Tag Archive for: steel bridge design

The Lifespan of Structurally Deficient Bridges in America

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Have you ever driven over a bridge and wondered how old it was? In the United States alone there are more than 617,000 bridges, 12% of which are aged 80 years or older. But were all those bridges created at the same time or with the same method? What exactly is the typical lifespan of a bridge? And how many bridges are considered structurally deficient?

Contributing Elements to a Bridge’s Lifespan

Nowadays, bridges have become a natural part of everyday life. Your daily commute may even consist of traveling through a bridge or maybe two. Since they are vital to our economy and public safety, the government periodically mandates national bridge inspections to determine structurally deficient bridges.

Ultimately, there is no one number that fits the lifespan of all bridges across America. Each bridge has its own expected lifecycle but there are ways to estimate its lifespan. Generally, it’s believed that bridges are expected to function for 50-70 years however this is often not the case. Currently, only 42% of all bridges in the United States are at least 50 years old.

The lifespan of a bridge differs according to its design, construction, and location. Each component contributes either positively or negatively to the overall lifespan and structure of a bridge.

Materials

One of the most obvious factors that contribute to the lifespan and eventual structural deficits of a bridge is the material. In fact, both the concrete industry and the steel industry claim several advantages above the other for the Life Cycle Costs of a bridge.

Steel

Steel is a popular construction material due to its flexible and durable nature. The great thing about steel is that it is recyclable and still maintains its initial strength and integrity. Galvanized steel is even more durable plus it requires less upkeep.

Structural steel is a high-quality material that is readily available worldwide in certified grades and produced in various shapes and sizes. Currently, it is estimated that steel bridges have a lifespan of over 100 years. However, this number rapidly decreases as the bridge erodes or even with poor construction quality.

The deterioration of a bridge is created by a combination of several elements, for steel, it is often caused by corrosion, fatigue, stress corrosion, and damage from accidents.

Concrete

Another commonly utilized material is concrete. Concrete bridges are estimated to have a lifespan of over 100 years, again this number changes with daily wear and tear.

The causes of concrete deterioration are typically cracking, spalling, scaling, corrosion, and damage from accidents. In addition, cracks over reinforced steel allow water and chemicals to penetrate accelerating rusting which exerts great forces that pop the concrete.

Not to mention, extreme weather conditions, the presence of chlorides in de-icing salts, and cycles of freeze and thaw all contribute to the erosion of a bridge and its lifespan.

Timber

Timber, which is used for short-span and rural areas or pedestrian bridges is estimated to last only 20–30 years. This could be due to several reasons such as many engineers are less familiar with this material than their counterparts, or because there are fewer treatment options available for timber.

Nevertheless, the accurate range of which timber lasts is uncertain as there are very few data that exist that are based on actual performance data.

However, that doesn’t make timber a poor option. Timber is a lightweight material compared to concrete but still strong. This advantage plus low maintenance and repair costs make timber ideal in certain situations.

Plus studies suggest that timber is a durable option in highway bridge superstructures and that it can perform well for more than 70 years when properly pressure-treated with preservatives.

Location

The location of a bridge plays an instrumental part in its overall structural deficiency. Depending on the environment, it could accelerate the deterioration of the bridge.

Recently, there has been a slightly positive trend in addressing the maintenance of structurally deficient bridges. However, progress is not universal because states face different challenges when it comes to maintaining, repairing, and replacing bridges.

Urban

When it comes to urban locations, the major factor to watch out for is a higher traffic volume. The combination of a heavier load and volume further leads to the wear of the bridge. There are various ways for builders to slow this process down such as galvanization and other special treatments.

Rural

Unlike urban settings, rural bridges don’t have such a large volume of traffic. Unfortunately, it is because of this that rural bridges are typically not designed to withstand the growing numbers and weight of traffic and freight trucks. In actuality, rural bridges and transportation play a key role in our economy’s success and for rural communities.

However, more and more bridges in rural communities are experiencing rapid deterioration without the proper care and maintenance to last.

