Bridge types pdf

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Documents Similar To Bridges-Lecture1. Tied arch bridges — are similar in design to arch bridges, but they transfer the weight of the bridge and traffic load to the top chord that is connected to the bottom cords in bridge foundation.

The bottom tying cord can be reinforced decking itself or a separate deck-independent structure that interfaces with tie-rods.

They are often called bowstring arches or bowstring bridges and can be created in several variations, including shouldered tied-arch, multi-span discrete tied-arches, multi-span continuous tied-arches, single tied-arch per span and others. However, there is a precise differentiation between tied arch bridges and bowstring arch bridges — the latter use diagonally shaped members who create a structure that transfer forces similar to in truss bridges.

Tied arch bridges can be visually very stunning, but they bring with them costly maintenance and repair. Suspension bridges — utilize spreading ropes or cables from the vertical suspenders to hold the weight of bridge deck and traffic. Able to suspend decking over large spans, this type of bridge is today very popular all around the world. Because only abutments and piers one or more are fixed to the ground, the majority of the bridge structure can be very flexible and can often dramatically respond to the forces of wind, earthquake or even vibration of on-foot or vehicle traffic.

Cable-stayed bridges — use deck cables that are directly connected to one or more vertical columns called towers or pylons that can be erected near abutments or in the middle of the span of the bridge structure. This is a very different type of cable-driven suspension than in suspension bridges, where decking is held with vertical suspenders that go up to main support cable. Originally constructed and popularized in the 16th century , today cable-stayed bridges are a popular design that is often used for spanning medium to long distances that are longer than those of cantilever bridges but shorter than the longest suspension bridges.

The most common build materials are steel or concrete pylons, post-tensioned concrete box girders and steel rope. These bridges can support almost every type of decking only not including heavy rail and are used extensively all around the world in several construction variations.

The famous Brooklyn Bridge is a suspension bridge, but it also has elements of cable-stayed design. The vast majority of all bridges in the world are fixed in place , without any moving parts that forces them to remain in place until they are demolished or fall due to unforeseen stress or disrepair.

However, some spaces are in need of multi-purpose bridges which can either have movable parts or can be completely moved from one location to another. Even though these bridges are rare, they serve an important function that makes them highly desirable. They are designed to stay where they are made to the time they are deemed unusable due to their age, disrepair or are demolished.

Use of certain materials or certain construction techniques can instantly force bridge to be forever fixed. This is most obvious with bridges made out of construction masonry, suspension and cable-stayed bridges where a large section of decking surface is suspended in the air by the complicated network of cables and other material. Small and elevated bridges like Bridge of Sighs , ancient stone aqueducts of Rome such as Pont du Gard , large medieval multi-arched Charles Bridge , and magnificent Golden Gate Bridge are all examples of bridges that are fixed.

Temporary bridges — Temporary bridges are made from basic modular components that can be moved by medium or light machinery. They are usually used in military engineering or in circumstances when fixed bridges are repaired, and can be so modular that they can be extended to span larger distances or even reinforced to support heightened loads.

The vast majority of temporary bridges are not intended to be used for prolonged periods of time on single locations, although in some cases they may become a permanent part of the road network due to various factors.

The simples and cheapest temporary bridges are crane-fitted decking made out of construction wood that can facilitate passenger passage across small spans such as ditches. As the spans go longer and loads are heightened, prefabricated bridges made out of steel and iron have to be used. The most capable temporary bridges can span even distances of m using reinforced truss structure that can facilitate even heavy loads.

As such, there may be less rollers around the rim as they only serve to guide the truss when moving, and are not load-bearing. Some swing bridges are designed such that the swing pier is not in the center of the bridge, with one arm offering a swing span over the waterway, and another shorter arm having a counterweight to keep the bridge balanced. These are known as bobtail swing bridges. A movable bridge type, vertical lift bridges rise directly up to provide clearance for boats.

The two most common forms utilize tall towers that house counterweights that move to keep the span in balance as it is lifted by motors. These types of vertical lift bridges are categorized based on where these motors are located.

The above diagram, created by famous vertical lift bridge engineer J. Waddell shows the many parts of a vertical lift bridge.

Many vertical lift bridges house the motors on the lift span itself, with a series of cables leading off of the span and onto the tower to move the counterweight and lifting uphaul cables.

Other vertical lift bridges house the motors on the towers, typically at the top next to the sheaves. These are known as Tower Drive Vertical Lift Bridges, and they tend to be newer vertical lift bridges. Historic Bridge Foundation. Bridge Types Table of Contents. Through Bridge. Pony Bridge. Deck Bridge. Muti-Beam bridges, commonly called stringer bridges, feature more than two often 6 or more parallel beams upon which the deck rests. Concrete T-Beam.

Slab Bridge Concrete, Timber. We have revised and added some terms to reflect modern usage. Pratt Truss. Pratt Half-Hip. Whipple Double-Intersection Pratt. Pennsylvania Petit. Warren With Verticals. Polygonal Warren. Double-Intersection Warren. Quadruple-Intersection Warren. Bowstring Parabolic. Pinned Connection Diagram. Riveted Connection Diagram. Howe Single. Howe Usual. Howe Western.

Multiple Kingpost. Multiple Kingpost With Counters. Smith Type 2 and 3. Smith Type 1. Suspension Inverted Bowstring. Town Lattice. Open Spandrel. Parts of an Open Spandrel Arch Bridge. When the first cantilever bridge was designed it was seen as a major engineering breakthrough. The bridge works by using cantilevers which may be simple beams or trusses.

They are made from pre-stressed concrete or structural steel when used to accommodate traffic. When you consider that the horizontal beams making up the cantilever arm are only supported from one side it does begin to sound a little dangerous. The bridge load is supported through diagonal bracing with horizontal beams as opposed to typical vertical bracing.

Extremely safe and very secure, the design of cantilever bridges is one which still lives on today. There are many different types of arch bridge but they all have central elements in common.

Each bridge has abutments, which are used to support the curved arch structure under the bridge. The most common type of arch bridge is a viaduct, a long bridge made up of many arches. The lateral pressure created by the arch span is transferred into the supporting abutments.

It is therefore essential that these parts of the bridge remain solid, intact and well founded. You will see many arch bridges with decorative brickwork which is an integral part of the design. Simple yet so very effective an arch bridge can carry everything from pedestrians to heavy rail. The tied arch bridge is a fascinating design which incorporates an arch structure usually metal supported by vertical ties between the arch and the deck.

The tips of the arch structure are connected by a bottom chord. This acts in a similar fashion to the string of a bow. The downward pressure from the arch structure to the deck of the bridge is translated into tension by the vertical ties.

Many people assume that the abutments ensure that the tied arch bridge and arch structure stay in place. The best example of this is a bowstring which absorbs pressure, keeping both sides of the bow in contact, until it eventually flattens out.

The structure of a stereotypical suspension bridge looks very simple but the design is extremely effective. The deck of the suspension bridge is the load-bearing element of the structure. This is held in place by vertical suspenders which support the cables. The suspension cables extend out beyond each side of the bridge and are anchored firmly into the ground.

It will depend upon the size of the bridge but a number of towers will be installed to hold up the suspension cables. Any load applied to the bridge is transformed into tension across the suspension cables which are the integral part of the structure. Cables are connected from the pylons to the deck below.

Either directly from the top of the tower or at different points of the column. When connected at different points of the column this creates a fan like pattern. This is the feature many people associate with cable stayed bridges. This type of structure tends to be used for distances greater than those achieved with a cantilever bridge design but less than a suspension bridge.