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Questions tagged [bridges]

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From the viewpoint of a civil engineer, what was the purpose of this bridge?

I have been searching for historical structures in the province of Van, Turkey, by examining the publicly available satellite imagery like Bing Maps. There is a historic bridge near Kaçit, Çatak. Its ...
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0answers
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Is there a particular reason the Moléson funicular is built as a giant bridge?

So I live in Switzerland and there is lots of funiculars in my country. Most of those were built between 1890 and 1930, and for most of those the line is on the ground most of the time, there is ...
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1answer
2k views

Why was a coil chosen over a straight for this overbridge?

I saw this meme on Facebook showing a coiled railway overbridge and an alternative plan. I replied that straightening that overbridge will force it to start at the other side of the road, and you need ...
5
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1answer
51 views

Bridge terminology - railing-like parapet

If a bridge has a parapet that is nota fully solid block and resembles railings with posts, as the following image What is this type of parapet called? What are the top, bottom, post, and hole of the ...
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1answer
2k views

What is the deepest bridge pier in the world?

I have tried searching for this, but I am unable to find a good answer. There is all sorts of stats about the longest bridge in the world, the highest, the longest span, but I think one of the most ...
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2answers
57 views

Light frame at tunnels and bridges

I actually don't know on which SE to ask this. Since there are quite often too low bridges/tunnels, or too high trucks or trailers, why isn't there 100m ahead of those bridges, some light frames (...
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1answer
65 views

Did this artist take some licence with the Royal Albert Bridge - or has its appearance changed?

Here is how this artist rendered Brunel's Saltash Bridge: Here is how it appears today. Did the appearance change, or was some artistic licence taken in the painting? My question is: Did this ...
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1answer
108 views

Is it possible to apply different boundary conditions on the same model for different load cases?

Instead of creating multiple bridge models with different boundary conditions for differential settlement, and combining the forces output manually in Excel, is it possible to specify different ...
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3answers
52 views

Is there a specific name for diagonally braced truss members like those on the Queensboro Bridge?

I am wondering about this specific type of truss in particular, any links to further source information and images regarding this particular geometry would be much appreciated.
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1answer
776 views

How and WHY does the tension in an arch dam or bridge change as the degree of curvature and radius of curvature change?

Arch bridges operate according to the following (I am assuming arch dams are the same): Tensional force in arch bridges are virtually negligible. The natural curve of the arch and its ability to ...
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1answer
253 views

When should anti-bursting reinforcement be used?

When designing a bearing plinth, should anti-bursting reinforcement be provided? Under BS 5400, it was only mentioned in the section for end block anchorages of tendons. How should the code be ...
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1answer
89 views

What is the preferred composition for modern concrete bridges?

It seems that most bridge are composed of concrete, e.g in Latvia However, concrete encompases a lot of bridge types: Most concretes used are lime-based concretes such as Portland cement ...
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0answers
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What is the best way to model a beam and slab bridge? [closed]

I notice bridges designed by bridge engineers in my company invariably uses two models. One model for seismic load case and another for other load cases. I was told that some bridge elements, such as ...
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0answers
61 views

How to obtain relative movement and rotation of bridge bearings?

In structural analysis of a bridge using whatever software, such as MIDAS or SAP 2000, it is easy to obtain the deformation of individual nodes. However, for bearings, what we want is the relative ...
5
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1answer
343 views

What kind of simplified structural system would a Leonardo bridge use?

What kind of simplified structural system would a Leonardo bridge use? I've tried approximating the system to a simple statically determined beam (see below) but our calculations did not give any ...
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1answer
2k views

Determining the difference between US Bailey Bridge, UK Bailey Bridge, Mabey Compact 100 and Acrow 300

Background The Bailey Bridge panel bridge system has been around since WWII. It has been credited as being one of the top 3 technological advancements that allowed the allies to win the war. After ...
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3answers
2k views

Why would a bearing plate that further concentrates load onto small surface be used?

