Pre-tensioned Bridge

Post-Tensioning prestressed concrete

Allplan can streamline design of post-tensioning for pre-stressed concrete.

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Anyone working in the concrete sector of the AEC knows that concrete is not a flexible building substance; that’s why rebar is needed. But, rebar has it’s load-bearing limitations. Post-tensioning can achieve what rebar alone cannot. It’s a particular method of concrete reinforcement that has increased in popularity over the past thirty years. The basic functionality is to place the concrete under compression in areas where load-bearing will cause tensile stress, and lead to greater chance of cracking.

The post-tensioned tendons, which are pre-stressed, highly durable steel cables inside of plastic sleeves, are positioned along with the other reinforcement before concrete is poured. After the concrete is poured and set, these cables are pulled taut and anchored against the outer edges of the form. Then, service loads can be applied.

Post-tensioning for slabs and walls for buildings

Post-tensioning is commonly used in building slabs on ground, or on grade where there is soft soil content prone to shifting, like in geographic areas with a lot of sand. It’s also used in parking garages, skyscrapers, and other high rise buildings.

Don't miss our LIVE WEBINAR Bringing BIM to Post-Tensioned Buildings 

On June 27 at 1pm eastern, Monica Rennick, Senior Technical Consultant, Allplan, Inc., will discuss the complex issues concerning model creation for a typical post-tensioned concrete building, and how to properly address them.

 

PT in action - The Harrer Chocolate Factory

Post-tensioning slabs: The Harrer Chocolate Factory in Sopron, Hungary

A building is more than just a structure, it is also a complete work of art, created in harmony between visionary architecture and innovative engineering.

There were many technical obstacles to overcome, particularly during shell planning. As the construction site previously contained the clay pit of a brickyard, the engineers were required to develop a sophisticated foundation. A 16 to 23 foot thick, non-tight filling layer meant a pile foundation combined with cast-in-placeconcrete slabs to provide sufficient load-bearing capacity. The designers used a rapid construction method using cavity wall elements, hollow-core planks and tensioned slab floors to meet the owner's tight time line. 

Learn more about this fascinating project 

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Post-tensioning for bridges

Post-tensioning has gained in popularity with bridge designers using precast segmental construction. It reduces shrinkage cracking, and any cracks that do form are held more tightly together. Post-tensioning enables slabs and concrete sections to be thinner, with longer spans between supports, allowing for increased design flexibility.

Check out our RECORDED WEBINAR A SMARTER WAY TO CREATE A PARAMETRIC BRIDGE DESIGN

This webinar takes an advanced approach to parametrically designing both simple & complex bridges. Frank Holz, Senior Technical Consultant, Allplan, Inc. demonstrates how to create complex bridge geometry, easily define 3D geometry based on a 3D axis, and control cross-sections parametrically.

 

Post-tensioned tendons: Versamertobel Bridge in Switzerland

PT tendons case study: Versamertobel Bridge

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Post-tensioned tendons: Versamertobel Bridge in Switzerland

The final design of the Versamertobel Bridge in Switzerland followed a simple aesthetic, with structural supports only at either end. To meet the needs for a slim, long-span structure, post-tensioning came into play even during construction. It was built from both ends without the use of temporary supports, so the piers were tied using tension rods. Then the bulk of the superstructure was completed in three separate stages.

The modern high-capacity, post-tensioned concrete structure spans between elegant combined abutments/inclined piers over the Versam Gorge. This bridge design resulted from close cooperation between the client (Graubünden Canton Highways Department) and the architect. The model had to consider the dramatic surroundings, the slender lines of the adjacent existing steel bridge, the difficulties of construction and the requirements for durability.

Learn more about the constructuion of this graceful structure