Post-Tensioning prestressed concrete
Allplan can streamline design of post-tensioning for pre-stressed concrete.
> Draw prestressed tendons in 2D: get a full 3D model with a few clicks
> Generate accurate cost appraisals
> Automatically detect clashes
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. Watch the Post Tensioned Slab video to see how to easily and quickly model and reinforce typical post-tensioned concrete slab for buildings.
Want to go a little deeper? Watch our informative webinar, "Bringing BIM to Post-Tensioned Buildings"
The process of modeling a PT building can be tedious and error prone. Engineers and drafters are faced with analysis coordination, complex reinforcing, clash detection and more. Accurate modeling in the design stage can save the overall project time and money. Learn how 3D modeling of tendons and reinforcing can help on your next project. Learn more about common problems with post tensioned concrete buildings, how to model PT Tendons and reinforcing, and the importance of 3D visualization
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.
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. Watch our Bridge Tendon Modeling video to see how to easily and quickly model and reinforce typical post-tensioned concrete slab for buildings.
Want to go a little deeper? Watch our informative 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
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.