Engineering mechanics The science that considers theeffects of forces on rigid bodies

Force What exchanges or tends to changethe state of motion of a body

External effects 1.shear2.moment3.torque

Internal effects Type of effect; Refers to stress

Resultant force a single force that represents the neteffect of a force system

Moment of a force Measure of the: tendency to rotate at a pointforce, moment arm rotation, and moment

center

Free body diagram A drawing of the structure/part ofthe structure under consideration

Types of supports 1.cable2.roller support

3.pin or hinge support

Equilibrium state or condition in a bodywherein resultant is zero

Conditions of equilibrium 1.resultant is zero2.the sum of moments about any point in

system is zero

Moment arm distance between the axis of rotation and theperpendicular of the line of action of a force

Components of a force Fx-F x cos and Fy- Fx sin refers tothe ______________

Statics The part of mechanics that considers theeffects of and the distribution of forces onrigid bodies which are and remain at rest

Rigid body A definite amount of matter whose parts arefixed in position relative to one another

Concurrent force system A type of force system wherein the lines ofaction of forces meet at a common point

Method of joints Finding the reactions at eachsupport

Method of sections Utilizes the principle of moments and theresolution of a force into its components

Axial force This component measures the pullingor pushing action over the section

Shear force These are components of the total resistanceto sliding the portion to one side of the

exploration section

Torque This component measures theresistance to twisting the members

Bending moments These components measure the resistanceto bending the member about the Y or Z

axes

Stress Unit strength of a material

Concentrated load Load acting on a particular point

Uniformly distributed load (Rectangular loading) uniformmagnitude

Uniformly varying load (Triangular loading) distributed loadwhich uniformly varies with the distance

Simple beam or simply supportedbeam

Supported by a roller and a hingeat both ends

Overhanging beam Supported by a roller and a hinge withone or both extending beyond supports

Cantilever beam (beam) Supported by a fixedsupport at one end only

Fixed or restrained beam Type of beam having fixed supportat both ends

Propped beam ...

Continuous beam type of beam With three or moresupports

Mechanics Science of mechanics treats on forces,motion and the effects of forces on the

bodies which they act

Applied mechanics Concerns mainly on the applications of theprinciples of mechanics to the solution of

problems commonly encountered

Structural system A system of structural components that makes up astructure. It is interconnected as to provide rigidity andresist the effect of forces whether directly or indirectly

Structural system components These are structural elements such asbeams, girders, columns, trusses, etc

Statics Deals with forces and effect onrigid bodies at rest

Dynamics Deals with motion and with the effectsforces acting on rigid bodies in motion

Kinematics Study of motion without consideration offorces causing the motion

Kinetics Study of forces acting on rigid bodies inmotion and their effect in changing such

motion

Force Influence on a body producing achange in shape or movement

Compressive force An applied force which producescompression in an elastic material

Tensile force An applied force which producetension in an elastic material

Vector A quantity possessing both magnitude and directionrepresented by an arrow whose length is proportional tothe magnitude. Force, velocity, acceleration, moment

Scalar Quantity having magnitude only.Ft, kg, newton

Characteristics of a force MagnitudeLine of actionPoint of application

Direction

Applied or contacting forces Forces that refers to the push orpull produced by mechanical effort

Acting force Force acting directly on a body

Reacting force Generated by the action of onebody to another

Non-applied or non contactingforce

Gravitational pull, magnetic forceor inertia force

Coplanar Condition where all forces lie onone plane

Parallel force system Non-concurrent forces havingparallel lines of action

Concurrent Where the lines of action of all theforces intersect at a common point

Non-coplanar Forces do not lie on one plane

Non-concurrent Lines do not intersect at acommon point

Collinear All forces in a parallel system actalong a single line of action

Triangle method Graphic technique for finding the vector sum of 2 concurrentforces by displacing one force vector parallel to itselfcompleting the triangle with a vector that represents theresultant force

Parallelogram law System of determining the resultant force of 2concurrent forces obtained from the diagonal at aparallelogram having adjacent sides which represent the2 force vectors being added

