In the world of structural engineering, analyzing trusses is crucial for creating safe and efficient designs for things like bridges, towers, and roofs. A truss consists of straight members that are connected at joints, and each member usually only experiences axial forces—either pulling (tension) or pushing (compression). When these structures are set up so that we can figure out the internal forces using just the principles of static equilibrium, we call them statically determinate trusses.
1. TRUSSES
It is the structure in which all members are subjected to Axial forces only ( Tension & Compression). Bending Moment is Zero every where in this structure.
Notes :
a) In a truss all members called as links
b) What is Links:
It is a structural members connected by pins at the ends and not loaded at intermediate locations.
2. FRAME
It is a structure in which members are subjected to bending moment also (In addition to tension and compression).
3. ASSUMPTIONS IN THE ANALYSIS OF STRUCTURE
a. All members must be straight and Connected by Smooth Pins at the ends (otherwise if the members are Curved than they will bend & Stracture Can’t be Called as Struss)
This is not a struss (curved member AB bends due to load
Member must be straight but need not be prismatic (having Same cls throughout its length).
b. Loads must be applied only at the joints (otherwise, if loads are applied at intermediate location of the members, than they will bend & Stractur Can’t be Called as struss).
This is not Struss (Link/member BC bend)
4.MECHANISM (Unstable Stracture)
If any stracture under goes rigid body translation or rigid body rotation due to loads, than it is called unstable Stracture or mechanism. (without developing any it member translates Stress or rotates, than it is called rigid body translation and rigid body rotation).
5.
a) In a struss, The Total No. of Members (m) and the tolal No. of joints (J) are related by m=2J-3*
b) For the first 3 joint, 3 members are requested for each additional joint, 2 members are required are required Combining these two state members we get M=2J-3
CONCLUSION
If the above Condition is satished, than we get stable trangulated & determinate Struss.
a) If m < (2J-3) — Deficient or Unstable truss. b) If m = (2J-3) — Perfect stable truss C) If m> (2J-3) — Redundant or Indeterminate truss.
(we provide more members than (2J-3) to make the Structure more stable. These additional members are called Counter bracing).
