INTERNATIONAL NAVIGATIONASSOCIATIONASSOCIATION INTERNATIONALEDE NAVIGATIONSEISMIC DESIGN GUIDELINESFOR PORT STRUCTURESWorking Group No. 34 of the Maritime Navigation CommissionInternational Navigation Association- 915 A.A. BALKEMA PUBLISHERS / LISSE/ ABINGDON / EXTON(PA) / TOKYOLibrary of Congress Cataloging-in-Publication DataApplied forCover design: Studio Jan de Boer. Amsterdam. The Netherlands.Typesetting: Macmillan India Ltd.. Bangalore. India.Printed by: Grafisch Produktiebedrijf Gorter. Steenwijk. The Netherlands.CD ~ O O I Swets & Zeitlinger B.Y.. LisseTechnical Commentary 5 is exempt from the copyright because the original material\ \ ' J ~ produced by the US Navy for the state of California. USA. No one can exercise thecopyright.The figures and table in Technical Commentary 6 have been reprinted from:Handbook on liquefaction remediation of reclaimed land. Port and Harbour ResearchInstitute (ed.). ISBN 90 54 j() 653 O. 1997. 25 em. 324 pr..EL"R 82.50/USS97.00/GBP5SAll rights reserved. No part ( ~ f this publication may he reproduced. stored in a retrieve!svstrm. or transmitted in 0I1y/0l"/11 or hy means. electronic. mechanical. hy plunocopving.recording or otherwise. without prior written permission ( ~ ( the publishers.ISBN 90 265 1g18 8 (hardback)ContentsPREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IXMembers of PIANClMarComIWorking Group 34 XIList of Tables and Figures: Main Text XIIIMain TextChapter 1. INTRODUCTION .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 3Chapter 2. EARTHQUAKES AND PORT STRUCTURES .2.1 Earthquake Motion .?? L' f: ._._ Ique action .2.3 Tsunamis '..2.4 Port Structures .2.5 Examples of Seismic Damage ~ .Chapter 3. DESIGN PHILOSOPHY .3.1 Performance-Based Methodology .3.2 Reference Levels of Earthquake Motions .3.3 Performance Evaluation .Chapter 4. DAMAGE CRITERIA .4.1 Gravity Quay Walls .4.2 Sheet Pile Quay Walls .4.3 Pile-Supported Wharves .4.4 Cellular Quay Walls .4.5 Quay Walls with Cranes ~ .4.6 Breakwaters ~ .Chapter 5. SEISMIC ANALYSIS .5.1 Types of Analysis .5.2 Site ResponselLiquefaction Analysis .7791213152323?--)2731313336434552555556v r t'JAJ\lL5.3 Analysis of Port Structures .5.4 Inputs and Outputs of Analysis .Technical CommentariesTC1: EXISTING CODES Al\.TD GUIDELINES .Tl .1 List of Seismic Design Codes and Guidelines for PortStructures .TI.2 Reviewed Aspects of Codes and Guidelines .Tl.3 Seismic Design Practice for Port Structures around the WorldTC2: CASE HISTORIEST2.1 Damage to Gravity Quay Walls .T2.2 Damage to Sheet Pile Quay Walls .T2.3 Damage to Pile-Supported Wharves .T2.4 Damage to Cellular Quay Walls .T2.5 Damage to Cranes .T2.6 Damage to Breakwaters .TC3: EARTHQUAKE MOTION .T3.1 Size of Earthquakes .T3.2 Strong Ground Motion Parameters < T3.3 Seismic Source and Travel Path Effects .T3.4 Local Site Effects .T3.5 Seismic Hazard and Design Earthquake Motion .T3.6 Ground Motion Input for Seismic Analysis of Port StructuresTC4: GEOTECHNICAL CHARACTERISATION .T4.1 Mechanical Behaviour of Soil under Cyclic Loads .T4.2 Measurement of Soil Parameters .T4.3 Evaluation of Pre-Failure Soil Properties through EmpiricalCorrelations .T4.4 Assessment of Liquefaction Potential .T4.5 Geotechnical Characterisation Strategy with Reference to theAnalysis Requirements .Appendix: Interpretation (>f Geophysical TeSTS .TC5: STRUCTURAL DESIGN ASPECTS OF PILE-DECK SYSTE!\1S .T5.1 Design Performance and Earthquake Levels .T5.2 Modelling Aspects .T5.3 Methods of Analysis for Seismic Response .T5.4 Structural Criteria for Pier and Wharf Piles .6066-\'{7779808991939494959596127129130]34]38141]51]55 ,]57]68]82]91204:!08215217:!]911JI"',.:s:Contents VIIT5.5 PilelDeck Connection Details. . . . . . . . . . . . . . . . . . . . . . .. 253T5.6 Existing Construction 262TC6: REMEDIATION OF LIQUEFIABLE SOILS 271T6.1 Overview....................................... 273T6.2 Outline of Remedial Measures against Liquefaction . . . . . .. 275T6.3 Compaction Method: Design and Installation 282T6..+ Drainage Method: Design and Installation 284... ...T6.5 Premix Method: Design and Installation 287. ... .T6.6 Preload Method: Desizn and Use 290...T6.7 Design of Liquefaction Remediation 294T6.8 Influence on Existing Structures during Soil Improvement . 299TC7: ANALYSIS METHODS 307T7.1 Simplified Analysis 309T7.2 Simplified Dynamic Analysis . . . . . . . . . . . . . . . . . . .. 330T7.3 Dynamic Analysis 355T7.4 Input Parameters for Analysis. . . . . . . . . . . . . . . . . . . . . . .. 369TC8: EXAMPLES OF SEISMIC PERFORMANCE EVALUATION '" 379T8.1 Gravity Quay Wall (Grade A) 381T8.2 Sheet Pile Quay Wall (Grade B) 397T8.3 Sheet Pile Quay Wall (Grade S) 420T8.4 Pile-Supported Wharf (Grade B) 423T8.5 Pile-Supported Wharf (Grade S) 432LIST OF SYMBOLS 441REFERENCES 453INDEX .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 469PrefaceAlthough the damaging effects of earthquakes have been known for centuries. itis only since the mid-twentieth century that seismic provisions for port structureshave been adopted in design practice. In 1997, the International NavigationAssociation (PIANC; formerly the Permanent International Association forNavigation Congresses) formed a working group, PIANClMarComIWG34, tofocus international attention on the devastating effects of earthquakes on portfacilities. This book. entitled 'Seismic Design Guidelines for Port Structures: isthe culmination of the efforts of this working group.This book is the first of its kind in presenting international guidelines for seis-mic design. The provisions reflect the diverse. nature of port facilities. Althoughconstructed in the marine environment, the port facilities are associated withextensive waterfront development, and provide multiple land-sea transport con-nections. The port must accommodate small to very large vessels, as well as spe-cial facilities for handling potentially hazardous materials and critical emergencyfacilities that must be operational immediately after a devastating earthquake.The primary goal of the working group was the development of a consistent setof seismic design guidelines that would have broad international support. Thediverse characteristics of port structures led the working group to adopt an evolu-tionary design strategy based on seismic response and performance requirements.Proven simplified methods and state-of-the-art analysis procedures have beencarefully selected and integrated in the guidelines in order to provide a flexibleand consistent methodology for the seismic design of port facilities.This book consists of a main text and eight technical commentaries. The maintext introduces the reader to basic earthquake engineering concepts and a strategyfor performance-based seismic design. The technical commentaries illustrate spe-cific aspects of seismic analysis and design, and provide examples of variousapplications of the guidelines.The working group members, technical editors, and graphics experts are listedbelow. The working group would like to express their sincere gratitude to a groupof New Zealand wharf designers/earthquake engineering experts, including Mr.Dick Carter, Prof. Bob Park, Dr. Rob Park, Mr. Grant Pearce and Mr. StuartPalmer, who are not apart of the working group, for their contributions on NewZealand design code and practice. Many colleagues in Greece, Japan and USAX PlANeprovided constructive critical reviews of the book, including Mr. Hisao Oouchi,Prof. Kyriazis Pitilakis, Dr. Craig Taylor, Dr. Tadahiko Yagyu, Dr. ShujiYamamoto, and Dr. Hiroshi Yokota. Sincere thanks are due to them for sugges-tions that improved the quality of the book. The working group would also like toexpress their sincere appreciation to the Coastal -Development Institute ofTechnology, Japan, for funding the publication, to the PlANC regional sectionsand organizations for sponsoring the working group meetings and activities, andmany 'of the member's organizations for partially funding activities associatedwith the development of these guidelines.The working group hopes that the recommended seismic guidelines for portfacilities will make a significant contribution towards mitigating seismic disastersin port areas around the world.December 15, 2000Susumu IaiChairmanPlANCIMarComIWG34Members of PIANCMarComiWorking Group 34Chairman:.Susumu Iai, Port and Harbour Research Institute, JapanSecretaries:Takahiro Sugano, Port and Harbour Research Institute, JapanKoji Ichii, Port and Harbour Research Institute, JapanPrimary Authors:Alberto Bernal, ByA Estudio de Ingenieria, SpainRafael Blazquez, Universidad Politecnica de Madrid, SpainHans F. Burcharth, Aalborg University, DenmarkStephen E. Dickenson, Oregon State University, USAJohn Ferritto, Consulting Engineer, USAW.D. Liam Finn, University of British Columbia, Canada/KagawaUniversity, JapanSusumu Iai, Port and Harbour Research Institute, JapanKoji Ichii, Port and Harbour Research Institute, JapanNason J. Mcflullough, Oregon State University, USAPiet W.H. Meeuwissen, Delta Marine Consultants bv, Netherlands (fromMay 1998)Constantine D. Memos, National Technical University of Athens, GreeceMJ.N. Priestley, University of California, San Diego, USAFrancesco Silvestri, Universita della Calabria, ItalyArmando L. Simonelli, Consiglio Nazionale delle Ricerche, ItalyR. Scott Steedman, Whitby Bird & Partners Ltd., UKTakahiro Sugano, Port and Harbour Research Institute, JapanContributing Working Group Members:Steve J. Bowring, Delta Marine Consultants bv, Netherlands (through May1998)Valery M. Buslov, Han-Padron Associates, USABrad P. Erickson, TranSystems Co., USA.x11 PlANeD. Mandja, Ministere de I'Equipement et de I' Amenagement duTerritoireIDIMA, AlgeriaWerner Pall oks, Bundesanstalt fur Wasserbau, GermanyFilippo Vinale, Universita degli Studi di Napoli Federico II, ItalyMentors:Thorndike Saville, Jr., USA(through Oct. 1998)Thomas H. Wakeman, Port Authority of New York & New Jersey, USA(fromOct. 