Effect of ground motions on structures

An earthquake produces seismic waves that cause the earth’s crust to vibrate. These waves impart a momentary acceleration to the earth’s ...



An earthquake produces seismic waves that cause the earth’s crust to vibrate. These waves impart a momentary acceleration to the earth’s crust and it starts moving in the direction in which the wave is travelling at that instant. The characteristics of vibration, such as intensity, duration, etc at any location depend upon a number of factors which includes as follows;

  •  Magnitude f earthquake

  • Depth of focus

  • Epi-central distance

  • The characteristics of the material through which the seismic waves travel.



Inertia force:

When the ground motion occurs, the foundation of the structure must also move with it to avoid its rupture. When the foundation moves, the structure on it tries to stay back due to inertia. Consequently, the structure is subjected to inertia forces. In the earthquake-resistant design of structures, the inertia forces due to earthquake are considered in addition to the normal loads and forces.

When the horizontal shaking of ground is set up, the horizontal inertia forces are generated at the level of the mass of the structure, which is generally assumed to be concentrated at the floor levels. These inertia forces are then transferred from the slab through the walls or columns to the foundation and finally to the strata below the foundation. In earthquake resistant design it is ensured that each of the structural components including floor slabs, walls, columns, beams, and foundations can safely transfer the inertia forces through them. Moreover, the connections between the various structural elements needs to be properly design and constructed.

Response spectrum:

If the buildings were rigid, then every point on it would be moved by the same amount as the ground and consequently the inertia force would be equal to the mass multiplied by the ground acceleration. But the buildings are flexible and different parts move back-and-forth by different amounts during ground shaking.

The natural period of vibration of a structure is the time period of its un-damped, free vibrations. Te fundamental natural period of vibration is that for the first (or fundamental) mode of vibration of that structure. Each structure has a unique fundamental period of vibration at which it tends to vibrate when it is allowed to vibrate freely without any external excitation. The fundamental natural period depends upon the form and configuration of structure, the stiffness (or flexibility) of the various structural members, the type and material of construction, etc. For the determination of the fundamental natural period of vibration a structure can be done using the structural code which gives the empirical formulae to be utilized.

For the estimation for seismic forces in structures, the response spectra are commonly used in practice. The response spectrum of a structure shows the maximum response induced by the structure during the ground motion. It is generally plotted in terms of maximum absolute acceleration against natural period; sometimes the maximum relative velocity or the maximum relative displacements may also be used. During plotting the response spectrum, it is assumed that the structure has single degree of freedom and it may have different dampening. In other words, the maximum response spectrum represents the maximum acceleration of an idealized single degree freedom systems having a certain natural period of vibration and dampening when it is subjected to earthquake ground motion.

Use of response spectrum:

  1. The response of the system decreases as the damping of the system increases. In buildings usually 5 percent damping is allowed/assumed.

  2. As the natural period increases, the acceleration ratio first increases to a maximum value and then decreases. For the structural system shown, the greatest acceleration occurs when natural period is about 0.3 s.

  3. In the usual practice in the earthquake-resistant design to represent the structural response by the response factor or spectral coefficient in the normalized form as “Sa/g”.

  4. The response spectrum helps the earthquake engineer to predict how a particular structure with a certain natural period will respond to the earthquake.

