S THE SOCIETY FOR EARTHQUAKE AND CIVIL E S E C E D ... vol 17 no 3.pdf · THE SOCIETY FOR EARTHQUAKE AND CIVIL ENGINEERING DYNAMICS NEWSLETTER ... wythe of masonry and where these

ISSN 0967-859XTHE SOCIETY FOR EARTHQUAKE AND CIVIL

ENGINEERING DYNAMICS

NEWSLETTERVolume 17 No 3December 2003

SECED NEWSLETTER - DECEMBER 2003 - Page 1

SE

S E C E DED

Page 1 The Bingol Turkey Earthquake

Page 6 Structural Dynamics of OffshoreWind Turbines

Page 9 The Ninth Mallet-Milne Lecture -May 2003

Page 10 ICE Coopers Hill War MemorialPrize

Page 11 Earthquake Competition 2003

Page 11 MCEER Appoint New DeputyDirector

Page 11 SECED & Imperial College. ShortCourse.

Page 12 Notable Earthquakes August -October 2003

Page 12 Website Developer Required

Page 12 Forthcoming Events

ContentsThe Bingol Turkey EarthquakeA field report on the May 2003 Earthquake by Frederick Ellul.

Introduction

As part of ongoing research at theUniversity of Bath into the vulnerabilityof low-engineered reinforced concretemasonry infilled framed buildings, apost earthquake visit was organised todocument the effects of the event thatoccurred on the 1st of May 2003, atBingol, Turkey.

At 3.27 a.m. local time (00.27 GMT),an earthquake measuring 6.4 on theRichter magnitude scale occurred at adepth of circa 10 km, in the south

Anatolian high-mountainous provinceof Bingol, in eastern Turkey. The eventwas centred about 15 km North Westof the city of Bingol (Fig. 1), theprovince’s capital, 665km East ofAnkara. In all, 177 fatalities werereported and around 519 people wereinjured. However, the event will mostlybe remembered for the tragedyoccurring at the Celtiksuyu schoolwhere 84 people, nearly all children,lost their lives in the collapse of thedormitory block. Another 70 people losttheir lives in collapses throughoutBingol town itself.

Figure 1 Map of Turkey and event location bounded by 100 km radius


Bingol town is around 1150 metresabove mean sea level and straddles theCapakcur River which flows through anentrenched alluvial valley. The mostnotable event to have affected the townof Bingol in living memory, is that of the22nd of May 1971, when a magnitude6.7 event with an epicentral distanceof just 17 km from the presentearthquake, resulted in the death ofaround 875 people and injured 1000.

Bingol Town and its BuildingStock

The town is administratively composedof 13 districts (Fig. 2). However, it istopographically divided in two by theriver Capakcur flowing east-west. Thesouthern bank includes districts withpredominantly traditional buildingsmostly of 1 to 2 storeys high. Thedistricts of Inonu, Yesilyurt and Kulturare effectively the town’s centre,housing institutional buildings. On thenorthern bank, the town is essentiallycomposed of a recent settlement areawhich has been generally establishedafter the 1971 earthquake, and is builtupon deep alluvial deposits composedof coarse gravel to boulder size material

within a stiff plastic clay matrix. This partof the city includes a grosspredominance of in situ cast reinforcedconcrete framed buildings with hollowclay brick infills.

By far the majority of all new buildingsin Bingol are reinforced concrete framestructures with hollow clay infilledmasonry. Most people live in suchbuildings, which are termed beskatsbecause of their five storey height.These buildings consist of reinforcedconcrete slabs cast monolithically withreinforced concrete beams andcolumns. Masonry infill is mortared inplace between the cast in-situ frame toform partition walls without any positiveconnection to the latter. No lifts areusually provided and a single reinforcedconcrete staircase simply connected tothe floor slabs provides access to upperstoreys. Most buildings have anirregular three dimensional frame gridowing to complex functionalrequirements and often infills of partialheights create short columns,especially around window openings. Inthe central part of the town, mostbuildings adjacent to each other did nothave any gap between them, howevermany of the buildings are completely

isolated in the newer districts. Theorientation of the columns is haphazardin plan and depends on the location ofthe infill walls, leading to irregularcolumn spacing and orientation, withmost columns having a rectangularconstant section throughout thebuilding height. Often a largepercentage of columns are oriented inthe same direction, making buildingsmuch weaker in one lateral direction.Column bars usually terminate inhooks.