Coastal

Bridges that are located in coastal environments face unique challenges due to their location. Bridges in marine environments often experience corrosion-induced damage due to high sea salt and humidity. In addition, strength loss in the splash and the tidal zone is more common and significant than in the atmospheric zone.

An example of the distinct problems faced by coastal bridges is illustrated by the Morandi Bridge in Italy. In 2018, this cable-stayed bridge suddenly collapsed causing the death of 43 individuals. The collapse was reported as the fault of a weakened cable that deteriorated from corrosion. The degradation was caused by atmospheric agents and the proximity of the marine environment eroded the structure and integrity of the bridge.

Structural Deficient Bridges in America

Structurally deficient bridges are those that are in need of repair or maintenance due to the deterioration incurred throughout the bridge’s lifetime. Recently, 7.5% of highway bridges were designated structurally deficient. This is a striking improvement from the previous 12% record. In addition, the average age of America’s bridges is increasing to 44 years.

The plan is that the overall lifespan of a bridge should increase over time as more techniques, treatments, and designs are discovered in the future.

Build a Bridge that will Last Lifetimes with U.S. Bridge

Are you looking for an experienced industry leader company to assist with your building projects? Here at U.S. Bridge, we’ve built for different projects all across the globe; and we know that choosing the right material for your bridge takes a combination of experience, expertise, and skill.

To learn more about our bridge engineering and manufacturing, contact us for a quote or to answer any questions. Or start building your scope and bridge with our new interactive tool the Bridge Scope.

What Does a Bridge Engineer Do?

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Bridges play a key role in our lives by connecting our communities, promoting commerce travels, and contributing to our country’s economic development. But who designs these bridges and what does a bridge engineer do?

Bridge Engineers

Bridge Engineers are civil engineers responsible for designing and building bridges and other highway-related structures. Typical tasks for bridge engineers include designing and maintaining bridge structures, minimizing environmental impact, and supervising the fabrication process. As well as completing site investigations, data collection, identifying environmental risks, analyzing manufacturing processes, supervising construction, and more.

Although the exact duties of a bridge engineer may differ, it’s safe to say they’ll always play a critical role in any bridge construction project.

Designing and maintaining a bridge is no easy task. That’s why bridge engineers are required to have skills such as analytical thinking, leadership, supervisory skills, organization, and creativity. Not to mention, time management and budgeting skills which are essential for projects with restricted time or resources.

Bridge Engineering: It’s All About The Details

Meetings & Details

Naturally, the first part of any construction project is understanding the full scope. This meeting typically covers topics and details such as bridge series and styles, special enhancements or treatments, railing criteria, etc. This will help the bridge engineer to draw up some preliminary sketches of the bridge’s general framing plan, bridge geometry, and basic construction.

These designs help illustrate the bridge and prepare the project for its next step.

Digital Renderings

One of the most powerful tools for bridge engineers to utilize is technology. Bridge engineers will often use computers to create virtual models to assist in visualizing a project. This helps the team picture the visual impacts of the bridge to any given site as well as the aesthetic qualities. Our bridge engineers are able to model your proposed bridge over a digital terrain model or incorporate it into photos of your existing site.

This aspect is extremely useful, especially if a construction project requires models to help stakeholders buy-in or make a sale.

Final Process

Once a commitment has been made, the design process officially begins and a team is assigned. The project engineer analyzes the proposed bridge including the specified design loads and appropriate load factors, along with applying numerous code checks. Eventually, the bridge engineer begins to sketch the design details and information for the designer. These sketches convey all the information previously discussed and finalized.

The engineer will also markup the general notes and list the design assumptions and pertinent bridge data onto the title sheet.

Part of this process involves reviewing the design calculations and construction plans to verify the scope and specifications. Also checked is the plan content to ensure it reflects the engineer’s design intent and that no conflicts exist and that no omissions have occurred. The final step before submittal is usually the application of the Professional Engineer’s seal and signature.

