This document discusses statically determinate and indeterminate structures. A statically determinate structure can be analyzed using equilibrium equations alone, while an indeterminate structure has more unknowns than equations. A structure is determinate if the number of reactions r equals 3 times the number of parts n, and indeterminate if r is greater than 3n. Examples are given of determinate and indeterminate structures. Indeterminate structures can be made determinate by removing redundant supports or adding hinges. The advantages of indeterminate structures are that they allow for lighter, more rigid designs with increased safety through redundancy.

1. Prepared By
TAMEEM SAMDANEE
ID: 10.01.03.127
4th Year, 2nd Semester
Section: C

2. Solving Statically Determinate
Structures

3. Static Equilibrium
A system of particles is in static equilibrium
when all the particles of the system are at
rest and the total force on each particle is
permanently zero.

4. Statically Determinate
A member or structure that can be analyzed and the reactions
and forces determined from the equations of equilibrium.
Statically Indeterminate
A member or structure that cannot be analyzed by the
equations of statics. It contains unknowns in excess of the
number of equilibrium equations available.

5. Determinacy
r = 3n , statically determinate
r > 3n , statically indeterminate
where,
n = the total parts of structure members
r = the total number of unknown reactive forces and
moment components

6. Examples

7. Redundants
 The excess members or reactions of an
indeterminate structures are called
redundants.
 Redundant forces are chosen so that the
structure is stable and statically determinate
when they are removed.

8. How do we make an
indeterminate
structure statically
determinate?

9.  If there is two degrees of indeterminacy,
we have to remove two reactive forces,
remove three for three degrees and so
forth.
 By removing excess supports.
 By introducing hinges.

10. What are the advantages
of statically indeterminate
structures over
determinate structures?

11. There are several advantages in designing
indeterminate structures. These include
the design of lighter and more rigid
structures. With added redundancy in
the structural system, there is an increase
in the overall factor of safety.