Pony truss analysis pdf

The buckling problem of the compressive top chord of a pony truss, or, as is called, half through truss, is a problem of members with elastic lateral restraints. Computational analysis and design of bridge structures. Consider computing displacements there are 4 nodes and 4 elements making up the truss. Lost warren pony truss bridge over south skunk river on 16th street in ames replaced, one span lays abandoned in a field on west side of waterway, span on the east side of the waterway removed from field in 2015. This chapter deals with the static analysis of two dimensional trusses, which are basically bars oriented in two dimensional cartesian systems. Loboquintero i architectural faculty, university of the andes, venezuela enginneriq faculty, university of the andes, venezuela abstract this paper presents the fragility curves for a steel pony truss bridge with a 25 meter span. This type is generally used for shorter spans 45 to 100 long. Nondestructive evaluation and loadcarrying tests article pdf available in construction and building materials 243. There are four main assumptions made in the analysis of truss. Aug 12, 2017 free model railroad bridge drawings plans and details of a timber howe pony truss. Method of sections the method of joints is good if we have to find the internal forces in all the truss members.

Truss structures university of kentucky college of. The idea of the k truss is to break up the vertical members into smaller sections. Two important assumptions are made in truss analysis. The typical new truss is assumed to be a warrentype or pratttype pony truss with vertical truss web members at each panel point. In situations where we need to find the internal forces only in a few specific members of a truss, the method of sections. A truss bridge is a bridge whose loadbearing superstructure is composed of a truss, a structure of connected elements usually forming triangular units. The popularity of the howe truss resulted, in part, from its comparatively. The bridge is assumed to fail either when the structure reaches collapse or the maximum displacement reaches a value of span length50 which is a very high value used to simply stop the analysis when a very large level of. The connected elements typically straight may be stressed from tension, compression, or sometimes both in response to dynamic loads.

Please practice handwashing and social distancing, and check out our resources for adapting to these times. The aashto guide specification for pedestrian bridges has a good example for the analysis of a pony truss, particulary due to lateral loads. Free model railroad bridge drawings plans and details of. 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. Truss bridge top chord buckling analysis and redundancy analysis. Truss is a structure of connected elements forming triangular units, and a bridge whose loadbearing superstructure is composed of a truss is a truss bridge. High resolution modeling and modeling of connections in pony. A structure that is composed of a number of bars pin connected at their ends to form a stable framework is called a truss. Howe truss covered bridge built in 1936 24 photograph 5. Truss members are connected together at their ends only. A pratt truss is one of the most common type of truss. Megson, in structural and stress analysis fourth edition, 2019.

Sep 15, 2014 eighth edition 6 7 simple trusses a rigid truss will not collapse under the application of a load. Modern timber bridges concepts of modern timber bridges use of gluedlaminated timbers. Weiwei lin, teruhiko yoda, in bridge engineering, 2017. It is generally assumed that loads and reactions are. The structure was built in the 1950s and was based on a standard pony truss design with an h15 load requirement. Fracture critical analysis procedures and design and. In this video, i walk through a spreadsheet i use to check my simple truss for failures in yield stress, shear stress at the gusset plates, and buckling fail. In a simple truss, m 2n 3 where m is the total number of members and n is the number of joints. Mimic beam behavior truss definitions and details 2.

The simplest form of a truss is one single triangle. Analysis of the intact truss bridge the push down analysis is performed on the originally intact bridge labeled as model 1. Analysis of truss structures common bridge truss analysis of truss structures assumptions for truss design to design both the members and connections of a truss, the force in each member for a given loading must be determined. The loading conditions for tl3 consist of a 54kip force. The k truss design was a variant from the parker truss design. Aug 17, 2017 today i found out what exactly a pony truss is. This joint use of metal and wood materials for bridge components, called a combination truss, was a significant transitional feature in the development of an all metal truss. Warren pony truss bridge moved 2018 to private property just west of old 98th st.

Before discussing the various methods of truss analysis, it would be appropriate to have a brief introduction. The bridge inspector should assume that all tension. A truss is an assembly of beams or other elements that creates a rigid structure. Load test and rating report steel truss bridge, bonham 1. Pony truss analysis o i f r h bilit tioverview of rehabilitation presented by.

