Wind_Energy_Essentials_Lecture 10

Wind_Energy_Essentials_Lecture 10 - EE5940 Wind Energy...

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Unformatted text preview: EE5940 Wind Energy Essentials Lecture 10: Introduction to Wind Turbine Foundation Engineering resourceful. naturally. 1 A. Introductions resourceful. naturally. 2 Chris Kopchynski • 22 yrs consulting engineer • 16 yrs with Barr • civil, geotechnical and structural engineering Chris Kopchynski, PE Principal, Vice President, Structural Engineer • professional engineer in 12 states and 5 provinces • 12 yrs wind turbine foundation engineering yrs wind turbine foundation engineering resourceful. naturally. 3 Jennifer Entwistle • University of Minnesota – B.S. Civil. Eng. • 5 yrs consulting with Barr • structural engineering • professional engineer Jennifer Entwistle, PE Structural Engineer • 5 yrs wind turbine foundation engineering yrs wind turbine foundation engineering on over 60 wind projects • Barr project manager for UMore Park wind turbine project resourceful. naturally. 4 Barr Engineering Company • 500 engineers, scientists, technical specialists, support staff • Employee owned • Headquarters in Minneapolis • Offices in Minnesota, Michigan, Missouri, and North Dakota, Calgary resourceful. naturally. 5 Barr experience MW's Supported by Barr Foundations 4000 3528 3500 3000 MW's of Windpower • wind turbine foundations since 1992 – over 160 operating projects – 40% of the US capacity 2514 2432 2500 2000 1595 1586 1627 1500 1000 679 500 0 1998-2004 2005 resourceful. naturally. 2006 2007 2008 2009 2010 6 windpower projects across the the western hemisphere X X X X X X X – recently added states resourceful. naturally. 7 other wind experience • 200 other wind projects without Barr foundations over 100 preliminary foundation designs over 40 desktop civil/geotechnical design studies over 100 geotechnical investigations over 50 civil road designs 10 independent reviews 4 project studies or environmental studies and permitting – 40 structural evaluations and studies – – – – – – resourceful. naturally. 8 B. Impressions resourceful. naturally. 9 unseen and underestimated this is the foundation? resourceful. naturally. 10 most loaded, reliable & robust nacelle hub height blades this IS the foundation tower resourceful. naturally. 11 C. Objectives resourceful. naturally. 12 appreciation for factors • terminology • integrated process • structural loads • geotechnical engineering • foundation engineering • construction • codes and regulations • case study study resourceful. naturally. 13 appreciation for process • many people interact – wind turbine and tower engineer turbine and tower engineer – geotechnical engineer – foundation engineer engineer – construction contractor resourceful. naturally. 14 D. Integrated resourceful. naturally. 15 integrated process Mechanical & Electrical Factors Structural Factors The Physical World Foundation Materials Geotechnical Factors Construction resourceful. naturally. 16 mechanical to electrical resourceful. naturally. 17 U.S. wind resource resourceful. naturally. 18 E. Structural Loads resourceful. naturally. 19 overturning moment resourceful. naturally. 20 wind turbine load document • Wind Turbine Manufacturers: resourceful. naturally. 21 wind turbine load document • International Electrotechnical Commission (IEC) load cases – Extreme Wind – Abnormal Extreme Wind – Normal Operating – Fatigue resourceful. naturally. 22 F. Geotechnical Eng resourceful. naturally. 23 geological assessments • what soils & rock are present? soils rock are present? • how did they form? • weathering and erosion and erosion • temperature • wind • water • deposition • wind • water • pressure and time (From Sims and Morey, eds., 1972; modified from Leverett, 1932.) resourceful. naturally. 24 geologic risks and hazards • what risks and hazards are present? risks and hazards are present? • fatal flaws? • mitigated? POTENTIAL SLIDE A SAND =A CLAY MINE OR CAVE COLLAPSE FAU LT CLIFF LIMESTONE resourceful. naturally. 25 soil & rock characteristics • soil and rock stratigraphy Soil has different has different particle sizes • composition • strength • compressibility • stiffness Soil is voids(air), moisture (water) and particles resourceful. naturally. 26 field investigations – sampling • test pits • soil borings • split spoon sampling • shelby tube sampling • rock coring • depth of foundation influence of foundation influence soil boring track rig resourceful. naturally. 27 field investigations – cpt in-situ testing – cpt cone penetration test truck penetration test truck resourceful. naturally. 28 lab testing • physical property tests • strength tests • compressibility tests • density tests • special tests – California bearing ratio - roads bearing ratio roads – thermal conductivity - electrical resourceful. naturally. laboratory strength test 29 geotechnical analysis – foundation type • soil conditions conditions – good – spread footing – bad – pile foundation foundation – rock – rock socket or anchor foundation • economics – rock - spread footing verses rock socket • schedule – spread footing verses anchor • construction risk resourceful. naturally. 