unitary, monolithic 
structure having a pair of spaced haunches, a span, and a web depending 
from the span. The span extends between the haunches and presents opposed 
upper and lower surfaces. The web depends from the span lower surface and 
extends generally axially therealong between the haunches. The web 
provides support along the longitudinal axis of the structure. 
Each of the haunches defines a support-engaging underside. These undersides 
are configured for resting on a pair of support surfaces, and thus for 
supporting the structure on the support surfaces. The lower surface of the 
span extends upwardly from each of the haunches to present a maximum rise 
relative to the haunch undersides at a general midpoint of the span. 
A prestressed cable is positioned within the web as a reinforcement means 
for increasing the load bearing capacity of the structure. The cable is 
held in tension by opposed anchoring devices, such as end plates, attached 
at the ends of the cable. Use of such a cable eliminates the need for 
placement of rebar within the span. As prestressed cables are much easier 
to position relative to rebar, using such a cable significantly lowers the 
labor, and thus expense, of reinforcing bridges. 
Various other reinforcing elements may be used which are also relatively 
inexpensive. For example, a threaded bar may be inserted through the web, 
and fixed within the web by anchoring devices, such as end plates. Post 
tensioned cable may be used as well. 
In a preferred configuration, the structure includes a pair of parallel, 
axially extending webs depending from the span. Such a double "T" 
configuration allows the structure to be wide enough and strong enough to 
be used as a bridge, such as a golf cart bridge at a golf course. In an 
alternative configuration, the structure includes only one web. Such a 
single "T" configuration allows the structure to serve as a bridge for 
agricultural devices such as a center pivot sprinkler tower, and as a 
walkway bridge. 
As a result of its unitary construction, the structure may be fabricated 
away from the construction site, transported to the site, and placed for 
use. The integral haunches are configured for supporting the structure at 
its ends, and for simplifying the placement of the structure. 
In another application, the structure is used as a roof element for a 
building having concrete walls. When used as a roof element, the single 
"T" configuration of the haunches are placed atop opposed walls of the 
building so that the structure spans across the opposed walls. The 
haunches extend beyond the outer portion of the walls to define soffits. 
The structures are spaced apart, such as about 12'-15', and purlins are 
placed between the structures. The structures and purlins cooperably 
define an aesthetically pleasing arched roof. Alternatively, the 
structures are placed side by side. The double "T" configuration of the 
structure may also be used as a roof element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 1 and 2, a monolithic cast bridge constructed in 
accordance with the invention is illustrated. In broad terms, the bridge 
includes structure 12 having spaced haunches 14, 16 and span 18. Span 18 
extends between haunches 14, 16, and includes upper and lower surfaces 20, 
22. Webs 24, 26 depend from span lower surface 22. 
Haunches 14, 16 define support-engaging haunch undersides 28, 30, upper 
surfaces 32, 34, and end faces 36, 38. In addition, haunch 14 includes 
opposed side walls 40, 42, and haunch 16 includes opposed sidewalls 44, 
46. Upper surface 32 is sloped so that surface 32 and underside 28 
converge toward end face 36. Upper surface 34 is sloped so that surface 34 
and underside 30 converge toward end face 38. 
Haunches 14, 16 are flat and define a support level, shown at numeral 48. 
Haunches 14, 16 are thus configured for supporting structure 12 on a pair 
of opposed support surfaces (not shown). Haunches 14, 16 thus support 
structure 12 above the support level, at 48. 
Span lower surface 22 extends upwardly from each of the haunches 14, 16 to 
present a maximum rise relative to haunch undersides 28, 30 at midpoint 50 
of span 18. In the illustrated preferred embodiment, each of span upper 
and lower surfaces 20, 22 defines a profile which substantially 
corresponds to an arc segment a circle. 
Webs 24, 26 are substantially parallel with respect to each other, and 
extend axially along structure 12 between haunches 14, 16. Web 24 includes 
lower surface 52 and a pair of opposed, converging faces 54, 56. Web 26 
includes lower surface 58, and a pair of opposed converging faces 60, 62. 
Lower surfaces 52, 58 are substantially flat and correspond with haunch 
undersides 28, 30, and thus the support level, at 48. Lower surfaces 52, 
58 also substantially correspond to a secant line of the arc segment 
defined by the profile of span lower surface 22. 
Prestressed cables 64, 66 are positioned within respective webs 24, 26 as a 
reinforcement means for increasing the load bearing capacity of structure 
12. Cables 64, 66 are anchored at their respective ends by end plates (not 
shown). The end plates, which are positioned within structure 12, hold 
cables 64, 66 in tension. The end plates may alternatively be mounted 
outside structure 12, such as adjacent to end faces 36, 38. 
In a preferred form, structure 12 is used as a bridge, and is constructed 
of cast material, such as concrete. It will be appreciated that structure 
12 constructed of concrete has sufficient load bearing capacity to 
function as a bridge. Cables 64, 66 further increase the load bearing 
capacity of structure 12. 
Structure 12 is fabricated using a two piece form (not shown) having a top 
portion removably coupled with a bottom portion. When the top and bottom 
portions are coupled, the form includes walls which define substantially 
the same interior dimensions and shape as the exterior of structure 12. 
The form walls also define an upper opening through which the cast 
material is poured. 
When fabricating structure 12, cables 64, 66 are first positioned within 
the bottom portion. The top portion is then coupled with the bottom 
portion. Next, the cast material is poured in two layers. 
