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# Presentation (truss) by imran khan.

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Civil Engineering ( Frames & Truss)

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### Presentation (truss) by imran khan.

1. 1. UNIVERSITY OF INFORMATION TECHNOLOGY & SCIENCES
2. 2. CE 302  Structural Analysis & Design Lab 1
3. 3. Civil Engineering An outlook on
4. 4. PREPARED BY MD. IMRAN HOSSAIN (ID:12310177)
5. 5. DEFINITION OF FRAME  A-Frame is a basic structure designed to bear a load in a light weight economical manner.  A frame is a structural system that supports other components of a physical construction.  Multi forced members are generally known as Frames.  Frames are commonly used to support various external loads.
6. 6. FRAME
7. 7. FRAME
8. 8. ANALYSIS OF FRAME  A free body diagram of the complete frame is used to determine the external forces acting on the frame.  Internal forces are determined by dismembering the frame and creating free-body diagrams for each component.
9. 9. WHAT IS TRUSS ? A truss is a structure comprising one or more triangular units constructed with straight members whose ends are connected at joints or nodes. If all the bars lie in a plane, the structure is a planar truss. The main parts of a planar truss. TRUSS ANALYSIS  In other words, Trusses are designed to form a stable structure.
10. 10. TRUSS ANALYSIS Following characteristics of Truss * The members of the truss should be in a plane. * Members are connected at their intersections by means of frictionless pins or hinge. * Loads and reactions are applied only at joint. * The centroid of the members must coincide with centroid of the joints.
11. 11. Truss Members  The members which from the outline or perimeter of a truss are generally called the chord members. There are two chord members - 01. Top Chord: Top members 02. Bottom Chord: Bottom members  Web Members – The interior members connecting the joints of the chords are called the web members. There are two members- 01. Diagonal members 02. Vertical members TRUSS ANALYSIS
12. 12. TRUSS ANALYSIS Why are trusses strong? Trusses derive their strength from the triangle. The simplest of plane polygons, a triangle is unique in that it is defined by the length of its sides. That is, one and only one triangle can be drawn if the length of all three sides is given.
13. 13. TRUSS ANALYSIS Why are triangles used in trusses?  Rectangles and squares are not very strong because the middle of each side would tend to bend or buckle easily. And these are not used in truss.  A truss is a structure made up of triangles. Because triangles are strong because when you define the length of the three sides the relationship between the nodes is fixed. Similarly when you identify any two angles an a side or two sides and a common angle all other properties are fixed. In any other shape there are more degrees of rigidity required to create a fixed structure. Triangles have sides that reinforce each other. They divide up the load.
14. 14. TRUSS ANALYSIS Application of trusses-  Roof of factory shade.  Ware house  Railway platform  Garage shed  transmission towers  Crane truss  Bridge Truss  Sport Stadium Truss
15. 15. TRUSS ANALYSIS
16. 16. TRUSS ANALYSIS
17. 17. TRUSS ANALYSIS
18. 18. TRUSS ANALYSIS
19. 19. TRUSS ANALYSIS
20. 20. TRUSS ANALYSIS  Joint Method  Determine the Support Reaction.  Apply Fx = 0 and Fy = 0 to every node and determine member force  Dismember the truss and create a free-body diagram for each member and pin. METHOD OF TRUSS ANALYSIS
21. 21. TRUSS ANALYSIS  SECTI ON METHOD  Determine the Support Reaction.  To determine the force in member BD, pass a section through the truss as shown and create a free body diagram for the left side.  With only three members cut by the section, the equations for static equilibrium may be applied to determine the unknown member forces, including FBD. METHOD OF TRUSS ANALYSIS
