Evercross Bridge
CNAS certificate Steel Cable Suspension Bridge ODM Steel Frame Bridge
Description:
Steel Cable Suspension Bridge is a flexible suspension combination system composed of a main cable
and a stiffened beam has the stress characteristics of both cable and beam.
It consists of bridge tower, main cable,
sling, stiffening beam, anchor, saddle and other main parts.
At present, most of the bridges with a span
greater than 1000m are suspension bridge structures.
Load characteristics: the load is transmitted from the sling to the cable, and then the
cable is transmitted to the anchor, to the pier and to the tower.
Under the external load, the main cable and
stiffened beam bear the same force.
The main cable is the main load-bearing
component, which deforms under load.
It directly affects the internal force and
deformation of the bridge.
The main cable is the main load-bearing
component in the structural system, which is mainly strained.
The bridge tower is the main load-bearing
component of suspension bridge to resist vertical load.
The stiffening beam is a secondary
structure of suspension bridge to ensure vehicle running and provide structural
stiffness, and it mainly bears bending internal force.
The sling is a force transmission component
that transmits the self-weight and external load of the stiffened beam to the
main cable, and is the link connecting the stiffened beam and the main cable.
An anchor is a structure that anchors the
main cable, which transmits the tension in the main cable to the foundation.
Main cable: The load is borne by the clamps
and boom, and it is passed directly to the top of the tower.
The main cable is divided into two types:
wire rope main cable and parallel wire bundle main cable.
1.Wire rope main cable: wire rope main
cable is twisted into strands by wire, and then twisted into rope by strands.
Generally, it adopts 7 strands and used for small span suspension bridges.
2.Parallel wire bundle main cable.
Prefabricated parallel steel wire strand
method (PPWS method): the use of parallel steel wire to speed up the
construction progress of the main cable, the section shape is divided into
pointed and flat top shape.
Bridge tower:
1. Bridge to form
According to the mechanical properties, it
can be divided into three structural forms: rigid tower, flexible tower and
rocking column tower.
A rigid tower refers to a bridge tower with
relatively small horizontal displacement at the top. The flexible tower. It
refers to the bridge tower with relatively large horizontal displacement at the
top. Rocking column tower, it is only used for suspension bridges with small
span, and the lower end is hinged single-column structure.
2. Cross bridge form
The bridge tower of transverse bridge
adopts three forms: truss type, rigid frame type and mixed type structure.
Main parameters involved:
The main parameters that affect the design
of bridge tower are: material parameters, environmental parameters and
structural size parameters.
Stiffening beam:
The types of stiffened beams mainly include
steel truss beams, steel box beams, concrete beams, steel-mixed composite beams
and other structural forms, as shown in the figure:
Sling:
(1) The material of the sling:
It can be made of steel wire rope, parallel
steel wire bundle or steel strand.
(2) Connection mode with cable clamp
Straddle type, pin type
(3) Vertical sling and diagonal sling
Traditional slings are vertical, starting
with the Severn Bridge in the United Kingdom.
Anchorage:
The anchorage of ground anchored suspension
bridge is divided into two structural forms: gravity anchorage and tunnel
anchorage, as shown in the figure: Gravity anchorage is composed of anchor
body, bollard, anchor chamber and foundation. Tunnel anchorage is composed of
anchor plug body, loose saddle support pier and anchor chamber.
Compared with gravity anchorage, tunnel
anchorage has much less concrete consumption and more significant economic
performance. In terms of applicability only, gravity anchorage is suitable for
almost all occasions. From the economic point of view, the possibility of
building tunnel anchors should be considered first. Only when the construction
conditions are considered comprehensively and the comprehensive technical and
economic comparison shows that tunnel anchors are obviously unsuitable, the
gravity anchors are chosen to be built.
Saddle:
The saddle sits between the main cable and
the top of the tower. The saddle is an important member that supports the main
cable and gives the main cable a turning angle here. Through it, the pull force
in the main cable can be evenly transmitted to the top of the tower and the
anchor in the form of vertical force and unbalanced horizontal force.
The saddle is divided into the main rope
saddle at the top of the tower and the loose rope saddle at the anchor.
Classification of steel cable suspension
bridges:
1.According to the number of suspension
span are divided into: single-span suspension
bridge, three-span suspension bridge, four-span suspension bridge, five-span
suspension bridge.
2.According to the main cable anchoring form are divided into:
ground anchor and
self-anchoring.
Ground anchorage: The tension of the main
cable is transferred to the foundation by the gravity anchorage or tunnel
anchorage at the end of the bridge.
Self-anchoring: The main cable tension is
transmitted directly to its stiffening beam.
Steel cable suspension bridge construction method:
The construction process of suspension
bridge is: anchor foundation construction, anchor construction, bridge tower
foundation construction, bridge tower construction, main cable construction,
stiffened beam construction, bridge deck construction, etc.
Protection design of Steel Cable Suspension Bridge
(1) Concrete structure
Concrete structure protection design mainly
adopts the following measures:
- Improve the thickness of concrete protective layer.
- Adopting high performance concrete, with durability.
- The sound concrete coating or sealing layer has the
characteristics of preventing the contact between the corrosive medium and
the concrete, thus extending the life of concrete and reinforced concrete.
- Improve the steel bar material and steel bar coating.
- Add reinforcement corrosion inhibitor (rust inhibitor) to
concrete.
- The concrete structure uses cathodic protection (protection)
system.
(2) Steel structure
The protection design of suspension bridge
steel structure mainly adopts the following measures:
- Paint coating.
- Metal zinc, aluminum or their alloys are thermally sprayed on
the surface of steel structures and then coated with high-performance
fluorocarbon resin topcoat to form a high-efficiency protection system.
- Weathering steel is used in steel structure.
- Improve the environment of steel structure members.
Advantages of Steel cable suspension bridge:
steel cable suspension bridge has
become more and more the preferred type of bridge with large span (over 1000m)
because of its large span capacity, good seismic performance and light
appearance.
Long-Span Capabilities: Steel cable
suspension bridges can span long distances without the need for intermediate
supports. This allows for uninterrupted transportation over obstacles such as
wide rivers, deep valleys, or expansive bodies of water. The long-span
capability of suspension bridges reduces the need for extensive piers or
support structures, minimizing environmental impact and construction costs.
Aesthetics and Iconic Status: Steel cable
suspension bridges are renowned for their elegant and visually striking
appearance. The graceful curves of the cables and the slender towers contribute
to their aesthetic appeal, making them iconic landmarks in many cities.
Suspension bridges can become architectural symbols and tourist attractions,
enhancing the beauty and identity of a location.
Application of steel cable suspension bridge:
Highway Bridges: Steel cable suspension
bridges are frequently used to span large bodies of water or deep valleys where
conventional bridge designs are not feasible. They provide efficient and
cost-effective solutions for highway crossings, allowing for uninterrupted
traffic flow over significant distances.
Pedestrian Bridges: Steel cable suspension
bridges are popular choices for pedestrian and cyclist crossings, especially in
scenic locations or urban environments. They offer safe and visually appealing
pathways, enhancing connectivity and accessibility for pedestrians and
non-motorized transportation.
Valley Crossings