Product Testing Report

7/24/2019 Product Testing Report

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MAGNUM HELIX FOUNDATION

TECHNICAL REFERENCE GUIDE

PRODUCT TESTING

REPORT

August 30, 2001

by Howard A. Perko, P.E.Consulting Engineer for Magnum Piering, Inc.


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TABLE OF CONTENTS

INTRODUCTION ................................................................................................................. -2-

SECTION 1. Helix Blade Compressive Strength ................................................................... -3-

SECTION 2. Coupling Tensile Strength ............................................................................... -6-

SECTION 3. Coupling Torsional Strength ............................................................................ -9-

SECTION 4. Bracket Mechanical Capacity ......................................................................... -12-

SECTION 5. Bracket Concrete Anchor Capacity ................................................................ -15-

SECTION 6. Full-Scale Field Capacity ............................................................................... -18-

INTRODUCTION

This document contains an overview of the types of testing used by Magnum Piering,Inc. to determine capacities of its helix foundation products. Procedures and results of various

field and laboratory tests are presented. Tests include helix blade compressive strength, couplingtensile strength, coupling torsional strength, bracket mechanical capacity, bracket concrete

anchor capacity, and full-scale field capacity. Only a sample of the results from the first roundof testing are provided. For quality assurance, Magnum Piering, Inc. periodically tests various

components of its product line. For Magnum Piering, Inc., product testing and quality assuranceis an ongoing effort. Contact Magnum Piering, Inc. headquarters for additional information and

test results on any product.


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SECTION 1. Helix Blade Compressive Strength

Theoretical Helix Blade Capacity

Weld:

Shaft Diameter, d = 3 inShaft Circumference, d = 9.42 in

Minimum Weld Thickness, tw= 0.25 in x 2 (both sides)Minimum Steel Yield Strength,

y= 36 ksi

Approximate Steel Shear Strength, s= 0.7 x y

Weld Strength =

d tw s= (9.42)(0.5)(36)(0.7) = 120 kips

Blade Folding:Blade Diameter, D = 8 to 14 in

Minimum Blade Thickness, tp = 3/8 in

Blade Moment of Inertia, I = 1/12 L tp3

Centroid of Half-Circle: 2D/3

Length of Fold*, L = D + d

*accounts for opening in helix bladeDistance from Fold to Centroid, = 2D/3 - d

Area of Half-Circle, A = 1/8

D2

Assume Uniform Folding Pressure, P

Applied Bending Moment per Fold = P A Resisting Moment per Fold =

y(tp ) / I

Find Folding Pressure by M, P = y(tp ) / I A

Maximum Blade Folding Capacity, Q = 2 A P

Results

D L I

A P Q

8 in 5.5 in 0.024 in4 0.20 in 25 in2 56 ksi 2,800 kips

10 in 6.5 in 0.029 in4 0.62 in 39 in2 10 ksi 780 kips

12 in 7.5 in 0.033 in4 1.05 in 57 in2 3.4 ksi 390 kips

14 in 8.5 in 0.037 in

4

1.47 in 77 in

2

1.6 ksi250 kips

Maximum Capacity is Theoretically Governed by Weld Shear and is = 120 kips


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Helix Blade Capacity Test

Materials: Test Specimen

helix blade welded to 1' longtubular shaft with blunt ends

Load Fixturethick wall tube with diameter

equal to 2/3 blade diameter, cut toreceive helix blade, and fitted with

center positioning rod

Test Equipment: 100+ kip Capacity Load Frame

Test Location: Cooperheat - MQS, Inc.,Woodlawn, OH

Test Procedures:

1. Using a caliper, measure, verify, and record helixplate and weld thicknesses

2. Position test specimen on load fixture3. Place test specimen and load fixture in load

frame4. Photograph specimen and load frame prior to

start of test5. Mount displacement gage and record initial reading

6. Apply compressive load in 10 kip increments7. Record displacement for each increment

8. Periodically photograph test specimen condition9. Continue test until failure

10. Record maximum load applied11. Plot load vs. displacement and establish yield point


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Magnum Blade Test

0

20

40

60

80

100

120

0 0.2 0.4 0.6 0.8 1 1.2

Deflection (in)

Load(kips)

Ultimate Strength of Blade = 103 kips

Yield Strength of Blade = 80

Note: Deflection

Measurements Include

Deformation of Test

Fixture

Helix Blade Capacity Test Results

Blade at 50 kips Blade at 70 kips Blade at 90 kips

Example Graphical Test Results

Summary of Test Results

Magnum Helix Foundation Type Yield Capacity Ultimate Cap.

Standard and Heavy Duty 80 kips 103 kips

Light Duty 40 kips 59 kips


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SECTION 2. Coupling Tensile Strength

Theoretical Coupling Tensile Capacity

Weld:

Shaft Diameter, d = 3 inShaft Circumference = d = 9.42 in

Minimum Weld Thickness, tw= 1/4 inMinimum Steel Yield Strength,

y= 46 ksi

Approximate Steel Shear Strength, s= 0.7 x y

Weld Strength =

d tw s= (9.42)(1/4)(0.7)(46) = 76 kips

Sleeve Shear:Length of Shear Path, l = 2 in x 2 paths x 2 sides of sleeve = 8 in

Thickness of Sleeve*, ts= 0.25 in

*(inner shaft has same thickness and same strength)

Sleeve Strength = l ts s= (8)(0.25)(0.7)(46) = 64 kips

Bolt Shear:

Bolt Diameter, db= 7/8 inBolt Grade = SAE 5

Minimum Bolt Yield Strength, y = 92 ksiApproximate Bolt Shear Strength, s= 0.7 x yBolt Area = 1/4

db

2x 2 sides = 1.20 in2

Bolt Strength = 1/4

db2

s= (1.20)(0.7)(92) = 77 kips

Shaft Tension:

Shaft Thickness, t = 0.25 inMinimum Steel Tensile Strength, t= 62 ksi

Bolt Hole Diameter = 1 in

Shaft Tension Strength = d t t= 134 kips

Reduction due to Bolt Holes = (1 in)(2 holes)/(9.42) = 21%

Modified Shaft Tension = 105 kips

Maximum coupling tensile strength is theoretically governed by sleeve shear and is = 64 kips


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Coupling Tensile Strength Test


sections of helix shaft connected with external sleeve coupling and boltLoad Fixture

solid bar stock welded to opposing ends of helix shaft sections and fittedwith bolted connection

Test Equipment: 100+ kip Capacity Load Frame

Test Location: Cooperheat - MQS, Inc., Woodlawn, OH

Test Procedures:

1. Using a caliper, measure, verify,

and record thicknesses ofcoupling sleeve, bolt holes, and

shaft diameter2. Draw axial and circumferential

grid lines on test specimen3. Place test specimen with load

fixtures in load frame4. Photograph test specimen and

load frame prior to start of test5. Mount displacement gage and

record initial reading6. Apply tensile load in 10 kip increments

7. Record displacement for each increment8. Periodically photograph condition of test specimen

9. Continue test until failure10. Record maximum load applied

11. Plot load vs. displacement and establish yield point


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Magnum Connector Tension Test

0

10

20

30

40

50

60

70

0 0.2 0.4 0.6 0.8 1 1.2

Displacement (in)

Load(kips)

Ultimate Strength of Connector =64 Kips

Yield Strength of Connector =60 Kips

Coupling Tensile Test Results

Coupling Failure Close Up #1 Coupling Failure Close Up #2

Example Graphical Test Results

Magnum Helix Foundation Type Yield Capacity Ultimate Cap.