1998)Technical Editors:Elizabeth Hausler, University of California, Berkeley, USAJohn Stebila, Berkeley, USAGraphics:Yoko Sato, Port and Harbour Research Institute, JapanList of Tables and Figures: Main TextTablesTable 3.1. Acceptable level of damage in performance-based design.Table 3.2. Performance grades S, A, Band C.Table 3.3. Performance grade based on the importance category of portstructures.Table 4.1. Proposed damage criteria for gravity quay walls.Table 4.2. Proposed damage criteria for sheet pile quay walls (when an anchor ismore difficult to restore than a wall).Table 4.3. Proposed damage criteria for pile-supported wharves.Table 4.4. Proposed damage criteria for cellular quay walls.Table 4.5. Proposed damage criteria for cranes.Table 4.6. Tolerance for ordinary maintenance of container cranes.Table 5.1. Types of analysis related with performance grades.Table 5.2. Methods for site response analysis and liquefaction potentialassessment.Table 5.3. Analysis methods for port structures.Table 5.4. List of analysis methods and references.Table 5.5. Major input parameters for analysis.Table 5.6. Analysis output.Table 5.7. Outputs from dynamic analysis.FiguresFig. 1.1.Fig. 2.1.Fig. 2.2.Fig. 2.3.Fig. 2.4.Fig. 2.5.Fig. 2.6.Worldwide zoned average earthquake hazard (modified from Bea,1997; GSHAP, 1999).Schematic figure of propagation of seismic waves.Peak horizontal bedrock accelerations over various return periods.Mechanism of liquefaction.Evidence of sand boils due to liquefaction at Hakodate Port, Japan,during the Hokkaido-Nansei-oki earthquake of 1993.Damage to a breakwater at Okushiri Port, Japan, during the Hokkaido-Nansei-oki earthquake of 1993.Typical port structures.Fig. 3.1.Fig. 3.2.Fig. 3.3.Fig. 4.1.XIV PlANeFig. 2.7. Damage to a caisson quay wall at Kobe Port, Japan, during the GreatHanshin earthquake of 1995. .Fig. 2.8. Cross section of a caisson quay wall at Kobe Port.Fig. 2.9. Damage to a sheet pile quay wall at Ohama Wharf, Akita Port, Japan,during the Nihonkai-chubu earthquake of 1983.Fig. 2.10. Cross section of a sheet pile quay wall at Ohama Wharf, Akita Port.Fig. 2.11. Damage to a sheet pile quay wall at Shimohama Wharf, Akita Port,Japan, during the Nihonkai-chubu earthquake of 1983.Fig. 2.12. Cross section of a sheet pile quay wall at Shimohama Wharf, AkitaPort.Fig. 2.13. Cross section of a pile-supported wharf at Takahama Wharf, KobePort, Japan, and damage during the Great Hanshin earthquake of 1995.Fig. 2.14. Damage to piles at Takahama Wharf, Kobe Port (after extraction forinspection.Fig. 2.15. Damage to a crane at Kobe Port, Japan, during the Great Hanshin. earthquake of 1995.(a) Overview.(b) Close-up.Fig. 2.16. Damage to a composite breakwater at Kobe Port, Japan, during theGreat Hanshin earthquake of 1995.Fig. 2.17. Damage to a rubble mound breakwater at Patras Port, Greece. after aseries of earthquakes in 1984.(a) Typical cross section.(b) Cross section before and after the failure.Flowchart for seismic performance evaluation.Schematic figure of performance grades S, A, Band C.Examples of seismic performance evaluation.Deformation/failure modes of gravity quay wall.(a) On firm foundation.(b) On loose sandy foundation.Fig. 4.2. Parameters for specifying damage criteria for gravity quay wall.Fig. 4.3. Deformation/failure modes of sheet pile quay wall.(a) Deformation/failure at anchor.(b) Failure at sheet pile wall/tie-rod.(c) Failure at embedment.Fig. 4.4. Parameters for specifying damage criteria for sheet pile quay wall.(a) With respect to displacements.(b) With respect to stresses.Fig. 4.5. Preferred sequence for yield of sheet pile quay wall.Fig. 4.6. Deformation/failure modes of pile-supported wharf.(a) Deformation due to inertia force at deck.(b) Deformation due to horizontal force from retaining wall.(c) Deformation due to lateral displacement of loose subsoil.Fig. 4.8."-Fig. 4.9.Fig. 4.14.Fig. 4.15.Fig. 4.16.LlSl Ol l a O l ( ; ~ dllU 1 15UI\o , , ~ . .Fig. 4.7. Parameters for specifying 'damage criteria for pile-supported wharf.(a) With respect to displacements.(b) With respect to stresses.Preferred sequence for yielding of pile-supported wharf.Deformation/failure modes of cellular quay wall.(a) On finn foundation.(b) On loose sandy foundation.Fig. 4.10. Deformation/failure modes of cellular quay wall involving crossdeformation.Fig. 4.11. Parameters for specifying damage criteria for cellular quay wall.(a) With respect to displacements.(bjWith respect to stresses.Fig. 4.12. Schematic figure of gantry crane..Fig. 4.13. Deformation modes of gantry crane.(a) Widening of span between the legs.(b) Narrowing span between the legs due to rocking motion.ec) Tilting of crane due to differential settlement of foundation.ed) Overturning of one-hinged leg crane due to rocking/sliding.Parameters for specifying damage criteria for crane.Parameters for evaluation overturning of crane."-Deformation/failure modes of breakwater.(a) Caisson resting on sea bed.(b) 'Vertically composite' caisson breakwater.(c) 'Horizontally composite' caisson breakwater.(d) Rubble mound breakwater.Fig. 4.17. Examples of berthing behind breakwater.Fig. 4.7. Parameters for specifying damage criteria for pile-supported wharf.(a) With respect to displacements.(b) With respect to stresses.Fig. 4.8. Preferred sequence for yielding of pile-supported wharf.Fig. 4.9. Deformation/failure modes of cellular quay wall.(a) On firm foundation.(b) On loose sandy foundation.Fig. 4.10. Deformation/failure modes of cellular quay wall involving crossdeformation.Fig. 4.11. Parameters for specifying damage criteria for cellular quay wall.(a) With respect to displacements.(b) With respect to stresses.- Fig. 4.12. Schematic figure of gantry crane.Fig. 4.13. Deformation modes of gantry crane.(a) Widening of span between the legs.(b) Narrowing span between the legs due to rocking motion.(c) Tilting of crane due to differential settlement of foundation.(d) Overturning of one-hinged leg crane due to rocking/sliding.Fig. 4.14. Parameters for specifying damage criteria for crane.Fig. 4.15. Parameters for evaluation overturning of crane.Fig. 4.16. Deformation/failure modes of breakwater.(a) Caisson resting on sea bed.(b) 'Vertically composite' caisson breakwater.(c) 'Horizontally composite' caisson breakwater.(d) Rubble mound breakwater.Fig. 4.17. Examples of berthing behind breakwater.MAIN TEXTCHAPTER IIntroductionThe occurrence of a large earthquake near a major city may be a rare event. butits societal and economic impact can be so devastating that it is a matter ofnational interest. The earthquake disasters in Los Angeles, USA, in 1994 (61fatalities and -W billion US dollars in losses); Kobe, Japan, in 1995 (over 6.400fatalities and 100 billion US dollars in losses); Kocaeli, Turkey, in 1999 (over15,000 fatalities and 20 billion US dollars in losses); Athens, Greece, in 1999 (143fatalities and 2 billion US dollars in losses); and Taiwan in 1999 (over 2,300 fatal-ities and 9 billion US dollars in losses) are recent examples. Although seismicityvaries regionally as reflected in Fig. 1.1, earthquake disasters have repeatedlyoccurred not only in the seismically active regions in the world but also in areaswithin low seismicity regions, such as in Zones 1or 2 in the figure. Mitigating theoutcome of earthquake disasters is a matter of worldwide interest.In order to mitigate hazards and losses due to earthquakes, seismic designmethodologies have been developed and implemented in design practice in manyregions since the early twentieth century, often in the form of codes andstandards. Most of these methodologies are based on a force-balance approach, inwhich structures are designed to resist a prescribed level of seismic forcespecified as a fraction of gravity. These methodologies have contributed to theacceptable seismic performance of port structures, particularly when the earth-quake motions are more or less within the prescribed design level. Earthquakedisasters, however, have continued to occur. These disasters are caused eitherby strong earthquake motions, often in the near field of seismic source areas, orby moderate earthquake motions in the regions where the damage due to groundfailures has not been anticipated or considered in the seismic design.The seismic design guidelines for port structures presented in this book addressthe limitations inherent if) conventional design, and establish the framework for anew design approach. In particular, the guidelines are intended to be:- performance-based, allowing a certain degree of damage depending onthe specific functions and response characteristics of a port structure andprobability of earthquake occurrence in the region;- user-friendly, offering design engineers a choice of analysis methods, whichrange from simple to sophisticated, for evaluating the seismic performance ofstructures; and -4 Y1ANCEARTHQUAKE INTENSITYZONEO=O.OO-O.05gZONE1=O.OS-O.15gZONE2=O.1S-0.25gZONE3=O.2S-0.35gZONE4=O.3S-0.45gZONE5=O.4S-0.55g':,SEISMOTECTONIC TYPEA=Shaliow crustal fault zonesB=Deep subduction zonesC=Mixed shallow crustal faultand deep subduction zonesD=lntraplate zones13NOTE: Values of acceleration corresponding to a return period of475 years.Some areas of low average seismic hazard have historically experienced major destructiveearthquakes.Fig. 1.1. Worldwide zoned average eanhquake hazard (modified from Bea. 1997;GSHAP, 1999).general enough to be useful throughout the world, where the required functionsof port structures, economic and social environment, and seismic activities maydiffer from region to region.The expected users of the guidelines are design engineers, port authorities, andspecialists in earthquake engineering. The applicability of the guidelines willreflect regional standards of practice. If a region has no seismic codes or standardsfor designing port structures, the guidelines may be used as a basis to .developeanew seismic design methodology, or codes applicable to that particular region. Ifa region has already developed seismic codes, standards, or established designpractice, then the guidelines may be used to supplement these design and analy-sis procedures (see Technical Commentary I for existing codes and guidelines). Itis not the intent of the authors