  5. The response spectra are commonly used in the estimation of seismic forces.


Name

• compression couplers,1,• tension couplers,1,1997 UBC,1,56 days Concrete test,1,ADDICRETE,1,additives,1,administer computer networks,1,admixtures,1,Advises Subcontractors,1,alignment of the shafts,1,Allowable Stress Design,1,Anchor Bolts,1,Annual depreciation expense,1,approval of drawings,1,ASCE7,1,ASD,1,Assist in Quantity,1,Assist the Project Manager,1,Authority to Delegate,1,AutoCAD,2,AutoCAD to Etabs,1,bagger,1,bars,1,bars in a bundle,1,BASE ISOLATED DAMAGE,1,base plates,1,basement wall,1,Basic soil properties,1,basic wind speed,1,Beams Inspection Checklist,1,Bearing capacity,1,bell pile bottom,1,bent bars,1,Bitomeneous,1,Blockwork,1,Bowels,1,breaching spillway,1,BS 8007:1987,1,BS5400,1,BS6399,1,BS8007,1,BS8110-1997,1,building materials,1,buildings height,1,CALCULATION OF CRACK WIDTH,1,Canary Island Dates,1,cantilever footing,1,Carbon Equivalent,1,carbon test,1,cast in-situ,1,cast-in-place anchors,1,cast-in-place concrete pile,1,Cause-and-effect diagram,1,Chairs,1,Check sheets,1,Chemical Admixtures,1,Chute spillway,1,CIRIA,2,CIRIA Report 136,1,civil engineering,1,civil structures,1,Coal ash,1,collars,1,Collision Load,1,columns,3,columns and walls,1,Combination of combinations,1,combinations in Etabs,1,Company's Health,1,Compliant Towers platforms,1,compression test,1,compressive strength,1,concrete,4,concrete block buildings,1,CONCRETE IN HOT WEATHER,1,CONCRETE MOMENT FRAME,1,concrete pile,1,Concrete Rebound Hammer,1,Concrete Shrinkage,1,Concrete Slump Test,1,concrete walls,1,Construction and Stressing,1,Construction companies in Dubai,1,construction drawings,1,construction industry,1,Construction joints,1,Construction Manual,1,continuous external restraint,1,continuous slabs,1,contract planresponsibilities of QA/QC,1,Contracts Manager,1,cooling pipe system,1,Corner reinforcement,1,Cost Plus Award Fee,1,Cost-reimbursable,1,COUPLED SHEAR WALL,1,Couplers,1,couplers in columns,1,CP3,1,CRACK WIDTH,1,Creep,1,CURING,1,day to day work progress,1,Dead load and Self-weight,1,Deck,1,Deflection,1,Deflection discussion,1,Deflection in Prestressed,1,deformed bars,1,Demolition,1,design drawings,1,Design Requirements,1,designing a tall building,1,Designs projects,1,detailed review,1,detailing and implementation,1,Development length,1,different codes in one structure,1,Differential elastic shortening,1,dimensions,1,DIRECT TENSION,1,Draftsman responsibilities,1,drawings and specifications,1,Drift Limitations,1,Drop beams,1,dust loads,1,dust on roof,1,Dynamic Pile Head,1,dynamic wind pressure,1,Early age Crackwidth,1,early strength cement,1,Earth pressure,1,Earthquake Design,1,earthquakes,1,EBT adhesive sealant,1,Elastic Shortening,1,electrical and manual,1,elevator requirement,1,Elevators,1,Encasement of pipes,1,end plate connection,1,Energy dissipater,1,engineering design,1,Environmental procedures,1,epoxy compound,1,Epoxy grout,1,equipment performance records,1,Error and warning free model,1,Errors in Etabs,1,establishment of construction,1,Estimating Flow Standard,1,Etabs,2,Etabs Design,1,ETABS to ROBOT,1,excavation,1,Excavation slopes,1,external concrete surfaces,1,Finishing of slip-forms,1,Fire,1,Firm Fixed Price,1,Fixed platforms,1,Fixed Price Incentive Fee,1,Fixed Price with Economic,1,Flexible Joints,1,Flexible pipes,1,floors,1,Flow charts,1,Fly ash,1,Foundation analysis,2,Foundations,2,framed openings,1,Free over fall spillway,1,FRP,1,FRP advantages,1,FRP disadvantages,1,FRP technology,1,full length bar,1,General Notes,1,Geophone