All reinforcement is generally smoothmild steel, however evidence was seenof increasing use of deformed hightensile steel bars in some of the mostrecently constructed buildings. Thebuildings are constructed in-situ and theaggregate and sand is obtained fromthe river bed. It is not washed or sievedand any water source which is at handis used in the mix. Mixing of concreteis done by volume and not by weight,using either portable concrete mixersor even simple manual mixing. A readymix batching plant is present in the city,but concrete from this source isconsiderably more expensive thanconcrete mixed on site. The resultingconcrete is generally of poor quality,

Figure 2 Map of Bingol Town


with a weak compressive strengthbelow the 20MPa minimum allowablecylinder strength in zone 1, as requiredby the Turkish Seismic Code.

Once the frame is partially or totallycomplete, the infill walls are constructedagainst the narrow side of the columnbonded to it with cement. The masonryinfills are hollow clay bricks laid incement mortar. The outer walls areusually constructed in two wythesseparated by a 20mm polystyreneinsulation layer with no structuralconnection either between the wythesor to the reinforced concrete frames. Acoat of cement-lime plaster circa 30mm thick is generally applied to eitherside. Room partitions are built from onewythe of masonry and where these donot intersect the frame underlyingbeams spanning in between beams areprovided for their support. Reinforcedconcrete shear walls are the exceptionin most buildings, even when lift shaftsare present as these are usuallyconstructed from infill masonry. Slopingroofs are constructed from a roughtimber framework and sheathing overa horizontal reinforced concrete slab.Constructions built after the year 2000did evidence more attention to detail,such as closer stirrup spacing and theuse of high tensile deformed bars.However, even if the approved plans

comply with the current Code, itappears that no mechanisms are inplace to ensure that constructionconforms to these plans. Governmentbuildings such as schools, military andsocial housing projects often evidencedhigher construction standards,especially through the quality of theconcrete, although glaring exceptionswere also noted.

Traditional Buildings and TheirPerformance

In the Eastern part of Turkey, traditionalconstruction comprises variants of thehimis type buildings and also un-reinforced masonry construction. Theformer is usually built by the owner,relying solely on experience. A typicalhimis building is composed of timberlaced masonry, where the latter canrange from rubble held in place withmud mortar, to mud brick or to morecarefully chosen stone blocks. Thetimber lies in bands of typically up to 1metre height. All these buildings havea timber roof possibly with metallicsheeting. Such buildings are usuallysmall in size, of no more than onestorey in height and provideaccommodation for one family at most.In addition many un-reinforcedmasonry buildings were also observedin various parts of the town. The qualityof these constructions varies from

rubble buildings of one storey heightwith timber roofs to carefullyconstructed houses with hewn stonemasonry units. These buildings areusually small dwellings of no more thantwo storeys.

The damage to such constructions isgenerally commensurate with thequality of construction through thebuilder’s experience and therefore thedamage observed in theseconstructions varied widely, with manyapparently suffering no damagewhatsoever and standing next tocollapsed reinforced concrete framedbuildings. A few of these buildings didhowever collapse whilst others sufferedmoderate to heavy damage. It didappear however that where suchconstructions exceeded certain sizes,such as two or more storeys, severedamage to them was common. Rubblewalled houses suffered heavy damageand out-of-plane wall failures, howeverunreinforced masonry structures alsogenerally suffered severe damage inmany areas. The prevalent damagetype was the x-shaped shear crack inthe masonry panels, whilst in otherbuildings out-of-plane collapses werenoticed. Most of the damage to thesestructures occurred in the villagesaround Bingol town.

Figure 3 The town of Bingol and its building stock, note the mosque in the centre


Observations

The most interesting fact about theBingol event is the general uniformityof the building stock in Bingol town, withtypically only slight variations to thebasic 5 storey structure, such as acommercial ground floor, differentstorey height or the presence of astructural wall, thus allowing for theclear identification of strengths andweaknesses. All new buildings arereinforced concrete masonry infilledframes, employing weak hollow clayblocks. No construction is higher than6 storeys (except for the mosque) andonly few have reinforced concreteshear walls included in their design.Compliance with seismic provisions ismandatory, and investigations ofdocumentation submitted for planningapproval revealed that detailedstructural designs accompanyarchitectural plans.

Collapses were few, thoughunfortunately tragic, as the occupancyof apartment buildings is invariably highand thus the possibility of a highcasualty rate is obvious. Two differentcollapse modes were observed. Thegreatest number of lives were lost whenbuildings collapsed in a pancake typemode, which occurred in at least onebuilding, the Celtisuyuk dormitory block,and possibly in an apartment buildingin the town, which could not be

confirmed. However, the gross majorityof the collapsed buildings failed due toa soft ground storey, with the remainingupper floors or underlying basementremaining practically intact.

