Fig 73- Stadium Design Requirements as per Competition Brief

Superstructure: Tensile- Compression Rings

The spoke wheel principle is used to create a tensile-compression ring. Engineers discovered that using a spoke wheel as a roof construction had numerous advantages. A lightweight, costeffective roof structure can be built using the spoke wheel method.

Fig 106- Tensile Compression Rings at Football Stadium Source- Tensile-compression ring- A study for football stadia roof structures by Ivar Boom becomes stronger and stiffer (Boom, 2012).

In comparison to a bicycle wheel, the prerequisites for a spoke wheel roof structure are different. The leading load is first directed transverse to the roof. The roof must have adequate transverse strength and stiffness to bear the structure’s dead weight as well as additional variable loads (snow, wind, etc.). The manner the structure is supported is the second condition difference. Only the hub of a bicycle wheel is supported by the bicycle frame. The entire ring of a roof construction must be supported. The manner in which the roof structure is supported is critical. The roof must be able to translate in its radial plane to generate ring action.

Is Spoke Wheel Principle applicable for the roof structures of Cricket Stadium?

The rim, the hub, and the spokes that connect the ring and the hub make up a spoke wheel. The interaction of these features is what distinguishes the spoke wheel. The amount of ring activity in the construction determines the wheel’s strength and stiffness. The rim must be squeezed to generate ring action, such as by pre-tensioning the spokes. The rim becomes crushed when radial tensile forces occur on it due to its curvature. The more the pre-tension in the spokes, the more compression forces are generated, and the wheel

Fig 107- Oval shaped structure (Left); Spoke wheel with outer compression ring (Right) Source- Tensile-compression ring- A study for football stadia roof structures by Ivar Boom

Engineers have modified the design of the spoke wheel in the past to expand its applicability, such as in football stadiums. By adding an extra inner ring to the construction, engineers were able to create an aperture in the roof. The bending of the circular shape into an oval shaped roof was the next adaptation. Despite the fact that the spoke wheel’s structural efficiency reduces, the spoke wheel principle can be applied to a stadium roof construction. The strength of the framework for oval-shaped roofs could be boosted by adding an extra inner or outer ring. It is also feasible to utilise non-pretensioned spokes with ordinary steel profiles instead of pre-tensioned spokes in the form of cables.

In the case of typical steel profiles, beam motion will affect the roof structure’s stiffness capacity. The number of bending moments can be minimised by adopting a spatial truss structure (Boom, 2012).

The design variables are the following:

1. Shape of the (opening of the) roof 2. Double inner / outer ring 3. (Non) pre-tensioning of the spokes 4. Profile / elements 5. Supports / connections

The amount of ring action that a spoke wheel roof can offer determines its efficiency. Curvature is the most important component. As a result, the spoke wheel roof is an excellent alternative for circular roofs and a more appealing option than other roof forms. When using the spoke wheel principle for noncircular shaped roofs, it is recommended that the ring action be increased to improve efficiency. The greatest approach is to change the roof’s shape (Boom, 2012). Construction of Truss System Tensile - Compression Rings

The construction procedure for the final truss structure is discussed in this paragraph.

Step 1 – Assembly of the components

The roof structure can be separated into components for construction. The components are pre-assembled outside the stadium and will be installed on the stadium’s stands later.

Fig 108- Components of the roof structure Source- Tensile-compression ring- A study for football stadia roof structures by Ivar Boom

Step 2 – Temporary columns/structure

Fig 109- Temporary columns or a temporary steel structure (right) supporting the roof structure (left) Source- Tensile-compression ring- A study for football stadia roof structures by Ivar Boom The components must be stabilised before being placed on the stands. During building, the inner ring will be supported by temporary columns or steel structures (Boom, 2012).

Fig 110- Supporting structure numbers Source- Tensile-compression ring- A study for football stadia roof structures by Ivar Boom

Step 3 – Lifting of the components to its final place

The hoisting of the components to their final location is the third phase. The components are put on the rocker bearings and temporary columns with the use of a crane on the stadium’s outside. The components can be precisely guided to their ultimate location by deploying an auxiliary crane on the inside of the stadium.

Fig 111- Placement of the units on top of the Feyenoord stadium Source- Tensile-compression ring- A study for football stadia roof structures by Ivar Boom

Step 4 – Repeat step 1-3

Step 1-3 must be repeated until all components are placed.

Step 5 – Closing the roof structure

The final component is the most difficult to put in its ultimate position. The final chasm is left unfilled. In theory, a whole component might be inserted into the final gap. The final component is not anticipated to fit flawlessly in practise. It’s possible that the variable space is either too tight or too wide. A narrow area is purposefully left open in order to fit the final component. The final structure can be raised into place by providing extra room to the framework. The structure is completed by tying the last elements together, such as using ropes (Boom, 2012).

Fig 112- Closing of the structure Source- Tensile-compression ring- A study for football stadia roof structures by Ivar Boom Step 6 – Removing of the temporary structure

The temporary construction will be removed once all of the components have been installed. A temporary structure erected on jackets supports the roof framework. The entire roof will be supported at the same time. Every jacket’s pressure will be reduced at the same time (Boom, 2012).

Step 7 – Assembly of the roof covering