A truss is an assembly of members such as beams , connected by nodes , that creates a rigid structure.
77-575: Woolsey Bridge (NRHP listed as Washington County Road 35 Bridge ) was a truss bridge built in 1925, formerly located near West Fork, Arkansas . It carried County Route 35 over the West Fork of the White River for 303 feet (92 m). It is listed on the National Register of Historic Places . The bridge is historic as the only surviving bridge in the area built in the camelback style. Engineered in
154-412: A lattice . The Vierendeel truss is a structure where the members are not triangulated but form rectangular openings, and is a frame with fixed joints that are capable of transferring and resisting bending moments . As such, it does not fit the strict definition of a truss (since it contains non-two-force members): regular trusses comprise members that are commonly assumed to have pinned joints, with
231-416: A mountain bike frame, the top tube is almost always sloped downward toward the seat tube. Radically sloped top tubes that compromise the integrity of the traditional diamond frame may require additional gusseting tubes, alternative frame construction, or different materials for equivalent strength. ( See Road and triathlon bicycles for more information on geometries. ) Step-through frames usually have
308-492: A utility bicycle emphasizes comfort and has higher handlebars resulting in an upright riding position. Frame geometry also affects handling characteristics. For more information, see the articles on bicycle and motorcycle geometry and bicycle and motorcycle dynamics . Frame size was traditionally measured along the seat tube from the center of the bottom bracket to the center of the top tube. Typical "medium" sizes are 54 or 56 cm (approximately 21.2 or 22 inches) for
385-415: A European men's racing bicycle or 46 cm (about 18.5 inches) for a men's mountain bike . The wider range of frame geometries that now exist has also led to other methods of measuring frame size. Touring frames tend to be longer, while racing frames are more compact. A road racing bicycle is designed for efficient power transfer at minimum weight and drag. Broadly speaking, the road bicycle geometry
462-482: A cross: a seat tube from the bottom bracket to the saddle, and a backbone from the head tube to the rear hub. A truss frame uses additional tubes to form a truss . Examples include Humbers , Pedersens , and the one pictured. A monocoque frame consists only of a hollow shell with no internal structure. Folding bicycle frames are characterized by the ability to fold into a compact shape for transportation or storage. Penny-farthing frames are characterized by
539-454: A distinct way, the camelback truss is uncommon and this well-preserved example was listed on the National Register of Historic Places on June 9, 2000. Bridge designers and engineers of the early 20th century had seen the Pratt truss prove itself as a durable and economically feasible bridge. The Woolsey Bridge was designed as a camelback through truss design. The camelback is a modification of
616-503: A fixed depth, the Pratt configuration is usually the most efficient under static, vertical loading. The Southern Pacific Railroad bridge in Tempe , Arizona is a 393 meter (1,291 foot) long truss bridge built in 1912. The structure is composed of nine Pratt truss spans of varying lengths. The bridge is still in use today. The Wright Flyer used a Pratt truss in its wing construction, as
693-451: A large front wheel and a small rear wheel. Tandem and sociable frames support multiple riders. There are many variations on the basic diamond frame design. The cycle types article describes additional variations. It is also possible to add couplers either during manufacturing or as a retrofit so that the frame can be disassembled into smaller pieces to facilitate packing and travel. The diamond frame consists of two triangles,
770-403: A larger cross section than on a previous iteration requires giving other members a larger cross section as well, to hold the greater weight of the first member—one needs to go through another iteration to find exactly how much greater the other members need to be. Sometimes the designer goes through several iterations of the design process to converge on the "right" cross section for each member. On
847-436: A lower standover height . This was to allow the rider to dismount while wearing a skirt or dress . The design has since been used in unisex utility bikes to facilitate easy mounting and dismounting, and is also known as a step-through frame or an open frame. Another style that accomplishes similar results is the mixte . In a cantilever bicycle frame the seat stays continue past the seat post and curve downwards to meet with
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#1732852115556924-437: A main triangle and a paired rear triangle. The main triangle consists of the head tube, top tube, down tube and seat tube. The rear triangle consists of the seat tube, and paired chain stays and seat stays. The head tube contains the headset, the bearings for the fork via its steerer tube . In an integrated headset, cartridge bearings interface directly with the surface on the inside of the head tube, on non-integrated headsets
1001-402: A matrix method such as the direct stiffness method , the flexibility method , or the finite element method. Illustrated is a simple, statically determinate flat truss with 9 joints and (2 x 9) − 3 = 15 members. External loads are concentrated in the outer joints. Since this is a symmetrical truss with symmetrical vertical loads, the reactive forces at A and B are vertical, equal, and half