Few buildings throughout the town witha soft storey at ground floor did notsuffer severe damage. The ones thatdid not were probably located in areaswhere ground shaking was not asintense as the main record available.Moreover, for the buildings in the towncentre which abutted each other,consideration has to be given to the factthat the adjacent blocks providedmutual support during the event, andthus had reduced displacements andconsequently less damage. Themajority of buildings with a soft groundstorey did however evidence significantdamage in the ground storey columns,which suffered various shear typeeffects. These were accompanied byvertical hairline cracks between thebeam column joints, and almost totalmasonry infill destruction in the internalpartitions at ground floor. Damage tothe reinforced concrete elements wasnearly solely confined to the groundfloor, apart from a few very narrowcracks in other storeys. The masonryinfills in the first floor then sufferedmoderate damage in most cases, butall semblance of damage was gone bythe second storey with nominal frameinfill separation in the upper storeys.

As expected, the reinforced concreteframes with masonry infills formed arelatively stiff and strong lateral loadresisting system in the upper storeys,unlike the frames with few or no infillwalls in the ground storey, in order toprovide more space for commercialoutlets. The smaller stiffness at groundfloor thus induces increaseddeformation demand in the framemembers of the soft ground storey andalmost the entire lateral deformation isconcentrated in the ground storeycolumns with the upper storeys movinglaterally as a rigid block. Additionally,unlike the upper storey columns, theground storey columns in suchbuildings could not share the lateralshears with the infill walls. Many ofthese then sustained brittle shearfailure. The generally poor concretestrength, with a typical value of lessthan 15MPa compressive cylinderstrength, only made matters worse.Volume batching, which does notaccount for moisture in the aggregates,as against weight batching, manualmixing techniques and placement, allresulted in a higher water content toensure good workability, and in a weakporous concrete. The smooth roundlargish river pebbles further contributedtowards a weak mix.

The lack of ductility of the constructionswas evidenced by the general lack ofsignificant cracks in the reinforcedconcrete elements. Fully developedplastic hinges were noted onlysparingly, as they seemed to bepreceded by shear cracking. This isalso a direct consequence of thedetailing practice adopted for thereinforcing stirrups in the columns,which offered only light confinement tothe core concrete. These thereforefailed in a brittle shear mode and wereprone to catastrophic failure. Damagein beams was rare, as the weak columnstrong beam mechanism did not allowthese elements to develop their fullstrengths and the columns failedbefore. Only in buildings without adominant soft ground storey wasconcrete spalling and evidence ofcracking noted in beams. Rarer stillwere beam-column joint failures.

Many fully infilled apartment buildings,without commercial premises in theirground floor, suffered non-structuraldamage to the masonry infills, in theFigure 4 School buildings suffered heavy damage during the event. A

complete ground storey failure was suffered by the one in the picture.


form of shear cracks at the groundstoreys. Though such damage provedalarming to the local populace, thedamage was generally slight,predominantly in the ground storey andgradually dying out to hairline cracks inthe finishes of the upper storeys. Thereinforced concrete elements of theseconstructions generally suffered onlylocalised damage to particular details,such as at construction joints orintersecting beam junctions. Evidentlythe masonry infills supplanted the lackof ductile detailing in theseconstructions. Few out-of-planecollapses of the infill walls were visible,however complete corner collapses,where the infill walls formed the buildingcorner, were noted.

The presence of reinforced concreteshear walls generally ensured thatbuildings suffered much less damagethan for constructions without them,especially when these were combinedwith small room spans and a regularstructure. Though many governmentbuildings suffered severe damage, asevidenced by the number of schoolsand police stations rendered unusable,general concrete quality and on-site

attention to detail did appear to bebetter than for the typical 5 storeyapartment block.

The very poor performance of irregularstructural configuration was noted,such as short column effects andtorsionally irregular structural systems.Buildings with plan asymmetryexperienced significant torsionalmotions. As a result, the flexible sideof the building experienced largerdisplacements than the stiff side. Theexcessive deformations causedconsiderable damage to the columnson the flexible side. Buildings with planirregularities, such as those with re-entrant corners or L-shape plans, wereuncommon as were those withelevation irregularities involving largevertical setbacks in elevation, whilst nofloating columns were noticed in theconstructions. The total absence ofintermediate storey collapse was alsoobserved.