Standard and Heavy Duty 60 kips 64 kips

Light Duty 50 kips 59 kips


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SECTION 3. Coupling Torsional Strength

Theoretical Coupling Torsional Capacity

Light & Standard Duty Single-Sleeve Connectors

Inner Shaft Torsional Shear:

Shaft Outside Radius, b = 1.50 inShaft Inside Radius, a = 1.25 in Standard, 1.375 in Light

Shaft Circumference = 2 b = 9.42 inMinimum Steel Tensile Strength, t= 62 ksi

Approximate Steel Ultimate Shear Strength, s= 0.7 x t

Bolt Hole Diameter, dh= 1 in

Polar Moment of Inertia, J = (b4- a4)/2J = 4.12 in4Standard, J = 2.34 in4Light

Shaft Torsional Strength =

sJ/b = 0.7(62)(4.12)/(1.5)120 kip-in Standard, 68 kip-in Light

Reduction due to Bolt Holes = (1 in)(2 holes)/(9.42) = 21%

Standard Coupling Torsional Strength = 94 kip-in = 7,800 ft-lbs

Light Coupling Torsional Strength = 53 kip-in = 4,400 ft-lbs

Ultimate coupling torsional strength is theoretically governed by inner shaft shear and is = 7,800ft-lbs and 4,400 ft-lbs for the Standard and Light Duty Single-Sleeve Connectors, Respectively

Heavy Duty Double-Sleeve Connector

Torsional Shear

Inner sleeve prevents shearing of inner shaftConsequently, the coupling is stronger than the shaft itself

Thus, the torsional strength is given by

Shaft Torsional Strength = 120 kip-in = 10,000 ft-lbs

Ultimate coupling torsional strength is theoreticallygoverned by total shaft shear and is = 10,000 ft-lbs for the

Heavy Duty Double-Sleeve Connector


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Magnum Shear

Pin Indicator

Shear Pin Calibration

Coupling Torsional Strength Test


sections of helix shaft connected with externalsleeve coupling and bolt

Load Fixturefloor mounted torque reaction plate

Test Equipment: 12,000 ft-lb Eskridge Hydraulic Torque Motor

CASE BackhoeMagnum Shear Pin Torque Indicator

Hydraulic Pressure Gauges

Test Location: Magnum Headquarters - West Chester, OH

Test Procedures:

1. Calibrate shear pin indicator2. Draw axial and circumferential grid

lines on test specimen3. Mount one end of test specimen to

torque reaction plate and the other endto the shear pin indicator

4. Photograph both sides of test specimenprior to start of test

5. Insert appropriate number of shearpins for a torque equal to significantly

less than the theoretical torque value6. Gradually increase hydraulic pressure

to torque motor until shear pin failure7. Photograph and sketch any strains

observed in test specimen8. Record input and output hydraulic

pressure and backhoe throttle settings9. Increase number of shear pins by 1

10. Repeat steps 6 through 9 until couplingfailure

11. Remove connector and disassemble ontest bench

12. Observe, sketch, and photographfailure modes


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Coupling Torsion Test Results

Example

DisassembledTested

Connectors

Torsion Test in Progress Double-Sleeve Connector

Summary of Test Results

Calibrated Strength of Test Pins = 550 ft-lbs

Connector Type Number of Pins Ultimate Torsional Strength

Magnum Light Duty(Single-Sleeve)

7 3,900 ft-lbs

Magnum Standard Duty(Single-Sleeve)

15 8,300 ft-lbs

Magnum Heavy Duty(Double-Sleeve)

19 10,000 ft-lbs


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SECTION 4. Bracket Mechanical Capacity

Theoretical Bracket Mechanical Capacity

The capacity of foundation brackets is a function of mechanical strength of bracket components,

strength of concrete anchors, and integrity of the structure upon which the bracket is affixed. Astructural engineer and/or an experienced installer must judge the integrity of an existing

structure. This section regards tests conducted by Magnum Piering, Inc. to evaluate mechanicalstrength of bracket components.