to claim that these guidelines should be used insteadof the existing codes or standards or established design practice in the region ofIntroduction 5interest. It is anticipated, however. that the guidelines will, with continual modifi-cation and upgrading, be recognized as a new and useful basis for mitigatingseismic disasters in port areas. It is hoped that the guidelines may eventuallybe accepted worldwide as recommended seismic design provisions.Earthquake engineering demands background knowledge in several disci-plines. Although this background knowledge is not a pre-requisite to understand-ing the guidelines, readers may find it useful to have reference textbooks readilyavailable. Pertinent examples include Kramer (1996) on geotechnical earthquakeengineering and Tsinker (1997) on design practice for port structures.This Main Text provides an overview of the seismic design guidelines. More.details in the particular aspects of the seismic design guidelines can be found inthe following Technical Commentaries (TC):TCI: Existing Codes and GuidelinesTC2: Case HistoriesTC3: Earthquake MotionTC4: Geotechnical CharacterisationTC5: Structural Design Aspects of Pile-Deck SystemsTC6: Remediation of Liquefiable SoilsTC7: Analysis MethodsTC8: Examples of Seismic Performance EvaluationsCHAPTER 2Earthquakes and Port StructuresThis chapter addresses issues fundamental to understanding seismic effects onport structures. As illustrated in Fig. 2.1, seismic waves are generated along acrustal fault and they propagate through upper crustal rock, travelling to the sur-face of the bedrock at a site of interest. The ground motions then propagatethrough the local soil deposits, reaching the ground surface and impacting struc-tures. Depending on the intensity of shaking and soil conditions, liquefaction ofnear-surface soils and associated ground failures may occur and could signifi-cantly affect the port structures. If an offshore fault motion .involves verticaltectonic displacement of the seabed, tsunamis may be generated. The engineeringaspects of these phenomena are collectively important in the evaluation of theseismic effects on port structures.2.1 EARTHQUAKE MOTION(l) Bedrock MotionThe bedrock motions used for seismic analysis and design at a particular site arecharacterized through seismic hazard analysis. If a specific earthquake scenario isassumed in the seismic hazard analysis, the bedrock motion is defined detennin-istically based on the earthquake source parameters and wave propagation effectsalong the source-to-site path. Most often, however, the bedrock motion is definedprobabilistically through the seismic hazard analysis, taking into account uncer-tainties in frequency of occurrence and location of earthquakes.One of the key parameters in engineering design practice is the intensity ofbedrock motion defined in terms of peak ground acceleration (PGA), or in somecases peak ground velocity (PGV). This parameter is used either by itself or toscale relevant ground motion characteristics, including response spectra and timehistories. In the probabilistic seismic hazard analysis, the level of bedrock motionis defined as a function of a return period, or a probability of exceedance over aprescribed exposure time. An example is shown- in Fig. 2.2, in which PGAs atbedrock are obtained based on geologic, tectonic and historical seismic activity8 PlANe }SOil Layers /. BedrockFig. 2.1. Schematic figureof propagation ofseismic waves.Fig. 2.2. Peak horizontal bedrockaccelerations over van-OllS return periods.1000500Return Period (years) SanFrancisCO//.

.::t.cg 0.0 o 100Oi 1.0-r----------------,-co;;cg 0.8Q)oo dJHe, whereJ..4,: coefficient of friction; d\: expansion of leg span (m), He: height of the hingefrom the apron (m) (refer to Fig. 4.15).4) Damage Degree IV of the quay wall should be the state beyond the upper limitof the damage Degree III.A set of tolerances for ordinary maintenance of cranes is shown in Table 4.6(Japan Cargo Handling Mechanization Association, 1996). This set of tolerancesFig. 4.15. Parameters for evaluationoverturning of crane.N: Axial load from a crane legTable 4.6. Tolerance for ordinary maintenance of container cranes.Parameters ToleranceRail Span Lspan ( ~ < 25 m)(25 m ~ u: ~ 40 m)Level difference between sea and land side railsCurving in vertical directionCurving in horizontal directionInclinationRail joint Differential displacements (vertical and horizontal)Gap*Relative to original layout.10mm 15mm~ 1 0 0 05 mrn per 10m5 mrn per 10m1/500Imm5mm*52 PlANecould be used as one of the references to establish more restrictive damagecriteria than discussed earlier.4.6 BREAKWATERSA breakwater is usually made of a rubble mound, a massive structure such as acaisson, or a combination of both placed on a seabed. Stability against a horizon-tal external load is maintained by shear resistance of rubble, friction at the bottomof the caisson, -and with associated resistance to overturning and bearing capacityfailure. Typical failure modes expected during earthquakes are shown in Fig. 4.16.Breakwaters are generally designed to limit wave penetration and waveovertopping during specific design storms, and at the same time designed to resistthe related wave actions. It is unlikely that a major earthquake will occur simul-taneously with the design sea state because the two events are typically not relat-ed. Consequently, design storm wave action and an earthquake can be treated astwo independent load situations. Only wave actions from a moderate sea stateshould be considered together with the design earthquakes. Decision on this seastate has to be made based on the site-specific long-term statistics of the storm.Selection of the appropriate design criteria depends on the functions of thebreakwater and the type of earthquake-induced failure modes. However, for allbreakwaters, the main criterion is the allowable settlement of the crest levelbecause it determines the amount of overtopping and wave transmission. Forbreakwaters carrying roads and installations, additional criteria for allowable dif-ferential settlement, tilting and displacement of superstructures and caissons areneeded.Shaking of the breakwater may cause breakage of concrete armour units.Criteria have been proposed with regard to maximum breakage in terms of num-ber of broken units that may occur while the breakwater remains serviceable (e.g.Zwambom and Phelp, 1995). The same criteria may be adopted for the earth-quake-related damage.Since the damage criteria for breakwaters have not been fully developed atpresent, the performance grade is being described in order to indicate the relativedegree of allowable damage. The level of damage to various kinds of breakwaters,according to the primary and secondary functions of breakwaters, is as follows:- reduce wave penetration in basins (Grade C);- recreational (access for people) (Grade C; but can be Grade Aor B dependingon the level of acceptable human life safety);- provision of berthing on the port side of the breakwater, and related accessroads (Grade B) (see Fig. 4.17);- provision of cargo handling facilities on the breakwater, including conveyorbelts (Grade B), and pipelines for oil and liquid gas (Grade A or S. dependingon the level of threat of explosion).Damage Criteria 53-Crest lowering due to settlement ofsubsoil.Oifferentialsettlementandtilt ofcaissons.Possible damage tocaissonshearkeys Slip failures andsubsequentcrest loweringdue to liquefaction subsoil-. Differential settlementandtilt ofcaissons Damage111 caisson shear keys iftheyexist(a)Rubble Mound Crest lowering due to shakedawn of rubble foundation Differential settlement ofcaissonsCaisson.Crest lowering andlateral spreading due to settlemenl/liquefactionof subsoil Differential settlement ofcaissons-Slip failures and subsequentcrest loweringdue to liquefaction ofsubsoil Differential tilt andsettlement ofcaissons Damage 111 caiSSOll shearkeysif they exist(b)11-----c..sscn III of slender types ofconcrete armour units.Subsequent increasedovertoppinlt and risk ofdisplacement ofcaisson(c) .. "'. ......::::{'t:.::;-===- 2 ;/ ., ',RUllllle Mound "-- ------------- ----- Crest loweringdue toshake downof rubblematerial Differenrial settlement of superstructure elements'5? -Crest loweringandlateralspreadingdue 111setdemenl/liquefaction of subsoil-Differential settlement of superstructure elements Failures due to liquefaction ofsubsoil.Subsequent lowering ofcrest-Possible tilt anddisplacement ofsuperstructure elements(d)Fig. 4.16. Deformation/failure modes of breakwater.(a) Caisson resting on sea bed.(b) 'Vertically composite' caisson breakwater.(c) 'Horizontally composite' caisson breakwater.