The difference in damage between onedistrict and another in Bingol town canbe attributed to local site amplifications.However, even if the possibility existsof larger earthquake forces actuallybeing imposed on the structure than

Figure 5 Two identical buildings next to each other, one collapsing the other rendered unusable.

those originally designed for (as shownby the comparison of the strong motionrecord with the design spectra for theregion), regular structures in closeproximity to irregular ones, built to thesame standards and subjected to thesame ground motions, only sufferedslight damage. Therefore, theoverriding lesson conveyed from theevent is the need to have designprofessionals strongly conceptualisethe structural behaviour of theconstruction when subjected to lateralforces. Further improvement would beattained by the gradual educationtowards well detailed reinforcedconcrete structures. Given the level ofexpertise employed in the region inapplying a modern material, such asreinforced concrete using lowtechnology methods, heavy damageand collapse was almost exclusivelyprecipitated by “architectural” ratherthan structural design flaws.

A recent report based on the fieldmission has been written by FrederickEllul and Dina D’Ayala (senior lecturerUniversity of Bath) and can be found inthe link below:

http://www.istructe.org.uk/eefit/files/BingolFieldReport.pdf


The new season of SECED eveningmeetings began with a well-attendeddiscussion on the subject of OffshoreWind Turbines. With the UK’s first largescale offshore windfarm inconstruction, and the Crown Estateslease competition for a second roundof larger offshore windfarms nowunderway, it was evidently a subject ofwide interest. Those present weretreated to excellent talks from Dr ErvinBossanyi of Garrad-Hassan and DrByron Byrne of Oxford University,covering overall system dynamics andfoundation aspects respectively.

The meeting began with the award ofthe “Guess the Next Earthquake”competition prize by Chris Browitt toHarry Wahab and Riccardo Sabatinoof KBR. Their “shrewd interpretation

to the seismic hazard map of Scotland”was rewarded with Champagne allround.

The technical meeting began with ashort scene-setting introduction from DrByron Byrne. Byron summarised thedrivers for the development ofrenewable energy, the targets andaspirations that the government has setand the numbers of offshore windturbines that would need to bedeveloped to meet the government’stargets. Of the order of 4000 turbineswould be required to produce 10% ofthe UK electricity by 2010 - this isindeed a massive challenge! To getthis development moving thegovernment has already allowed for theinstallation of 540 turbines and has setaside land for a further 6GW of offshore

wind. These areas will be developedover the next few years. Typical loadsand sizes for the wind turbine werepresented. A 3.5MW turbine mightweigh 6MN and the wind/wave forcemight combine to be a horizontal forceof 4MN acting at 30m above the sea-floor. This leads to a massive momenton the foundation system. The hub ofthe turbine might be 90m above theseafloor and the rotor diameter mightbe about 95m. The loads can becompared to a typical large jack-up rigwhere the vertical load is approximately200MN and the horizontal load is about25MN acting at 80m above the seafloor.The wind turbine loads are very muchsmaller and the horizontal load is amuch higher proportion of the verticalload than for the jack-up rig. Thereforewhilst experience from the oil and gas

Figure 1 Comparison of Static and Dynamic Loads: Offshore Wind and jackup drilling platform.

Philip Cooper reports on the Joint SECED/OES/WES meeting held on 24th September 2003.Structural Dynamics of Offshore Wind Turbines


industry can be used it will still benecessary to develop specific designapproaches for the wind turbines. Inparticular the wind turbines are moredynamic than typical offshorestructures.

Byron then handed over to Dr ErvinBossanyi of Garrad-Hassan, a leadingspecialist consultancy with a 20 yearhistory in the wind energy industry. Hispresentation covered the varioussources of applied environmentalloading experienced by an offshorewind turbine, including wind, wave andcurrent loads in both normal andextreme conditions. To comply withappropriate standards, the turbine mustbe shown to be able to withstandappropriate combinations of theseapplied loads during the various designsituations, including construction,transportation, normal operation,maintenance and fault conditions.

To understand the loading on theturbine, time domain dynamic responsesimulations are used. This isnecessary because of non-linearities,for example in blade aerodynamicresponse, and resulting from theoperation of the control and safetysystem as it changes the operationalstate of the turbine. The simulationsmust take into account the structuralflexibility of the turbine, together withthe dynamics of the power train andcontrol system. An aeroelastic/hydroelastic model is required, sincethe vibrational velocities of thestructural elements themselves modifythe aerodynamic and hydrodynamicforces experienced by the structure.

The normal environmental conditionsmight include any combination of windspeeds, turbulence, wave heights andperiods, currents, and variousmisalignments between wind, waveand current directions. Potentially, ahuge number of simulations would beneeded to cover all possible situations;in practice it is necessary to define asmaller but representative subset ofconditions. The effect of wakes ofnearby turbines also needs to beconsidered.

Extreme wind gusts and non-linearextreme waves must also be modelled.Extreme environmental conditions withone or fifty year return times are used

in combination with the appropriatedesign situations. Breaking waves aredifficult to model, especially theplunging breaking waves which may beexperienced in shallow waters.

Some results from the detailedexperimental monitoring programmebased on the two 2MW offshoreturbines at Blyth were presented,showing excellent agreement betweenmonitored loads and those predicted bysimulation codes such as GH-Bladed.Results demonstrated that it is vital tomodel wind and wave loadingsimultaneously: separate treatment ofwind and waves results in veryconservative load estimates, as itignores the fact that the wave-inducedtower vibration is very significantlydamped as a result of the aerodynamicforces on the turbine rotor when it isoperating.

Byron Byrne then returned to the standto elaborate on prediction of foundationperformance, which strongly influencesthe dynamic response of offshore windturbines.

In the first round of development thetypical foundations will be monopiles asthis is established technology, and wellsuited to the predominantly shallowwater sites. As the developments moveinto deeper water and confidence is

gained with different designs, apreferred foundation could be a shallowskirted foundation. These foundationscan be installed using suction or evengravity alone, thus reducing installationcosts considerably. The talkconcentrated on the development oftheoretical models to describe theresponse of shallow foundations todifferent loading regimes. Thesemodels originated in the jack-upindustry where the understanding of thedynamic response of the rig isdependent on the fixity assumed at thefoundation.

The new theoretical models are basedon hardening plasticity and can modelthe non-linear behaviour of soils well.They can also be implemented withinstructural analyses packages easily sothat time domain analyses can becarried out. They require fourcomponents:a) yield surface - a locus of allowablecombinations of load on the footing;b) hardening rule - a definition of howthe yield surface expands or contracts(usually a function of vertical plasticpenetration);c) flow rule - a definition of the ratios ofdisplacement on yielding, and;d) elasticity - a description of the footingresponse when the load state is withinthe yield surface.

Figure 2: Comparison of Measured and Predicted dynamic response for Blythturbine. (Garrad Hassan)


These models have been developed forclay and sand but are restrictive in thatthey model only: i) planar loading; ii)circular plates or spudcans and; iii)monotonic loading.

The presentation then described alarge joint industry-academia researchproject at which some of theshortcomings of the plasticity modelsand the design of novel offshorefoundations is being addressed.Specifically, the research project isaimed at developing theoretical modelsfor skirted foundations for offshore windturbines. Three phases of work areunderway:a) laboratory scale tests: these aresmall scale but highly complex testsaimed at determining the response ofthe foundations to loading patternsapplicable to offshore wind turbines.Such tests include cyclic verticalloading and cyclic moment loading.Issues of installation resistance,ultimate capacity, serviceability and

fatigue are being addressed.b) field scale tests: tests are to becarried out at a larger scale atBothkennar (clay) and Luce Bay (sand)in Scotland. These will be to assess theeffects of scale on the laboratory testresults.c) theoretical development: theplasticity model will be improved toaccount for different geometries, sixdegree of freedom loading and tomodel cyclic loading. The latter is aparticularly important development asthis will have considerable influence onthe understanding of the dynamicresponse of the structure fromnumerical analysis.A few examples of preliminary versionsof a cyclic loading model werepresented which showed goodagreement with the experimental data(Figure 3).

The talk concluded by stressing that aproper treatment of the foundation isessential to the understanding of the

dynamics of offshore wind turbines.This treatment can be made by usingrelatively simple foundation modelsbased on hardening plasticity whichmodel the non-linear behaviour of soilextremely well. A research project isunderway to develop these modelsfurther and specifically for suctioninstalled skirted foundations. Thesefoundations may be applicable to anumber of sites that have beendesignated for offshore winddevelopment.

A lively question and answer sessionensued, initiated by Chris Browitt, whowas keen to learn why seismic actionshad not been included in the list ofdesign loads. Ervin Bossanyi assuredChris that seismic effects were oftenconsidered, but tended to be much lessonerous than wave loads for offshoremachines. Both speakers then adeptlyfielded a wide range of questions in theremaining time, before the meetingfinally adjourned to the ICE bar.

Figure 3 Measured and Predicted Cyclic Response of Shallow Foundation


Nigel Priestley is one of that small butinfluential band of New Zealandearthquake engineers who studied withBob Park and Tom Paulay atCanterbury University, and then wenton to make a mark on internationalseismic design practice quite out ofproportion to the small size of theircountry. Indeed, it is noteworthy thatof the five overseas based Mallet-Milnelecturers, two have come from themighty USA (population 260 million),one from Mexico (population 95 million)– and two from New Zealand(population 4 million, although thisdoesn’t include the sheep). Previously,Nigel was mainly based at theUniversity of San Diego, California,where he is now an Emeritus Professor,but he now also increasingly spends histime at Canterbury, New Zealand andin Italy, where he is co-director of theRose School, Pavia.

The lecture revisited some themes firstset out in one given ten years ago inNew Zealand. That previous lecturewas entitled: ‘Myths and fallacies inearthquake engineering: conflictsbetween design and reality’. Nigel’sthesis in his presentation to SECEDwas that those conflicts still exist;indeed, he believes that there are deepflaws in many of the fundamental basesby which we assess seismic actions instructures and provide the necessarystrength and ductility to satisfactoryseismic performance. If we are to takeon board the implications of Nigel’slecture, some significant (and perhapspainful) changes will be necessary inthe way we do things, although in manyways the procedures he presented aresimplifications of current methods.

Perhaps least painful may be changingour approach to multi-modal ductilitymodified response spectrum analysis.Yes, we are all more than slightly in lovewith it, but in our hearts we have alwaysknown that it is based on suspect andshaky foundations. Nigel demonstratedforcefully that there is no validity to the3-D multi-modal approach, and that itshould be consigned to the slag heap.For inelastically responding structures,it does not even give useful informationon higher mode and torsional effects –

often cited as a reason for carrying outsuch analyses.

Another theme was the need to relatethe stiffness of concrete members notprimarily to section geometry but tostrength; in other words, we need toestablish the reinforcement contentbefore we can assess stiffness. Thiswill involve a greater change in mindset.Priestley’s equation “normalised yieldcurvature equals Priestley’s number P”is easy to remember, particularly sinceP is (it seems) more or less alwaysequal to two. Can it really be thatsimple? Yet having to set memberstrengths before carrying out ouranalyses is going to be hard, if we stickto the old, force-based ways of doingthings. However, since in displacementbased design methods it is the initialyield curvature that is needed (not thestrength), the constant normalized yieldcurvature actually makes life simpler.

Harder still to take on board will be theidea that the full, buxom hystereticloops – which I think Nigel’s mentorTom Paulay taught us to love so much–may actually be less desirable than thecurvaceous but anorexic non-linearelastic ones that he showed in hispresentation (and of course since it wasNigel, also showed how to achieve inpractice).

And then there is the fundamental wayin which we carry out displacement

based designs. The lecture presentedin detail the ‘direct displacement baseddesign’ methodology that he hasdeveloped, which addresses thedeficiencies in forced based methodsof design outlined earlier in the lecture,and (just as important) represents asimple and direct methodology whichis easy to implement in design codes.Nigel at the dinner in his honour beforehis Mallet-Milne lecture said that theAmericans in recent guidance onperformance based design had got thistopic all wrong, but he was perhaps toopolite to mention what we Europeanshave done in Eurocode 8. Will we havethe courage to change on this side ofthe Atlantic, I wonder?

In a dazzling display at the end of hislecture, Nigel showed us some of thesurprising and disturbingconsequences of sticking to the oldways of doing things. Changing thoseways may be painful, but Nigel will haveconvinced many of the capacityaudience (and even maybe some ofthose who were turned away becausethe Telford Lecture Theatre was full)that changes there will have to be.

The lecture has been published by theIUSS Press at the Rose School, Pavia,Italy (www.roseschool.it/files/IUSSpress.htm) at a cost of Euro.28(plus Euro.5.70 postage in Europe).

Reported by Edmund Booth

Myths and fallacies in earthquake engineering, revisited by Professor Nigel PriestleyThe Ninth Mallet-Milne Lecture - May 2003

Nigel Priestley (left) and Peter Merriman (right)


ICE Coopers Hill War Memorial PrizeAwarded to Second Severn Crossing Dynamics Paper

The ICE Coopers Hill War MemorialPrize has been awarded to JohnMacdonald (Bristol University),Peter Irwin (RWDI) and MalcolmFletcher (Halcrow) for their paperentitled “Vortex-induced vibrations ofthe Second Severn Crossing cable-stayed bridge - full-scale and windtunnel measurements”. The paperwas published in the Structures andBuildings Journal - May 2002.

The Prize was founded in memoryof members of the Royal IndianEngineering College, Coopers Hill,who fell in the First World War. It isone of a number of prizes awardedfor papers in the ICEproceedings.The abstract of thepaper follows.

