Pony truss design pdf

Patapsco bridge and iron works, baltimore in addition to its work in baltimore, built a pratt pony truss in 1879. A new prefabricated steel pony truss superstructure with integral walkway will replace the existing truss bridge. The west virginia division of highways is proposing to replace the yonperaldo memorial bridge bramwell twin pony truss and the duhring street pony truss bridge, two bridges in the town of bramwell, west virginia project handout 22 mb pdf. Design considerations for pedestrian truss bridge structures. This 1870s bowstring arch truss represents the early days of metal bridge construction in indiana. He often cited this bridge as an example of the superiority of. Maraveas partnership, consulting engineers, greece 2school of mechanical, aerospace and civil engineering, university of manchester, uk. Aug 17, 2017 today i found out what exactly a pony truss is.

Northern route wabash riverdeer creek corridor bridge datetype location. The duhring street pony truss bridge is located on county route 2020 and consists of replacing the existing bridge that crosses over bluestone river. Bollman applied for a patent on his truss design in 1851 and received it in 1852. The structural components and features common to the design are present on the truss and remain unchanged. Jul 07, 2015 it is the intent of the author to present the unique design approach applying the theory of lateral stability to a pony truss bridge. The warren truss is one of several variants on the basic kingpost structural system, and it was patented in england by james warren and willoughby monzani in 1848 and by squire whipple inventor of the whipple truss in 1849.

Starting in 1920 the state highway department adopted the steel riveted parker truss as its standard pony truss design, with plans provided for trusses of. It is no longer in service, but it previously carried a minimummaintenance road over the nokasippi river. To a lesser extent, it was also found that truss members in properly designed and constructed bridges can also be redundant. The basic types of truss bridges shown in this article have simple designs which could be easily analyzed by. A highresolution model of a ponytruss bridge was assembled in abaqus.

Low trusses, or pony trusses, are an economical way to build shortspan bridges. The projects consist of replacing both bridges in their existing locations. Bridge replacement on a rehabilitation budget walnut. Characterized by pratt design but with an inclined top chord, the parker truss was popular for longer spans well into the twentieth century. The publication also applied those terms to queenpost and queenrod trusses. The proposed methodology relies on a computer software package that has the ability to perform a. Component connections are critical to the structural integrity ofa framing system. Stability of pony trussstability of pony truss design of transverse frame p d i f t f i ti l tproper design of transverse frames is essential to the safety of the pony truss bridge guide to stability design criteria for steel structuresguide to stability design criteria for steel structures, galambos. Bakht, research and development division, ontario ministry of transportation and communications at one time, low or pony truss bridges were popular for their economy and ease of construction. The howe truss design eliminated the need for skilled carpenters to notch and peg. Wcd1 details for conventional wood frame construction. Distribution statement bridge, fracture critical, fracture, truss, pony truss.

The pratt truss the pratt truss was first developed in 1844 under. Pawpaw creek parker pony truss spanning pawpaw creek vinita. Truss4 is another truss design software for windows. A truss bridge is a bridge whose loadbearing superstructure is composed of a truss, a structure of connected elements, usually forming triangular units. Once constructed of wooden timbers, and later including iron tension members, most truss bridges are built of metal. A very good discussion of this may be found in the ssrc guide to stability design criteria for metal structures, 5th edition, theodore v. The town lattice design was patented by ithel town in 1820 and consisted of a truss design depicting an rhombus x pattern. A lenticular pony truss bridge is a bridge design that involves a lenticular truss extending above and below the roadbed. The pratt type successfully survived the transition to iron construction as well as the. The top chord of a pony truss may fail due to outofplane. May 09, 2012 this truss style is onlysuitable for relatively short spansda lenticuler pony truss bridge is a bridge design that involves alenticuler truss extending above and below the roadbed.

