Plane Truss Calculation Spreadsheet
Tag: truss
Truss Analysis And Calculation Spreadsheet
What is a truss Bridge ? Types of Bridge Trusses
What is a truss Bridge ? Types of Bridge Trusses
Definition of a truss Bridge:
Truss is a structure of connected elements forming triangular units, and a bridge whose load-bearing superstructure is composed of a truss is a truss bridge.
From a mechanical point of view, truss structures are highly efficient in using the strengths of construction materials due to the fact that only axial forces are resisted in truss members.
Truss bridges are one of the oldest types of modern bridges. Trusses are generally assumed as pinned connection between adjacent truss members. Therefore, the truss members like chords, verticals, and diagonals act only in either tension or compression.
Axial forces in truss bridges under deadweight. (A) Pratt truss. (B) Warren truss.
Moreover, a truss is generally more rigid than a beam because a truss is composed of a variant of triangles and it has the ability to dissipate a load through the whole truss. The truss bridge is also called a beam bridge with braces.
For modern truss bridges, gusset plate connections are generally used, then bending moments and shear forces of members should be considered for evaluating the real performance of the truss bridges, which is achieved by the aid of finite element software.
For the design point of view, however, the pinned connection assumption is considered for security concerns and also for simplifying the structural design and analyses.
In addition, as the axial forces (but not bending moments and shear forces) are generally governs the stress conditions of the members, such assumption generally will not cause large errors between the real bridges and the design models.
According to this assumption, the truss members can be in tension, compression, or sometimes both in response to dynamic loads.
Owing to its simple design method and efficient use of materials, a truss bridge is economical to design and construct.
Short-span truss bridges are built as simply supported, while the large span truss bridges are generally built as continuous truss bridges or cantilever truss bridges.
Truss bridge examples
Types Of Trusses :
There are three common truss configurations that are often used in bridges, namely Warren truss, modified Warren truss, and Pratt truss.
All these truss configurations can be used as an underslung truss, a semithrough truss, or a through truss bridge.
Warren trusses have parallel chords and alternating diagonals. Warren trusses with verticals to reduce panel size are named as modified Warren truss.
Pratt trusses have diagonals sloping downward toward the center and parallel chords.
Truss types according to structural forms. (A) Warren truss. (B) Modified Warren
truss. (C) Pratt truss
What are Truss Structures?
What are Truss Structures?
A truss is a special type of structure renowned for its high strength- to- weight and stiffness- to- weight ratios.
This structural form has been employed for centuries by designers in a myriad of applications ranging from bridges and race car frames to the International Space Station.Trusses are easy to recognize: lots of straight slender struts joined end- to- end to form a lattice of triangles, such as the bridge in Fig.1.
Fig.1 Truss bridge in Interlaken, Switzerland
In large structures, the joints are often created by riveting the strut ends to a gusset plate as shown in Fig.2.
A structure will behave like a truss only in those regions where the structure is fully triangulated; locations where the struts form other polygonal shapes (e.g., a rectangle) may be subject to a loss of stiffness and strength.
Fig.2 Joint formed by riveting a gusset plate to converging members
The special properties of a truss can be explained in terms of the loads being applied to the individual struts. Consider the three general types of end loadings shown in Fig.3 tension, compression, and bending.
If you were holding the ends of a long thin steel rod in your hands and wanted to break it or at least visibly deform it, bending would be the way to go. Thus, if we could eliminate bending of the struts as a potential failure mode, the overall strength and stiffness of the truss would be enhanced.
Fig.3 Different end loading possibilities. The dashed represents the deformed shape produced by the applied forces
This is precisely the effect of the truss geometry on the structure, as the stiff triangular lattice serves to keep any bending induced in the struts to a minimum.
Hollow Structural Section – Connections And Trusses Free PDF
Hollow Structural Section – Connections And Trusses Free PDF
Rectangular hollow section (RHS) trusses can be formed by welding together single- or double-miter cut RHS web members and RHS chords. Web members may either be gapped or overlapped at the chord face.
Overlapped connections (or joints) are stiffer and stronger than gapped connections, but both are considered to be “semi-rigid” (neither pinned nor rigid).
Lack of connection rigidity is well-known to affect the force distribution and deflections in RHS trusses
Content :
- 1. Introduction
- 2. Previous truss tests
- 3. Truss test program
- 4. RHS truss models
- 5. Evaluation of truss models
- 6. Comments on CSA S16-14 and additional recommendations
- 7. Conclusions