1078-509: A simple truss to comprise only triangles. The traditional diamond-shape bicycle frame, which utilizes two conjoined triangles, is an example of a simple truss. A planar truss lies in a single plane . Planar trusses are typically used in parallel to form roofs and bridges. The depth of a truss, or the height between the upper and lower chords, is what makes it an efficient structural form. A solid girder or beam of equal strength would have substantial weight and material cost as compared to
1155-446: A stronger stroking position. The trade-off is comfort. Touring and comfort bicycles tend to have more slack (less vertical) seat tube angle traditionally. This positions the rider more on the sit bones and takes weight off the wrists, arms and neck, and, for men, improves circulation to the urinary and reproductive areas. With a slacker angle, designers lengthen the chain stay so that the center of gravity (that would otherwise be farther to
1232-423: A top tube that slopes down steeply to allow the rider to mount and dismount the bicycle more easily. Alternative step-through designs may include leaving out the top tube out completely, as in monocoque mainframe designs using a separated or hinged seat tube, and twin top tubes that continue to the rear fork ends as with the mixte frame. These alternatives to the diamond frame provide greater versatility, though at
1309-499: A truss. For a given span , a deeper truss will require less material in the chords and greater material in the verticals and diagonals. An optimum depth of the truss will maximize the efficiency. A space frame truss is a three-dimensional framework of members pinned at their ends. A tetrahedron shape is the simplest space truss, consisting of six members that meet at four joints. Large planar structures may be composed from tetrahedrons with common edges, and they are also employed in
1386-422: Is a single plane framework of individual structural member [sic] connected at their ends of forms a series of triangle [sic] to span a large distance". A truss consists of typically (but not necessarily) straight members connected at joints, traditionally termed panel points . Trusses are typically (but not necessarily ) composed of triangles because of the structural stability of that shape and design. A triangle
1463-474: Is also routed along the chain stay. Occasionally (principally on frames made since the late 1990s) mountings for disc brakes will be attached to the chain stays. There may be a small brace that connects the chain stays in front of the rear wheel and behind the bottom bracket shell, called a "chainstay bridge". Chain stays may be designed using tapered or untapered tubing. They may be relieved, ovalized, crimped, S-shaped, or elevated to allow additional clearance for
1540-418: Is attached. It consists of the seat tube and paired chain stays and seat stays. The chain stays run connecting the bottom bracket to the rear fork ends. The seat stays connect the top of the seat tube (often at or near the same point as the top tube) to the rear fork ends. Historically, bicycle frames designed for women had a top tube that connected in the middle of the seat tube instead of the top, resulting in
1617-410: Is based on the safety bicycle , and consists of two triangles : a main triangle and a paired rear triangle. This is known as the diamond frame . Frames are required to be strong, stiff and light, which they do by combining different materials and shapes. A frameset consists of the frame and fork of a bicycle and sometimes includes the headset and seat post . Frame builders will often produce
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#17328521155561694-468: Is categorized as either a traditional geometry with a horizontal top tube, or a compact geometry with a sloping top tube. Traditional geometry road frames are often associated with more comfort and greater stability, and tend to have a longer wheelbase which contributes to these two aspects. Compact geometry allows the top of the head tube to be above the top of the seat tube, decreasing standover height, and thus increasing standover clearance and lowering
1771-404: Is most appropriate when used as part of a rear triangle subframe on a bicycle with independent rear suspension. A dual seat stay refers to seat stays which meet the front triangle of the bicycle at two separate points, usually side-by-side. Fastback seat stays meet the seat tube at the back instead of the sides of the tube. On most seat stays, a bridge or brace is typically used to connect
1848-496: Is preferable to a braced-frame system, which would leave some areas obstructed by the diagonal braces. A truss that is assumed to comprise members that are connected by means of pin joints, and which is supported at both ends by means of hinged joints and rollers, is described as being statically determinate . Newton's Laws apply to the structure as a whole, as well as to each node or joint. In order for any node that may be subject to an external load or force to remain static in space,
1925-422: Is the force in the member, γ is a safety factor (typically 1.5 but depending on building codes ) and σ y is the yield tensile strength of the steel used. The members under compression also have to be designed to be safe against buckling. The weight of a truss member depends directly on its cross section—that weight partially determines how strong the other members of the truss need to be. Giving one member