sensor,1,Hammer Schmidt Type,1,HDP,1,Health and Safety procedures,1,helical piering,1,helical piles,1,High Early Strength Portland Cement,1,High quality additives,1,high rise / tower,1,highly effective,1,Histograms,1,hooked bars,1,Horizontal steel,1,Human Comfort,1,hydraulic,1,hydraulic jump,1,Hydraulic resistance,1,Hydro technical tunnels,1,IBC/ASCE,1,immediate reaction,1,importance of Plasticizers,1,Importing,1,IMS,1,Inspection Checklist,6,INSTRUMENT CALIBRATION,1,inter-story drift,1,interest payments,1,IT engineer responsibilities,1,Jack-up Platforms,1,Jacking Systems,1,Japanese code for escalators,1,Kicker,1,largest man-made machine,1,largest man-made machine on earth,1,largest oil platform,1,lateral forces,1,lateral loads,1,LFD,1,lifting hooks,1,Load Factor Design,1,load resisting elements,1,load-bearing wall,1,Loading,1,Loads and Resistances,1,LRFD,1,Maintain contract database,1,Maintains close scrutiny,1,maintenance cost,1,Makes recommendations,1,manage,1,manufacturer,1,manufacturing process,1,Maximum allowable slopes,1,maximum deflection,1,maximum difference,1,maximum pressure,1,maximum reinforcement,1,maximum temperature,1,Mechanical couplers,1,Mechanical damage,1,membrane floors,1,Metal sleeves swaged,1,Method of dissipation,1,METHOD OF TESTING,1,Method statement,2,Mineral Admixtures,1,minimize the seepage,1,minimizing the cost,1,minimum eccentricity moment,1,Minimum reinforcement,1,mixing concrete,1,modelling in Etabs,1,Monitors performance,1,monthly invoice,1,Monthly Safety Report,1,Most Useless Megaprojects in the World,1,multi-storey buildings,1,multistory buildings,1,Natural frequency,1,Necessity of tunnel lining,1,new structural systems,1,O&M,1,of concrete block buildings,1,office buildings,1,Office Tall Buildings,1,offshore platforms,1,oil platform,1,oil rigs,1,on beams from loaded slab can be achieved by defining the slab as a membrane,1,opening reinforcement,1,ordinary Portland cement,2,Other bars,1,Overlap,1,overlap locations,1,Oversee and review,1,palm trees weight,1,parallel threads,1,parapet,1,Perform data backups,1,Performance Bonds,1,Performs design drafting,1,physical properties,1,pile cap,1,Pile Dynamic Test,1,Pile Head Preparation,1,Pile Integrity Testing,1,Pile Shaft Overbreak,1,piles foundations,1,Pindos,1,Pipe Classifications,1,PLACING,1,Placing boom,1,Plan and prioritize work,1,Planning Engineer,1,plant and equipment,1,Plant and Equipment Engineer,1,plaster walls,1,Platform types,1,pneumatic,1,Post-Tensioning Grouting,1,Pour strip,1,precast panel,1,Prepares monthly report,1,Pressure Ratings,1,Prestressed Concrete,1,prevent uplift,1,principal load resisting,1,procedure of fixing,1,Project Coordinator,1,Project manager assignment,1,project schedule,1,project's compliance,1,Provides technical expertise,1,provisional Sum,2,PT slabs,2,pump,1,PVC,1,QA,1,QA/QC Engineer,1,QC,1,Quality,1,quotes,1,Quotes of Engineers,1,raft foundations,1,Raft Slab Inspection Checklist,1,reaction as an engineer,1,rebound hammer,1,recommended tests,1,Recorded experience,1,Reinforced concrete columns,1,reinforcement,1,Reinforcement at openings,1,reinforcing bars,2,reinforcing-steel,1,Residential Tall Buildings,1,RESISTING SYSTEMS DAMAGE,1,Retaining Wall Inspection Checklist,1,Retaining walls,1,retarder,1,Review contract documents,1,review contracts,1,review expiring contracts,1,Reviews accidents,1,reviews contract drafts,1,Reviews shop drawings,1,Reviews the terms and conditions,1,Rice husk ash,1,rigid foundation,1,Rigid pipes,1,Road layers,1,Robot Millennium,1,Rock Strata and Excavation,1,Roles and Responsibilities,8,Roller