(d) Rubble mound breakwater.Damage Criteria 54Fig. 4.17. Examples of berthingbehind breakwater.CHAPTER 5Seismic AnalysisSeismic analysis of port structures is accomplished in three steps that includeassessment of the regional seismicity, the geotechnical hazards, and soil-structureinteraction analysis. The first step is to define the earthquake motions at thebedrock (see Fig. 2.1 for the relative location of the bedrock with respect to theseismic source, ground surface and port structures). This is typically accom-plished by seismic hazard analysis based on geologic, tectonic and historical seis-micity data available for the region of interest. The second step involves thefollowing two interrelated aspects of dynamic soil response: (1) an evaluation oflocal site effects for obtaining the earthquake motions at or near the groundsurface; and (2) an assessment of the liquefaction resistance of the near surfacesandy soils and the associated potential for ground failures. Once the groundmotion and geotechnical parameters have been established, then seismic analysisof the port structure(s) can proceed.As in all engineering disciplines, reasonable judgement is required in specify-ing appropriate methods of analysis and design, as well as in the interpretation ofthe results of the analysis procedures. This is particularly important in seismicdesign, given the multidisciplinary input that is required for these evaiuations, andthe influence of this input on the final design recommendations. This chapterprovides general recommendations for the type and level of analysis required forvarious port structures.5.1 TYPES OF ANALYSISThe objective of analysis in performance-based design is to evaluate the seismicresponse of the port structure with respect to allowable limits (e.g. dis-placement, stress, ductility/strain). Higher capability in analysis is generallyrequired for a higher performance grade facility. The selected analysis methodsshould reflect the analytical capability required in the seismic performanceevaluation.A variety of analysis methods are available for evaluating the local site effects,liquefaction potential and the seismic response of port structures. These analysis56 PlANemethods are broadly categorized based on a level of sophistication and capabilityas follows:1) Simplified analysis: Appropriate for evaluating approximate threshold limitfor displacements and/or elastic response limit and an order-of-magnitude esti-mate for permanent due to seismic loading. .2) Simplified dynamic analysis: Possible to evaluate extent of displacementlstress/ductility/strain based on assumed failure modes.3) Dynamic analysis: Possible to evaluate both modes and the extent ofthe displacementlstress/ductility/strain.Table 5.1 shows the type of analysis that may be most appropriate for eachperformance grade. The principle applied here is that the structures of higherperformance grade should be evaluated using more sophisticated methods. Asshown in the index in Table 5.1, less sophisticated methods may be allowed for screeniJ}g or ... Wi\ excitation.In the present state of practice, it is desirable to confirm the applicability ofmethods for analysis of port structures by using suitable case histories or modeltest results before accomplishing the seismic performance evaluation.5.2 SITE RESPONSEILIQUEFACTION ANALYSISSite response analysis and liquefaction potential assessments are typically accom-plished using the methods outlined in Table 5.2. Useful references that highlightthe applicability of the various modeling procedures, have been prepared byseveral investigators (e.g.. Finn, 1988; Idriss, 1991).(l) Site response analysisIn simplified analysis, local site effects are evaluated based on the thickness of thedeposits and the average stiffness to a specified depth (generally 30 m), or overthe entire deposit above the bedrock. This information is then used to establishthe site classification, leading to the use of specified site amplification factors orsite dependent response spectra. This type of procedure is common in codes andstandards.In simplified dynamic analysis. local site effects are evaluated numerically withmodels such as common equivalent linear. total stress formulations. Soil layersare idealized as horizontal layers of infinite lateral extent (i.e. one-dimensional(ID. These methods are used to generate time histories of acceleration, shearstress, and shear strain at specified locations in the soil profile.In both of these categories of analyses, the computed ground surface earth-quake motion parameters are used as input for subsequent simplified structuralanalysis as discussed in Section 5.3.Table 5.1. Types of analysis related to performance grades.Type of analysis Performance gradeGrade C Grade B Grade A Grade S'Simplified analysis:Appropriate for evaluating approximate threshold level and/or elastic limitand order-of-magnitude displacementsSimplified dynamic analysis:Of broader scope and more reliable. Possible to evaluate extent ofdisplacement/stress/ductility/strain bused on assumed failure modesDynamic analysis:Most sophisricated. Possible to evaluate both failure modes and extent ordisplacement/stress/ductiIity/strainIndex: Standard/final design Preliminary design or low level of excitations.IINU ..,!t.)e""; . 'N. . .. :.;. . . ,." ' ",' "." '. . ,: : ''l!. Li1I..... ,.,,, .1 ..L.cJl ..'.; 1",/.1..:11: t. .\..14 i .... C/J(\I_.'Jl:;jo'

::Jeo'- What factor is adopted for specifying the effective seismic coefficientas a fraction of peak ground acceleration for retaining structuredesign?>- What types of response spectra are used for pile-supported structures indesign?An overview of the existing codes and guidelines reviewed with respect to theaforementioned aspects is shown in Table T1.1. Additional specifics. to backupthe descriptions in Table T1.1, are presented below.(1) Japanese design (Port and Harbour Research Institute, 1997: Ministry ofTransport, Japan, 1999).The dual level approach has been adopted for structures of Special Class ofImportance. However, the single level approach is adopted for structures of ClassA, B, and C of Importance.For structures of Special Class of Importance, the performance level is speci-fied as follows:For L1: Minor or no damageflittle or no loss of serviceability.For L2: Minor or little damagellittle or short-term loss of serviceability.rn.i )Existing Codes and Guidelines 81For retaining structures of Special Class of Importance. the criteria for struc-tural damage and criteria regarding serviceability are shown in Tables Tl.2 andT1.3.The seismic coefficient for use in retaining structures is defined as follows forSpecial Class structures.tk: - Q max( O? )h - -- a max:S; ._gg( )/ 3I am:tllkh =3 g (a max >0.2g)For Class B structures (designed with importance factor of 1.0), the code-speci-fied seismic coefficients are about 60% of those given by Eqn. (T1.1).For a pile-supported wharf with vertical piles, analysis is performed based ona simplified procedure and pushover method. The ductility limits for use in thesimplified procedure (see Technical Commentary 7) for Ll earthquake motionare specified as shown in Table TIA. Pushover analysis is performed for SpecialClass structures and the strain limits prescribed are:Level I motion: equivalent elastic,Level 2 motion: Cmax =O.44tp/Dp for the embedded portion.Pile-supported wharves with .vertical steel piles are designed using theresponse spectra shown in Fig. T1.1 for L1 motion. These spectra have been com-puted based on 2D soil-structure interaction analysis for typical pile-supportedwharf cross sections. For L2 motion, time history analysis should be performedand the results should meet the ductility limits for L2 earthquake motion shownin Table T1.5.Comprehensive guidelines are shown on liquefaction potential assessment andimplementation of remedial measures (Port and Harbour Research Institute, 1997).(2) Spanish design (ROMO.6, 2000)Dual earthquake levels must be considered in the design, but only Level 2 earth-quake motion is considered for low seismic design acceleration.Analysis procedures specified in ROM ranges from the simpler methods forthe lower design acceleration to the more sophisticated methods for the higherdesign acceleration.In most cases, liquefaction is one of the main aspects to be considered. In addi-tion, the codes specifies the criteria with respect to: Gravity walls, breakwaters: overall stability, post-earthquake displacements. Sheet pile walls, piled decks: structural behaviour.Pile-supported wharves/piers with vertical steel piles are designed using theductility factors given as follows:Wharves: Pile cap: J1 = up to 5.0 Embedded portion: J1 = 2.0Piers: Pile cap: J1 =up to 4.0 Embedded portion: J1 =1.5Table '1'1./. Overview ofexisting codes and guidelines for port structures.Japanese Dual level for For Special Class:(1997, 1999) Special Class No damage for LI;Single level for Minor damage andClass A, B, C lillIe or short-termloss of serviceabilityfor L2Codes/ McthodologyGuidelines S' I I I, IIIg C (II' uualevel approachDamage criteria00NAnalytical procedure Remarks 'i:l.....The factor a for Response spectra zspecifying the (Jeffective seismiccoefficient as afraction of anlulgSee Eqn. (TI.I) LI: See Fig. Tl. I These codesL2: Time history andanalysis [no guidelinesresponse spectra have beenspecified] specificallyestablishedfor designinga=0.7 See Eqn. (Tl.2) I port structuresDuctility/strainlimit for pile-supportedwharf/pierSimplifiedprocedure usesdisplacementductility factors.Pushoveranalysis usesstrain limitDuctility factorsfor pile headand embeddedportions.Different forwharf and pierDisplacementfor retainingstructuresNut SpecifiedSee TablesTI.2 & TI.3Performance level(Acceptabledamage level)Little or short-termloss of serviceabilityfor L I: No collapsefor L2Dual levelapproach:Seismic inputin each leveldepends on theimportanceand life timeof structureSpanish(2000)German(1t)9(j)Single level Not specifiedapproach.More detailedanalysis isrequired ifdamage canendangerhumane liveNot specified Not specified Not specified;a to be takenfrom nationalcodeNot specifiedu US DUlll Method Serviceable Soil limits Ductility limits N/A Linear orS Navy LI 75 year under LI and specified for specified for NonlinearA (.1997) L2 500 year repairable wharf dikes piles DynamicEvents under L2 AnalysisASCE- Dual level Critical structures: Site-specific Ductility limits See Eqn. (T1.1) a) responseTCLEE approach: Serviceable under based on specified for spectrum( 1998) exposure time LI and repairable serviceability piles methodsand ground under L2 and effect on b) time historymotion are Other structures: adjacent analysisbased on the Repairable for LI structures c) pushoverimportance. analysisand design lifeCalifornia Dual Method Serviceable Soil Strain limits for N/A A) Single ModeMarine Ll 75 year under LI and deformation piles under 8) Multi-modeOil L2 500 year repairable under L2 limits for soil limit conditions C) PushoverTerminals Events structure D) Inelastic(2000) interaction Time HistoryEurocode Dual level No reference to Not specified Not specified. Design ground See Eqn. (TI.3) These codestT1( 1(94) approach Port Structures A guidance is acceleration refer to xVi'given for the fraction for buildings ...._.::;)design of { l J c s i ~ n and other OQplastic hinging is specified civil ()0engineenng 0-New Zealand Dual method The Ultimate Limit Not specitied Both are Design Spectra Based on