2002-442: Is the simplest geometric figure that will not change shape when the lengths of the sides are fixed. In comparison, both the angles and the lengths of a four-sided figure must be fixed for it to retain its shape. The simplest form of a truss is one single triangle. This type of truss is seen in a framed roof consisting of rafters and a ceiling joist , and in other mechanical structures such as bicycles and aircraft. Because of
2079-504: Is two regular tetrahedrons along with an octahedron. They fill up three dimensional space in a variety of configurations. [REDACTED] The Pratt truss was patented in 1844 by two Boston railway engineers, Caleb Pratt and his son Thomas Willis Pratt . The design uses vertical members for compression and diagonal members to respond to tension . The Pratt truss design remained popular as bridge designers switched from wood to iron, and from iron to steel. This continued popularity of
2156-570: Is typically larger, unthreaded, and sometimes split. The chain stays, seat tube, and down tube all typically connect to the bottom bracket shell. There are a few traditional standard shell widths (68, 70 or 73 mm). Road bikes usually use 68 mm; Italian road bikes use 70 mm; Early model mountain bikes use 73 mm; later models (1995 and newer) use 68 mm more commonly. Some modern bicycles have shell widths of 83 or 100 mm and these are for specialised downhill mountain biking or snowbiking applications. The shell width influences
2233-451: The Q factor or tread of the bike. There are a few standard shell diameters (34.798 – 36 mm) with associated thread pitches (24 - 28 tpi). On some gearbox bicycles , the bottom bracket shell may be replaced by an integrated gearbox or a mounting location for a detachable gearbox. The length of the tubes, and the angles at which they are attached define a frame geometry . In comparing different frame geometries, designers often compare
2310-408: The headset , the interface with the fork . The top tube connects the head tube to the seat tube at the top. The top tube may be positioned horizontally (parallel to the ground), or it may slope downwards towards the seat tube for additional stand-over clearance. The down tube connects the head tube to the bottom bracket shell. The rear triangle connects to the rear fork ends , where the rear wheel
2387-449: The seatpost of the bike, which connects to the saddle. The saddle height is adjustable by changing how far the seatpost is inserted into the seat tube. On some bikes, this is achieved using a quick release lever. The seatpost must be inserted at least a certain length; this is marked with a minimum insertion mark . The seat tube also may have braze-on mounts for a bottle cage or front derailleur . The chain stays run parallel to
Woolsey Bridge - Misplaced Pages Continue
2464-471: The Pratt truss by Charles H. Parker that features a top chord that is not parallel to the bottom chord. Although stronger in the center than parallel bridges, the style is less common due to its complexity. The Woolsey Bridge was likely built by a county workforce in 1925, possibly consisting of area residents. The bridge was closed to traffic in January, 2015 and a replacement bridge opened in 2018. The old bridge
2541-418: The Pratt truss is probably due to the fact that the configuration of the members means that longer diagonal members are only in tension for gravity load effects. This allows these members to be used more efficiently, as slenderness effects related to buckling under compression loads (which are compounded by the length of the member) will typically not control the design. Therefore, for given planar truss with
2618-457: The areas inside the webs are called panels , or from graphic statics (see Cremona diagram ) 'polygons'. Truss derives from the Old French word trousse , from around 1200 AD, which means "collection of things bound together". The term truss has often been used to describe any assembly of members such as a cruck frame or a couple of rafters. One engineering definition is: "A truss
2695-480: The base structures of large free-standing power line pylons. There are two basic types of truss: A combination of the two is a truncated truss, used in hip roof construction. A metal plate-connected wood truss is a roof or floor truss whose wood members are connected with metal connector plates . Truss members form a series of equilateral triangles, alternating up and down. Truss members are made up of all equivalent equilateral triangles. The minimum composition
2772-411: The bearings (in a cartridge or not) interface with "cups" pressed into the head tube. The top tube , or cross-bar , connects the top of the head tube to the top of the seat tube. In a traditional-geometry diamond frame, the top tube is horizontal (parallel to the ground). In a compact-geometry frame, the top tube is normally sloped downward toward the seat tube for additional standover clearance. In
2849-408: The cables from damage and dirt, which can e.g. make gear shifting unreliable. The space between the top tube and the rider's groin while straddling the bike and standing on the ground is called clearance. The total height from the ground to this point is called the height lever. The down tube connects the head tube to the bottom bracket shell. On racing bicycles and some mountain and hybrid bikes,
2926-404: The center of gravity. Opinion is divided on the riding merits of the compact frame, but several manufacturers claim that a reduced range of sizes can fit most riders, and that it is easier to build a frame without a perfectly level top tube. Road bicycles for racing tend to have a steeper seat tube angle , measured from the horizontal plane. This positions the rider aerodynamically and arguably in