AbstractIn the first winter after opening, theSecond Severn Crossing cable-stayed bridge exhibited occasionalvortex-induced vertical oscillations.

Vortex excitation had been detectedby the wind tunnel tests on sectional

models during design and anaerodynamic solution partlydeveloped but, based on dampingand turbulence assumptions fromrecognised design codes, it hadbeen concluded that the probabilityof large vibrations occurring wassmall. Full-scale monitoring of bothwind and structural responseenabled the causes of the observedoscillations to be investigated. Thestructural damping and windturbulence were found to differsignificantly from the assumedvalues.

Additional wind tunnel tests wereundertaken using the full-scalemeasured values with a view toreplicating the full-scale behaviourand developing a solution. Takinginto consideration the reviseddamping and turbulence and anoften-ignored factor to correct for thefull-scale mode shape, goodagreement between the model andfull-scale measurements wasobtained. Also, aerodynamicsolutions were further explored, as

a result of which baffle plates wereinstalled under the bridge. Sincetheir installation, no further signs ofvortex-induced oscillations havebeen observed.

In Brief• The large amplitude vibrationsoccurred in the first vertical bendingmode, with a natural frequency of0.326Hz.• The structural damping of thismode was found to be only 0.29%from the full-scale measurements,after allowing for the contribution ofaerodynamic damping (c.f. structuraldamping values of 0.7% used indesign and 0.48% in the latestversion of BD49/01).• The maximum measured RMSamplitude was 191mm at midspan(i.e. 540mm peak-peak).• The mode shape correction factor,giving the increase in the maximumfull-scale response (at midspan)relative to the uniform displacementof the sectional model, was found tobe 1.4.


Earthquake Competition 2003 SECED &Imperial College.

Short Course.Advanced Notice

Practical Seismic Design:

Principles and Application to

Eurocode 8

16-17 September 2004 at

Imperial College London

SECED will be organising a shortcourse jointly with Imperial Collegeon 16 and 17 September 2004. Thefirst day will be on principles ofseismic design and the secondfocusing on Eurocode 8 guidance.The course will link with theEurocodes Expert initiative,established by the Institution of CivilEngineers to assist the UKconstruction industry with itsadoption of the new StructuralEurocodes. The programme anddetails will be published in February2004. For further informationcontact Dr Ahmed Elghazouli atImperial College (e-mail:[email protected]).

The joint Earthquake Competitionwinners for 2003 were Harry Wahab& Riccardo Sabatino - they predictedthat the next event over 2.5 ML (fromwhen the competition started at the2003 SECED meeting) would occurin Square Number 6 or 8 – and it

occurred on the line between thesetwo squares (700 KmN). Both Harry& Riccardo work for Kellog, Brown& Root. The event they predictedwas the Aberfoyle Earthquake whichoccurred at 06:44 UTC on 20 June,2003 with a magnitude of 3.2ML.

MCEER Appoint New Deputy Director

Andre Filiatrault, Ph.D, a leading expert on shake-table testing of structural and nonstructural building components,including electrical substation equipment, has been named deputy director of the Multidisciplinary Center for EarthquakeEngineering Research (MCEER) headquartered at the University at Buffalo. Filiatrault, formerly a professor of structuralengineering at the University of California-San Diego, will be responsible for coordinating MCEER's nationwide researchprogram in advanced technology applications.

"Dr. Filiatrault’s extensive experience with shake-table testing will be especially valuable to research initiatives ofMCEER and the UB School of Engineering and Applied Sciences upon completion of UB's state-of-the-art StructuralEngineering and Earthquake Simulation Laboratory" said Michel Bruneau, MCEER director. The $20 million expansionof thelaboratory will be completed in 2004. The facility will be equipped with twin shake tables capable of real-timeseismic testing of structures up to 120 feet in length.


SECED NewsletterThe SECED Newsletter is publishedquarterly. Contributions are welcome andmanuscripts should be sent on a PCcompatible disk or directly by Email. Copytyped on one side of the paper only is alsoacceptable.

Diagrams should be sharply defined andprepared in a form suitable for directreproduction. Photographs should behigh quality (black and white prints arepreferred). Diagrams and photographsare only returned to the authors onrequest. Diagrams and pictures may alsobe sent by Email (GIF format is preferred).

Articles should be sent to:

John Sawyer,Editor SECED Newsletter,Scott Wilson,Scott House,Basingstoke,Hants,RG21 4JG,UK.

Email: [email protected]

SECEDSECED, The Society for Earthquake andCivil Engineering Dynamics, is the UKnational section of the International andEuropean Associations for EarthquakeEngineering and is an affiliated society ofthe Institution of Civil Engineers.