22. 22. TRUSS ANALYSIS Comparison of Trusses and Frames Trusses Frames  Members are subjected to tension/compression only  At least one member is subjected to bending, shear or torsion  Forces are applied at the joints only.  Forces may act anywhere on the member.  Member does not bend.  Members may bend/may not bend.  Composed of rods.  Composed of bars.  Used for large loads.  Used for small and medium loads.
23. 23. TRUSS ANALYSIS Advantages of Truss & Frame  Cost Effective.  Can be installed quickly even without heavy equipment to lift it into place  Unique properties of a triangular object allow trusses to span across longer distances
24. 24. TRUSS ANALYSIS Common Types of Trusses-  King post & Queen post Truss.  Warren Truss.  Howe Truss.  Pratt Truss.  English Truss.  K- Truss.  Baltimore Truss.  Continuous Truss.  Bowstring Truss.
25. 25. TRUSS ANALYSIS  Also known as Crescent Truss  Is a truss consisting of curved top chord meeting bottom chord at each end.  Has diagonal load-bearing members.  Often confused with tied arch bridges Bowstring Truss-
26. 26. TRUSS ANALYSIS  King post  It is used for simple short-span bridges.  Fewest number off truss members.- two diagonal members, kingpost braces, that meet at the apex of the truss, one horizontal beam and the king post which connect the apex to the horizontal beam below. King post & Queen Post Truss-
27. 27. TRUSS ANALYSIS  Queen post  It has two vertical post.  Very strong and stable.  It s more stable and can support a wider span than a kingpost. King post & Queen Post Truss-
28. 28. TRUSS ANALYSIS  It uses equilateral triangles to spread out the loads on the bridges. The equilateral triangles minimize the forces to only compression and tension.  This bridges are often used with verticals to reduce the panel size. Warren Truss-
29. 29. TRUSS ANALYSIS  It became very popular and was considered one of the best designs for railroad bridges back in the day.  Wooden beams for the diagonal members, which were in compression. It used iron (and later steel) for the vertical members, which were in tension. Howe Truss-
30. 30. TRUSS ANALYSIS
31. 31. TRUSS ANALYSIS  Very common type but has many variations (Baltimore, Pennsylvania, and the Parker)  The basic identifying features are the diagonal web members which form a V-shape. (Howe truss bridge has a A-shape).  Commonly used for supporting railways.  The Pratt truss’s verticals functioned as compression members and diagonals functioned as tension members.  The Pratt truss required more iron than a Howe truss, Pratt Truss-
32. 32. TRUSS ANALYSIS
33. 33. TRUSS ANALYSIS  The length of members undergoing compression is reduced. This reduction in length enables components of bridges to endure the compressional force.  The design is complicated and it is considered to be one of the hardest bridges to build. K- Truss-
34. 34. TRUSS ANALYSIS
35. 35. TRUSS ANALYSIS Roof Truss-  Roof trusses, which are structural components of houses or commercial buildings, support the weight of roof timbers and coverings.  Usually, they are constructed from pieces of timber or steel which are nailed, bolted, or pegged together to form a mutually supporting and strong base for a roof.
36. 36. TRUSS ANALYSIS
37. 37. TRUSS ANALYSIS Design of industrial roof truss:  Steps of work 1. Selection of truss type. 2. Estimation of loads. 3. Analysis & design of purlin. 4. Analysis & design of sag rod. 5. Dead load(DL) and Wind load(WL) analysis of truss member. 6. Combination of DL and WL to determine the design bar forces. 7.Design of member according to the bar forces. 8.Design of bracing system. 9.Design of connection. 10.Detailing.
38. 38. TRUSS ANALYSIS We will design a Industrial roof truss
39. 39. TRUSS ANALYSIS  Design of Purlin  Then calculating of purlin number and Purlin spacing.  Then load analysis- 01. Dead load analysis. 02.live load analysis.  Then we find out member force by grasp software.  Bracing design- 01. Top chord bracing. 02. Bottom chord bracing. 03. Vertical bracing.
40. 40. TRUSS ANALYSIS Types of Truss Connection- 01. Pinned Connection.
41. 41. TRUSS ANALYSIS Types of Truss Connection- 02. Gusset plate Connection.