In the first layer, the material is poured into the form until the material 
reaches the intersection of midpoint 50 and span lower surface 22. Thus 
the first layer includes all of load bearing webs 24, 26. Once the first 
layer is poured, the material is agitated by vibrating devices (not shown) 
strategically mounted along the form. The vibrating devices act to compact 
the material and reduce the quantity and size of air pockets therein. 
Next, the second layer is poured. This layer includes the remaining volume 
of structure 12. It will be appreciated that the second layer does not 
include any of webs 24, 26, and thus does not support as great a load as 
the first layer. As a result, compaction of the second layer is not 
necessary. Therefore, less cast material is required, reducing the costs 
associated with constructing structure 12. 
Additionally, the relatively gentle arc of span 18 allows the form to be 
used without a top hinged cover for the opening. Such covers are difficult 
and time consuming to position. Therefore, by eliminating the need for the 
top hinged cover, the labor associated with fabricating arched structure 
12 is reduced. 
Once the cast material has cured, the top portion is de-coupled from the 
bottom portion, and structure 12 is removed. Hydraulic jacks (not shown) 
are provided at the bottom of the form for assisting in the removal of 
structure 12 from the form by separating the surfaces of structure from 
the form walls. Attachment devices (not shown), such as internally tapped 
sleeves, eyelets, or other devices, are positioned along span upper 
surface 20. A lifting device, such as a crane, is connected with the 
attachment devices so that once the jacks have separated structure 12 from 
the form walls, the crane is able to lift structure 12 out of the form. 
It will be appreciated that structure 12, fabricated in the above mentioned 
manner, advantageously may be fabricated away from the construction site, 
and later transported to the site as a unitary body. Structure 12 may be 
transported by any known means of transportation, such as by trailer, 
rail, etc. When transported by trailer, structure 12 is lifted from the 
trailer and placed on the support surfaces. 
Structure 12 is configured for placement in a spanning relationship with a 
gully, ditch, or other topographic feature generally characterized by an 
elongated depression and opposed banks. Structure 12 thus serves as a 
bridge over the depression. The support surfaces are configured for 
engaging undersides 28, 30, and are formed on each of the banks. For 
example, a poured concrete pad is fabricated on each of the banks to 
provide a support surface. The pad may be made of other cast material as 
well. Of course, it is also possible to level the banks and cover the 
support surfaces with gravel, or simply level the banks and compact the 
support surfaces. After the support surfaces have been prepared, structure 
12 is placed on them. 
In a preferred use, structure 12 is a golf cart bridge. It will be 
appreciated that structure 12 offers an aesthetically pleasing arched 
appearance which serves to enhance the attractive setting of a golf 
course. The combination of arched span 18 and sloped haunches upper 
surfaces 32, 34 allows structure 12 to readily shed water during inclement 
weather. 
Of course, structure 12 may serve a variety of other purposes as well, such 
as being a walkway bridge, or an agricultural bridge for center pivot 
sprinkler towers. Such towers include an elongated sprinkler line which is 
positioned within a field, and is configured to rotate about the center 
pivot for irrigation of the field. However, many fields include ditches 
and other depressions having steep banks which prevent passage of the 
sprinkler line. Structure 12 is then positioned in a spanning relationship 
with such a ditch, allowing the sprinkler line to pass over the ditch. 
Although the monolithic cast bridge has been described in accordance with 
the illustrated preferred embodiment, it is noted that variations and 
changes may be made, and alternatives employed herein without departing 
from the scope of the invention as set forth in the claims. It will also 
be understood that the use of the term "bridge" herein is meant to include 
all structures for bridging the gap between or spanning two support 
surfaces, such as bridges, trestles, walkways, roof elements, etc. 
Span upper and lower surfaces 20, 22 are illustrated which define profiles 
that substantially correspond to an arc segment a circle. Surfaces 20, 22 
may alternatively define various other profiles, which correspond to 
segments of polygonal shapes, and segments of other geometric shapes, such 
as a parabola, hyperbola, ellipse, etc. 
Prestressed cables 64, 66 have been shown, however, other reinforcement 
means for increasing the load bearing capacity of structure 12 may be 
used. As an example, threaded bar is positioned within webs 24, 26. Each 
bar is coupled at their respective ends with end plates. The end plates 
are configured to retain the bar in a tensioned state. After the bar has 
been positioned, the cast material is poured into the form. Post tensioned 
cable may, of course, also be used as a means of increasing the load 
bearing capacity of structure 12. 
In an alternative configuration, a single "T" configuration of structure 12 
includes a single web depending from span 18, and extending axially 
therealong between haunches 14, 16. The single "T" configuration, which is 
narrower than the illustrated double "T" configuration having webs 24, 26, 
reduces the relative material requirements, and thus the cost, of 
fabrication. The single "T" configuration may be used as a walkway bridge, 
and also as a sprinkler tower bridge. 
Structure 12 may also be used as a roof element for a building having 
concrete walls. In such a use, a plurality of structures 12 are positioned 
atop opposed walls. Haunches 14, 16 extend beyond the walls to define 
soffits. Structures 12 are positioned approximately 12-15' apart. Purlins 
are then placed on top of structures 12 to present an aesthetically 
pleasing arched roof. It will be appreciated that the combination of 
purlins and structures 12 may be easily sealed for weatherproofing. 
Structures 12 may alternatively be placed side-by-side and sealed for 
weatherproofing. Either the single "T" or double "T" configuration may be 
used as a roof element.