Weld Shear:

Bracket Plate Dimensions = 21 in x 8 in x 3/8 in

Length of welds, L = 8 inMinimum Weld Thickness, tw= 0.25 in x 2 (both sides)

Minimum Steel Yield Strength, y= 36 ksi

Approximate Steel Shear Strength,

s= 0.7 x

y

Weld strength = L tw s= (8)(0.5)(0.7)(36) = 100 kips

Inner Shaft Bolt-Hole Shear:

Length of Shear Path, l = 1.7 in x 2 paths x 1 side = 3.4 in

Thickness of Shaft, ts= 0.25 in Stnd, 0.13 in LightMinimum Steel Yield Strength,

ys= 46 ksi

Approximate Steel Shear Strength, ss= 0.7 x ys

Shaft Strength = l ts ssx 2 bolt holes = following

Standard Duty: (3.4)(0.25)(0.7)(46)(2) = 55 kips

Light Duty: (3.4)(0.13)(0.7)(46)(2) = 28 kips

Bolt Shear:

Bolt Diameter, db= 3/4 in

Bolt Grade = SAE 8Minimum Bolt Yield Strength, y = 130 ksi

Approximate Bolt Shear Strength, s= 0.7 x y

Bolt Area = 1/4

db

2x 2 bolts = 0.88 in2

Bolt Strength = 1/4 db2 s= (0.88)(0.7)(130) = 80 kips

Bracket mechanical capacity is theoretically governed by inner shaft bolt-hole shear and is =

55 kips and 28 kipsfor double bolted standard and light duty shaft, respectively.


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Bracket Mechanical Capacity Testing


Magnum plate bracketLoad Fixture

12" thick, high-strength concrete slab-on-grade

Test Equipment: Twin 25 ton hydraulic power packsHorizontal Load Frame

Vibrating wire load cellOptical displacement monitoring equipment

Test Location: Magnum Headquarters - West Chester, OH

Test Procedures:

1. Mount bracket to concrete slab2. Set-up horizontal load frame3. Photograph mounted bracket and

load frame configuration prior to startof test

4. Apply pressure in increments to thebracket using the hydraulic rams

5. Monitor bracket displacement andmeasure applied load

6. Record maximum capacity of bracket7. Plot load vs. displacement and

establish yield point8. Sketch and photograph bracket

failure modes


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Bracket Mechanical Capacity Test Results

As anticipated, the failure mode for the plate bracket was observed to be shearing of the bolt

holes. The strength of the bolted connection is approximately double for two bolts comparedwith one bolt. Sample results of the tests are given in the table below.

Summary of Results

Test Specimen Single-Bolt Strength Double-Bolt Strength

Bracket Mounted toLight Duty Pier

(1/8" Wall Shaft)

14 kips 34 kips

Bracket Mounted to

Standard Duty Pier(1/4" Wall Shaft)

25 kips 58 kips

Bracket Mounted toHeavy Duty Pier

(1/4" Wall Shaft)

25 kips 58 kips


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SECTION 5. Bracket Concrete Anchor Capacity

Theoretical Bracket Concrete Anchor Capacity

The capacity of foundation brackets is a function of mechanical strength of bracket components,

strength of concrete anchors, and integrity of the structure upon which the bracket is affixed. Astructural engineer and/or an experienced installer must judge the integrity of an existing

structure. This section regards tests conducted by Magnum Piering, Inc. to evaluate the strengthof concrete anchors used to attach a bracket to an existing structure.

