Seismic Design of StructuresSeismic Design of Structures

Reference:Reference:

11. . The Seismic Design Handbook, The Seismic Design Handbook, FarzadFarzad NaeimNaeim

رفتار و طرح لرزه اي ساختمانهاي بتن مسلح، دكتر تسنيمي، مركز تحقيقات ساختمان و مسكنرفتار و طرح لرزه اي ساختمانهاي بتن مسلح، دكتر تسنيمي، مركز تحقيقات ساختمان و مسكن --22 رفتار و طرح لرزه اي ساختمانهاي بتن مسلح، دكتر تسنيمي، مركز تحقيقات ساختمان و مسكنرفتار و طرح لرزه اي ساختمانهاي بتن مسلح، دكتر تسنيمي، مركز تحقيقات ساختمان و مسكن --22

33. . Other text booksOther text books

Evaluation:Evaluation:1.1. Final Examination Final Examination 7070%, %, Students must pass the final Examination to pass this courseStudents must pass the final Examination to pass this course

2.2. Reading Reading 1515%, %, At least At least 4 4 papers.papers.

3.3. H.WH.W 1515%%

SEISMICITY OF THE WORLD AND IRANSEISMICITY OF THE WORLD AND IRAN

Tectonic plates and worldTectonic plates and world--wide distribution of earthquakes.wide distribution of earthquakes.Iran, Iran, 44--55RichterRichter((22--4 4 weeks), weeks), 66..55RichterRichter((2 2 years), years), 7 7 RichterRichter((55--10 10 years)years)On the average, On the average, 1010,,000 000 people die each year from earthquakes. A UNESCO study gives damage people die each year from earthquakes. A UNESCO study gives damage losses amounting to $losses amounting to $1010,,000000,,000000,,000 000 from from 1926 1926 to to 1950 1950 from earthquakes.from earthquakes.

CAUSES OF EARTHQUAKES

1.1. Tectonic EarthquakesTectonic EarthquakesThe basic idea is that the Earth’s outermost part (called the lithosphere) consists of several The basic idea is that the Earth’s outermost part (called the lithosphere) consists of several large and fairly stable rock slabs called plates. Ten plates, a depth of about large and fairly stable rock slabs called plates. Ten plates, a depth of about 80 80 kilometers.kilometers.

plateplate--edgeedge earthquakesearthquakes..TheThe veryvery hazardoushazardousshallowshallow earthquakesearthquakes ofofChile,Chile, Peru,Peru, thethe easterneasternCaribbeanCaribbean,, CentralCentralAmericaAmerica,, SouthernSouthernMexicoMexico,, California,California,SouthernSouthern Alaska,Alaska, Japan,Japan,Taiwan,Taiwan, thethe Philippines,Philippines,Indonesia,Indonesia, NewNew Zealand,Zealand,HimalayanHimalayan beltbelt areare ofofplateplate--edgeedge typetype..

mechanicsmechanics ofof thethe

Itt doesdoes notnot explainexplain allall seismicityseismicity inin detail,detail, forfor withinwithin continentalcontinental regions,regions, awayaway fromfrom boundaries,boundaries, largelargedevastatingdevastating earthquakesearthquakes sometimessometimes occuroccur.. TheseThese intraplateintraplate earthquakesearthquakes cancan bebe foundfound onon nearlynearly everyeverycontinentcontinent..

lithosphericlithospheric platesplates becomebecomebetterbetter understood,understood, longlong--termterm predictions,predictions, maymay bebepossiblepossible forfor plateplate edgeedgeearthquakesearthquakes.. ForFor example,example,manymany platesplates spreadspread towardtowardthethe subductionsubduction zoneszones atatratesrates ofof fromfrom 22 toto 55centimeterscentimeters (about(about oneone tototwotwo inches)inches) perper yearyear..