Here's a photo of a bearing plate where a bridge reinforced concrete beam meets the earthfill The bridge span is about 20 meters long and consists of two reinforced concrete beams each resting on two ...
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3answers
360 views

Why would a column expand before accepting load through a narrow thunk?

Here's a column top which holds a driveway overbridge. The column is a reinforced concrete cylinder with an inverse truncated cone on top - so it expands sideways at its top. The column top holds ...
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3answers
3k views

How can large bridges be made resistant to earthquakes?

How can large bridges, with spans on the order of 1 km, be made resistant to earthquakes? I'm no expert on quakes, but there are at least two kinds of shaking: lateral and vertical. The vertical ...
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2answers
1k views

Most efficient way to build a toothpick bridge

In my stem class we are going to have a competition where we have to build a toothpick bridge that can support as must weight as possible, while using only toothpicks and glue. These are the rules: ...
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0answers
815 views

Calculating Tie Rod Force in Bridge Abutment System

I have a fairly tall bridge abutment (about 12 ft.). Vertical loads are supported by bearing piles and lateral loads from the retained soil are supported by a sheet pile wall. However, when I ...
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0answers
98 views

What is the theory behind Eurocode 1 - Part 2: Traffic loads on bridges?

I'm interested in some theory Eurocode 1: Actions on structures - Part 2: Traffic loads on bridges. How were the limits chosen (e.g. maximum deck acceleration = 3.50 m/s2)? Why is the lower limit of $...
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3answers
4k views

Why are concrete bridges more prevalent than steel bridges in the United States?

According to the United States 2014 National Bridge Inventory the number of concrete bridges far outstrips the number of steel bridges. Reinforced Concrete: 253,336 Prestressed Concrete: 148,333 ...
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2answers
460 views

Strand layout in prestressed concrete girders: is a partially filled bottom row acceptable/advisable?

My state (USA - Nebraska) uses "NU" type prestressed girders (though the question should equally apply to all geometric variants of prestressed concrete "I" girders). There are 6 "rows" available for ...
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1answer
78 views

Derivation of the AASHTO formula of interior girder moment

The interior girder moment formula for one lane loaded for the AASHTO LRFD method is: $$\begin{align} mg^{SI}_{moment}&=\left(1.75+\frac{S}{3.6}\right)\left(\frac{1}{L}\right)^{0.35}\left(\frac{1}...
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2answers
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How are loads transferred to bearing piles in a wall pier?

I've been working on the design of a reinforced concrete wall pier for a three-span bridge. I roughed out the design based on a number of example plan sets and now that I'm taking a crack at the ...
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3answers
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Why design a cable stayed bridge with pylons inclined towards the obstacle being spanned?

Here's a YouTube video with a concept of a bridge which is currently under construction in Saint Petersburg. The bridge largest span is cable stayed and designed to drive traffic over the Neva river ...
5
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1answer
119 views

Why is this box girder made of lattice on one side only?

Here's a zoomed piece of this image from Wikipedia That's a close-up of a tower holding a railroad bridge. A and B are two of the four columns in the tower's corners. I assume that they are placed ...
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1answer
1k views

How should a bridge deck closure pour be positioned?

The Question: Where should a closure pour be located relative to centerline of girder and how should the closure pour width be detailed/designed? And now, a little background: When designing a ...
8
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1answer
227 views

Simple Finite Element Modeling of Wall Piers

I'm working on analysis of a bridge wall-pier for dead and live loads. When modeling the pier in finite element software (LARSA), I'm running up against several modeling questions: Is it valid to ...
9
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1answer
2k views

What is the effect of end diaphragms on prestressed girder forces/deflections?

I'm encasing the abutment ends of prestressed concrete bridge girders in concrete before the deck pour. (For lateral stability and to prevent the soil from spilling through.) Discussion of ...
10
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1answer
344 views

Detailing Fixed Cotton Duck Bridge Bearings

I'm looking for a justification for the use of cotton duck bearing pads without a sole plate. I'm specifically considering their use with precast I-girders. Say I have a two span bridge, simply ...
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2answers
312 views

Should long-term prestressed girder camber always be upward?

