Tie (engineering)

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A hurricane tie used to fasten a rafter to a stud H2A..jpg
A hurricane tie used to fasten a rafter to a stud

A tie, strap, tie rod, eyebar, guy-wire, suspension cables, or wire ropes, are examples of linear structural components designed to resist tension. [1] It is the opposite of a strut or column, which is designed to resist compression. Ties may be made of any tension resisting material.

Contents

Application in wood construction

In wood frame construction they are generally made of galvanized steel. [2] Wood framing ties generally have holes allowing them to be fastened to the wood structure by nails or screws. The number and type of nails are specific to the tie and its use. The manufacturer generally specifies information as to the connection method for each of their products. Among the most common wood framing ties used is the hurricane tie or seismic tie used in the framing of wooden structures where wind uplift or seismic overturning is a concern.

Hurricane tie

Hurricane ties are in place at the top of the wall as the roof trusses are being placed. Defense.gov photo essay 100713-A-5170O-167.jpg
Hurricane ties are in place at the top of the wall as the roof trusses are being placed.

A hurricane tie is used to help make a structure (specifically wooden structures) more resistant to high winds (such as in hurricanes), resisting uplift, racking, overturning, and sliding. [3] Each of the crucial connections in a structure, that would otherwise fail under the pressures of high winds, have a corresponding type of tie, generally made of galvanized or stainless steel, and intended to resist hurricane-force and other strong winds. [4]

A connecting tie that provides a continuous structural load transfer path from the top of a building to its foundation, helping to protect buildings from damage resulting from high wind. These devices are primarily used in areas affected by high winds including hurricanes and are generally suitable for any area that may be impacted by windstorm damage. They are also known as hurricane clip or strips. Among the most common style used along the gulf coast area are plywood fasteners or oriented strand boards over the windows and openings of brick homes. Hurricane clips meet the minimum requirements for code approval and are only as strong as their weakest install point; which is generally half the strength of the wood.[ clarification needed ]

A hurricane clip has two meanings in building construction:

Seismic tie

Seismic tie provides facility to securely fix cabinets, bookcases, desks, appliances, machinery & equipment to walls and/or floors to constrain their movement during earthquakes. [6]

Girder tiedown

Top mount, face mount, sloped/skewed, and variable pitch hangers for dimensional lumber, engineered wood I-joists, structural composite lumber and masonry wall. To give added strength in increase various load requirements over wood only.

Strap tie

When building subfloor the joists must always bear on the ledge for all it support. The use of steel stap tie to connect opposite joist when the top of the joists and beam are flush. [7]

Twist strap

Twist straps provide a tension connection between two wood members. They resist uplift at the heel of a truss economically. When the strengthening is being done from the inside, the ideal connector to use is one that connects rafters or trusses directly to wall studs. This can only be done where the rafter or trusses are immediately above or immediately to the side of studs below. In that case a twist strap connector can be used. [8]

Floor span connector

A connector for connecting wall studs of two adjacent floors in a light frame building structure, the connector having a first attachment tab, a seat member, a diagonally slanted support leg, and a second attachment tab, all substantially planar. The connector is intended to be paired and the paired connectors joined by an elongated tie member that pierces the sill plates of the intervening floor structure.

Angle tie

Sometimes referred to as an angle brace. The Angle tie is used to prevent displacement of building elements due to thrust. A brace/tie across an interior angle of a wooden frame, forming the hypotenuse and securing the two side pieces together. [9]

Z-clip

Similar to a French cleat, a Z-Clip allows for the installation of wall panels without screwing into the front of the panels. The clips provide a secure mount for wall panels, partitions, frames, cabinets, and more. Once installed, clips wedge together to lock panels in place. To disengage panels, simply lift and remove.

Plate

Metal connector plates. Wood truss plates.jpg
Metal connector plates.

See

Rafter tie (and Tie-beams)

Rafter ties are designed to tie together the bottoms of opposing rafters on a roof, to resist the outward thrust where the roof meets the house ceiling and walls. This helps keep walls from spreading due to the weight of the roof and anything on it, notably wet snow. In many or most homes, the ceiling joists also serve as the rafter ties. When the walls spread, the roof ridge will sag. A sagging ridge is one clue that the home may lack adequate rafter ties. Rafter ties form the bottom chord of a simple triangular roof truss. They resist the out-thrust of a triangle that's trying to flatten under the roof's own weight or snow load. They are placed in the bottom one-third of the roof height. Rafter ties are always required unless the roof has a structural (self-supporting) ridge, or is built using engineered trusses. A lack of rafter ties is a serious structural issue in a conventionally framed roof.

