Structural dynamics
ANS:1
STATIC ANALYSIS:
STATIC ANALYSIS CAN ONLY BE PERFORMED IF THE SYSTEM BEING SIMULATED DOES NOT DEPEND ON TIME AND IF THE LOADS BEING APPLIED ARE CONSTANT.
STATIC ANALYSIS DON'T CONSIDER INERTIA.
STATIC REFERS TO THE FORCE THAT HAS CONSTANT SIZE POSITION AND DIRECTION ON OR WITHIN A STRUCTURE.
THERE IS NO NECESSITY TO COUNT INERTIA AND DAMPING FORCE IN CASE OF STATIC ANALYSIS BUT THE ELASTIC FORCE SHOULD BE ACCOUNTED.
DYNAMIC ANLYSIS:
IN DYNAMIC ANALYSIS THE SYSTEM ITSELF THE LOAD APPLICATION OR BOTH MIGHT CHANGE WITH TIMME
THE INERTIAL FORCE DEVELOPED BY THE SYSTEM DUE TO ACCELARATION ARE TAKEN INTO ACCOUNT.
DYNAMIC REFERS TO AFORCE ON ASTRUCTURE THAT CHANGE SIZE POSITION OR DIRECTION.
IN DYNAMIC TWO ADDITIONAL FORCES MUST BE ACCOUNTED SUCH AS INERTIA AND DAMPING FORCE IN EQUILLIBRIUM EQUATION IT CAN BE DISREGARDED IN STATIC ANALYSIS.
ANS:2
ELASTIC BEHAVIOR
ELASTIC ABILITY OF A DEFORMED MATERIAL BODY TO RETURN TO ITS ORIGINAL SHAPE AND SIZE WHEN THE FORCE CAUSING THE DEFORMATION ARE REMOVED.
A BODY WITH THE ABILITY IS SAID TO BEHAVE ELASTICALLY.
THE THEORY OF ELASTICITY IS USED TO DESIGN SAFE AND STABLE MAN-MADE STRUCTURE SUCH AS SKYSCRAPPERS AND OVERBRIDGES TO MAKE LIFE CONVENIENT.
FROM GRAPH IT IS CLEARLY MENSIONED THAT UPTO CERTAIN POINT FROM O THE GRAPH IS LINEAR AND SHOWS ELASTIC PRPERTIES.
INELASTIC BEHAVIOR:
DEFORMATION MATERIAL THAT DOES NOT DISAPPEAR ON THE REMOVAL OF FORCE PRODUCED BY IT.
INELASTIC MATERIAL WILL EXPERIENCE NO ELONGATION OR DEFLECTION AND UP TO ITS ULTIMATE STRENGTH IS REACHED WILL JUST RUPTURE SUDDENLY USUALLY THROUGH SHEAR BREAK.
EXAMPLE WOOD FABRICETC
IN GRAPH INELASTIC BEHAVIOR HAS BEEN SHOWN IN THE UPPER SHAPE OF THE CURVE UP TO POINT "A"
PLASTIC BEHAVIOR:
FOR STRESS BEYOND THE ELASTIC LIMIT A MATERIAL EXHIBITS PLASTIC BEHAVIOR.
THIS MEANS TE MATERIAL DEFORMS IRREVESIBLY AND DOES NOT RETURN TO ITS ORIGINAL SHAPE AND SIZE EVEN WHEN THE LOAD IS REMOVE.
PLASTIC WRAP IS AN EXAMPLE OF PLASTICITY
IN GRAPH THE PLASTIC BEHAVIOUR OCCURS DURING UNLOADING AFTER POINT "a"
NON LINEAR INELASTIC BEHAVIOR:
MATERIAL HAVE ELASTIC BEHAVIOR USUALLY ONLY UPTO A CERTAIN POINT AFTER THAT DEFORMATION ARE PLASTIC AND THE RELATION IN THIS IS NOT LINEAR ELASTIC BEHAVIOR.
NON-LINEAR ELASTIC BEHAVIOR OCCURS AFTER THE LINE FROM "o" TENDS TO BEND TOWARDS POINT "a"
ANS:3
MASS COMPONENT:
THE ROOF MASS WITHOUT STIFFNESS OR DAMPING OF THE FRAME.
THE EXTERNAL FORCE fi ON THE MASS COMPONENT IS RELATED TO TE ACCELARATION.
STIFFNESS COMPONENT:
THE FRAME WITHOUT DAMPING OR MASS.
THE EXTERNAL FORCE 'fs" ON THE STIFFNESS COMPONENT IS RELATE TO DISPLACEMENT U BY fs=ku
IF THE SYSTEM IS LINEARLY ELSTIC.
DAMPING COMPONENT:
THE FRAME WITH ITS DAMPING PROPERTY WITH NO STIFFNESS OR MASS.
THE EXTENAL FORCE ON THE DAMPING COMPONENT IS RELATED TO VELOCITY BY fd=cv
ANS:4
NATURAL PERIOD OF VIBRATION:
IT IS TIME REQUIRED FOR THE UNDAMPED SYSTEM TO COMPLETE ONE CYCLE OF FREE VIBRATION
UNIT IN SECONDS
IT IS RELATED TO THE NATURAL CIRCULAR FREQUANCY OF VIBRATION Wn IN UNIT OD RADIANS PER SECOND.
NATURAL CYCLIC FREQUENCY:
THE NUMBER OF CYCLE EXECUTED BY SYSTEM IN 1 SEC
UNIT IN HERTZ
ANS:5
RESPONSE SPECTRUM:
IT IS A CENTRAL CONCEPT IN EARTHQUAKE ENGINEERING RESPONCE SPECTRUM IS A PRACTICAL MEANS OF CHARACTERIZING GROUND MOTION AND TEIR EFFECTS ON STRUCTURE OF DIFFRENT Tn
IT PROVIDE A CONVENIENT MEANS TO SUMMARIZE THE PEAK RESPONCE OF ALL POSSIBLE LINEAR SDF SYSTEM TO APARTICULAR COMPONENT OF GROUND MOTION
IT ALSO PROVIDE A PARTICULAR APPROACH TO APPLY THE KNOWLEDGE OF STRUCTURAL DYNAMIC TO THE DESIGN STRUCTURE AND DEVLOPMENT OF LATERAL FORCE REQUIREMENTS IN BUILDING CODE.
A PLOT OF THE PEAK VALUE OF ARESPONCE QUANTITY AS A FUNCTION OF THE NATURAL VIBRATION PERIOD Tn OF THE SYSTEM IS CALLED THE RESPONSE SPECTRUM FOR THAT QUANTITY.
EACH SUCH PLOT IS FOR SDF SYSTEM HAVING A FIXED DAMPING RATIO AND SEVERAL SUCH PLOTS FOR DIFFERENT VALUE ARE INCLUDED TO COVER THE RANGE OF DAMPING VALUE ENCOUNTERED IN ACTUAL STRUCTURE.
THE RESPONCE SPECTRUM CAN BE OF 3 TYPES THE DEFORMATION RESPONCE SPECTRUM IS A PLOT OF PEAK u AGAINST THE FIXED DAMPING RATIO. ASIMILAR PLOT FOR PEAK u IS THE RELATIVE VELOCITY RESPONCE SPECTRUM AND FOR PEAK u^t IS THE ACCELARATION RESPONCE SPECTRUM.
