Nemetschek Group Modernizes Bridge Design
Roopinder Tara posted on June 03, 2020 |
Time for a new way to make concrete bridges, says Nemetschek’s leading bridge designer at ALLPLAN.
Nemetschek has sponsored this post.
 Automatic derivation of the simulation model with Allplan Bridge. (Picture courtesy of ALLPLAN Infrastructure.)
Automatic derivation of the simulation model with Allplan Bridge. (Picture courtesy of ALLPLAN Infrastructure.)

Seeing a bridge from a far, one can admire its beauty and elegance. Crossing it is to be in awe of its scale and to appreciate its detail. Is there any better testament to engineering on Earth? Bridges have spanned impossible distances and crossed ridiculous depths. Time after time, after ordinary folk insisted it couldn’t be done, engineers responded with “Done!”

Bridges crisscross the waterways of the San Francisco Bay and tie together shore communities, including the iconic Golden Gate Bridge. The smug grin when we go over these bridges? We’re thinking “Yeah, engineers did this.”

Yes, we are totally taking credit for the bridge engineer. The kid who drew bridges with crayons, who grew up to calculate catenaries, study concrete creep and on to work on impossible projects. The one who stamped the plans, ensured the spans met as they reached for each other, did the math over and over -- and sweated every detail.

A concrete bridge takes shape. Allplan Bridge’s simulation is time sensitive (4D) and takes the construction process into consideration. (Picture courtesy of ALLPLAN GmbH, Munich, Germany |
A concrete bridge takes shape. Allplan Bridge’s simulation is time sensitive (4D) and takes the construction process into consideration. (Picture courtesy of ALLPLAN GmbH, Munich, Germany |

Meet a Real Bridge Engineer

After hundreds of bridges admired and crossed, we jumped at the chance to interview a real bridge engineer—it’s like being invited into the kitchen of your favorite restaurant to talk to the chef. 

“Call me Vanja,” says Dr. Vanja Samec. She is not about her considerable laurels: a PhD in computer science in civil engineering and a masters in structural engineering. Vanja leads the Allplan Bridge team within the Nemetschek Group. “I don’t like people who see titles only. It is the content of the brain that’s important.” 

Vanja Samec, Managing Director at ALLPLAN Infrastructure. (Picture courtesy of ALLPLAN Infrastructure.)

Vanja Samec, Managing Director at ALLPLAN Infrastructure. (Picture courtesy of ALLPLAN Infrastructure.)

We are calling Vanja in her home in Slovenia, where she, like many others, is homebound due to the Coronavirus pandemic. Vanja is deep into bridges, with over 30 years designing bridges, project management, software development and leadership activities. 

What is your favorite bridge?

I like suspension bridges a lot; she says. I got tears in my eyes when I was walking across the Brooklyn Bridge, although it is a mixture of suspension and cable-stayed.

That old thing? Why?

It is a very beautiful old bridge, has a sad story behind it and was extremely, extremely well planned—by a woman.

We look into it, and there is another woman in bridge engineering.

The Brooklyn Bridge, when completed in 1883, was the longest suspension bridge ever, with a 1,600 ft span. Originally, the design was entrusted to John Augustus Roebling, an industrial engineer by education but one whose contributions to civil engineering were truss reinforced bridge decks hung from miles of steel cables. However, an accident with a boat while he was taking measurements caused a foot to be amputated, tetanus to set in and then his death. 

Inheriting the bridge design was his son, Washington Roebling. Washington was to become paralyzed from caissons disease—also known as the bends—an affliction that affected the workers making multiple trips from the depths of New York’s East River, where the towers’ foundations were dug, to the surface, in pressurized vessels. As Washington watched from his bed with a telescope, his wife, Emily Roebling, took over the project. 

At first, Emily would take messages from her immobile husband to the bridge workers. She started learning about the strength of materials, stress analysis, cable construction and calculation of catenary curves. Despite only having a degree in law from a women’s college, Emily became the Brooklyn Bridge’s chief engineer in duties, if not with an official title. This did not free her from the women’s work of the day – she still had her secretarial duties, according to the Roebling Museum.

When the bridge was finished, she rode across it with President Chester Arthur. 

“She was an extremely good scientist and mathematician,” says Vanja. “And she did it all without calculators and computers.”

Are there others like you?

Vanja’s team is packed with advanced degrees. Two other PhDs are working on the development of a solver. A university professor joined them at the end of last year. The rest of the team have Master’s degrees in computer science, math, physics, or structural engineering.

Having structural engineers on the development and project management team pays off when it comes to user support,” says Vanja. “We are engineers. We understand the problems and we know exactly what the project needs. So, we are thinking like engineers and we are also developing as engineers,” she elaborates. “Our goal is to work as engineers and give technical support to our users.” This user-centric approach is deeply entrenched in the Nemetschek Group's DNA. All brands in the Nemetschek Ecosystem are working extremely closely with their customers

In making the analytical model, a lot of detail can be lost, explains Vanja, but all of it is preserved with Allplan Bridge. You can get down to the rivet, says Vanja.