seismic I1lworks with til(1992-19(7) state peak response specified are used zone, subsoilno direct 15spectra is given condition, 0-reference C)structure period c10 port_.and ductility 0-I1lstructures -factor 5'I1ltil00VJDeeper than 7.5 m84 PlANCTable Tl.2. Structural damage criteria in Japanese standard.Type of retaining walls Water depth------------------Shallower than 7.5 mHorizontal displacement Horizontal displacementoto 0.2 m 0 to 0.3 moto 0.3 m 0.3 to 0.5 m_ Gravity quay wall No repair needed for operation Partial operation allowedSheet pile quay wall No repair needed for operation Partial operation allowedHorizontal displacementoto 0.2 m0.2 to 0.5 mHorizontal displacementoto 0.3 m0.3 to 1.0 mTable T1.3. Serviceability criteria in Japanese ports.Main body Upper limit of settlementof retaining Upper limit of tiltingstructure Upper limit of differential horizontal displacementApron Upper limit of differential settlement on apronUpper limit of differential settlement betweenapron and backgroundUpper limit of tilting0.2 to 0.3 m3-500.2 to 0.3 m0.3 to 1.0m0.3 to 0.7 m3-5% [towards sea]5% [towards land)Table TIA. Ductility factor for Ll motion in the simplified analysis.Special Class J.l = 1.0Class A u = 1.3Class B u = 1.6Class C J.l = 2.3Design response spectra are specified as follows:For T =0 to TA: SAladesign =1 + 1.5 TITAFor T =TA to TB: SA..!adesign =2.5For T> TB: SAladesign = KCITwhere adesign = 0.04 to 0.26g, TA =KC/lO, TB =KC/2.5K=1.0 to 1.5 (depends on type of seismicity)C= 1.0 to 2.0 (depends on ground conditions)(T1.2)(3) German design (EAU, 1996)The German recommendations for quay walls describe a single level approachwith a conventional seismic earth pressure based on the Mononobe-Okabe equa-tion (Mononobe, 1924; Okabe, 1924). Pressures are assumed to increase linearlywith depth, although it is accepted [R125] that tests have shown this not to be thecase. The soil-water system is assumed to move as one body. and no water hydro-dynamic suction in front of the wall is taken into account. The requirements foraccuracy of the calculations are correspondingly more stringent when earthquake ._._ .... 1 _."'- _ , .'Existing Codes and Guidelines 85Region A1.00 Region B1.0010 1.0Natural Period (s)/.\ I I : ,6-,I ",'@ i ;~ ! II D ~, ! ~,, III Il! Ii :, IiII! :CQl~o 0.10,!olEIII'ijjen0.0110 0.1 1.0Natural Period (5).,2': I I ' ~ I , ,(3) I :I1 iI~ ~ I'~II j , ,I I III1 ,0.00.1C- no damage or serviceable under L1 motion;>- repairable or short-term loss of serviceability under L2 motion;- damage criteria to specify limit conditions in engineering terms, includingwall displacement and pile ductility demand, have been under developmentand further studies may be needed to establish them;- analytical procedures adopted for design, including the factor for specifyingthe effective seismic coefficient for retaining structures and the response spec-tra used for pile-supported structures, vary depending on the region;liquefaction is considered a primary design factor for port structures.The current state of seismic design practice may be in a rapidly changing transi-tional state, from the conventional design toward the performance-based design,the latter of which is fully discussed and illustrated in this book.90 PlANeIt must be emphasized that there is a significant difference between the designapproach recommended in these guidelines and the conventional design concept.In the conventional design concept, especially when referring to the simplifiedanalysis, an equivalent seismic coefficient is used as an input parameter repre-senting adequately the ensemble of ground motions, and a factor of safety isapplied to detemiine the dimensions and" properties of the 'structure. In the pro-posed approach, the design is based on the seismic performance of the structureevaluated appropriately through response analysis for a variety of input earth-quake motions. The ensemble of the seismic responses, rather than the ensembleof input motions, is used as a basis for accomplishing the design in the proposedguidelines. For each response analysis, input parameters most appropriate arethose well defined in terms of applied mechanics, such as a peak ground accel-eration for the simplified analysis and/or an equivalent parameter clearly definedin terms of peak ground acceleration. Consequently, no factor of safety should beapplied to input data used in seismic analysis for evaluating the threshold level ofthe structure. This important distinction between conventional design and per-formance-based design should also be borne in mind when interpreting thedesign guidelines included in the various seismic codes.Te2: Case HistoriesT2.1T1.2T2.3T2.4T') -_.)T2.6Damage to Gravity Quay WallsDamage to Sheet Pile Quay WallsDamage to Pile-Supported WharvesDamage to Cellular Quay WallsDamage to CranesDamage to BreakwatersTECHNICAL COMMENTARY 2Case HistoriesSelection of well-documented case histories of damage to port structures(1980-1999) is presented for the events listed in Table T2.1. The sequential num-bers 1 through 29 shown in this table may be used as indexes in referring to therelevant case histories shown in Tables T2.2 through T2.30 in this technical com-....mentary. These case histories illustrate various seismic effects on port structures.T2.1 DAMAGE TO GRAVITY QUAY WALLSAs discussed in Section 4.1 in the Main Text, a gravity quay wall is made of acaisson or other gravity retaining structure placed on seabed. Stability againstearth pressures from the backfill soil behind the wall is maintained by the massof the wall and friction at the bottom of the wall. For gravity quay walls on firmfoundations, typical failure modes during earthquakes are seaward displacementsand tilting (Tables T2.3 through T2.5). For a loose backfill or natural loose sandyfoundation, the failure modes involve overall deformation of the foundationbeneath the wall, resulting in large seaward displacement, tilting and settlements(Table T2.7). A wall with a relatively small width to height ratio, typicallyless than about 0.75, exhibits a predominant tilting failure mode rather thanhorizontal displacements, resulting, in the extreme case, in the collapse of thewall (Table T2.2).The evidence of damage to gravity quay walls (Tables T2.2 through T2.9)suggests that:I) most damage to gravity quay walls is often associated with significant defor-mation of a soft or liquefiable soil deposit, and, hence, if liquefaction is anissue, implementing appropriate remediation measures against liquefactionmay be "an effective approach to attaining significantly better seismic per-formance;2) most failures of gravity quay walls in practice result from excessive deforma-tions, not catastrophic collapses, and, therefore, design methods based ondisplacements and ultimate stress states are desirable for defining thecomprehensive seismic performance; and94 PlANe3) overturning/collapse of concrete block type walls could occur when tilting isexcessive, and this type of wall needs careful consideration in specifyingdamage criteria regarding the overturning/collapse mode.T2.2 DAMAGE TO SHEET PILE QUAY WALLSAs discussed in Section 4.2 in the Main Text, a sheet pile quay wall is composedof interlocking sheet piles, tie-rods, and anchors. The wall is supported at theupper part by anchors and the lower part by embedment in foundation soil.Typical failure modes during earthquakes depend on structural and geotechnicalconditions, as shown in Tables TI.IO through T2.15. The evidence of damage tosheet pile quay walls suggests that:1) most damage to sheet pile quay walls is often associated with significant earthpressures from a soft or liquefiable backfill soil (Tables T2.10 and T2.12),and, hence, if liquefaction is an issue, implementing appropriate remediationmeasures against liquefaction may be an effective approach to attainingsignificantly better seismic performance (Tables T2.11 and T2.13);2) if the anchor is embedded in competent soil, most failures of sheet pile quaywalls occur at the sheet pile wall due to excessive bending moment (TablesT2.10 and T2.12), whereas, if the anchor is embedded in liquefiable soil, fail-ures occur at the anchor, resulting in overall seaward movement and tilting ofthe sheet pile wall and anchor system; and3) structural damage to a sheet pile quay wall is governed by stress states ratherthan displacements. It is therefore important to determine the preferredsequence and degrees of ultimate states that may occur in the composite sheetpile quay wall system.T2.3 DAMAGE TO PILE-SUPPORTED WHARVESAs discussed in Section-l.S in the Main Text, a pile-supported wharf is composedof a deck supported by a substructure consisting of piles and a rock dike/slope.The unsupported pile length above the dike/slope surface is variable. When rock-fill suitable for construction of the dike is uneconomical. a gravity or sheet pileretaining structure is also constructed to replace a portion of the dike. Theseismic response of pile-supported wharves is influenced to by interaCliQ!l.Q!!ring gr91!D.c! Typical failure modesduring earthquakes depend on the magnitude of the inertia force relative to theground displacement. In particular. the failure associated with the ground dis-placement shown in Tables T2.16. T2.] 