3003-413: The chain, connecting the bottom bracket shell (which holds the axis around which the pedals and cranks rotate) to the rear fork ends or dropouts. A shorter chain stay generally means that the bike will accelerate faster and be easier to ride uphill, at least while the rider can avoid the front wheel losing contact with the ground. When the rear derailleur cable is routed partially along the down tube, it
3080-407: The connections may also be required to transfer bending moment. Wood posts enable the fabrication of strong, direct, yet inexpensive connections between large trusses and walls. Exact details for post-to-truss connections vary from designer to designer, and may be influenced by post type. Solid-sawn timber and glulam posts are generally notched to form a truss bearing surface. The truss is rested on
3157-441: The derailleur cables run along the down tube, or inside the down tube. On older racing bicycles, the shift levers were mounted on the down tube. On newer ones, they are mounted with the brake levers on the handlebars. Bottle cage mounts are also on the down tube, usually on the top side, sometimes also on the bottom side. In addition to bottle cages, small air pumps may be fitted to these mounts as well. The seat tube contains
Woolsey Bridge - Misplaced Pages Continue
3234-452: The design decisions beyond mere matters of economics. Modern materials such as prestressed concrete and fabrication methods, such as automated welding , have significantly influenced the design of modern bridges . Once the force on each member is known, the next step is to determine the cross section of the individual truss members. For members under tension the cross-sectional area A can be found using A = F × γ / σ y , where F
3311-400: The down tube. Cantilever frames are popular on the cruiser bicycle , the lowrider bicycle , and the wheelie bike . In many cantilever frames the only straight tubes are the seat tube and the head tube. The recumbent bicycle moves the cranks to a position forward of the rider instead of underneath, generally improving the slipstream around the rider without the characteristic sharp bend at
3388-403: The equilibrium condition described. Because the forces in each of its two main girders are essentially planar, a truss is usually modeled as a two-dimensional plane frame. However if there are significant out-of-plane forces, the structure must be modeled as a three-dimensional space. The analysis of trusses often assumes that loads are applied to joints only and not at intermediate points along
3465-414: The exact arrangement of forces is depending on the type of truss and again on the direction of bending. In the truss shown above right, the vertical members are in tension, and the diagonals are in compression. In addition to carrying the static forces, the members serve additional functions of stabilizing each other, preventing buckling . In the adjacent picture, the top chord is prevented from buckling by
3542-411: The expense of added weight to achieve equivalent strength and rigidity. Control cables are routed along mounts on the top tube, or sometimes inside the top tube. Most commonly, this includes the cable for the rear brake, but some mountain bikes and hybrid bicycles also route the front and rear derailleur cables along the top tube. Inside routing, once only present in the highest price ranges, protects
3619-417: The following conditions must hold: the sums of all (horizontal and vertical) forces, as well as all moments acting about the node equal zero. Analysis of these conditions at each node yields the magnitude of the compression or tension forces. Trusses that are supported at more than two positions are said to be statically indeterminate , and the application of Newton's Laws alone is not sufficient to determine
3696-467: The frame and fork together as a paired set. Besides the ubiquitous diamond frame, many different frame types have been developed for the bicycle, several of which are still in common use today. In the diamond frame, the main "triangle" is not actually a triangle because it consists of four tubes: the head tube, top tube, down tube and seat tube. The rear triangle consists of the seat tube joined by paired chain stays and seat stays. The head tube contains
3773-504: The implication that no moments exist at the jointed ends. This style of structure was named after the Belgian engineer Arthur Vierendeel , who developed the design in 1896. Its use for bridges is rare due to higher costs compared to a triangulated truss. The utility of this type of structure in buildings is that a large amount of the exterior envelope remains unobstructed and can be used for windows and door openings. In some applications this
3850-477: The joints in a truss are treated as revolutes , as is necessary for the links to be two-force members. A planar truss is one where all members and nodes lie within a two-dimensional plane, while a space frame has members and nodes that extend into three dimensions . The top beams in a truss are called 'top chords' and are typically in compression , the bottom beams are called 'bottom chords', and are typically in tension . The interior beams are called webs , and
3927-501: The member forces. In order for a truss with pin-connected members to be stable, it does not need to be entirely composed of triangles. In mathematical terms, the following necessary condition for stability of a simple truss exists: where m is the total number of truss members, j is the total number of joints and r is the number of reactions (equal to 3 generally) in a 2-dimensional structure. When m = 2 j − 3 {\displaystyle m=2j-3} ,