Are bridge aesthetics overrated?

Aesthetics are admirable but a well-designed bridge, optimized naturally by the designer, has its own beauty. 

Designing aesthetically is for architects. They will make eye-catching designs. But sometimes the designs create forms that defy physics and are impossible to fulfill—at least in a world with gravity.

You do not even need a lot of architecture because the physics itself, the play of the forces—if you are a good bridge engineer, these will give you the beautiful forms automatically.

We ask about suspension bridges, which Allplan Bridge can model, but not yet analyze.

Suspension bridges are dynamically very sensitive, but also flexible structures. The longest distances can be reached by suspension bridges, says Vanja.

In the case of cable-stayed bridges, the erection control in the construction process is of the most importance. The software needs to predict the exact deformations of the bridge segments, the tension of the cable stays during the construction process until the last one – a connection segment in the middle of the bridge. Tensioning of cable-stays is additionally a very expensive process. Optimization of tensioning is needed. Both, suspension and cable-stayed bridges, are eye-catchers, landmark bridges and count as long-span bridges.  

“The cross sections of such segments can be huge, some over 50 meters in width with thicknesses of three to five meters.  These are big structures and erection control mistakes cannot be allowed.”

What we need is the simulation of suspension and cable-stayed bridges as they are being built, showing pieces coming together.

I will put in the request, says Vanja, good humoredly.

“Our strength is concrete bridges. Cantilever, cast in situ, pre-stressed. Cable-stayed and suspension bridges are mostly composites of concrete and steel. We are adding composite to our toolkit,” says Vanja. “We’ll have your wish come true by April.” 

“Before that, we will finalize our earthquake dynamics with our October release.” 

What exactly is Allplan Bridge?

Allplan Bridge is the new technical solution especially tailored for bridge engineering. The heart of it is the 4D parametric bridge modeler, with a powerful and growing analysis and design module. Code-based design and checks leads to the necessary reinforcement and pre-stressing tendons. 

In Allplan Engineering the reinforcement detailing, reports and the plans will all be created. Very reliable and accurate, which is most important for the construction site. We can exchange the data with many formats, also to DWG, DGN, but also nowadays very important for open exchange – IFC.

The entire bridge model adjusts in the event of any change. If the geometry of the cross-section or axis changes, the entire bridge model is automatically adjusted. This applies to the analytical model including construction sequences, design-code checks etc. Just a press to the recalculation button is needed and the update of internal stresses and required tendons and reinforcement area will take place immediately. 

Simplicity and intuitive usage should also ensure that engineers are not restricted in their freedom and creativity despite the high degree of automation at the same time. That is why I think Allplan Bridge is the total bridge solution. 

Who would use Allplan Bridge?

A bridge engineer would choose to use Allplan Bridge. Currently Allplan Bridge is split in modules, because not everyone may be interested in analysis or prestressing tendons, for example. If an engineer is designing a shorter bridge, they only need modeling, analysis and detailing. So, they would choose Allplan Bridge Modeler, Analysis and Code-Based Design with Allplan Engineering for detailing. Anytime later additional modules can be added – mostly due to the project needs. 

What’s new in the latest release of Allplan Bridge?

In October last year, we released Allplan Bridge 2020. We managed to realize the “single source of truth”: the mathematical calculation model is automatically derived from the physical model.

When the geometry is modified, the analytical model is automatically adapted (including all loads, construction sequences etc.). This greatly reduces the amount of work. That, to me is revolutionary.

Another big enhancement is a full live load calculation. 

Influence lines from analysis of traffic loads in Allplan Bridge. (Picture courtesy of ALLPLAN Infrastructure.)
Influence lines from analysis of traffic loads in Allplan Bridge. (Picture courtesy of ALLPLAN Infrastructure.)

We added also a module for code-based design and checks. In our April release there was a technical preview before finalization in October this year. Users can apply the code-dependent design capabilities to deter­mine the required reinforcement. Checks in the ultimate limit state (ULS) can be performed once the reinforcement has been calculated or manually specified. Currently linear stress checks are implemented, for reinforcement design flexure only is considered. 

 Code based design. After overall simulation, ALLPLAN Bridge determines the sizes of girders needed by code. (Image courtesy of ALLPLAN Infrastructure.)
Code based design. After overall simulation, ALLPLAN Bridge determines the sizes of girders needed by code. (Image courtesy of ALLPLAN Infrastructure.)

Most know of Allplan as BIM for buildings. Is that fair?

Allplan is not just building software. We think of Allplan as engineering detailing software. It is a pity that Allplan is not better known internationally. In Europe, ALLPLAN has a very, very long tradition. It was founded by Professor Georg Nemetschek, still a member of the Group’s supervisory board. The Group now counts a total of 16 brands, all strategically along the complete value chain – from planning and designing to building and operating buildings and infrastructure projects. Professor Nemetschek started the development of Allplan code as an engineer. Over the years, ALLPLAN added detailing for buildings, structures—and bridges. Several well-known companies use Allplan for concrete structures and also for bridges.