When considering long-term prestressed girder camber (for a bridge), what are the implications (if any) of long-term downward deflection on girder performance? Should prestressing be designed to ...
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1answer
815 views

What is a Tibetan Style Bridge?

The Tibetan Bridge Type I have a question regarding the bridge type called "Tibetan Bridge". Recently close by my home town a new tourist attraction was built, the Highline 179 bridge. It was ...
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2answers
282 views

How do protective coatings affect the lifetime of bridges?

I'm trying to understand the importance of protective coatings on steel structures like the Golden Gate Bridge. For example, if we stopped maintenance on the Golden Gate Bridge today and left it ...
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2answers
2k views

Why are earthfills fully covered in concrete where they join bridges?

Here's how a typical earthfill carrying a roadway joins a typical bridge Parts of the earthfill slopes are greenish - that's grass - and parts are whitish - that's concrete. The earthfill slope is ...
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1answer
2k views

Can nuts safely be removed from bolts where the threads have been intentionally damaged?

On old bridge plans I have occasionally seen a note to "burr threads after installation". This was done to keep the nuts of bolted connection from loosening all the way and falling off of the bolt. ...
4
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1answer
147 views

What is a good sensing element to monitor corrosion in a bridge structural health monitoring system?

The question relating to measuring structural integrity of bridges brought awareness to six categories of structural health monitoring of bridges. They are Bridge foundations Concrete ...
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3answers
952 views

Can the structural integrity of bridges be measured in real-time for safety?

As a follow up to this question, I wonder if structural integrity monitoring information can be provided real-time and to a sufficient degree that safety decisions can realistically be made from the ...
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4answers
1k views

How should the public raise questions about unsafe structures in the United States?

In a program on NPR that I was listening to, there was a bit about a bridge that from the description sounded to a layman as unsound and is still in use. The program described it as an old wooden ...
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2answers
640 views

Building a steel footbridge over a railway line and its catenary

I'm doing an investigation about building a bridge over a railway line and its catenary system. I'm mainly interested in the electromagnetic environment on the bridge as it is affected by the presence ...
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3answers
3k views

Does a roadway bridge experience more load when vehicles are parked or when they are moving?

Bridges are designed for the loads that come from the vehicles that are expected to cross them. This includes the weight the vehicle and any dynamic loads that may be introduced from movement of the ...
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2answers
178 views

How accurately are moveable span bridges balanced?

Movable span bridges (bascule and lift) typically employ a counterweight to help reduce the amount of energy and size of motor required to move the span. Due to variations in the the construction of ...
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1answer
1k views

How many units of HB are used for steel bridges?

Bridges in the UK can be assessed (to standard BA34/90) using an HB vehicle (to standard BD37/01). The HB vehicle is 16 wheel loads, each of 2.5kN times "units". For concrete bridges the number of ...
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4answers
4k views

What makes suspension bridges unsuitable for railways?

I recall reading in an old issue of Model Railroader an article about railroad bridges. In it, the author mentioned that you shouldn't have a model suspension bridge for a railroad track on your ...
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4answers
2k views

Derivation for bridge natural frequency estimate in Eurocodes

The Eurocodes gives the following equation for estimating a "simply supported bridge subject to bending only"*: $$n_0 = \frac{17.75}{\sqrt{\delta_0}}$$ Where $n_0$ is the natural frequency in hertz ...
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3answers
530 views

Are pontoon bridges being considered to extend bridge span?

Pontoon bridges differ from traditional bridges in that they are supported not by structures anchored to the floor of the body being spanned but by floating pontoons that are connected by a more rigid ...
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1answer
298 views

Additional jacking force to overcome stiction/dry friction

It is common to lift bridges to replace bearings, etc. In an ideal world the lifting capacity required of the jacks would be the self-weight of the bridge divided by the number of jacks (+ allowances ...