bucket,1,Rough Order of Magnitude,1,Rules of thumb,1,saddle beams,1,Safe 14,1,Safety Manager,1,sample letter,3,sand,1,SAP2000,1,Schmidt Hammer,1,Seismic,1,Seismic Design Principle,1,Seismic force,1,SEISMIC RESISTING SYSTEMS,1,seismic zone factor,1,Semi-structural welding,1,Semi-submersible Platforms,1,Senior Architect,1,Senior Contracts Engineer,1,Sequential Loading,1,Set work program,1,Seven Basic Quality Tools,1,shallow foundation,1,Shell,1,Ship-board Rigs platforms,1,shop drawings,1,shortening of columns,1,Shrinkage,1,Shrinkage and Temperature,1,Side channel spillway,1,simply supported,1,Site engineer responsibilities,1,site facilities,1,Site Investigation,1,SK Gosh,1,Ski-jump,1,slab assignment,1,slabs,2,Slabs Inspection Checklist,1,slings,1,slip forms,1,Slip-form,1,Slip-form construction,1,slip-forming,1,smooth finish,1,soffit slabs,1,Soil classification,1,Soil Sloping Systems,1,Soil Testing,1,speed of erection,1,Spring Force,1,standard size bolts,1,Static load,1,Static load multiplier,1,steel beam,1,Steel Columns,1,steel quantity,1,steel stress,1,Stiffness,1,stiffness and resistance,1,stilling basin,1,Strap footing,1,Strength and Stability,1,Stress on soil in etabs,1,Stressing sequence,1,Striking formworks,2,Strip footing,1,Strong Column,1,structural construction process,1,structural design spreadsheet,1,Structural Details,1,structural engineers,1,Structural Provisions,1,structural purposes pipes,1,strukts spreadsheets,1,Subcontract Agreement,1,Super-plasticizers,2,surfactants,1,Tack welding,1,Tall Building,1,tall buildings,1,taper-cut threads,1,Tdr Test Accuracy,1,Technical Engineer,1,technical submittals,1,test hammer,1,Test on Piles,1,Test specimens,1,TESTING,1,Thermal Expansion,1,threaded rods with nuts,1,time for completion,1,Top bars,1,torsion-load test,1,Total Shortening,1,tower cranes,1,Tower cranes installation,1,Transform AUTOCAD drawings,1,trough spillway,1,Trump Tower,1,Tunnel,1,tunnel lining,1,type of concrete,1,Types of contracts,1,types of foundation,1,Types of shallow foundation,1,Types of spillways,1,Types of waterproofing,1,Ultra Ever Dry,1,Uniform loads Safe 14,1,uniform thickness,1,Uplift Force,1,uplift test lateral-load test,1,vertical load resisting,1,Voided Biaxial Slabs,1,wall openings,1,walls,2,Warning,1,Water curing,1,Weak Beam Concept,1,Wedge locking sleeves,1,weekly and monthly program,1,weekly and monthly report,1,Welding of reinforcement,1,Welding procedures,1,What teachers never taught us,1,wind and seismic,1,Wind loads,1,Wind simulation,1,WOOD SHEAR WALL,1,workability,2,workshop drawings,1,Workshop repair,1,
ltr
item
Strukts: Effect of ground motions on structures
Effect of ground motions on structures
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoOGANi6d2zOSjC0HJleDwePL-C2BGmrlMPVp9Wp1pYLHcF_-yQovbqXMwKhGonqTpw1EmoGOjGARg0ir9gaFgKR5g-xe-yQwf9jWbFnle1vmr3Nte9iIJKK5oHsrU7O5r_4CeBo4Q40s/s320/Liquefaction_at_Niigata-1-300x178.jpg
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoOGANi6d2zOSjC0HJleDwePL-C2BGmrlMPVp9Wp1pYLHcF_-yQovbqXMwKhGonqTpw1EmoGOjGARg0ir9gaFgKR5g-xe-yQwf9jWbFnle1vmr3Nte9iIJKK5oHsrU7O5r_4CeBo4Q40s/s72-c/Liquefaction_at_Niigata-1-300x178.jpg
Strukts
https://www.strukts.com/2012/06/effect-of-ground-motions-on-structures_25.html
https://www.strukts.com/
https://www.strukts.com/
https://www.strukts.com/2012/06/effect-of-ground-motions-on-structures_25.html
true
7606260228666216043
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share to a social network STEP 2: Click the link on your social network Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy