Bridge structure with inclined towers

A bridge structure for large water crossing with inclined towers as main substructure members. The superstructure is a combination of suspension cables and stay cables supported by inclined towers which transfers the bridge loads to the ground. The inclined towers are tied with horizontally cables posttensioned in a such way to introduce a horizontal force which combined with the vertical forces from the bridge gives axial forces for the inclined towers, improving its load capacity.

BACKGROUND OF THE INVENTION 
The present invention is generally related to a bridge structure with long 
spans over large water crossing. Known methods for constructing bridge 
structures over large water crossing have as their objective to reduce the 
number of the structure supports increasing the length of the span between 
two adjacent supports. There are two main methods for spanning large water 
ways. 
According to the first alternate method the bridge structure is supported 
by vertical cables, known as hangers or suspenders cables which in turn 
are suspended from longitudinal cables known as suspension cables bearing 
on vertical towers and anchored at their ends. The loads due to the 
superstructure and design traffic are transferred by the suspension cables 
to the vertical towers and to the end anchorages. The bridge structure is 
known as a suspension bridge structure where the main span is the distance 
between the towers and the side span is the distance between the tower and 
the anchorage system and there are two side spans. 
According to the second alternate method, the bridge structure is supported 
by inclined cables which in turn are anchored to or supported by the 
vertical towers, the system being known as a stay cable bridge structure. 
The loads due to the superstructure and design traffic loads are 
transferred by the inclined cables to the vertical towers. 
The disadvantage of the first method is that the length of the main span is 
limited to the strength of the suspension cables. When the length of the 
main span increases the load in the suspension cables and the height of 
the vertical towers increases. Another disadvantage is that during 
erection the bridge structure requires additional measures for its 
stability. 
The disadvantage of the second method is that the horizontal component of 
the force in the inclined cables becomes too big for large structures and 
can not be taken by the bridge superstructure. Also, the required height 
of the tower increases with the span length. 
SUMMARY OF THE INVENTION 
The present invention represents a bridge structure with large span to be 
used for water crossings. To achieve this purpose, the bridge structure is 
provided with abutments, suspension cables, inclined cables, and inclined 
towers tied with horizontal cables. 
It is an objective of this invention to develop a bridge structure with 
large opening for water crossing. 
Another objective of this invention is to use inclined towers, reducing the 
length of the main span for the same water opening. 
Another objective of this invention is to reduce the height of the towers. 
Another objective of this invention is to transfer the vertical loads due 
to the bridge structure to the inclined towers in a form of axial loads 
minimizing the bending moment in the inclined towers. 
Another objective of this invention is to increase the stability of the 
bridge structure during erection of the bridge. Another objective of this 
invention is to improve the response of the bridge structure to the 
dynamic loads acting on the bridge. Another objective of this invention is 
to reduce the weight of the bridge structure hence its cost.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the drawing shown in FIG. 1: 
Numeral 1 designates a bridge superstructure which can be made of steel, 
concrete or a combination of these two materials, numeral 2 designates 
inclined towers which can be made of concrete, steel or a combination of 
these two materials, 
Numeral 3 designates the foundation of the inclined towers made of 
concrete, 
Numeral 4 designates a suspension cable made of steel with a high strength, 
Numeral 5 designates vertical hangers made of steel and suspended to the 
suspension cables, numeral 4, at one one end and anchored to the bridge 
superstructure, numeral 1, at the other end, 
Numeral 6 designates inclined cables made of steel with a high strength 
either and anchored to the inclined towers, numeral 2, at one end and to 
the bridge structure, numeral 1, at the other end or anchored to the 
bridge superstructure, numeral 1, at both ends and supported by the 
inclined towers, numeral 2, at its median portion, 
Numeral 7 designates horizontal cables made of steel with a high strength, 
anchored and stretched against the inclined towers, numeral 2, 
Numeral 8 designates abutments of the bridge structure provided with an 
anchorage system for the suspension cable, numeral 4. 
Referring to the drawing shown in FIG. 2, the vertical loads from the 
bridge structure, numeral 1, are transferred to the suspension cables, 
numeral 4, and the inclined cables, numeral 6. The loads to the suspension 
cables are transferred through the vertical hangers, numeral 5, in the 
central zone of the main span and in the zone adjacent to the abutments, 
numeral 8. The loads from the suspension cables are transferred in part to 
the inclined towers, numeral 2, and in part to the anchorage system of the 
abutment, numeral 8. The loads from the inclined cables, numeral 6, are 
transferred to the inclined towers, numeral 2. To increase the load 
capacity of the inclined towers, numeral 2, minimizing in the same time 
the bending moment in the inclined towers, numeral 2, the horizontal 
cables, numeral 7, are stretched against the inclined towers, numeral 2. 
The forces from the suspension cables, numeral 4, and inclined cables, 
numeral 6, combined with the prestressed forces from the horizontal 
cables, numeral 7, gives a resulting force having the direction of the 
inclined towers, numeral 2. Referring to the drawing shown in FIG. 3, the 
vertical loads from the bridge structure, numeral 1, are transferred to 
the suspension cables, numeral 4, and the inclined cables, numeral 6. The 
loads to the suspension cables are transferred through the vertical 
hangers numeral 5, in the central zone of the main span and in the zone 
adjacent to the abutments, numeral 8. The loads from the suspension cables 
are transferred in part to the vertical towers, numeral 9, and in part to 
the anchorage system of the abutment, numeral 8. The loads from the 
inclined cables, numeral 6, are transferred to the inclined towers, 
numeral 2. To increase the load capacity of the inclined towers, numeral 
2, minimizing in the same time the bending moment in the inclined towers, 
numeral 2, the horizontal cables, numeral 7, are stretched against the 
inclined towers, numeral 2. The forces from the inclined cables and 
suspension cables, numeral 4, numeral 6, combined with the prestressed 
forces from the horizontal cables, numeral 7, gives a resulting force 
having the direction of the inclined towers, numeral 2. 
Referring to the drawing shown if FIG. 4, the vertical hangers, numeral 5, 
are anchored to the bridge superstructure at one end, numeral 1, and 
attached to the suspension cable, numeral 4, at the other end. 
Referring to the drawing shown in FIG. 5, the inclined cables are either 
anchored to or supported by the bridge superstructure, numeral 1, at one 
end and anchored to the inclined tower at the other end.