Micropiles Design 101 - Structural Engineers

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1Micropiles Design 101Allen Cadden P EAllen Cadden, Chester, PALas Vegas, NV 2008Objective Develop a background understanding of the geotechnical and Structural Design processes for Micropiles in Structural foundation support for Considerations5Bi fD i Design for Engineers Fundamentals are similar to Fundamentals are similar to traditional pile Design However, due to the small Structural section, Structural Design and stiffness can often controloften control3Designers Must UnderstandAvailable Tools Drilling rigs Drilling rigs Drilling methods Available Structural Materials Reasonable Bond ValuesValues Quality ControlConstruction Techniques Drill Rig 4Micropile Materials Permanent Steel Pipe API 5CT & ASTM A252 80 ksi yield Flush joint threads Steel Reinforcement ASTM A615, Gr. 60 & 75 ASTM A722, Gr. 150 Mechanical coupling Hollow barsCtGtStar Iron Works Cement Grout Neat cement ASTM C150 W/C ratio of 4000 psi (min)Williams FormDesign Involves: Knowing the site Knowing the site Understanding the loads Understanding the geology Calculations Specifications Specifications Quality Control5A Word on Geology Review of Geotechnical Dataobtain samples anddevelop sections obtain samples and develop sections estimate Design parameters evaluat

and structural design processes for micropiles in structural foundation support applications. 2 Contents 1. Backggground for Engineers 2. Structural Design 3. Geotechnical Design 4. Additional Considerations 5. Bi fD i E lBrief Design Example ... factors for marginal ground or lack of redundancy LRFD Geotechnical Design

  Structural, Marginal