The 15th-century tie-beam roof at St Marys Church, Radnage, Buckinghamshire in England St Marys Church, Radnage, Bucks, England 15th century tie-beam roof.jpg
The 15th-century tie-beam roof at St Marys Church, Radnage, Buckinghamshire in England

A wooden beam serving this purpose is known as a tie-beam and a roof incorporating tie-beams is known as a tie-beam roof. [10]

See also

Related Research Articles

Truss structure that consists of two-force members only

A truss is an assembly of beams or other elements that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assemblage as a whole behaves as a single object". A "two-force member" is a structural component where force is applied to only two points. Although this rigorous definition allows the members to have any shape connected in any stable configuration, trusses typically comprise five or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes.

Beam (structure) structural element capable of withstanding load by resisting bending

A beam is a structural element that primarily resists loads applied laterally to the beam's axis. Its mode of deflection is primarily by bending. The loads applied to the beam result in reaction forces at the beam's support points. The total effect of all the forces acting on the beam is to produce shear forces and bending moments within the beam, that in turn induce internal stresses, strains and deflections of the beam. Beams are characterized by their manner of support, profile, equilibrium conditions, length, and their material.

Timber framing building technique, construction method using heavy squared-off and carefully fitted and joined timbers

Timber framing and "post-and-beam" construction are traditional methods of building with heavy timbers, creating structures using squared-off and carefully fitted and joined timbers with joints secured by large wooden pegs. It is commonplace in wooden buildings through the 19th century. If the structural frame of load-bearing timber is left exposed on the exterior of the building it may be referred to as half-timbered, and in many cases the infill between timbers will be used for decorative effect. The country most known for this kind of architecture is Germany. Timber framed houses are spread all over the country except in the southeast.

Seismic retrofit Modification of existing structures to make them more resistant to seismic activity

Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries and late 1970s for many other parts of the world, many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example.

A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members. When incorporated into a floor framing system, joists serve to provide stiffness to the subfloor sheathing, allowing it to function as a horizontal diaphragm. Joists are often doubled or tripled, placed side by side, where conditions warrant, such as where wall partitions require support.

Rafter structural member in architecture

A rafter is one of a series of sloped structural members such as wooden beams that extend from the ridge or hip to the wall plate, downslope perimeter or eave, and that are designed to support the roof deck and its associated loads. A pair of rafters is called a couple. In home construction, rafters are normally made of wood. Exposed rafters are a feature of some traditional roof styles.

Framing (construction) in construction, is the fitting together of pieces to give a structure support and shape

Framing, in construction, is the fitting together of pieces to give a structure support and shape. Framing materials are usually wood, engineered wood, or structural steel. The alternative to framed construction is generally called mass wall construction, where horizontal layers of stacked materials such as log building, masonry, rammed earth, adobe, etc. are used without framing.

Purlin structural member in a roof

In architecture, structural engineering or building, a purlin is any longitudinal, horizontal, structural member in a roof except a type of framing with what is called a crown plate. In traditional timber framing there are three basic types of purlin: purlin plate, principal purlin and common purlin.

The term structural system or structural frame in structural engineering refers to the load-resisting sub-system of a building or object. The structural system transfers loads through interconnected elements or members.

Portal frame construction method

Portal frame structures are designed to span between supports and rely on fixed joints with moment resisting capacity where vertical supports connect to horizontal beams or trusses. Portal frame structures can be constructed using a variety of materials and methods. These include steel, reinforced concrete and laminated timber such as glulam. The connections between the columns and the rafters are designed to be moment-resistant, i.e. they can carry bending forces. "They were first developed in the 1960s, and have now become the most common form of enclosure for spans of 20 to 60 m"

Domestic roof construction the supporting structure of a roof, necessary for its stability

Domestic roof construction is the framing and roof covering which is found on most detached houses in cold and temperate climates. Such roofs are built with mostly timber, take a number of different shapes, and are covered with a variety of materials.

