Ties

[edit] Introduction

In engineering, a tie is a linear structural component that has tension acting upon it, stretching it or pulling it apart.

Ties can be made from any kind of material that is able to resist tension. In order to function properly, ties must be adequately anchored.

[edit] Ties and struts in trusses

The counterpart of a tie is a strut, which is a structure that has compression acting upon it - pushing it together. For more information, see Strut.

Ties and struts are common components of structural elements such as trusses. The two components work together to support the weight of other parts of the structure and any imposed load. The struts generally provide compressive load-bearing capacity, but sometimes also contribute to tension resistance. Ties perform the opposite function and are sometimes referred to as tension members

[edit] Types of ties

Ties may be referred to as straps, tie rods, eyebars, suspension cables, wire ropes and so on.

There are many specific types of ties (taking varying degrees of tension), including:

• Cable tie. A cable tie is a long, thin strap made from nylon or stainless steel, which can be pulled into a loop and tightened to hold together cables, wires and other objects. It is a very simple design that is extremely effective, easy to use and very versatile. For more information, see cable tie.
• Railroad tie, crosstie or railroad sleeper is a form of support used for railroad tracks. Traditionally made from wood, railroad ties are sometimes used in the construction of retaining walls also known as sleeper walls. For more information, see Retaining sleeper walls.
• Tie bar. A horizontal metal bar supporting a window structure, spanning the entire width of the window, usually at springing level. It pierces and passes through any mullions.
• Tie beam. A horizontal beam connecting two rafters in a roof or roof truss.
• Tie stone. A large stone (also known as a bond stone) which passes through a wall from one side to the other. The purpose of the bond stone is to lock the layers of the wall together and reinforce the structure. For more information, see bond stone.
• Tied scaffolds. These are independent scaffolding structures that are connected (using some form of tie) to an adjacent, permanent structure for stability. The selection of tie positions should be tested and checked before use and the suitability of the permanent structures composition to carry the ties should be analysed. Common tied scaffolding methods include: through ties, reveal ties, box ties, lip ties and so on.
• Wall tie. Wall ties (sometimes referred to as brick ties) are strips or bars made of metal that span the cavity and tie the internal and external walls of bricks or blockwork together. For more information, see wall ties.
• Catenaries.
• Cables.
• Wire rope suspension systems.
• Tension cable and rod connectors.
• Ground anchors.

There are also ties that are specifically engineered for extreme weather conditions. These include hurricane ties and seismic ties.

For more information see: Tensile structures

[edit] Related articles on Designing Buildings

• Compression.
• Mechanisms of structural failure.
• Preventing wall collapse.
• Scaffolding.
• Structural stress.
• Strut.
• Tensile strength.
• Truss.