30 geotechnical analysis – bearing capacity • the transfer of the load from the foundation to the soil transfer of the load from the foundation to the soil • the ability of soil to carry load with shear failure • must know the strength properties of the soil or rock • loads are eccentric – off center • bearing pressure is idealized • based on empirically developed design formulas • geotechnical engineer working with the foundation engineer resourceful. naturally. 31 geotechnical analysis – settlement • the permanent deformation of the soil under load permanent deformation of the soil under load • in essence the reduction of air and water volume replaced by soil replaced by soil • differential settlement – tower tilt • soils loading history loading history • the ways soils were deposited • can be a long or short process • empirical formulas resourceful. naturally. 32 geotechnical analysis – stiffness • the elastic movement of soil under back and forth loads elastic movement of soil under back and forth loads • dynamic behavior • soil stiffness affects – wind turbine oscillations – tower vibration – power output – fatigue in the tower and wind turbine • rock can be very stiff – soil can be very flexible resourceful. naturally. 33 geotechnical analysis – cement type • sulphates in soil in soil • water dissolves the sulphate • penetrates and attacks concrete and attacks concrete • concrete deterioration can be severe • solutions: – resistant cement types – less permeable concrete – surface seals resourceful. naturally. 34 geotechnical analysis – soil modifications • wind blown soils – either cemented or loosely deposited blown soils either cemented or loosely deposited • granular uncontrolled fills • weak soils soils • mitigates collapse, settlement and increases bearing capacity capacity • easiest solution: – remove and replace with suitable soil – engineered fill fill resourceful. naturally. 35 soil modifications – dynamic compaction compacting wind blown silt resourceful. naturally. 36 soil modifications – stone columns ram stone auger soil installed stone columns resourceful. naturally. 37 geotechnical reporting • desktop studies - evaluation • preliminary geotechnical studies - planning • final geotechnical studies - construction • special reports reports – electrical – thermal and field resistivity – California bearing ratio – roads – thermal conductivity – electrical resourceful. naturally. 38 G. Foundation Types resourceful. naturally. 39 tower types Lattice Steel Tubular Tubular resourceful. naturally. Cast Post-Tensioned Concrete 40 tower connection types anchor bolt – embedment plate resourceful. naturally. 41 tower connection types embedded tower section “foundation mounting part” resourceful. naturally. 42 spread footings resourceful. naturally. 43 p&h patented caisson resourceful. naturally. 44 pile foundation resourceful. naturally. 45 rock socket foundation resourceful. naturally. 46 rock anchor foundation resourceful. naturally. 47 H. Foundation Eng resourceful. naturally. 48 design basis • loads (extreme, normal operating, fatigue) • tower flange dimensions • serviceability requirements (stiffness, settlement) • materials • geotechnical parameters resourceful. naturally. 49 stability • overturning and sliding • resisted by weight of footing and soil above footing above footing • affects: – width of footing of footing – depth of soil above footing resourceful. naturally. 50 bearing capacity • soil not strong enough to resist pressure from footing • resisted by reducing pressure on soil • depends on soil properties • affects width of footing resourceful. naturally. 51 base contact length • Germanischer Lloyd (GL) Wind Guidelines Ll (GL) Wi – 100% bearing under normal operating load – 50% bearing under extreme load resourceful. naturally. 52 stiffness • turbine manufacturer requirements for rotational and translational stiffness • becomes more important as turbines get more important as turbines get bigger and taller • affects foundation size foundation size • depends on soil properties resourceful. naturally. 53 differential settlement • turbine manufacturer requirements for differential settlement • 0.17 degrees or 3 mm/m degrees or mm/m resourceful. naturally. 54 tower connection • bottom flange bearing on grout fl • bottom flange bearing on concrete • anchor bolt design • embedment plate design • reinforcing steel design for anchor bolt pullout resourceful. naturally. 55 reinforced concrete strength • load and resistance factor design (LRFD) (LRFD) • calculate soil bearing pressure • one-way and two-way shear – usually controls footing thickness • footing top and bottom reinforcing bending moment design resourceful. naturally. 56 reinforced concrete fatigue • concrete fatigue design – failure due to compressive stress stress – failure due to shear • concrete reinforcement fatigue design – failure due to tensile stress resourceful. naturally. 