Bridges are one of the fundamental aspects of a nation’s infrastructure, playing a vital role in transporting raw materials and people from one point to the other.
When it comes to beam bridges (also identified as girder bridges), some people bash their architecture, while others admire their minimalism. Engineers scorn the beam bridge’s appearance and development and support its continued existence.
In this article, you will learn about the benefits and drawbacks of Beam Bridge.
Table of Contents
What is Beam Bridge?
The Second Stringer Bridge is another name for the Beam Bridge. This type of beam has a relatively simple structural engineering.
This basic beam bridge type is a longitudinal beam supported at each end by piers or abutments. In this bridge design, the load of the horizontal beam pushes straight down on the pillars or abutment.
Simple beam bridges were built in the early stages of the bridge out of wooden boards or stone pavers.
Bridges in modern infrastructure are typically constructed of steel, reinforced concrete, or a blend of the two components. Construction materials such as solid reinforced, precast concrete, or post-tensioned concrete, among others, can also be used.
An example of a continuous-span beam bridge is the Lake Pontchartrain Causeway of Louisiana which is almost 24 miles long. The bridge completed in 1956 has a pair of two-lane sections that run parallel to each other.
Pros of Beam Bridge
In some cases, the beam bridge has more benefits than other bridge styles. The following are the primary benefits of beam bridges:
1. Simple To Assemble
Beam bridges are simple to construct because they have little architectural specifics on both ends. They are constructed by placing two beams on the upper end of a pier and bolstering them as needed.
They are also endorsed by being driven into the land surface or attached to an existing structure like a bridge or support beam.
2. Cost Effective
For some, the minimalism of a beam bridge is a disadvantage; for others, it saves money on the building works of critical infrastructure, cheaper to build than most other types of bridges.
As a result, they are an excellent choice for short spans and low-traffic areas such as country roads or rural towns. The cost savings are owed to the simplicity of its design and raw materials requirements rather than imported steel or concrete.
3. Quick Set-up
Compared with other types of bridges, a beam bridge generally takes the least time to build. The operation is much more convenient on good roads where transportation is not a problem.
Steel and reinforced concrete are other factors contributing to the construction process’s speed.
Heavy transportation needs may have timeframes of up to six months. If you want something more straightforward, you can build a bridge over a stream in under a day using just a single tree.
4. Multiple Material
Steel and reinforced concrete are typically used in bridges that use beam architecture because they are both relatively inexpensive materials. Both on-site fabrications of some bridge components and shipping of ready-made parts to the site of construction are options.
If the weight of the stone slabs won’t damage your support pillars, you can build a bridge like this. In naturalistic environments, wooden bridges employ this design to lessen the labor required to transport materials to the site.
You can use any material to construct this bridge, but remember to make it sturdy and robust enough to withstand anticipated traffic weight.
5. Versatile
Modern modifications can enhance some beam bridges’ functionality, but they all function adequately in almost any setting.
The majority of railroads and highways use this type of bridge. In highways, it can rapidly and efficiently provide sufficient support while simultaneously allowing space for traffic to flow from underneath.
This bridge design has a history of success on everything from hiking trails to interstates. The beam bridge design works well in various settings, including neighborhood parks, hiking trails, and private residences.
6. Less Environmental Impact
Because standard beam bridges don’t need to be built on cleared land, they have little impact on the local biodiversity.
Some other constructions, like piers, might disturb underground animal habitats or completely block waterways. This straightforward design could reduce traffic disturbance for animals using the new road.
Cons of Beam Bridge
Erecting a beam bridge has some drawbacks, just like any other bridge design, depending on the requirements of your project.
1. Drooping And Sagging
Due to the loads on the bridge creating a downward pulling tensile force, beam bridges frequently droop and sag significantly. This impact intensifies as more weight transfer to the load on the bridge.
Bridge beams will likely slump between the piers as the downward force is exerted on the bridge’s surface.
The forces pushing up at the pier supports also influence the drooping effect. When the bridge span or load is expanded, the slumping tendency increases. In addition, over time, a bridge becomes more susceptible to collapsing if regular maintenance is not performed.
2. Span Limitation
Beam bridges are still limited by their length, even though they can span great distances. The optimum span of a beam bridge is not predetermined and can change depending on the materials employed. The material’s thickness, mass, and peak span will all have an impact.
The height of the supports may also have an impact, as they may cause the center of gravity to move outward if they are too tall to accommodate the weight of the equipment or traffic congestion.
3. Limited Deck Span
The span will naturally be constrained in size because the deck is fully supported in this category of bridge design. Because of this, most traffic-carrying beam bridges only have space for two lanes of traffic.
If four lanes of traffic must be supported, two bridges will typically be constructed rather than one. This procedure will present unique and complex infrastructure concerns, but it might still be less expensive than building a more extensive, heavy-duty bridge.
4. High Wear And Tear
Beam bridges can experience a lot of deterioration over the course of their lifetime. Beam bridges typically last 50 years or less on average. Even if the bridge is made of reinforced concrete and steel, a span that sees a lot of traffic may only last 25 years on average.
Poorly maintained bridges typically deteriorate more quickly, shortening their lifespan. Regular maintenance enhances the beam bridge’s lifespan.
5. Weakening issues with aging
Beam bridges deteriorate with age, which could pose a problem if one of the beams is compromised. An old beam bridge may crumble over a new one treated with surface coatings of varnish and sealant.
The outcome is structural destruction to the joints that keep the pieces together and fissures forming in other parts of the framework, such as at concrete abutments underneath the supports.
The more degradation there is, the greater the risk of using that bridge, so many individuals will choose not to navigate through it because their well-being is jeopardized.
6. Not Aesthetically Pleasing
Those who relish seeing new and fascinating structures are not always thankful for what the beam bridge offers. The beam’s goal is to complete a specific task successfully, not beautifully!
There are no critical aesthetic components of building works in this bridge artwork design that is required to improve its visual effect. The conventional beam bridge resembles a table.
The deck is on top, the supports are below, and the piers work to support the load. Many people consider them to be the dullest and bland bridge designs.
Although simplicity and cost-effective construction are advantages, they are not always aesthetically pleasing. This design is not architecturally interesting because it looks like any other road.
Summary (pros and cons of beam bridge)
| Pros |
|---|
| Simple To Assemble |
| Cost Effective |
| Quick Set-up |
| Multiple Material |
| Versatile |
| Less Environmental Impact |
| Cons |
|---|
| Drooping And Sagging |
| Span Limitation |
| Limited Deck Span |
| High Wear And Tear |
| Weakening issues with aging |
| Not Aesthetically Pleasing |
Beam bridges have evolved a great deal in terms of design alternatives over the years, but the fundamental elements of this principle have not changed.
Despite their downsides, beam bridges are frequently chosen for projects where the system’s dynamics are restricted due to cost issues. A better design option is included when seismic constraints limit a structure’s ability to withstand ground shaking.
These beam bridge advantages and disadvantages show that this inexpensive and simple bridge can be feasible for areas with basic traffic arterials or impediments to navigate. However, due to design constraints, it will not be the cornerstone of a significant network.
The technological aspect of construction has not just been successful for bridges. Dams are another highly utilized construction upliftment. Check dams’ pros and cons and whether they are to hold water or more.
(Last Updated on November 10, 2022)
