Presented by

Md. Shariful Islam

Student ID: 10.01.03.112

Department of Civil Engineering

AUST, Dhaka

Presentation onsupport system

CE 416 PRE-STRESSED CONCRETE

LAB

Course TeachersLecturer Mr. Galib Muktadir Ratul

Lecturer Ms. Sabreena Nasrin

Department of Civil EngineeringAhsanullah University of science and Technology

EQUILIBRIUM OF NON-CONCURRENT COPLANAR FORCE SYSTEM

When a body is in equilibrium, it has neither translatory nor rotatory motion in any direction. Thus the resultant force R and the resultant couple M are both zero, and we have the equilibrium equations for two dimensional force system

Fx = 0; Fy = 0  M = 0These requirements are both necessary and

sufficient conditions for equilibrium.

Supports: A structure is subjected to external forces and transfers these forces through the supports on to the foundation. Therefore the support reactions and the external forces together keep the structure in equilibrium.

Types of supportsThere are different types of supports. Some of

them are  a) Roller Support b) Hinged or pinned support

c) Fixed or built in support  Some supports are shown in the figure along

with the reactions that can be mobilised.

Real example of various supports systems

Roller Support

Hinged Support

Fixed Support

 

Types of Supports Action on body

(a) Flexible cable ,belt ,chain, rope

BODYBODY

T

Force exerted by cable is always a tension away from the body in the direction of cable

(b) Smooth surfaces

Contact forces are normal to the surfaces

FF

Contact force is normal to the surface on which the roller moves. The reaction will always be perpendicular to the plane of the roller . Roller support will offer only one independent reaction component.(Whose direction is known.)

(c) Roller support

RvR

Rh

θ

This support does not allow any translatory movement of the rigid body. There will be two independent reaction components at the support. The resultant reaction can be resolved into two mutually perpendicular components. Or it can be shown as resultant reaction inclined at an angle with respect to a reference direction.

( d )pinned Support / hinged support

Rv

MRH

M

(e) Fixed or Built-in Support

This type of support not only prevents the translatory movement of the rigid body, but also the rotation of the rigid body. Hence there will be 3 independent reaction components of forces. Hence there will be 3 unknown components of forces, two mutually perpendicular reactive force component and a reactive moment as shown in the figure.