Early in the development and throughout, Allplan was 3D already. That was pioneering 20 years ago. 

The 3D parametric modeling, analysis and code-based design complement the fantastic 3D reinforcement detailing in Allplan. At the end of the day the drawings and reports need to be delivered to the construction site. It is fantastic what capabilities Allplan has. 

So, with all that ALLPLAN offers, I’d say we are not just about Allplan Bridge but a total Allplan Bridge Solution.

What is the mission and roadmap of Allplan Bridge?

Infrastructure is a strategic pier for ALLPLAN and the Nemetschek Group.

Allplan Bridge was first released in April 2018 with a tough challenge—to release a new version every six months. We launched the fully parametric Allplan Bridge Modeler first. After half a year we added pre-stressing and further with 6-month cycles analysis and code-based design.   

We wanted to achieve a general, efficient tool which would handle all phases of the bridge life cycle. What a miracle if a bridge engineer could, over the bridge’s life cycle, have one model with enough geometric detail that the same model could be used for both detailing and drafting. But to determine what needs to be reinforced, or what rebar to be used? You need to calculate your model.

What is 4D in bridge design?

In the construction process we must consider time as important information for time dependent calculation. Bridges are much different than buildings and other structures. They are built in sequences over time. Every sequence represents a different model with its own deformation and stress situation. Additionally, time consideration is important for some non-linear effects of concrete and pre-stressing steel – like creep, shrinkage, and relaxation.

What’s wrong with “traditional” methods of bridge design? 

The civil engineer or designer start with a preliminary design of a bridge and create a model. Then the structural engineer creates a new model, based on that from preliminary design – but a different one—mathematical for simulation, the finite element model adding the loads, live loads and creating design code check to evaluate the necessary reinforcement and pre-stressing geometry with its amount.

The detailer will also start over for the purpose of making the detail drawings. This is still the case in most bridge design all around the world. 

How is Allplan Bridge different?

The biggest advantage of Allplan Bridge over all other competition is that we offer one overall and complete model, used for the concept, the detailed geometry as well as analysis: the mathematical model used for the calculations and also the design code checks, which deliver the necessary amount of reinforcement. The same model will be the detailed model for all the details, reinforcement, the layout drawings, production sequences, part callouts—everything.

You can imagine what a big advantage a single model gives us if we make the modifications. If the engineers change the prestressed tendons diameter only recalculation is needed. If the bridge section needs to be wider or taller, the dimensions can be very easily corrected, the pre-stressing tendons will accordingly adapt, because they are also parametrically connected with the boundaries in the bridge model. The same logic works for any other change – loads, construction sequence tasks, superposition rule etc. You just press a recalculation button and the complete model with all implemented changes is recalculated.

The simplicity of the most elegant bridge belies their complexity. The software to design and simulate the bridge must be able to handle the complexity. How complex is Allplan Bridge to use and how long does it take to learn? 

That is one of our advantages. The software is so intuitive, so user-friendly, so precise and so reliable.

Our customers can be trained on their own projects, on something real to them. It takes them two or three days maximum before they are able to use it themselves. Not once have we heard “this is complicated." On the contrary, it is intuitive.

What makes Allplan Bridge different?

Nowadays BIM for bridges became a reality. What is needed to get a grip on this challenge is a "single source of truth". The bi-directional data exchange between BIM model and structural analysis is required. The digital model must suit all needs of the process, from the preliminary design phase via detailed design, detailing and construction to the operation phase throughout lifetime. With our bridge and development experiences we developed a revolutionary solution Allplan Bridge, which we think is the future of bridge design and construction. We are listening to the bridge community and sharing the experiences of the bridge community. We know the problems they face, we know how much time is lost. We are fixing those hurdles.

Developing very closely to specific customer needs is what we in the Nemetschek Group consider "true innovation" – innovation to solve immediate customer needs.

Given that Allplan Bridge enters an industry with other software in place, how well can Allplan Bridge play with others? 

It is true that the bridge engineering community has already invested in software. We do not expect that companies will drop their existing software. So we offer the Allplan Bimplus platform to exchange the models and data. ALLPLAN is a pioneer of OpenBIM solutions. Bimplus is an open platform – also for non Allplan users. The Nemetschek Group in general is strongly believing in and advocating "open standards" because we think it is the key driver for fair competition and thus driving innovation.

In Allplan Bridge 2020 we transferred our bridge analytical model to the Bimplus platform. By using the development API this analytical model could be transferred to other structural analysis solutions. Some software companies are already using our API to connect to their solution.

Another way to connect is by using IFC standard. We also have a direct connection between Allplan and other software by import and export. We know the technology of the future IFC. The Bridge industry is a little behind in comparison to the building industry, but the links from the geometry model and the early stage of the analytical model are happening. ALLPLAN is a member of Building Smart and proponent of OpenBIM, following the latest development in the IFC world.

Vanja, thank you for talking to us about bridges we love and about how you and your team will be helping make more of them. 

Visit Nemetschek to learn more about Allplan Bridge.

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