Wind Turbine Support Structure Benjamin Boyett ET 493 Senior Design I Advisor – Dr Mohamed Zeidan Instructor - Dr. Cris Koutsougeras 05/09/2014

Objectives Research and compare different towers Design lattice support structure Structurally sound Cost efficient Minimal maintenance Occupy least amount of space

Types of Towers Three Main Types Lattice Monopole Guy-Wired Pros/Cons Cost Space

Types of Towers

Tower Overview 500lb Turbine 50ft tall 5’-6’ base A36 Low Carbon Steel Steel Angle Legs, Bracing Connections Welded or Bolted 4’x4’ Top Plate Constructed In Sections 6’x6’x5’Concrete foundation

Lattice Designs Designs appropriate for height Single Diagonal Bracing Double Diagonal X-X Bracing X-B Bracing

AutoCAD 50’ Tower 5’x5’ Base Section height 3’ Single Diagonal Bracing X-B Bracing Double Diagonal X-X Bracing Single DiagonalX-B BracingX-X Bracing

AutoCAD Single DiagonalX-B Bracing 50’ Tower 6’x6’ Base Section height decreased incrementally from 6’-2’ Single Diagonal Bracing X-B Bracing

Tower Design B/H ratio between 1/8 and 1/12 1/10 B/H = 5/50, equally spaced sections (3’) 1/8 B/H = 6/50, section size varies (6’-2’) Inclination of base legs must be between 30 and 60 degrees

COMSOL A finite element analysis (FEA) Determines most calculations Deformation of members Example: 6’ tall 12’ wide 2x 500lb point load

COMSOL Simple Truss Tower Buckling Analysis of a 19m tower Model example from COMSOL

Materials Steel angles beam Steel Plate Concrete (foundation) High-Strength Bolts Welding materials

Wind Load Calculations Worst case, wind turbine stopped at max wind velocity Design Wind Pressure P at height z ASCE7 Pz = q*G*Cp – qi(G*Cpi) Velocity Pressure ASCE7 Eq (6-15) qz = (Kz*Kzt*Kd*V^2*I) Design Wind Force ASCE7 Eq (6-25) F = qz*G*Cf*D Pz39.37 psf qz35.07 psf F (lb/ft)

Challenges Learning to use COMSOL Calculating wind loads Keeping inclination of tower legs between 30 and 60 degrees Finding standards for support structures considering turbine is a prototype

Deliverables Research Structures ✔ Determine Tower Type ✔ Calculate Loads ✔ Sketch (AutoCAD) ✔ Design – IN PROGRESS Finite Element Analysis (COMSOL) – IN PROGRESS Use COMSOL Analysis to Determine Steel Members Determine Connections Bolt or Weld Compare variations of lattice towers. Excel Estimate Construction Schedule

TIMELINE Fall 2014 Design and compare lattice support structures 08/04/14 – 08/25/14 Implement design(s) into COMSOL finite element analysis 08/25/14 – 09/25/14 Simulate loads and determine size steel angle COMSOL 09/25/14 – 10/20/14 Estimate material quantities and cost Compile estimate using excel 10/20/14 – 11/12/14 Develop a construction schedule using Primavera or Microsoft Project 11/12/14 – 12/01/14

References American Society for Civil Engineers 7 (ASCE7) Minimum Design Loads for Buildings and Other Structures American Wind Energy Association (AWEA) ASCE/AWEA RP2011 Recommended Practice for Compliance of Large Land-based Wind Turbine Support Structures AISC Steel manual Standards for small wind energy systems

Questions? Comments?

Thank You!