Designed for Success at U.S. Bridge

At U.S. Bridge, we’ve been engineering and building bridges for over 80 years. Our engineers have the skills and experience to build bridges in many different styles and sizes to fit the needs of your project. Find out more about how U.S. Bridge has everything you need to make your project a success.

Contact us for a free quote or check our exclusive Bridge Scope tool to start building your project today.

Bridge Kits: A Solution for Accelerated Bridge Construction

U.S. Bridge Kits

Accelerated bridge construction (ABC) is an evolution in project planning for bridge construction. Often, bridges need to be constructed quickly and under a tight budget. Meanwhile, they need to maintain safety, quality, durability, and costs. To solve these problems, U.S. Bridge created Bridge Kits, a DIY solution for accelerated bridge construction.

Bridge Kits work best for bridge builders who have the labor and equipment to install bridges, but not the engineering or manufacturing capabilities. Therefore, construction teams across the country use our Bridge Kits to accelerate bridge construction and decrease costs.

U.S. Bridge has decades of experience in manufacturing and engineering steel bridges. Just like all of our bridges, the Bridge Kits are custom designed to provide a sustainable bridge structure that fits your needs. Additionally, they are a paradigm shift in bridge construction to fast-track quality bridge projects everywhere.

Bridge Kits are a Cost-Effective Bridge Solution

Our bridge kits improve site constructability and project delivery time by fully preparing our materials to be installed. In turn, we’re able to save bridge owners money. All of our kits currently come with our Cortez Bridge design. This design has already proven useful in quick builds. However, construction is even easier now, with manufactured parts shipping directly to job sites.

“Three main benefits of using ABC methods include minimized impact to traffic, increased
safety during construction, and minimized impacts in environmentally sensitive areas,” according to the Wisconsin Department of Transportation.

Bridge Kits Engineering

Engineering and Design

We have decades of experience in engineering and designing bridges to particular specifications. As a result, our team knows how to build great bridges. We can ensure the durability of our high-quality materials to keep bridges in shape for decades to come.

Bridge Kits - Manufacturing

Manufacturing

Following design, we manufacture all of the parts for your bridge. We work with environmentally-friendly materials to produce aesthetically-pleasing, long-lasting bridges. Off-site work on parts of the bridge leads to faster bridge construction on-site. In turn, projects are completed faster, lane closures decrease, and work-zone safety increases.

Lastly, we provide galvanizing for corrosion protection for steel in all of our Bridge Kits. As a result of galvanizing, we create long-lasting structures that keep bridges maintenance-free for 50 years or more.

Shipping

U.S. Bridge has delivered bridges worldwide for decades. Our Bridge Kits are no different. Firstly, we deliver the manufactured parts right to your construction site. Then your team can construct it from the first day materials are on-site.

What the Bridge Kits include

Once the span and width of the bridge are set, we manufacture every part you need to build the bridge. In our accelerated bridge construction, we deliver all the parts you need for easy construction.

  • Bridge and Pedestrian Railings
  • Bearings
  • Expansion Joints
  • Anchor Bolts
  • Structural Fasteners
  • Floor or Deck System
  • Various additional customizations

U.S. Bridge manufactures steel per AISC certifications. Coupled with extensive experience, our manufacturers are fabricating high-quality bridges. Bridge Kits are consistent with our efforts to improve infrastructure and the nation’s transportation system with innovative bridge construction.

Our Cortez Bridge Design

Currently, all of our Bridge Kits come in our Cortez design. The Cortez design is perfect for short spans, but is very adaptable and versatile to fit the needs of your bridge. It’s a simple span beam bridge, which supports a concrete deck slab and stay-in-place forms. Above all, it’s easy to install without highly-specialized equipment. Similarly to all of our bridges, Cortez’s high-quality steel constructions are extremely durable and guarantee minimal to no maintenance.

Let’s Piece it Together

U.S. Bridge proudly delivers on long-lasting bridge construction projects around the world. We regard every detail of your bridge with a high level of attention and efficiency to ensure it’s high-quality. If you’d like to know more about our Bridge Kits and accelerated bridge construction, please contact us today for a free quote.