Quantity of anchors = 18Anchor type = in diam., 5- in long, Zinc Plated Trubolt Carbon Steel

Shear strength in 2,000 psi concrete = 7,240 lbs ea.Load factor to account for close spacing = 0.40

Load factor to account for edge distance = 0.20

Shear strength of anchors:

top row = (6 anchors)(7.24 kips ea)(0.20 factor) = 9 kipsmiddle row = (6 anchors)(7.24 kips ea)(0.4 factor) = 17 kips

bottom row = neglect due to test geometry* = 0 kips

Total = (9 + 17 + 0) = 26 kips

*due to unbalanced moments, bottom row of anchors can be placed in tension, therefore shearcontribution of bottom row should be neglected when structure lacks lateral and moment

resistance


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Bracket Concrete Anchor Capacity Testing


Magnum Heavy Duty bracketLoad Fixture

8" thick 2,000 psi concrete field-test footing

Test Equipment: Twin 25 ton hydraulic power packsMagnum Load Frame

Vibrating wire load cellOptical displacement monitoring equipment

Test Location: Magnum Headquarters -

West Chester, OH

Test Procedures:

1. Select test site and clear utilities2. Layout pins for reaction piers in a 6'x6'

square3. Layout pin for test pier offset from center

location4. Cast concrete test footing so that edge is

below hydraulic ram location5. Cure concrete for prescribed time period

6. Install reaction piers and test pier to similardepths

7. Periodically record torque and depth duringinstallation

8. Photograph installation of piers9. Set-up load frame

10. Mount bracket over test pier and attach toconcrete footing

11. Photograph mounted bracket and loadframe configuration prior to start of test

12. Apply an initial pressure to the concretefooting using the hydraulic rams so that the pressure is approximately 1/3 the ultimate

capacity of the bracket13. Record vertical position of bracket under initial pressure

14. Apply lifting pressure to bracket until failure15. Monitor bracket displacement during lifting pressure application

16. Record maximum capacity of bracket attached to concrete footing17. Sketch and photograph bracket or concrete footing failure modes


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Bracket Concrete Anchor Capacity Test Results

Close-Up of Concrete Failure Close-Up of Concrete Failure

Measured concrete anchor capacity for example shown above = 20 kips

Note: See table contained in Section 4 of Magnum Helix Foundation Technical Reference Guide

for more information on connection of helix foundations to structures and more test results forthe plate bracket.


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SECTION 6. Full-Scale Field Capacity

MAGNUM HELIX FOUNDATION

INSTALLATION AND FIELD TESTFebruary 2, 2001

TEST PIER DESCRIPTION

3-Inch O.D. Shaft

8" and 12" Helical Blades on 5' Lead2 - 5' Extensions

Final Depth = 15 feetMagnum Moment Balanced Blade Style

REACTION PIER DESCRIPTION

3-Inch O.D. Shaft

8" and 12" Helical Blades on 5' Lead2 - 5' Extensions

Final Depths = 11-14 feetDifferent Orientations of Circular Blades

and One Magnum Blade Style

SITE

The test was conducted at the North edge of the parking lot at Dwyer Companiesconstruction yard in West Chester, Ohio.

INSTALLATION

The helix piers were installed using a CAT Backhoe with

Eskridge 12,000 ft-lb Hydraulic Torque Motor

Test Pier Installation Torque (Based on Hydraulic Pressure)

Depth (ft) Input Pressure (psi) Approximate Torque (ft-lbs)

1 200 500 4 1100 4000

6 1000 3500 9 1100 3700

11 1200 4200 14 1700 6000

15 1100 3700

PREDICTED PERFORMANCE

Final Installation Torque = 3700 ft-lbsTheoretical Capacity/Torque Ratio = 8 ft -1

Theoretical Ultimate Capacity = 8 x 3700 = 29,600 lbs


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Magnum Full-Scale Field Load Test

0

5

10

15

20

25

30

35

40

-2.5-2-1.5-1-0.50

Displacement (in)

Applied

Load

(kips)

FULL-SCALE FIELD TEST RESULTS

Setting-up Magnum Load Frame Bearing Capacity Test in Progress

SUMMARY OF TEST RESULTS

Measured Ultimate Capacity in Bearing = 35 kips

Measured Ultimate Capacity in Tension = 30 kips


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