7, TI.20, and T2.22 suggests that specificdesign consideration is required in the geotechnical aspect of seismic design.Case Histories 95Among various structural components in the pile-supported wharves. specialattention should be paid to the application of batter piles. Batter piles remain themost efficient structural component for resisting lateral loads due to mooring.berthing and crane operation. However, the batter pile-deck system results in amuch more rigid frame than one with vertical piles. As a result. large stress con-centrations and shear failures of concrete batter piles have been observed duringearthquakes (Tables T2.16 and T2.18). This mode of pile failure demonstratesthat the structural design of batter piles used in regions of high seismicity mustaccount for displacement demand and appropriate ductility.Structural damage to a pile-supported wharf is governed by stress/strain. states rather than displacements. It is important to determine the preferredsequence and degrees of ultimate states to occur in the composite pile-supportedwharf system. Most pile failures are associated with liquefaction of soil whichcan result in buckling of the pile, loss of pile friction capacity, or development ofpile cracking and hinging. Hinging may be at the cap location or at aninterface between soil layers of differing lateral stiffness (Table T2.20). Damageto piles in the soil may also occur about I to 3 pile diameters below grade innon-liquefying soils due to the dynamic response of the wharf (see TechnicalCommentary 5).T2.4 DAMAGE TO CELLULAR QUAY WALLSAs discussed in Section 4.4 in the Main Text, a cellular quay wall is made of asteel plate or sheet pile cell with sand or other fill. Resistance against inertiaforces and earth pressures is provided by the fill friction at the bottom surface ofthe cell for a non-embedded cell, or by the resistance of the foundation subsoil atthe cell embedment. Typical failure modes during earthquakes depend on cellembedment and geotechnical conditions, resulting in varying degrees of seawarddisplacement, settlement and tilting. In addition to the gross deformation, warp-ing of the cellular cross section can occur (Table T2.23). Such performance ofcellular quay walls should be considered in the seismic design criteria.T2.5 DAMAGE TO CRANESAs discussed in Section 4.5 in the Main Text, a crane consists of an upper struc-ture ~ o r handling cargoes, and a supporting structure for holding in place andtransporting the upper structure. The crane is generally made of a steel frame.The supporting structure is either a rigid frame type or a hinged leg type,andrests on rails through the wheels.96 PlANeA crane at rest is fixed to rails or to a quay wall with clamps or anchors. Thestrengths of these clamps or anchors provides the upper limit resistance againstexternal forces acting on the crane. A crane in operation, however, is not supportedwith clamps or anchors. The lateral resistance of the crane against external forcesduring operation is only due to friction and resistance from the wheel flanges. ..Typical failure modes during. earthquakes are derailment of wheels, detach-ment or pull-out of the vehicle, rupture of clamps and anchors, buckling, andoverturning. Widening of a span between the legs due to the deformation of thequay wall results in derailment or buckling of the legs (Table T2.26). Conversely,narrowing of a leg span can also occur due to the rocking response of the crane(Table T2.24). This is due to an alternating action of the horizontal component ofresisting forces from the quay wall during a rocking type response involvinguplifting of one side of the legs. The rocking response can also result in thederailment, leading to tilting. If the tilting becomes excessively large, overturn-ing of the crane may result (Tables T2.25 and T2.27). The overturning typicallyoccurs toward land because of the location of the center of gravity of the cranesat rest, and differential settlement on the crane foundation associated with thedeformation of quay walls.Crane rails are often directly supported either by a portion of a retaining wall,or by the deck of a pile-supported wharf. When the width of the gravity wall issmall, or the quay wall is a sheet pile or cellular type, a separate foundation oftenconsisting of piles is provided to support the rails. In order to achieve desirableseismic performance of quay walls with cranes, special consideration is requiredfor the rail foundation. One such consideration could include providing a dedi-cated and cross-tied upper structure to support the rails.T2.6 DAMAGE TO BREAKWATERSAs discussed in Section 4.6 in the Main Text. a breakwater is usually made of a. Jrubble mound, a caisson, or a combination of both placed on the seabed. Stabilityagainst a horizontal external load is maintained by shear resistance of the rubble.friction at the bottom of the caisson, and with associated resistance to overturn-ing and bearing capacity failure. Typical failure modes during earthquakes aresettlement associated with significant foundation deformation beneath thecaisson/rubble foundation (Table T2.28). It should be noted that even withmoderate earthquakes, failure can happen due to extremely soft clay deposits andlarge seismic amplification within and beneath the rubble mound (Table T2.29).Damage to breakwaters from a tsunami typically results in the caissons beingwashed off or tilting into the rubble mound (Table T2.30). If the performanceobjective of a breakwater includes preventive measures against a tsunami. appro-priate design criteria need to be established with respect to both the earthquakemotion and tsunamis.Case Histories 97Table T2.1. Selected case histories of damage to port structures (1980-1999).No. Port structure Earthquake Portyear (magnitude")1 Gravity Block 1985 (A,t =7.8) San Antonio Port Chile")quay 1986 (.H\ =6.2) Kalarnata Port Greece3 wall 1989 (M =6.0) Port of Algiers Alseriac4 Caisson 1993 UII!l =7.8) Kushiro Port Japan5 1993 (Ml=7.8) Kushiro Port Japan6 1995 (Ml=7.2) Kobe Port Japan.7 Block 1999 (Mw=7.4) Derince Port Turkey8 Caisson 1999 (Ms=7.7) Taichung Port Taiwan9 Sheet pile quay wall 1983 (Ml=7.7) Akita Port Japan10 1983 (MI=7.7) Akita Port Japan11 1993 (Ml=7.8) Kushiro Port Japan12 1993 (Ml=7.8) Kushiro Port Japan13 1993 (Ml=7.8) Hakodate Port Japan14 1993 (Ms=8.1) Commercial Port, Guam USA15 Pile- RC pile** 1989 (.Ws = 7.1) Port of Oakland USA16 supported 1990(Ms=7.8) Port of San Fernando Philippines17 wharf PC pile** 1994(Ms = 6.8) Port of Los Angeles USA18 1994 (Ms=6.8) _Port of Los Angeles USA19 Steel pile 1995 (Ml =7.2) Kobe Port Japan20 PC pile 1995 (Ms = 7.2) Port of Eilat Israel21 Dolphin Steel pile 1995 (lV!l =7.2) Kobe. Sumiyoshihama Japan22 Cellular quay wall 1995 (Ml=7.2) Kobe Port Japan23 Crane 1983 (Ml =7.7) Akita Port Japan24 . 1985 (Ms=7.8) San Antonio Port Chile25 1995 (Ml =7.2) Kobe Port Japan26 1999 (Mw =7.4) Derince Port Turkey27 Break- Composite 1995 (Ml =7.2) Kobe Port Japan28 water Rubble 1984(M =4.5) Patras Port Greece29 Composite 1993*** (M, =7.8) Okushiri Port Japan* For definition of magnitude. refer to Technical Commentary 3.** RC: Reinforced concrete; PC: Prestressed concrete.*** Damage due to Tsunami.98 PlANeTable T2.2. Case history No.1: San Antonio Port, Chile. (Ms =-7.8)Structural Structure and location: Berths 1 & 2and seismic Height: + 4.9 mconditions Water depth: - 9.6 mConstruction (completed): 1918-1935Earthquake: March 3, 1985 Chile earthquakeMagnitude: M, =7.8Peak ground surface acceleration (PGA): 0.67 gPGA evaluated based on strong motion earthquake records.Cross section: Block quay wall6.0'9'41815Scal. level I, T1m) 1m) Soil type ISPNvalue.4 7ft t, or. >n ,n 4n .. no - Sand and I"':1 gravel fill :, ! :2 2.S! : : : i :3 1.'0 Coarse sane ;::.::: : : , If' I5 Fine sand :,:, 1 '.: i, ;6 '.20 1'9: :Medium to ::: Icoarse sane ' , 8 3.65 r:: :9 '1 iClay 10",10 I: :l' :::12 .7.50 witn silly 1m... 5: ,'o?F'lne sane I13 8.65 "" h stone ::: "PO''l II.... I. .I I I Fmeto : : :medium sand iii : :16 -12.00 : : I ';'0'17 I II : I :Fine sand ' .,, : : ,pO;(Unit: m)Hydraulic fill9.03.84 1.0I..0.16 1.0oN-+4.9';7 000-9.6Concrete Backfillblocks --+I..r-.-..........,---t (5-100kg stoneswith gravel)+1.68MS.l +0.9 _ ...... Boring log at the backfillFeatures of damagelcommentsCollapse of block type quay wall over 60% of wharf length (452 m) due to strong earth-quake motion and backfill liquefaction.References: Tsuchida et al. (1986): Wyllie et al. (1986)Structuraland seismicconditionsCase Histories 99Table T2.3. Case history No.2: Kalamata Port. Greece.Height: + 2.1 mWater depth: - 9.5 mEarthquake: September 13, 1986 Kalarnata earthquakeMagnitude: M, = 6.2Peak ground surface acceleration (PGA): 0.2 to 0.3 gPeak ground surface velocity (PGV): 0.4 mlsPGA/PGV evaluated based on 1D & 2D equivalent linear analysis.Seismic Horizontal displacement: 0.15 0.05 mperformance Tilt: 4 to 5 degreesCross section: Block quay wall000--------- .... -_... -....... ------_.. ----3.0m~SG(Unit: m)SPT N-value10 20 30 40 50FillIndex: SM=silty sand, SG=gravely sandFeatures of damage/commentsSeaward displacement with tilt of block type quay wall constructed on firm foundation.The backfill settled 20 cm behind the wall with no settlement at a distance of 30 to' 40meters away. The quay wall remained serviceable.Reference: Pitilakis and Moutsakis (1989)100 PIANCTable T2.4. Case history No.3: Port of Algiers, Algeria.. Structural Structure and'location: Quay No. 34and seismic Height: + 2.2 mconditions Water depth: - 10.0 mEarthquake: October 29, 1989 Chenoua earthquakeMagnitude: M =6.0, Epicenter located 60 km to the west of AlgiersSeismic Horizontal displacement: 0.5 mperformance Vertical displacement: 0.3 mCross section: Block quay wall-10.00sz L.W.L. 0.00""F"o"- interplate> intraplateInterplate earthquakes originate in the great stress accumulated in contactsbetween tectonic plates (the principal fragments into which the earth crust isdivided). Most destructive earthquakes, with magnitude above 7 to 8. belong toEarthquake Motion 1350.5.,.--------------------------.,------, ..L.-villi"IJ '" .. I'Ci 0.3 Cg 0.1to.. -0.1 +-:..I.a0.4 ~ l - - - - __-..J_0~::l< 0.24 6.5r.20.8,..--------,-------,Stress-Strain Curve0.60.4o 0.2bE...... >-....>< 0.20.40.6t1AZ1/fliWIVVlrVf 6.5(d)0.8 Computedfor0.6 Fuji river sand0.4 Or=75%- 0 0.2bE 0.0