Polygon method Graphic technique for finding the vector sum of a coplanar forcesystem of several concurrent forces by drawing to scale each forcevector in succession with the tall of each of the head of one precedingit and completing the polygon with a vector that represents theresultant force

Strength of materials Extends the study of forces that was begun inmechanics. Deals with relations between externallyapplied loads and their internal effects on bodies

Theory of structures Deals with the principles and methods by which the directstress, shear and bonding moment and the deflection art anysection of each constituent member in the structure may becalculated

Moment Tendency of a force to produce rotation of a body abouta point or line, equal in magnitude to the product of theforce and the moment arm acting in aclockwise/counter direction

Moment center Point at which the axis of a momentintersects the plane of the forces causing the

moment

Moment arm Perpendicular distance from the line ofaction of a force to the point or line about

which a moment occurs

Couple Force system of 2 equal, parallel forcesacting in opposite directions and tending to

produce rotation

Moment of a force Tendency to produce a rotation of thebody on which it acts about an axis

Static equilibrium Condition in which forces in a state of restare acting in opposite direction of the same

magnitude

Force law of equilibrium Implies a balance of opposingforces within a system

Stress Resistance to external forces

Strain Subjected to an external force

Tensile stress it is a type of stress that refers to"Pull"

Compressive stress Push

Normal stress Perpendicular to stressed surface

Shearing stress Parallel

Axial stress External stress acting on a member parallelto its major axis and member is of constant

cross section

Bearing stress Compressive stress exerted on anexternal surface of a body

Ultimate stress Greatest unit stress a material canwithstand

Allowable stress Portion of the ultimate strengthwhich may safely be used in design

Live load Moving load on a structure, actsdownward

Dead load Static load, downward

Dynamic load Often with rapid change inmagnitude and location

Moving load Kinetic load of a short duration due to moving vehicles

Occupancy load Live on structure resulting fromthe weight of people, etc

Wind load Exerted by the kinetic energy of amoving mass of air

Transverse load Load applied perpendicular to thelongitudinal axis

Axial load Tensile acting along thelongitudinal axis

Roller type support Offers resistance in a direction normal to thesurface beneath the roller, does not resistmovement parallel to the supporting surface

Hinge type support Prevents movement along the horizontaland vertical directions but does not resist

rotation about the hinge

Link type support Offers resistance in the directionalong the link and through 2 pins

Fixed-end type support Type of support that resists rotation aboutthe support and to movements along the

horizontal and vertical directions

Section properties centroid Center of one or two dimensional figureabout which the sum of the displacements of

all points is zero

Center of gravity Point at which the entire weight isconsidered concentrated

Center of mass (Section property) Point at whichthe entire mass is concentrated

Moment of inertia Sum of the products obtained by multiplyingan element of mass by the square of its

distance from the axis

Radius of gyration Distance from its moment of inertia axis at which theentire area is considered concentrated without changingthe numerical value of its moment of inertia

Modulus of elasticity The ratio of the shearing stress to the shearing strain

Modulus of rigidity Coefficient of elasticity expressing the ratiobetween shearing stress and strain produced

by stress

Truss Structural frame based on the geometric rigidityof the triangle and composed of linear memberssubject to axial tension and compression

Creep Property which causes some materials underconstant stress to deform slowly over a

period of time

Machinability Readiness with which a materialyields to shaping with cutting tools

Strength Resist stress without failure

Elasticity Returns to original size

Stiffness Resist deformation

Ductility Drawn permanently through greatchange

Brittleness Opposite of ductility. Fail withoutwarning

Malleability Undergoes great change in shape withoutrupture

Hardness Resist indentation or abrasion

Resilience Material Property: Absorbs

Toughness Absorb energy at high stress

Chord Either of the 2 principal membersextending end to end

Web member Connects upper and lower chord

Panel Space between any 2 panel pointson a chord and joint

Panel point Joint between 2 or more membersof a truss

Panel length Space on the chord of a truss between 2adjacent joints made of principal web

members

Span Distance between supports