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#17328521155564004-407: The members connecting the nodes of the upper arc with those of the lower, straight sequence of members, from nearly isosceles triangles to a variant of the Pratt truss. One of the simplest truss styles to implement, the king post consists of two angled supports leaning into a common vertical support. The queen post truss, sometimes queenpost or queenspost , is similar to a king post truss in that
4081-510: 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 . In this typical context, external forces and reactions to those forces are considered to act only at the nodes and result in forces in the members that are either tensile or compressive . For straight members, moments ( torques ) are explicitly excluded because, and only because, all
4158-446: The members. Component connections are critical to the structural integrity of a framing system. In buildings with large, clearspan wood trusses, the most critical connections are those between the truss and its supports. In addition to gravity-induced forces (a.k.a. bearing loads), these connections must resist shear forces acting perpendicular to the plane of the truss and uplift forces due to wind. Depending upon overall building design,
4235-431: The members. The weight of the members is often insignificant compared to the applied loads and so is often omitted; alternatively, half of the weight of each member may be applied to its two end joints. Provided that the members are long and slender, the moments transmitted through the joints are negligible, and the junctions can be treated as " hinges " or "pin-joints". Under these simplifying assumptions, every member of
4312-405: The minimization of compression member lengths allowed for lower aerodynamic drag . Named for their shape, bowstring trusses were first used for arched truss bridges , often confused with tied-arch bridges . Thousands of bowstring trusses were used during World War II for holding up the curved roofs of aircraft hangars and other military buildings. Many variations exist in the arrangements of
4389-427: The minimum cross section of the members, the last step in the design of a truss would be detailing of the bolted joints , e.g., involving shear stress of the bolt connections used in the joints. Based on the needs of the project, truss internal connections (joints) can be designed as rigid, semi rigid, or hinged. Rigid connections can allow transfer of bending moments leading to development of secondary bending moments in
4466-523: The notches and bolted into place. A special plate/bracket may be added to increase connection load transfer capabilities. With mechanically-laminated posts, the truss may rest on a shortened outer-ply or on a shortened inner-ply. The later scenario places the bolts in double shear and is a very effective connection. Bicycle frame A bicycle frame is the main component of a bicycle , onto which wheels and other components are fitted. The modern and most common frame design for an upright bicycle
4543-438: The other hand, reducing the size of one member from the previous iteration merely makes the other members have a larger (and more expensive) safety factor than is technically necessary, but doesn't require another iteration to find a buildable truss. The effect of the weight of the individual truss members in a large truss, such as a bridge, is usually insignificant compared to the force of the external loads. After determining
4620-412: The other tubes in the frame, that runs side to side and holds the bottom bracket . It is usually threaded, often left-hand threaded on the right (drive) side of the bike to prevent loosening by fretting induced precession , and right-hand threaded on the left (non-drive) side. There are many variations, such as an eccentric bottom bracket, which allows for adjustment in tension of the bicycle's chain. It
4697-475: The outer supports are angled towards the centre of the structure. The primary difference is the horizontal extension at the centre which relies on beam action to provide mechanical stability. This truss style is only suitable for relatively short spans. Lenticular trusses, patented in 1878 by William Douglas (although the Gaunless Bridge of 1823 was the first of the type), have the top and bottom chords of
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#17328521155564774-425: The presence of bracing and by the stiffness of the web members. The inclusion of the elements shown is largely an engineering decision based upon economics, being a balance between the costs of raw materials, off-site fabrication, component transportation, on-site erection, the availability of machinery and the cost of labor. In other cases the appearance of the structure may take on greater importance and so influence
4851-430: The rear wheel, chain, crankarms, or the heel of the foot. The seat stays connect the top of the seat tube (often at or near the same point as the top tube) to the rear fork dropouts. A traditional frame uses a simple set of paralleled tubes connected by a bridge above the rear wheel. When the rear derailleur cable is routed partially along the top tube, it is also usually routed along the seat stay. Many alternatives to
4928-406: The relation (a) is necessary, it is not sufficient for stability, which also depends on the truss geometry, support conditions and the load carrying capacity of the members. Some structures are built with more than this minimum number of truss members. Those structures may survive even when some of the members fail. Their member forces depend on the relative stiffness of the members, in addition to