300 0oIIIIII200ll>.E.....;:III1.2 r---'"-------------------,50 40gravels a ~ d sandslsilts and clays io i'-------'! l! !20 30plasticity index. Ip10,cx~ 0.8ofCIlCIl.E 0.6....-;:;CIl(b)0.7 r----------------------,0.6E0.5~c~ 0.4o~ 0.3ll>5 0.2oo. ,(c)20 40 60plasticity index, Ip80 100Fig. T4.18. Variation of stiffness parameters with plasticity index Ip for natural soils(after Mancuso et al., 1997).(a) Parameter S.(b) Parameter 11.(c) Parameter m.Geotechnical Characterisation 18550 40!i... :I!20 30plasticity index, I p10!'-..------".c----;-------------15001250(/)'EC1l 1000'0cQi0750cIIIVIC1lc: 500~iii25000(a),I i,; I!_. ,1- - .- --1 ...... I, I! ... I t jI ... ... II -... , IiA... ... ... !... :... I ... ,I! , IIIit iI f: I , !0.8c:"IiCD0.6"0.::CIlCIlC1l0.4c:;;:iii0.20(b)o 10 20 30plasticity index, I p40 50Fig. T4.19. Soil stiffness parameter variation with plasticity index I p for normally con-solidated marine clays (after d'Onofrio and Silvestri, 2001).(a) Parameter S.(b) Parameter n.(T4.13) for fine-grained natural soils, the average values of Do and the rate of decreasewith stress level become higher going from stiff to soft clays; also, at the samestress state and history, Do increases with plasticity index; the values of Doof medium/fine-grained compacted materials are often high-er than those typical of natural clays, due to the relatively young age of theman-made soil deposits.For the same normally consolidated marine soils analysed to obtain the correla-tion in Fig. T4.19, d'Onofrio and Silvestri (2001) used the simple power functionrelationshipDo=Q(:J186 PlANe5r------r----r---,.-----,-----,50 40 20 30plasticity index, I p10(a)- - "0ECl.loC,) 2 ..........'i__---':::_""'::::::..---1Clc:'5.E o60 50 10 20 30 40plasticity index. I pI I I!,I-IAA I AAAI I- AI IiA II.- i , j(b)oo0.50.10.4x 0.3Clc:c.. 0.2Eco"CFig. T4.20. Soil damping parameters variation with plasticity index I p for normally con-solidated marine clays (after d'Onofrio and Silvestri, 2001).(a) Parameter Q.(b) Parameter j .to relate the decrease of the small-strain damping to the increase of mean effec-tive stress. The correlation with the plasticity index lp of the damping parametersQ (representing the value of Do. expressed in %. at a p' =pa) and j, shown in Fig.T4.20 was obtained. The plots confirm that both the values of Do and its rate ofdecrease with p' increase with soil plasticity.T4.3.3 Non-linear pre-failure behaviour.Several correlations have been proposed in the literature for specifying the strain-dependentproperties G(J1 andD(J1 using the plasticity index I.Geotechnical Characterisation 187Table T4.7. Typical ranges of soil density and shear wave velocity.Soils Typical ranges---:--------------p Organic soils. peatsVery soft claysLoose volcanic silts/sandsSoft clays. loose sandsDense/cemented volcanic silts/sandsStiff clays. dense sandsCemented sands and gravelsIntact rocksl.0 to 1.31.4 to 1.71.0 to 1.71.6 to 1.91.2 to 1.91.8 to 2.11.9 to 2.22.0 to 3.0800Based on the test data found in literatures, their own laboratory testdata, Vucetic and Dobry (1991) report the average G(y) and D("/) curves shownin Fig. T4.21. Both plots show that the degree of non-linearity (hence, theenergy dissipation) increases with decreasing plasticity. The granular soils with[p = 0, shownon-linearity over a linear threshold strain y, of about 0.001%. Notethat the curves relevant to the damping ratio are not scaled to the small-strainvalue, Do, and that, according to the observations in Section T4.3.2, such small-strain value should increase with I p and decrease with p',The strain dependent curves for Japanese marine clays have been proposed byZen et al. (1987) as shown in Figs. T4.22 and T4.23. The effects of variations inthe state variables (e, pi, OCR) on the shape of nonnalisedcurves were found tobe negligible for fine-grained high 'plasticity soils (Fig. T4.22(a. On the otherhand, the increase in stress level can significantly shift to the right the G(y)relationship for a medium to low plasticity soil (Fig. T4.22(b, c)). In contrast tothe soils compiled by Vucetic and Dobry (1991) (Fig. T4.2l), the Japanesemarine clays do not appear to exhibit dependency on plasticity for [p > 30. Again,the degree of non-linearity is seen to increase with decreasing plasticity. Theinfluence of state and consolidation variables on the increase of damping ratiowith shear strain was not clearly established, and the average D(i? curves givenin Fig. T4.23 were suggested.The linear threshold strain ri, beyond which soil non-linearity is observed, canbe also correlated with the plasticity index [P. Figure T4.24(a) shows that,depending on particle grading and microstructure, Yl may vary from 0.0001 % tomore than0.01%. The values of YI for granular soils increase with decreasing par-ticle size; those for volcanic sands and silts are higher with respect to those typ-ical of other non-plastic soils, due to the stronger inter-particle bonds providedby cementation and/or particle interlocking. The degree of non-linearity of com-pacted fine-grained soils may be moderately affected by plasticity (Mancusoet al., 1995), whereas that of natural clays can be strongly affected by]88 PlANe0.001 0.01 0.1CYCLIC SHEAR STRAIN.'" (%)0.8c.s-C) a.'/'0.2 (a)IOCR =1-151Ip =2003 10101530501000.001 0.01 0.1CYCLIC SHEAR STRAIN .., (%)IOCR=1-S!aL..-__--"__ a.OOO1(b)25520

eo615.- 1.0Sampling method Standard sampler Cs 1.0Sampler without liners 1.1 to 1.3The curve indicated by Seed et at (1983) for Cq is shown in Fig. T4.28(b);NCEER workshop (Youd and Idriss, 1997) suggested to use the generalizedexpreSSIOnc = q a'.va(T4.20)with n dependent on grain characteristics of the soil, and ranging between 0.5(clean sands) and 1.0 (clayey soils).The measured shear-wave velocity Vs can be normalised to a reference effec-tive overburden stress through the expression(T4.21)where n can be 3 (Tokimatsu et al., 1991) or 4 (Finn, 1991; Robertson et al., (3) Use of liquefaction chartsA liquefaction chart is usually expressed as a curve in a plane defined with thecyclic stress ratio on the ordinate and the selected field estimator of liquefactionresistance on the abscissa. The curve limits the boundary between the experi-mental points representing observed liquefaction cases (above) and non-liquefiedcases (below). Thereforecit empirically represents the locus ofthe eRR, i.e. the196 PlANeminimum CSR required to produce liquefaction of a soil layer characterised bythe reference field property.Figures T4.29 through T4.31 show the criteria obtained as the consensus atthe NCEER workshop (Youd and Idriss, 1997) for evaluation of liquefactionresistance, respectively, based on normalised and corrected values of SPT blowcount (N1) 60, CPT tip resistance qa, and shear-wave velocity VS 1 The curves inthese figures are given for earthquakes with moment magnitude Mw = 7.5, ongently sloping ground (slopes lower than about 6%) with low overburden pres-sures (depths less than about 15m). The values of CRR for moment magnitudesother than 7.5 need to be corrected by a scaling factor, CM, decreasing with thedesign earthquake magnitude. Table T4.9 shows the values originally suggestedby Seed and Idriss (1982), together with the upper and lower bounds suggested 25'Percent Fines =35 15 s 5II0.51------4-----fl'----t"--i-----+------lCRR curves for 5.15. and35 percent fines. respectivelyIIII, AIOI20AdjustmentRecommendedByWorlcshop".50+FINES CONTENT 5%Modified ChineseCodeProposaJ (claycontent== 5%) @0.1 Marginal NoLiquefaction Liquefaction LiquefactionPan American data eJapanese data 0 eChinese data. A 0 O.4I------+-----f-:::+--++----+------lt{

N".2-Cl:l0::: (/)(/)E....CI:l

U 10 20 30 40Corrected BlowCount, (NJ)6O50. Youd and ldriss (1997)Fig. Evaluation ,ofCRR from SPT N-value (Youd and Idriss, 1997, modified afterSeed et al., 1985).Geotechnical Characterisation 197Fig. T4.30. Evaluation of eRR fromCPT data (Robertsonand Wride, 1997).3001:--/0 Li4uelaction I6. 6.Bo 0 Oqjo6.t:Ol'ico I 0.5-zc:: =n..gCl)"0Q)cr:Geotechnical Characterisation 203The two corrected equivalent N-values are plotted in Fig. T4.34 against theequivalent acceleration, and the zone to which a soil layer belongs is deter-mined as follows:,. When N ~ ; is in Zone 1. liquefaction potential is evaluated by Zone I.,. When N ~ ; is in Zone II, liquefaction potential is evaluated by Zone II.,. When N ~ ; is in Zone III or IV, and when N;5 is in Zone 1. II, or IIIliquefaction potential is evaluated by Zone III.,. When N ~ ; is in Zone III or IV, and when N;s is in Zone IV, liquefactionpotential is evaluated by Zone IV.Case 3: The plasticity index lp >20, and the fines content Fe > 15%.Acorrected equivalent N-value is calculated using Eqns. (T4.29) and (T4.30),and then liquefaction potential is evaluated using Fig. T4.34.(2) Cyclic triaxial test (2nd step)When the liquefaction potential cannot be determined from the grain size distri-bution and SPT N-value (i.e. for zones II and II!), it is evaluated based onundrained cyclic triaxial tests using undisturbed soil samples. Based on therelationship between the cyclic stress ratio and number of cycles to cause lique-faction in the laboratory tests, the cyclic resistance ('l",1( ) ~ ) N l = 20 for use in theliquefaction potential assessment is obtained by reading off the cyclic stress ratioat 20 cycles of loading (Fig. 1'4.36). Using this cyclic resistance, the in-situliquefaction resistance Rmax is obtained using the following equation:(T4.31)0.50.4b(J

Ql"0 Ol-:l--+--""""----------@c..E-cFig. A1. Example of time domain analysis of a CH test with two receivers.The waveform velocity between two receivers located along a straight line canbe determined by the Cross Correlation function, provided that the signals areacquired in digital form, The Cross Correlation [CCt).('r)] of two signals x(t) andy(t) is defined as+-CC.t:'.(r)= Jx(t)y(t+r)dt (A.2)where r is the variable time delay between signals x(t) and yet).Hence, a Cross Correlation value is given by the sum of the products of thetwo signal amplitudes, after having shifted the second record, yet), with respectto the first, x(t), by a time interval 1:. The Cross Correlation function yields dif-ferent values by varying the time delay 1:, and reaches its maximum CCm:u whenthe degree of correlation between the signals x(t) and y(t+r) is maximum (i.e.when 'the waveforms are practically superimposed). The time delay 1:max corre-sponding to CCmax is the best estimate of the travel time of the whole waveformbetween the two receivers,The Cross Correlation shown in Fig. A2 is obtained using two receiver signals(5 waves) of Fig. AI. The Cross Correlation values have been normalised with., .. _".' re210 PlANe50 100 150 't'(ms) 200Fig. A2. Cross-correlation function of the receiver signals in Fig. AI.respect to the maximum CCrnax, hence the function varies between -1 and 1. Thetravel time is approximately 62 ms.A.2 Frequency domain analysisBy means of the Fourier analysis, a generic signal x(t) can be decomposed into asum of a series of sinusoidal functions, each one characterised by its amplitude(A), phase (4)) and frequency (f) (see Fig. A3). The sine functions are the fre-quency components of the signal x(t), and their complex representation in the fre-quency domain is defined as the Linear Spectrum (Lx) of the signal xU).The transformation of a signal in the correspondent Linear Spectrum can beperformed by means of the algorithm Direct Fourier Transform (DIT); inverse-ly, it is possible to convert a Linear Spectrum into the correspondent time recordby means of the algorithm Inverse Fourier Transform (Iff). The frequency con-tent of a signal is effectively represented by the amplitude versus frequency plotof the Linear Spectrum; in Fig. A4, such diagrams are plotted for the receiver(RI and R2) signals in Fig. AI.Each sine function of a Linear Spectrum can be effectively represented by avector (with length proportional to the amplitude, and direction equal to the phaseof the sine function), and therefore, by a complex number. The rules and tools ofcomplex algebra are applicable to signal analysis in the frequency domain. In thefollowing paragraphs, the most useful functions for frequency domain analysisare reviewed.The Cross Power Spectrum CPSxy of two signals x(t) and yet) is the product of thecorrespondent Linear Spectra L, and 4(A.3)Each frequency component (f) of the CPS has an amplitude [AcpsCfl] equal tothe product of the amplitudes of the same frequency components of the linearspectra. and phase [4>cps(f)] equal to their phase difference. The Acps(j) allowsGeotechnical Characterisation 211A++A AAtO==C>- ~=t-It+A +Fig. A3. Transformation of an amplitude-time signal to an amplitude.frequency signalby means of the OFf.>E.....IV'"0:;,.-Q.EE.Q.Eo Io100100F" A7 Phase velocity diazram from a CH test.19. . 214 PlANeA.3 Spectral analysis and propagation velocityThe Cross Correlation function (previously defined in the time domain analysisparagraph), and hence the travel time and the correspondent waveform velocity,can be immediately determined utilising the frequency domain analysis. TheCross Correlation of two signal x(t) and y(t) is given by the Inverse FourierTransform of the Cross Power Spectrum of the two signalsCC.l).(r) =Jx(t)y(t+ T)dt =IFT[cPSyx(!)] (A.5).The Cross Power Spectrum allows for the determination of the velocity of eachof the frequency components of the propagating waveform, by means of its phase[(/)cps(f)]. Using the delay of phase t1cfJ(f) for a given frequency component (f),wave propagation between two points at known distance is represented by thecorresponding number of wavelengths N: given byNJ!) = - ~ ~ ) (A.6)If rl2 is the distance between the two points, the wavelength A(J) and the veloci-ty Vph(f), defined as phase velocity, of the component (f) are given by(A.?)The phase velocity diagram Vph(f), calculated for a series of signals x(t) and yet)from a CH test is shown in Fig. A7. together with the relative Acps(f), COxy(f)and (JJcps(j). It is clear that, for frequencies greater than 25 Hz. the Vph(! ) dia-gram is practically horizontal, slightly varying around the value of about 78 m!s,which can be assumed as the group velocity of the whole waveform.TCS: Structural Design Aspects of Pile-Deck SystemsT5.1T5.2T5.3T5.4T5.5T5.6Design Performance and Earthquake LevelsT5.1. 1 Performance goalT5.1.2 Design earthquake levelsT5.1.3 Limit statesT5.1"+ Seismic load combinationsModelling AspectsT5.2.1 Soil-structure interactionT5.2.2 Movement jointsMethods of Analysis for Seismic ResponseT5.3.1 Method A: Equivalent single mode analysisT5.3.2 Method B: Multi-mode spectral analysisT5.3.3 Method C: Pushover analysisT5.3..+ Method D: Inelastic time-history analysisT5.3.5 Method E: Gross foundation deformation analysisStructural Criteria for Pier and Wharf PilesT5.4.l Deformation capacity of pile plastic hingesT5.4.2 Implication of limit statesT5.4.3 Moment-curvature characteristics of pilesT5.4.4 Primary structural parameters and response of pilesT5.4.5 Plastic hingesT5.4.6 Shear strength of pilesT5.4.7 Design strength for deck membersT5.4.8 Batter and timber pilesPilelDeck Connection DetailsT5.5.l Steel-shell pilesT5.5.2 Prestressed pilesT5.5.3 Practical connection considerationsT5.5.4 Capacity of existing substandard connection detailsExistinz Construction....T5.6.1 Structural criteria for existing constructionT5.6.2 Strengthening of an existing structureT5.6.3 Deterioration of waterfront structuresTECHNICAL CONIMENTARY 5Structural Design Aspects of Pile-Deck SystemsThis technical commentary will further illustrate the general design methodo-logies developed in the Main Text and present some numerical guidelines for theperformance of pile-deck structures. Piles are a common and significant elementof waterfront construction. This technical commentary will provide guidance inpile design.The following guidance is directly based on Technical Report TR 2103-SHR'Seismic Criteria For California Marine Oil Terminals' by J. Ferri tto,S. Dickenson, N. Priestley, S. Werner and C. Taylor, July 1999. This reportwas sponsored by the California State Lands Commission, Marine FacilitiesDivision. The structural criteria defined herein are based largely on the workof: Nigel Priestley. These criteria are developed from a compilation of currentpractice in North America, with state-of-the-art technology for evaluatingseismic damage potential. Although the guidance addresses structural designof concrete, steel and wooden piles, the focus of attention is directed toconcrete piles, reflecting the practice in North America. Design criteria adoptedin other regions, where steel piles have been typically used, notably in Japan,might be different from this guidance as briefly discussed in TechnicalCommentary 7.T5.1 DESIGN PERFORMANCE AND EARTHQUAKE LEVELST5.1.1 Performance goalThe general performance goals were discussed in Chapter 3 in the Main Text.This technical commentary focuses on pile-deck structures, specifically piers andwharves. The reader is referred to Tables 3.1 to 3.3 in the Main Text. In this tech-nical commentary, piers and wharves are as Grade A structures andare expected to perform as follows:( 1) To resist earthquakes of moderate size that can be expected to occur oneor more times during the life of the-structure (Level 1) without structuraldamage of significance (Degree I: Serviceable)......... ,218 PlANe(2) To resist major earthquakes that are considered as infrequent events (Level 2),and to maintain environmental. protection and life safety, precluding totalcollapse but allowing a measure of controlled inelastic behaviour that willrequire repair (Degree II: Repairable).T5.1.2 Design earthquake levelsThis section utilizes the following earthquake levels presented in Chapter 3 in theMain Text as defined events.. Level 1 - (Ll) Ground motions with a 50% probability of exceedance in50 years exposure. This event has a return time of 75 years and is considered amoderate event, likely to occur one or more times during the life of the facility.Such an event is considered a strength event.Level 2 - (L2) Ground motions with a 10% probability of exceedance in50 years exposure. This ~ v e n t has a return time of 475 years and is considered amajor event. Such an event is considered a strength and ductility event.T5.1.3 Limit statesServiceability Limit State (Degree I: Serviceable) All structures and theirfoundations should be capable of resisting the Level I earthquake without sus-taining damage requiring post-earthquake remedial action.Damage Control Limit State (Degree II: Repairable) Structures and theirfoundations should be capable of resisting a Level 2 earthquake. without collapseand with repairable damage, while maintaining life safety. Repairable damage tostructures and/or foundations, and limited permanent deformation are expectedunder this level of earthquake.T5.IA Seismic load combinationsWharves and -piers may be checked for the following seismic load combinations,applicable to both Level 1 and Level 2 earthquakes:(l + kJ(D ffi rL) ffi E (T5.1)(1 - kJD ffi E (T5.2)where D = Dead LoadL'= Design Live Loadr = Live Load reduction factor (dependson expected L present in actualcase; typically 0.2 but could be higher)Structural Design Aspects of Pile-Deck Systems 219E =Levell or Level 2 earthquake load. as appropriatek, =Vertical seismic coefficient (typically one half of the effective peakhorizontal ground acceleration in g)EB = Load combination symbol for vector summationNote: seismic mass for E should include an allowance for rL, but need notinclude an allowance for the mass of flexible crane structures.Effects of simultaneous seismic excitation in orthogonal horizontal directions.....indicated by x and y in Fig. T5.1. may be considered in design and assessment ofwharves and piers. For this purpose, it will be sufficient to consider two charac-teristic cases: .1000/c E/B 30% e,30% Ef $ 100% s,(T5.3)(T5.4)where Ex and E; are the earthquake loads (E) in the principal directions x and y,respectively.Where inelastic time history analyses in accordance with the requirements ofMethod D in Section T5.3 are carried out, .the above loading combination maybe replaced by analyses under the simultaneous action of x and y directioncomponents of ground motion. Such motions should recognize the direction-dependency of fault-normal and fault-parallel motions with respect to thestructure principal axes, where appropriate.T5.2 MODELLING ASPECTSThis section further illustrates the modelling aspects of pile-deck structures sum-marized in Technical Commentary 7.ILandward F.dL'C ,. x...... (. (Seaward Edge(a)1--------IIIIIIII(b)1-----