Explain on Analysis of Simple Plane Truss.

ANALYSIS OF SIMPLE PLANE TRUSS :

Assumptions :

(i). Each truss is composed of rigid members lying in one plane.
(ii). Weight of the members are neglected because they are small in comparison with the loads.
(iii). Forces are transmitted from on member to another through smooth pins fitted in the members.

Methods of Analysis of a Framed Structure

1.Analytical method. 2.Graphical method.

1.Analytical Method

This is method includes...

(i). Methods of joints : In this method, the free body diagram of each joint is separately analysed to obtain the magnitude of stresses in the truss members. The unknown forces are then determined by equilibrium equation ∆V= 0 and ∆H= 0, sum of all the vertical forces as well as the horizontal forces is equated to zero. The analysis also yields nature of stresses ( whether compression or tension).
The principale of triangle of forces, or resolution of forces is applied for analysis. Logic is applied so that isolated joint is in equilibrium under the action of external forces and internal stresses (called forces in the member). Car should be taken to select a joint which does not have more than two unknown forces.

(ii) Methods of Sections :The method is convenient, when the forces in the few members of a truss is required to be found out. Take such a section that the external forces. On one side of the section yield the forces in the member cut by the section.

Use of Bow's notation has been found convenient in the analysis of frames.

In this method, either left or right side of the section is considered. While taken moments at a point,the appropri
-ate sign of the moment should be used.
Considering left hand side of the section X-X, the forces AE, AB and HI should be used for computation and not GF, DC and HD.

【 Only that joint can be solved either analytically or graphically which has not more than two unknown forcess 】

Bow's Notation : Bow's notations are used to name the different members of a truss.
Every member of truss is deborer by two capital letters, placed in the spaces on either side of the member of the space diagram.
Therefore the load W will be named as PQ, the reaction R1 as RP and R2 as QR. The member of the frame will be named as PS, QS and RS respectively.

Graphical Method :

This method is based on...
(a) Law of triangle of forces.
(b) Law of polygon of forces.
(c) Baw's notation.
(d) Link or funicular polygon :
The funicular or link polygon is used for the graphical determination of support reactions.

* Consider a horizontal string AB suported atA and B.If a force PQ applied at point 'C' of the string,the string will distort in the shape
Shown by dotted lines.The distorted shape of the string is called 'funicular string or link polygon.

Writer - Sk Najmul ( Munna )