It is also sponsored by the Institution ofMechanical Engineers, the Institution ofStructural Engineers, and the GeologicalSociety. The Society is also closelyassociated with the UK EarthquakeEngineering Field Investigation Team.The objective of the Society is to promoteco-operation in the advancement ofknowledge in the fields of earthquakeengineering and civil engineeringdynamics including blast, impact and othervibration problems.

For further information about SECEDcontact:The Secretary,SECED,Institution of Civil Engineers,Great George Street,London SW1P 3AA, UK.

SECED WebsiteVisit the SECED website which can befound at http://www.seced.org.uk foradditional information and links to itemsthat will be of interest to SECEDmembers.Email: [email protected]

Forthcoming Events

NOTICE: From February 2004SECED evening meetings will start at6pm rather than 5.30pm.

28 January 2004Seabed Liquefaction and Slope StabilityICE 5.30pm

25 February 2004Rail Induced VibrationICE 6.00pm

31 March 2004Seismic Hazards

28 April2004This Year’s Earthquake and AGM

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NOTABLE EARTHQUAKES AUGUST - OCTOBER 2003Reported by British Geological Survey

YEAR DAY MON TIME LAT LON DEP MAG LOCATIONUTC KM

2003 4 AUG 04:37 60.53N 43.41W 10 7.5 SCOTIA SEA

2003 14 AUG 05:14 39.16N 20.61E 10 6.3 GREECEAt least 50 people were injured.

2003 16 AUG 10:58 43.77N 119.64E 24 5.4 EASTERN NEI MONGOL,CHINAAt least 4 people were killed, more than 1,000 people were injured and 83,000 houses weredamaged.

2003 19 AUG 19:46 53.48N 1.01W 13 3.1 DONCASTER,S YORKSHIREFelt throughout Retford with intensities of 3 EMS.

2003 21 AUG 12:12 45.10S 167.14E 28 7.2 S.ISLAND OF NEW ZEALANDMinor damage occurred.

2003 23 AUG 03:35 56.17N 4.44W 3 1.5 ABERFOYLE,CENTRALFelt throughout Aberfoyle with intensities of 3 EMS.

2003 3 SEP 21:29 56.26N 3.73W 7 2.2 BLACKFORD,TAYSIDEFelt throughout Blackford with intensities of 3 EMS.

2003 15 SEP 08:00 56.18N 4,45W 5 2.2 ABERFOYLE ,CENTRALFelt throughout Aberfoyle with intensities of 3 EMS.

2003 22 SEP 04:45 19.78N 70.67W 10 6.5 DOMINICAN REBUBLIC REGIONOne person was killed at Puerto Plata and many buildings were damaged.

2003 25 SEP 19:50 41.79N 143.900E 27 8.3 HOKKAIDO,JAPAN REGIONAt least 589 people were injured and extensive damage occurred throughout south-easternHokkaido.

2003 25 SEP 21:08 41.79N 143.57E 33 7.4 HOKKAIDO,JAPAN REGION

2003 27 SEP 11:33 50.02N 87.82E 16 7.3 SOUTHWESTERN IBERIA,RUSSIAUnconfirmed reports that 3 people died from heart attacks, 5 people were injured and 1,800 people wereleft homeless.

2003 16 OCT 12:28 25.91N 101.28E 33 5.6 YUNNAN,CHINAAt least 3 people were killed, more than 32 people were injured and 12,000 buildings were damaged ordestroyed.

2003 25 OCT 12:41 38.38N 100.96E 10 5.8 GANSU-QINGHAI BORDER REGIONAt least 9 people were killed, more than 43 people were injured and thousands of people were lefthomeless.

2003 31 OCT 01:06 37.83N 142.63E 10 7 OFF E COAST OF HONSHU,JAPAN

Issued by: Bennett Simpson, British Geological Survey, November 2003.Non-British earthquake data supplied by: The United States Geological Survey

Applications are invited from post-graduate students or professionalindividuals with appropriateexperience to prepare a web-baseddirectory of UK academicresearchers in earthquakeengineering. A lump sum fee willbe paid to the successful applicanton completion of the project. Forfurther information, contact theSECED coordinator at ICE (e-mail:[email protected])

Documents

S THE SOCIETY FOR EARTHQUAKE AND CIVIL E S E C E D ... vol 17 no 3.pdf · THE SOCIETY FOR EARTHQUAKE AND CIVIL ENGINEERING DYNAMICS NEWSLETTER ... wythe of masonry and where these