5005-400: The same function as the flanges of an I-beam . Which chord carries tension and which carries compression depends on the overall direction of bending . In the truss pictured above right, the bottom chord is in tension, and the top chord in compression. The diagonal and vertical members form the truss web , and carry the shear stress . Individually, they are also in tension and compression,
5082-434: The seat tube angle, head tube angle, (virtual) top tube length, and seat tube length. To complete the specification of a bicycle for use, the rider adjusts the relative positions of the saddle, pedals and handlebars: The geometry of the frame depends on the intended use. For instance, a road bicycle will place the handlebars in a lower and further position relative to the saddle giving a more crouched riding position; whereas
5159-426: The stability of this shape and the methods of analysis used to calculate the forces within it, a truss composed entirely of triangles is known as a simple truss. However, a simple truss is often defined more restrictively by demanding that it can be constructed through successive addition of pairs of members, each connected to two existing joints and to each other to form a new joint, and this definition does not require
5236-399: The stays above the rear wheel and below the connection with the seat tube. Besides providing lateral rigidity, this bridge provides a mounting point for rear brakes, fenders, and racks. The seat stays themselves may also be fitted with brake mounts. Brake mounts are often absent from fixed-gear or track bike seat stays. The bottom bracket shell is a short and large diameter tube, relative to
5313-548: The top tube was patented by Volagi Cycles . This frame element added length to the traditional design of seat stays, making a softer ride at the sacrifice of frame stiffness. Another common seat stay variant is the wishbone , single seat stay , or mono stay , which joins the stays together just above the rear wheel into a monotube that is joined to the seat tube. A wishbone design adds vertical rigidity without increasing lateral stiffness, generally an undesirable trait for bicycles with unsuspended rear wheels. The wishbone design
5390-421: The total load. The internal forces in the members of the truss can be calculated in a variety of ways, including graphical methods: A truss can be thought of as a beam where the web consists of a series of separate members instead of a continuous plate. In the truss, the lower horizontal member (the bottom chord ) and the upper horizontal member (the top chord ) carry tension and compression , fulfilling
5467-500: The traditional seat stay design have been introduced over the years. A style of seat stay that extends forward of the seat tube, below the rear end of the top tube and connects to the top tube in front of the seat tube, creating a small triangle, is called a Hellenic stay after the British frame builder Fred Hellens, who introduced them in 1923. Hellenic seat stays add aesthetic appeal at the expense of added weight. This style of seat stay
5544-403: The truss arched, forming a lens shape. A lenticular pony truss bridge is a bridge design that involves a lenticular truss extending above and below the roadbed. American architect Ithiel Town designed Town's Lattice Truss as an alternative to heavy-timber bridges. His design, patented in 1820 and 1835, uses easy-to-handle planks arranged diagonally with short spaces in between them, to form
5621-415: The truss is said to be statically determinate , because the ( m +3) internal member forces and support reactions can then be completely determined by 2 j equilibrium equations, once we know the external loads and the geometry of the truss. Given a certain number of joints, this is the minimum number of members, in the sense that if any member is taken out (or fails), then the truss as a whole fails. While
5698-519: The truss is then subjected to pure compression or pure tension forces – shear, bending moment, and other more-complex stresses are all practically zero. Trusses are physically stronger than other ways of arranging structural elements, because nearly every material can resist a much larger load in tension or compression than in shear, bending, torsion, or other kinds of force. These simplifications make trusses easier to analyze. Structural analysis of trusses of any type can readily be carried out using
5775-542: The waist used by racers of diamond-frame bicycles. Banned from bicycle racing in France in 1934 to avoid rendering diamond-frame bicycles obsolete in racing, manufacturing of recumbent bicycles remained depressed for another half century, but many models from a range of manufacturers were available by 2000. The uncommon prone bike moves the cranks to the rear of the rider, resulting in a head-forward, chest-down riding position. A cross frame consists mainly of two tubes that form
5852-449: Was disassembled and given to the town of West Fork with the intention it would be repurposed into a pedestrian bridge. Truss 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
5929-435: Was popularized again in the late 20th century by GT Bicycles (under the moniker "triple triangle"), who had incorporated the design element into their BMX frames, as it also made for a much stiffer rear triangle (an advantage in races); this design element has also been used on their mountain bike frames for similar reasons. In 2012, a variation of the traditional seat stay that bypasses the seat tube and connects further into
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