57 electrical conduit & grounding grounding conduit layout design layout design ground grid design grid design power, control & communication cables control communication cables ground fault protection, worker safety fault protection, worker safety & equipment protection resourceful. naturally. 58 documents • design report • engineering design drawings • technical specifications • construction documentation resourceful. naturally. 59 research • UMore Park foundation research resourceful. naturally. 60 I. Construction resourceful. naturally. 61 site preparation resourceful. naturally. 62 excavation resourceful. naturally. 63 mud mat resourceful. naturally. 64 lay down bearing bars resourceful. naturally. 65 place remaining bottom bars resourceful. naturally. 66 set anchor bolt cage resourceful. naturally. 67 place top mat rebar resourceful. naturally. 68 set forms resourceful. naturally. 69 place footing concrete resourceful. naturally. 70 finish top of footing resourceful. naturally. 71 set conduit and grounding resourceful. naturally. 72 set pedestal form & place place concrete resourceful. naturally. 73 remove pedestal forms resourceful. naturally. 74 backfill and compact soil over over foundation resourceful. naturally. 75 finish grade site resourceful. naturally. 76 extend conduit into transformer transformer pad resourceful. naturally. 77 set bottom tower and grout resourceful. naturally. 78 tension anchor bolts resourceful. naturally. 79 erect remaining turbine parts resourceful. naturally. 80 commission wind farm resourceful. naturally. 81 J. Codes & Standards resourceful. naturally. 82 local codes • county and city zoning ordinances • building permits permits • not much oversight • California – plans and calculations reviewed by a county appointed engineer county appointed engineer resourceful. naturally. 83 state codes • adopt national model codes • modified to meet special state to meet special state requirements – Minnesota – snow snow – California – earthquakes – Texas – hurricanes resourceful. naturally. 84 national standards and and codes • International Building Code 2006 • American Society of Civil Engineers – ASCE 7-05 – Minimum Design Loads for Buildings and Other Structures • American Concrete Institute – ACI 318 – Building Code Concrete Instit 318 Code Requirements for Structural Concrete • Electric Power Research Institute – Manual for Power Research Institute for Estimating Soil Properties for Foundation Design resourceful. naturally. 85 international standards • Deutsches Institut fur Normung, e.V. – DIN 1054 – Ground – Verification of the Safety of Earthworks and Foundations Foundations • Eurocode 2: Design of Concrete Structures, General Rules for Buildings • Comite Euro-International du beton, CEB-FIP Model Code 1990 – Model Code for Concrete Structures resourceful. naturally. 86 industry standards • International Electro-technical Commission - 61400 – Wind Turbines Design Standards • Germanischer Lloyd – Guidelines for the Certification of Wind Turbines • Det Norske Veritas – DNV-OS-C502 – Offshore Norske Veritas Concrete Structures resourceful. naturally. 87 engineering principles and and practices • DNV, Riso National Laboratory, Guidelines for the Design of Wind Turbines • Day, Foundation Engineering Handbook: Design and Construction Foundation Engineering Handbook: Design and Construction with the 2006 IBC • Arya, Design of Structures and Foundations for Vibrating Machines • Bowles, Foundation Analysis and Design • Peck, Hanson, and Thornburn, Foundation Engineering • Das, Principles of Foundation Engineering • Wang and Salmon, Reinforced Concrete Design resourceful. naturally. 88 professional duty • professional engineers – geotechnical, civil and structural competency – licensed in each state project is constructed • firm registration in some states • business registration • state taxes on work taxes on work resourceful. naturally. 89 third party reviews • independent engineers review and critique the design – standards of practice – errors – judgment • performed on behalf of: – investors – banks – owners resourceful. naturally. 90 K. Case Study resourceful. naturally. 91 Casselman wind project • western Pennsylvania • former coal mines • mine spoils • micropile foundation • first wind project to use micropiles • 2009 Minnesota Society of Minnesota Society of Professional Engineers “Seven Wonders of Engineering” award resourceful. naturally. 92 Casselman wind project • (24) 8.5” diameter battered micropiles di • extend to bedrock located 50-100 ft below the surface below the surface • socketed 15 ft into bedrock • 6 ft thick reinforced concrete pile cap resourceful. naturally. 93 L. Closing resourceful. naturally. 94 highlights • foundations are underestimated but critical • integrated engineering process • unusual loading • extensive geotechnical investigation program and foundation design process • numerous codes and regulations resourceful. naturally. 95 M. Questions resourceful. naturally. 96 ...
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