By T.M.SUPRAJA FINAL YEAR TENSEGRITY STRUCTURE By T.M.SUPRAJA FINAL YEAR

WHAT IS TENSEGRITY? Tensegrity -a word combining tension and integrity. “Tensile integrity”-stability of the system comes from the tension members.

TENSEGRITY STRUCTURE? Consist of isolated compression members (rigid bars) suspended by a continuous network of tension members (cables) enclosing a space Concept invented by Buckminster Fuller.

A comparison Tensegrity structure vs Human structure Bones are the compression struts and muscles are the tension bearing members. The connective tissues are always prestressed and under continuous tension.

KURILPA BRIDGE Montreal Biosphère Models Olympiastadium

IN INDIA Jawaharlal nehru stadium Rajiv Gandhi airport Sahar airport Mumbai

MATERIALS COMPRESSION MEMBER Rigid bars - M.S Stainless steel Aluminium TENSION MEMBER Cables -Tendon ROOFING STRUCTURE Ethylene tetrafluoric ethylene

JOINT DETAILS Materials are in highly prestressed state

BASIC CONCEPT… Resultant balancing at the joint:

ANALYSIS Types of analysis: 1)Kinematical Methods 2)Statical Methods Kinematical Methods: Determine the geometry of structure Statical Methods: Determine the forces in its members

An Example Let us take a simple structure T-3 prism It has 3 compression member and 9 tension member.

Step 1: Length are fixed for given loading and stress are within permissible limit. Step 2: Position of the members are varied to required tensegrity form such that members are in their required nature(eg tension) step 1 step 2

Step 3: Actual models are created to check the ease of construction (optional stage) Link can be extended and the model is studied. For large structures like stadium and airport, models are created.

Case study-Kurilpa Bridge,Brisbane Reinforced concrete spiral ramp. 120m long . a series of steel masts and cables. Solar powered pedestrian bridges. Use of LED minimizes maintenance and operating costs.

CONSTRUCTION

Solar panel: 84 photovoltaic panels- Joints: Solar panel: 84 photovoltaic panels- Panels supply between 75% and 100% of the power.

ADVANTAGES Larger span coverage Reduction of cost due to relative ease of installation. Lengths of cables adjusted by pulleys.

Continue… Sustainability factor : Allow daylight inside providing natural lighting.

DISADVANTAGES Prestressed to resist deformation-determination of amount to be prestressed in initial stage. Exist under specific geometries. Mathematics involved in analysis of tensegrity structures is difficult.

REFERENCE Thesis submitted By William Brooks Whittier on “Kinematic Analysis of Tensegrity Structures”. A paper by W. O. Williams on “A Primer on the Mechanics of Tensegrity Structures” Master Builder edition August 2012 www.brisbanetimes.com

Let us start creating artistic structures…… THANK YOU….