Structural Analysis : Classification of Structures Unit 1 Part 3

Que2.2. What are  colorful types of trusses? Explain with the  help of neat sketches. 

Answer  The  colorful types of the trusses are described as follows  Roof Trusses  1. Roof trusses are  frequently used as part of an artificial  structure frame, as  shown inFig.2.2.1. Then, the roof  cargo is transmitted to the stilt at the  joints by means of a series of purlins.  2. The roof stilt along with its supporting columns is called as  fraudulent.  3. naturally, roof trusses are supported either by columns of wood,  sword,  or  corroborated concrete, or by masonry walls.  4. To keep the  fraudulent rigid, and thereby able of  defying vertical wind  forces, knee braces are  occasionally used at the supporting columns.  5. The space between  conterminous bents is called a bay. kudos are economically  spaced at about4.6 m for spans around 18 m and about6.1 m for spans  of 30m.  6. kudos are  frequently tied together using  slant bracing in order to maintain   severity of the  structure’s structure.  7. Trusses used to support roofs are  named on the base of the span, the   pitch, and the roof material.  8. Some common types of trusses are scissors band, the Howe and Pratt  stilt, Addict stilt or Fink truss, Warren truss, Sawtooth truss, Bowsting  stiltetc.  Bridge Trusses  1. The main structural  rudiments of a typical ground stilt are shown in Fig. . Then it’s seen that a  cargo on the  sundeck is first transmitted to  stringers,  also to  bottom  shafts, and eventually to the joints of the two supporting  side trusses.  2. The top and  nethermost cords of these side trusses are connected by top and  bottom side bracing, which serves to  repel the side forces caused  by wind and the sideway caused by moving vehicles on the ground.  3. fresh stability is  handed by the portal and sway bracing.  4. As in the case of  numerous long- span trusses, a comber is  handed at one end  of a ground stilt to allow for thermal expansion.  5. A many of the typical forms of ground stilt Pratt, Howe and Warren  trusses are  typically used for spans up to 61 m in length.  6. For larger spans, a stilt with a polygonal upper cord,  similar as the Parker  stilt, is used for some savings in material.  Structural Analysis 2- 5 C( CE- Sem- 5)  7. The  topmost frugality of material is  attained if the  inclinations have a   pitch between 45 ° and 60 ° with the vertical.  8. still,  also for spans lesser than 91 m, the depth of  If this rule ismaintained.the stilt must increase and accordingly the panels will get longer.  10. This result in a heavy  sundeck system and, to keep the weight of the  sundeck  within tolerable limits, subdivided trusses has been developed.    

Que2.3. What are different  styles of analysis of trusses?  Explain any bone in detail. 


What are the  styles available for the analysis of trusses? Explain. 

Answer  Different styles of Analysis of Trusses To  dissect a statically  determinate band we’ve following two  styles  1. system of joints.  2. system of sections.  1. system of Joints  i. In  system of joints, the principle used is, if a stilt is in equilibrium,  also  each of its joint must also be in equilibrium.  ii. common analysis should start at a joint having atleast one given force and  atmost two unknown forces. , member will be in  contraction and viceversa, If a force is pushing on the leg.  iv. During  result of a stilt always assume the unknown member force  amusement on the joint’s free body  illustration to be in pressure.  v. If our  supposition is correct  also  result will be positive for the member.  vi. Now use the correct magnitude and direction of force on  posterior  joint’s free body  illustration.  Procedure to Analyze  First calculate the external support  responses by drawing the free body   illustration of the entire stilt.  ii. Draw free body  illustration of a joint having at least one given force and  atmost two unknown forces.  iii. Assume the unknown member force as tensile in nature i.e., force is  pulling the joint.  iv. Now  exposure of X and Y axes are to made  similar that forces on the  free body  illustration can be  fluently resolved into their x and y  factors.  Apply two force equilibrium equations ΣFx =  0 and ΣFy =  0. break these  two equations to get unknown member force and  also  corroborate their  correct directional sense.  vi. Continue to  dissect each of the other joints, where again it’s necessary  to choose a joint having atleast one given force and atmost two  unknown forces.  2. system of Sections ,  also the  If the forces in only a many members of a stilt are to befound.method of sections generally used to  gain these forces.  ii. The  system of section involves passing an imaginary section through  the stilt,  therefore cutting it into two  corridor.  iii. Each of the two  corridor must also be in equilibrium.  iv. Try to  elect the  insulated portion of the stilt haven’t  further than three  unknown force members.  v. Since only three independent equilibrium equations are present as  Fx =  0, Fy =  0 and M =  0.  Procedure to Analyze  originally cut or choose a section of stilt where forces are to be determined.  ii. opting the section, it may first be necessary to determine the stilt’s  external  responses.  iii. Draw the free body  plates of the  named or sectioned stilt having  the least number of forces on it.  iv. Let the member force as tensile in nature, i.e., pulling on the member  common leg.  Take  totality of the moment about a point that lies at the  crossroad  of the lines of action of two unknown forces. , forces may be added  If two of the unknown forces areparallel.perpendicular to the direction of these unknowns to determine directly  the third unknown force.    Que2.4. bandy the conception of internal stability of a stilt.  Answer  Internal Stability  1. Internal stability of a stilt can be checked by  examination of the  arrangement of its members.  2. If each joint is held fixed so that it can not move in a rigid body sense  with respect to the other joints,  also the stilt will be stable.  3. A simple stilt will always be internally stable.  4. If a stilt is constructed so that it doesn’t hold its joints in a fixed  position, it’ll be unstable or have a critical form. 2.4.1( a) is internally stable. InFig.2.4.1( b) no fixity is  handed  between joints B and F or G and C, so the stilt will collapse under  cargo.  Internal Stability of a emulsion Stilt  1. For checking the internal stability of a  emulsion stilt we need to  identify the way in which the simple trusses are connected together.  2. InFig.2.4.2, when an external  cargo is applied to joint D, E or F can  beget the stilt DEF to rotate slightly i.e., internally unstable.  Internal Stability of a Complex Truss  1. It may not be possible to tell about internal stability of a complex stilt  whether it’s stable or unstable.  2. Flash back that,  still if a stilt is unstable, it doesn’t count  whether it’s statically determinate or indeterminate. The use of an  unstable stilt is always avoided. 

Que2.5. Explain the conception of Zero- Force Members in a stilt. 

Answer  Concept of Zero- Force Member  1. The member that supports no  lading are  nominated as zero- force members.  2. Zero force members are used to simplify the stilt analysis using the   system of joints.  3. Zero force members are necessary for the stability of the stilt during  construction.  4. Zero force members are used to  give support if the applied  lading  is changed.  5. Zero force members  do in following two cases  i. If no external  cargo is acting at a joint and the members joined at this  joint are at any angle  also force in both of the members must be zero  in order to maintain equilibrium.  Analysis of Trusses 2 – 8 C( CE- Sem- 5)  ii. If no external force is acting on a joint having three members for  which two of the members are collinear, the third member is a zero  force member.  Then F3 =  0, as no force is acting in y- direction to balance it.

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