22. . DilatancyDilatancy in the Crustal Rocksin the Crustal Rocks

TheThe crustcrust ofof thethe continentscontinents isis aa rockyrocky layerlayer withwith averageaverage thicknessthickness ofof aboutabout 3030 kmkm butbutwhichwhich cancan bebe asas thickthick asas 5050 kmkm underunder highhigh mountainmountain rangesranges.. UnderUnder thethe ocean,ocean, thethe crustalcrustalthicknessthickness isis nono moremore thanthan aboutabout 55 kmkm.. AtAt aa depthdepth inin thethe crustcrust ofof 55 kilometerskilometers oror so,so, thethe lithostaticlithostaticpressurepressure (due(due toto thethe weightweight ofof thethe overlyingoverlying rocks)rocks) isis alreadyalready aboutabout equalequal toto thethe strengthstrength ofof typicaltypicaluncrackeduncracked rockrock samplessamples atat thethe temperaturetemperature ((500500°° C)C) andand pressurepressure appropriateappropriate forfor thatthat depthdepth..presencepresence ofof waterwater providesprovides aa mechanismmechanism forfor suddensudden rupturerupture byby reductionreduction ofof thethe effectiveeffective frictionfrictionalongalong crackcrack boundariesboundaries..crackingcracking occursoccurs locallylocally andand thethe volumevolume ofof rockrock increasesincreases orordilatesdilates..CrackingCracking maymay occuroccur tootoo quicklyquickly forfor groundground waterwater toto flowflow intointo thethe dilateddilated volumevolume toto fillfill thethe spacesspacessoso thethe crackscracks becomebecome vaporvapor--filledfilled.. TheThe consequentconsequent fallfall inin porepore pressurepressure leadsleads toto aa reductionreduction mainlymainlyinin PP wavewave velocitiesvelocities.. SubsequentSubsequent diffusiondiffusion ofof groundground waterwater intointo thethe drydry crackscracks increasesincreases thethe poreporepressure,pressure,andandprovidesprovideswaterwaterforfor lubricationlubricationalongalongthethewallswalls ofof thethecracks,cracks,whilewhilepressure,pressure,andandprovidesprovideswaterwaterforfor lubricationlubricationalongalongthethewallswalls ofof thethecracks,cracks,whilewhileat the same time, the P wave velocity increases again.at the same time, the P wave velocity increases again.

33.. Explosions,Explosions,UndergroundUnderground nuclearnuclear Explosions,Explosions, artificialartificial earthquakesearthquakes (up(up toto magnitudemagnitude 66..00))..

44.. VolcanicVolcanic Earthquakes,Earthquakes,therethere areare alsoalso intraplateintraplate volcanic,volcanic, ((ii)) volcanicvolcanic explosions,explosions, (ii)(ii)shallowshallow earthquakesearthquakes arisingarising fromfrom magmamagma movements,movements, andand (iii)(iii) sympatheticsympathetic tectonictectonic earthquakesearthquakes..

55. . Collapse Earthquakes, Collapse Earthquakes, earthquakes is sometimes produced by massive landsliding.

66.. LargeLarge ReservoirReservoir--InducedInduced Earthquakes,Earthquakes,India,India, anan earthquakeearthquake (magnitude(magnitude66..55)) centeredcentered closeclose toto thethe damdam (height(height 103103 meters)meters) causedcaused significantsignificant damagedamage onon DecemberDecember 1111,, 19671967..

Earthquake fault sourcesEarthquake fault sources�� Abrupt changes in the structure of rocks,Abrupt changes in the structure of rocks,

�� InIn somesome placesplaces oneone typetype ofof rockrock cancan bebeseenseen buttingbutting upup againstagainst rockrock ofof quitequiteanotheranother typetype alongalong aa planeplane ofof contactcontact.. SuchSuchoffsetsoffsets ofof geologicalgeological structurestructure areare calledcalledfaultsfaults..

�� FaultsFaults maymay rangerange inin lengthlength fromfrom aa fewfewmetersmeters toto manymany kilometerskilometers andand areare drawndrawnonon aa geologicalgeological mapmap asas continuouscontinuous ororbrokenbroken lineslines..

Movement,Movement,SuchSuch

Normal fault at the Corinth Canal, GreeceNormal fault at the Corinth Canal, Greece

Movement,Movement,SuchSuchmovementmovement couldcouldhavehave beenbeen eithereitherslowslow slip,slip, whichwhichproducesproduces nonogroundground shaking,shaking, ororsuddensudden rupturerupture (an(anearthquake)earthquake)..