Steel building Part of civil engineering

A steel building is a metal structure fabricated with steel for the internal support and for exterior cladding, as opposed to steel framed buildings which generally use other materials for floors, walls, and external envelope. Steel buildings are used for a variety of purposes including storage, work spaces and living accommodation. They are classified into specific types depending on how they are used.

King post

A king post is a central vertical post used in architectural or bridge designs, working in tension to support a beam below from a truss apex above.

Collar beam

A collar beam or collar is a horizontal member between two rafters and is very common in domestic roof construction. Often a collar is structural but they may be used simply to frame a ceiling. A collar beam is often called a collar tie but this is rarely correct. A tie in building construction is an element in tension rather than compression and most collar beams are designed to work in compression to keep the rafters from sagging. A collar near the bottom of the rafters may replace a tie beam and be designed to keep the rafters from spreading, thus are in tension: these are correctly called a collar tie.

Cold-formed steel

Cold-formed steel (CFS) is the common term for steel products shaped by cold-working processes carried out near room temperature, such as rolling, pressing, stamping, bending, etc. Stock bars and sheets of cold-rolled steel (CRS) are commonly used in all areas of manufacturing. The terms are opposed to hot-formed steel and hot-rolled steel.

Timber roof truss

A timber roof truss is a structural framework of timbers designed to bridge the space above a room and to provide support for a roof. Trusses usually occur at regular intervals, linked by longitudinal timbers such as purlins. The space between each truss is known as a bay.

Tornadoes, cyclones, and other storms with strong winds damage or destroy many buildings. However, with proper design and construction, the damage to buildings by these forces can be greatly reduced. A variety of methods can help a building survive strong winds and storm surge.

A post is a main vertical or leaning support in a structure similar to a column or pillar but the term post generally refers to a timber but may be metal or stone. A stud in wooden or metal building construction is similar but lighter duty than a post and a strut may be similar to a stud or act as a brace. In the U.K. a strut may be very similar to a post but not carry a beam. In wood construction posts normally land on a sill, but in rare types of buildings the post may continue through to the foundation called an interrupted sill or into the ground called earthfast, post in ground, or posthole construction. A post is also a fundamental element in a fence. The terms "jack" and "cripple" are used with shortened studs and rafters but not posts, except in the specialized vocabulary of shoring.

American historic carpentry

American historic carpentry is the historic methods with which wooden buildings were built in what is now the United States since European settlement. A number of methods were used to form the wooden walls and the types of structural carpentry are often defined by the wall, floor, and roof construction such as log, timber framed, balloon framed, or stacked plank. Some types of historic houses are called plank houses but plank house has several meanings which are discussed below. Roofs were almost always framed with wood, sometimes with timber roof trusses. Stone and brick buildings also have some wood framing for floors, interior walls and roofs.

Most of the terms listed in Wikipedia glossaries are already defined and explained within Wikipedia itself. However, glossaries like this one are useful for looking up, comparing and reviewing large numbers of terms together. You can help enhance this page by adding new terms or writing definitions for existing ones.

References

  1. Trautwine, John Cresson (1919) [1871]. The Civil Engineer's Pocket-Book (20th ed.). Wallingford, Pennsylvania: Trautwine Company. p.  359 . Retrieved February 12, 2010 via Internet Archive. A long slender piece sustaining tension is called a tie. One sustaining compression is called a strut or post.
  2. "Different coatings available". strong-tie.com.
  3. "How wind affects your home". safestronghome.com. (A Simpson Strong-Tie website)
  4. 1 2 Rumbarger, Janet, Richard Vitullo, and Charles George Ramsey. Architectural graphic standards for residential construction. New York: John Wiley & Sons, 2003. 238. Print.
  5. Document from a commercial website
  6. "Seismic Technical Guide" (PDF). USGUSG Seismic Ceiling Resource Center. usg.com. Retrieved 23 May 2015.
  7. Anderson, LeRoy Oscar (28 Nov 1992). Wood-frame House Construction. USA: Craftsman Book Company. p. 35. ISBN   9780934041744.
  8. Douglas, Howard. "Wood Frame Roof-to-Wall Connections". Florida Hurricane Retrofit Guide. Division of Emergency Management. Retrieved 23 May 2015.
  9. "Right-angle brace gives you a corner on clamping tasks". Wood Magazine. Wood Magazine. Retrieved 24 May 2015.
  10. "2308.10.4.1 Ceiling joist and rafter connections". International Code Council. Retrieved 24 May 2015.