The bowstring truss bridge is located at the ironto rest area on interstate 81 in montgomery county, virginia. Preliminary design included an evaluation of truss alternatives and establishing an initial working line geometry that would allow truss chords to be fabricat. The 2006 bridge inspection reference manual 4 identifies three types of trusses, grouped according to deck position, as shown in figure 1. All of the wooden trusses in tennessee are pony trusses, but since the term kingpost. The only known previously surveyed maryland example of a. King iron bridge company, cleveland, ohio built pratt and bowstring trusses in maryland from 1880 through 1892. The typical new truss is assumed to be a warrentype or pratttype pony truss with vertical truss web members at each panel point. W e have identified six general trail bridge types. The design teams innovative solution included treating the top chord as a beamcolumn supported by an elastic foundation the truss verticals. The design of the new bridge included a threespan structure with w14 x 61 steel plate girders, the frp composite decking material, and a bituminous concrete wearing surface. Parker in a series of patents he filed between 1868 and 1871. Rehabilitation of a steel pony truss using maintenance. Rehabilitation of a steel pony truss using maintenance free.

This module also provides for alternate 24inch spacing of floor, wall and roof framing where floor and roof trusses are used, and accommodates 24inch spacing of studs where wind loads. Design strength and stiffness requirements for the uframe formed by the truss web members and the bridge floor beams. Elastic stability of the top chord of a threespan continuous. Sand creek camelback pony truss nash vicinity oklahoma.

The fhwa nhi 12049 bridge inspection reference manual is a. Evaluation and rehabilitation of historic metal truss bridges. The 80foot trusses are minnesotas longest surviving examples of this particular truss type. Coltman bridge, spanning fever river, on horseshoe bend. These different types of bridges, as well as different material types, have differing span limitations. The connected elements typically straight may be stressed from tension, compression, or sometimes both in response to dynamic loads. 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 the truss arched, forming a lens shape. Continental pedestrian truss bridge specification contech. Manual for bridge inspection mbe as steel tension members or steel. The purpose is to show the real vulnerability of a steel truss bridge.

Pier bridge, newport 1907, doubleweb town lattice truss. Retrofit and design strategies for pony truss bridge floor systems. Out of 443 wisconsin trusses of this design, this bridge is one of three of the best examples. I had heard the term before, but never understood what it meant. Although economical, the design was better suited for use on larger through trusses. The parker through truss, likely constructed by the federal bureau of public roads, represents a typical parker truss built at major river crossings in the 1920s and 1930s.

Concrete, steel concrete and wood and steel type of bridge. The warren pony truss has a polygonal top chord innovation in design and was designed or contructed by a regional or west virginiabased engineer or firm. The bridge design could incorporate architectural overhead truss. The top chord, truss verticals, and floor beams shall be. It is believed that the hemlock road bridge is an example of a michigan standard pony truss bridge. A short numerical example is included in appendix b to.

Strains were measured over a period of four years commencing during the construction period and continuing through subsequent occupation of the building. Bridge replacement on a rehabilitation budget walnut street. The problem studied was one of a lonj top chord which is essentially a beomcolumn elasticolly supported at intormediate points by a frame composed of the verticals of the truss. All of the wooden trusses in tennessee are pony trusses, but since the term. The bridge consists of two simple riveted and bolted steel pony truss spans sspt and is supported at each end by fullheight stone masonry. The new owner must pay for moving the bridge and constructing. Pony trusses have the same failure modes as a through or deck truss, but also require additional design considerations for the top compression chord. Design of halfthrough or pony truss bridges using square or. At one time, low or pony truss bridges were popular for their economy and ease of construction. The sand creek camelback pony truss bridge, built in 1936, is a rare example of a sixpanel, camelback pony truss bridge in north central oklahoma.

Today, pony trusses are seldom built, having been replaced by the multibeam bridge. The full version of this software is paid, but you can use its demo version free of charge. However, for a short period, approximately 1908 through 1915, the design was used to construct small pony trusses 85 to 110 feet. If the deck is located at the level of the bottom chord, the bridge is called a through truss. Limit state design and lateral buckling analysis of the steel. Such methods use a 4foot design module, which governs a 16inch spacing of joists, studs, rafters and panel sheathing products. As a pony truss, bowstrings are generally the most economical of all truss types for spans up to 100 feet. If crossbracing is present above the deck of the bridge, then the bridge is referred to as a through truss. The problem studied was one of a lonj top chord which is essentially a beomcolumn elasticolly supported at intormediate points by a frame composed of the verticals of the truss and the floor beams framing into the verticals. Illustrated in this paper is the development of an optimized of design methodology of these structures elements through the implementation of a spreadsheet to perform several iteration processes. Because of their height, pony truss bridges do not have overhead bracing and, when built of wood, need to be housed differently than fullheight timber bridges to allow for the passage of vehicles.