�� FaultsFaults seenseen atat thethe surfacesurface sometimessometimes extendextendtoto depthsdepths ofof tenstens ofof kilometerskilometers inin thethe Earth’sEarth’scrustcrust..�� ItIt mustmust bebe emphasizedemphasized thatthat mostmost faultsfaultsplottedplotted onon geologicalgeological mapsmaps areare nownow ininactiveactive..�� TheThe locallocal disruptivedisruptive forcesforces inin thethe EarthEarthnearbynearby maymay havehave subsidedsubsided longlong agoago andandchemicalchemical processesprocesses involvinginvolving waterwater movementmovementmaymay havehave healedhealed thethe ruptures,ruptures, particularlyparticularly atatdepthdepth.. SuchSuch anan inactiveinactive faultfault isis notnot nownow thethe sitesiteofof earthquakesearthquakes andand maymay nevernever bebe againagain..

Seismic wavesSeismic wavesk be the modulus of incompressibility (bulk modulus)

TheThe SS waveswaves cannotcannot propagatepropagate inin thethe liquidliquid partspartsofof thethe Earth,Earth, suchsuch asas thethe oceansoceans andand theirtheiramplitudeamplitude isis significantlysignificantly reducedreduced inin liquefiedliquefied soilsoil..

A seismograph record of the vertical component of a distant earthquakeA seismograph record of the vertical component of a distant earthquake

TTspsp=(=(11/V/Vss--11//VVpp))DD, , Near faults????Near faults????

EARTHQUAKE DAMAGE MECHANISMSEARTHQUAKE DAMAGE MECHANISMS

�� by inertial forces generated by severe ground by inertial forces generated by severe ground shaking.shaking.

�� by earthquake induced fires.by earthquake induced fires.

�� by changes in the physical properties of the by changes in the physical properties of the foundation soils (e.g. consolidation, settling, and foundation soils (e.g. consolidation, settling, and liquefaction).liquefaction).

�� by direct fault displacement at the site of a by direct fault displacement at the site of a structure.structure.

�� by landslides, or other by landslides, or other surficialsurficial movements.movements.

�� by seismically induced water waves such as by seismically induced water waves such as seismic sea waves (tsunamis) or fluidseismic sea waves (tsunamis) or fluid

�� motions in reservoirs and lakes (motions in reservoirs and lakes (seichesseiches).).�� by largeby large--scale tectonic changes in ground scale tectonic changes in ground

elevation.elevation.

Faults rupturing under Managua (Nicaragua) Faults rupturing under Managua (Nicaragua) during the earthquake of during the earthquake of 19721972

QUANTIFICATION OF EARTHQUAKESQUANTIFICATION OF EARTHQUAKES

�� Earthquake IntensityEarthquake Intensity�� Intensity is the measure of damage to Intensity is the measure of damage to

works of man, to the ground surface, works of man, to the ground surface, and of human reaction to the shaking.and of human reaction to the shaking.

�� do not depend on instruments, but on do not depend on instruments, but on the actual observation.the actual observation.

�� The first intensity scale was developed The first intensity scale was developed by de Rossi of Italy and by de Rossi of Italy and ForelForelof of by de Rossi of Italy and by de Rossi of Italy and ForelForelof of Switzerland in the Switzerland in the 18801880ss. This scale, . This scale, with values from I to X.with values from I to X.

�� A more refined scale was devised in A more refined scale was devised in 1902 1902 by the Italian volcanologist and by the Italian volcanologist and seismologist seismologist MercalliMercalli with a twelvewith a twelve--degree range from I to XII. degree range from I to XII.

�� Modified Modified MercalliMercalli Intensity Scale Intensity Scale ((MMIMMI) of ) of 19311931..

�� Japanese scale (Japanese scale (0 0 to VII)to VII)

�� Earthquake MagnitudeEarthquake Magnitude�� IfIf sizessizes ofof earthquakesearthquakes areare toto bebe comparedcompared worldworld--wide,wide, aa measuremeasure isis neededneeded

thatthat doesdoes notnot depend,depend, asas doesdoes intensity,intensity, onon thethe densitydensity ofof populationpopulation andand typetypeofof constructionconstruction..

�� AA strictlystrictly quantitativequantitative scalescale waswas originatedoriginated inin 19311931 byby WadatiWadati inin JapanJapan andanddevelopeddeveloped byby CharlesCharles RichterRichter inin 19351935 inin CaliforniaCalifornia..

�� RichterRichter defineddefined thethe magnitudemagnitude ofof aa locallocal earthquakeearthquake asas thethe logarithmlogarithm toto basebasetenten ofof thethe maximummaximum seismicseismic wavewave amplitudeamplitude inin micronsmicrons ((1010--44 centimeters)centimeters)recordedrecorded onon aa WoodWood-- AndersonAnderson seismographseismograph locatedlocated atat aa distancedistance ofof 100100kilometerskilometers fromfrom thethe earthquakeearthquake epicenterepicenter..