Pdf stress analysis of trusses bridges zafar anwar and. Although it is not within the scope of this report to teach truss analysis or design, a brief. In a deck truss bridge the road is above the trusses, and the deck system is on the top chords. A pony trussbridge is the same as a thru truss, but it does not have lateral bracing between the top chords. Bridge historians and early textbooks generally call a truss with alternating compression and tension diagonals a warren. Stability of pony trussstability of pony truss unique analysis requirements for pony truss st bilit f t h d b ith t l t l b istability. The howe truss was patented as an improvement to the long truss which is discussed with covered bridge types. The exceptions are the diagonals in the end panels where, in the pratt truss of fig. The partlcxxlar bridge studied was dosigned by the iowa highway commission in i9i1. A truss is a structure made of two force members all pin connected to each other. The new bridge replaced a onelane pony truss with a fourton load limit on an inadequate alignment. A computeroriented method of rigorous analysis of lateral buckling behaviour of pony truss bridges is briefly discussed. The howe truss used metal vertical tension rods and timber diagonal compression members.

Lateral buckling of pony truss bridges transportation research. Principle and modeling of bridge redundancy analysis. A diagonal member of a pratt truss will, as we saw for the member ec in ex. Loads on the bridge are transmitted by the deck to the. Fourth international conference on current and future. Rehabilitation of a steel pony truss using maintenance free. But, the last two conditions are true if and only if the truss is geometrically stable.

It is the longest and oldest single span truss still in continuous use in texas. Strengthening and widening of steel pony truss bridges. Because of 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. Parker in a series of patents he filed between 1868 and 1871. A steel pony truss bridge becomes an attractive alternative only if the aesthetics criteria prevail. 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 example of a real pony truss bridge. In engineering, a truss is a structure that consists of twoforce members only, where the members are organized so that the assemblage as a whole behaves as a single object.

A study submitted in partial fulfillment of the requirements for the degree of. It includes vertical members and diagonals that slope down towards the center opposite of the howe truss. Chapter 5 begins with a summary of the method proposed for a fracture critical analysis fca of pony truss bridges and concludes with. Probably the most famous pauli truss, better known as the lenticular truss named because of the lens shape, is pittsburghs smithfield street bridge. Evaluation and rehabilitation of historic metal truss bridges. We are going to do a two dimensional analysis so each node is constrained to move in only the x or y direction. 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. Truss structures university of kentucky college of engineering. Some bridges were designed for live loads that are only a fraction of present commercial vehicle weights. In design theory, the individual members of a simple truss are only subject to tension pulling and compression pushing forces and not bending forces. Slough creek crossing, now visible at dead end of 102nd st, new bridge at original location. Pdf structural analysis of two kingpost timber trusses. A twoforce member is a structural component where force is applied to only two points. Structural analysis of two kingpost timber trusses.

The problem of lateral instability of the compression chord of a pony truss is essentially that of a beam column elastically restrained at. Pony truss definition of pony truss by merriamwebster. Timber bridge wins awards constructed in 1906 by the joliet bridge and iron co. The basic types of truss bridges shown in this article have simple designs which could. A transformation of coordinate basis is necessary to translate the local element matrices stiffness matrix, force vector into the structural global coordinate system. The analysis of unstable trusses will always lead to inconsistent, indeterminate, or infinite results.

A simple truss is constructed by successively adding two members and one connection to the basic triangular truss. Fourth international conference on current and future trunds. Pony truss article about pony truss by the free dictionary. This is because the vertical members are in compression. The shorter a member is, the more in can resist buckling from compression. Design of industrial truss university of asia pacific. Modern timber bridges bridge types truss bridges pony truss, bowstring or parallel chord modern timber bridges bridge types truss bridge martis creek bridge 32 x 147 two lane vehicle bridge truckee, ca modern timber bridges bridge types truss bridges cosumnes river bridge 10 x 410 rancho murieta, ca modern timber bridges.

Request pdf high resolution modeling and modeling of connections in ponytruss bridges ponytruss bridges are usually modeled using simplifying assumptions, such as pinned connections and. Characterized by pratt design but with an inclined top chord, the parker truss was popular for longer spans well into the twentieth century. The majority of bridge engineers practicing their expertise today are rarely exposed to the design and analysis of through truss bridges. Stability of pony trussstability of pony truss unique analysis requirements for pony truss st bilit f t h d b ith t l t l b istability of top chord member without lateral bracing what is the unbraced length of top chord.

There are a variety of truss designs, and all have different ways. I had heard the term before, but never understood what it meant. Free model railroad bridge drawings plans and details of a. Pony truss definition is a truss as in bridge building so low that overhead bracing cannot be used. Elastic stability of the top chord of a threespan continuous pony. Eighth edition 6 7 simple trusses a rigid truss will not collapse under the application of a load.