The parker truss design, a modified pratt truss, was designed with an arched top chord that used less metal for construction. Types of truss bridges are also identified by the terms deck, pony and through which describe the placement of the travel surface in relation to the superstructure see drawings. Key terms to successfully complete this learning activity, you must understand the following key terms and concepts from previous learning activities. In linear mechanics of deformable bodies, displacements are proportional. The united states government defines a historic bridge. Design of halfthrough or pony truss bridges using square. The pony trusses were secured together with hot rivets. Metal stud framing gypsum supply steeler construction.

The existing bridge was built in 1915 by the virginia bridge and iron company of roanoke, virginia. The structure is a singlespan, fourpanel tubular arch pony truss measuring 55 feet long, 12 feet. Design of halfthrough or pony truss bridges using square or rectangular hollow structural sections. Due to modern construction practices, and increased costs, new truss connections will be bolted or welded gusset plates rather than antiquated pinned connections. Most bridges of this design type have five panels per span. Parallelchord trusses are constructed in various through truss or deck truss configurations for spans up to approximately 250 feet. Other wooden railroad bridges that survived until fairly recently. Maryland examples located through research include the bullfrog road bridge over the monocacy in frederick county mhtf68, a riveted through bridge built 1908 by york bridge company and several spans.

Bridge historians and early textbooks generally call a truss with alternating compression and tension diagonals a warren. The initial part of this paper will outline some of the research, testing, and investigation which has been done on halfthrough truss bridges. The demo version comes with many feature restrictions, e. All vertical truss members shall be perpendicular to the ground horizon after the bridge is erected and dead loads applied. Limit state design and lateral buckling analysis of the. The critical feature of the through truss walk way, or pony truss is that the top chord lateral bracing provided by elastic restraint from the web and floor beam members. Through truss, pony truss and deck truss elevations and crosssections mdot made direct contact with the local agency bridge owners who have steel deck truss. Elastic stability of the top chord of a threespan continuous pony. This research is primarily concerned with two items. Bridge l3942 is a steel, threepanel, halfhip, pratt pony truss resting on concrete abutments with flared wingwalls. The most common solution was to cover each truss separately. York bridge company, york, pennsylvania built pratt, warren, and. High resolution modeling and modeling of connections in pony.

Fracture critical analysis procedures and design and. Stability of ponytruss bridges the institution of structural engineers. Existing bridge 1895 pony truss 1952 rehabilitation singlelane 6 ton posting structural flags temporary shoring south approach photo. Limit state design and lateral buckling analysis of the steel pony. Design of the top chord of the truss considering outofplane buckling problems. Although the pony truss bridge was popular before world war ii, they are rarely used today and there is little guidance in aashto or other current references about their design. Fracture critical analysis procedures and design and retrofit. With the tremendous increase in commercial vehicle weights, especially after world war ii, the loadcarrying capacity of these bridges became suspect, and many were taken out of service or replaced by modern structures.

Starting in 1920 the state highway department adopted the steel riveted parker truss as its standard pony truss design, with plans provided for trusses of 100,110, and 120 feet. If the trusses run beside the deck, with no cross bracing above the deck, it is called a pony truss bridge. It is the earliest surviving example of a curved chord warren pony truss in the state, and one of seven built between 1900 and 1927. A pony truss is a truss bridge which allows traffic through the truss, but the top of the bridge is not joined together with cross braces. The coltman bridge is a representative example of the state highway commissiondesigned warren standard pony truss design, adapted to a skewed crossing. When the roadbed is atop the truss it is called a deck truss an example of this was the i35w mississippi river bridge. Abstract structural optimisation is a topic which gathers the interest of many research.

It is the intent of the author to present the unique design approach applying the theory of lateral stability to a pony truss bridge. The second part of the paper will outline continental bridges design approach to pony trusses. The bridge is also a works progress administration wpa bridge that. Types of truss bridges truss bridges are grouped into three general categories, based on their deck location. This paper presents the fragility curves for a steel pony truss bridge with a 25 meter span. Half through trusses carry the deck so high above the bottom chord that lateral and sway bracing cannot be placed between the bottom chords. A thesis submitted to the faculty of the of the graduate. The bridge is located in rural southwestern crow wing county.