�� ThisThis meansmeans thatthat everyevery timetime thethe magnitudemagnitude goesgoes upup byby oneone unit,unit, thetheamplitudeamplitude ofof thethe earthquakesearthquakes waveswaves increaseincrease 1010 timestimes..

�� Since the fundamental period of the seismograph is Since the fundamental period of the seismograph is 00..8 8 second, it amplifies second, it amplifies those seismic waves with a period ranging approximately from those seismic waves with a period ranging approximately from 00..5 5 to to 11..5 5 seconds. Because the natural period of many building structures are within seconds. Because the natural period of many building structures are within this range, the local Richter magnitude remains of value to engineers.this range, the local Richter magnitude remains of value to engineers.

�� definition of the magnitude, it has no theoretical upper or lower limits.definition of the magnitude, it has no theoretical upper or lower limits.

�� Shallow earthquakes have to attain Richter magnitudes of more than Shallow earthquakes have to attain Richter magnitudes of more than 55..5 5 before significant widespread damage occurs near the source of the waves.before significant widespread damage occurs near the source of the waves.

�� Surface Surface W aveW ave Magnitude (MMagnitude (M ss) Surface: ) Surface: waves with a period around waves with a period around 20 20 �� Surface Surface W aveW ave Magnitude (MMagnitude (M ss) Surface: ) Surface: waves with a period around waves with a period around 20 20 seconds are often dominant on the seismograph records of distant seconds are often dominant on the seismograph records of distant earthquakes (earthquakes (epicentralepicentral distances of more than distances of more than 2000 2000 kilometers). kilometers). GutenbergGutenberg

�� Body W ave Magnitude (MBody W ave Magnitude (M bb) Deep focus: ) Deep focus: earthquakes have only small or earthquakes have only small or insignificant trains of surface waves.insignificant trains of surface waves.P wave magnitudeP wave magnitude

�� Moment Magnitude (MMoment Magnitude (M WW )) : : Because of significant shortcomings of Because of significant shortcomings of MMLL, , MMbb, and to a , and to a lesser degree lesser degree Ms in distinguishing between Ms in distinguishing between great earthquakes.great earthquakes.seismic moment (seismic moment (MM00))

MM00==GDAGDA

Magnitude SaturationMagnitude Saturation

�� As described earlier, the Richter magnitude scale (As described earlier, the Richter magnitude scale (MMLL) measures the ) measures the seismic waves in a period range of particular importance to structural seismic waves in a period range of particular importance to structural engineers (about engineers (about 00..55-- 11..5 5 seconds). This range corresponds approximately seconds). This range corresponds approximately to waveto wave--lengths of lengths of 500 500 meters to meters to 2 2 kilometers.kilometers.MMLL = = 77. The body wave . The body wave magnitude (Mmagnitude (Mbb) ) saturates at about the same value.saturates at about the same value.

SEISMIC RISK EVALUATIONSEISMIC RISK EVALUATION�� Geological Input, Geological Input, Tectonic movements, Faults, Tectonic movements, Faults, Reports of landslides, Reports of landslides,

ground water levels, major settlements.ground water levels, major settlements.

�� Seismological Input, Seismological Input, earthquake History, the frequency of regional earthquake History, the frequency of regional earthquakes, ground shaking, damage, and other intensity information near earthquakes, ground shaking, damage, and other intensity information near the site, Definition of the design earthquakes.the site, Definition of the design earthquakes.

�� Soils Engineering Input,Soils Engineering Input,engineering properties of foundation soils, engineering properties of foundation soils, Determination of P and S wave speeds and Q attenuation values and in the Determination of P and S wave speeds and Q attenuation values and in the Determination of P and S wave speeds and Q attenuation values and in the Determination of P and S wave speeds and Q attenuation values and in the overburden layers.overburden layers.

EARTHQUAKE AND GROUND MOTION PREDICTIONEARTHQUAKE AND GROUND MOTION PREDICTION

تناوبتناوب دورهدوره��

گسلگسل فعاليتفعاليت��

تكتونيكيتكتونيكي حركاتحركات��

پيش لرزه هاپيش لرزه ها��

مردم در صورت پيش بينيمردم در صورت پيش بيني ترسترس��