Underpinning Design REV 0www.geostructuralengineering.com
7172 Regional Street #440 ~ Dublin, CA 94568
Email: andre.hawks@geostructuralengineering.com ~ Cell: 707-322-3507
Tunnels/Shafts ~ Underpinning ~ Micropiles ~ Soil Nails/Tiebacks ~ Helical Piles & Tiebacks ~ Auger Cast Piles
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GeoStructural Engineering Inc
January 20, 2021 P. 1 of 9
FROM: Andre Hawks, PE
Principal & Founder
TO: Ken Coleman
Foundation Strategies & Construction Inc.
RE: 879 Miller Ave Cupertino CA Voluntary Push Pier Underpinning Design REV 0
For Leveling Purposes Only NOT For Life Safety
Dear Mr. Coleman:
I am pleased to present my Push Pier underpinning design for your project in Cupertino, CA. The
Push Piers and all of their components shall be galvanized or have sacrificial thickness and shall be
installed per manufacturer’s recommendations.
The Push Piers will be installed with a 10 ft minimum embed. The Piers shall be installed with
minimum 1,500 psi of pressure.
The Push Pier embedment depth shall be determined by the onsite pressure readings and lifting
performance of the structure.
Listed below is an outline of the pages included in this design package:
Page 1: Cover Letter
Pages 2-5: Push Pier Calculations
Pages 6-9: Drawings
Please contact me via email at andre.hawks@geostructuralengineering.com with any questions.
Best Regards,
EXP: 3-31-22
1
Arnold Hom
05/03/21
GeoStructural Engineering Inc
Email: andre.hawks@geostructuralengineering.com Cell: 707-322-3507
Tunnels/Shafts ~ Underpinning ~ Micropiles ~ Soil Nails/Tiebacks ~ Helical Piles & Tiebacks ~ Auger Cast Piles
Soils Reports ~ Structural Engineering ~ Temporary & Permanent Shoring ~ Special Inspections ~ Retaining Walls
Push Pier Loading
Roof Tributary Width = ½ x 26 ft width = 13 ft
1st Floor Tributary Width = ½ x 10 ft width = 5 ft
Wall Height = 10 ft
PLF Loading = Tributary Width x Loading
Load Type Dead Load ( psf )Live Load ( psf )
Wall 16 N/A
Roof 20 N/A
1st Story 20 40
Roof
Dead Load = 13 ft x 20 psf = 260 plf
1st Story Floor
Dead Load = 6 ft x 20 psf = 120 plf
Live Load = 6 ft x 40 psf = 240 plf
Walls
Dead Load = 10 ft x 16 psf = 160 plf
Roof Dead Load ( D ) = 260 plf
Floor & Wall Dead Loads ( D ) = 280 plf
Floor Live Loads ( L ) =240 plf
Total Load = 780 plf
Will model existing T Shaped footing in Enercalc as a minimally reinforced Concrete Beam with 2500
psi concrete with an unsupported span equal to Push Pier spacing. Will vary the spacing until capacity
exceeds loading demand.
A test pit dug to expose the existing foundation and the following dimensions were measured:
Grade Beam Depth = Stem Height
= 18 inches
Grade Beam Width = Stem Width
= 6 inches
See attached Enercalc Output
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GeoStructural Engineering Inc
Email: andre.hawks@geostructuralengineering.com Cell: 707-322-3507
Tunnels/Shafts ~ Underpinning ~ Micropiles ~ Soil Nails/Tiebacks ~ Helical Piles & Tiebacks ~ Auger Cast Piles
Soils Reports ~ Structural Engineering ~ Temporary & Permanent Shoring ~ Special Inspections ~ Retaining Walls
FP3BA Push Pier Minimum Pressure Calculations
Internal Wall Total Load = 780 plf
Max Spacing per Enercalc = 7.5 ft
Push Pier Load = 780 plf x 7.5 ft
= 5,850 lbs
Push Pier Minimum Pressure = Push Pier Load x 2 / 9.63 in^2
= 1,215 psi
Therefore, require minimum 1,500 psi
3
Concrete Beam
Licensee : Andre HawksLic. # : KW-06011061
Description : Existing Foundation, Single Story Foundation
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Project Title:
Engineer:
Project ID:
Printed: 17 JAN 2021, 1:19PM
Project Descr:
File = C:\Users\yanng\Dropbox\KENCOL~1\2021PR~1\879MIL~1\879 Miller Ave Cupertino.ec6 .
Software copyright ENERCALC, INC. 1983-2018, Build:10.18.12.30 .
CODE REFERENCES
Calculations per ACI 318-11, IBC 2012, CBC 2013, ASCE 7-10
Load Combination Set : ASCE 7-10
Material Properties
2.50
7.50
145.0
Elastic Modulus 3,122.0 ksi
1
60.0
29,000.0
40.0
29,000.0
3=
2
= 0.90
0.750
f'c ksi
fy - Main Rebar ksi
Density
1/2
=
fr = f'c * 375.0
pcf
E - Main Rebar ksi
psi
=1.0O LtWt Factor
Fy - Stirrups ksi
==
=
E - Stirrups ksi
E 0.850
= =
=
Shear :
Stirrup Bar Size #
Number of Resisting Legs Per Stirrup
Phi Values Flexure :
\
I
. Cross Section & Reinforcing Details
Rectangular Section, Width = 6.0 in, Height = 18.0 in
Span #1 Reinforcing....
1-#4 at 3.0 in from Bottom, from 0.0 to 7.50 ft in this span
. Service loads entered. Load Factors will be applied for calculations.Applied Loads
Beam self weight calculated and added to loads
Load for Span Number 1
Uniform Load : D = 0.020 ksf, Tributary Width = 18.0 ft, (Roof)
Uniform Load : D = 0.020, L = 0.040 ksf, Tributary Width = 5.0 ft, (1st Floor)
Uniform Load : D = 0.0160 ksf, Tributary Width = 10.0 ft, (Wall)
. Design OKDESIGN SUMMARY
Maximum Bending Stress Ratio =0.642 : 1
Span # where maximum occurs Span # 1
Location of maximum on span 3.757 ft
Mn * Phi : Allowable 13.076 k-ft
Typical SectionSection used for this span
Mu : Applied 8.399 k-ft
Maximum Deflection
0 <360.0
12395
Ratio =0 <180.0
Max Downward Transient Deflection 0.002 in 57563 Ratio =>=360.0
Max Upward Transient Deflection 0.000 in Ratio =
Max Downward Total Deflection 0.007 in Ratio =>=180.0
Max Upward Total Deflection 0.000 in
.
Bar Layout DescriptionCross Section
Moment of Inertia ( in^4 )
Bottom Top I gross Icr - TopIcr - Bottom
Phi*Mn ( k-ft )
Cross Section Strength & Inertia Top & Bottom references are for tension side of section
Section 1 1- #4 @ d=15",13.08 0.00 2,916.00 320.43 9.38
.
Load Combination Support 1 Support 2
Vertical Reactions Support notation : Far left is #1
Overall MAXimum 3.483 3.483
Overall MINimum 0.750 0.750
4
Concrete Beam
Licensee : Andre HawksLic. # : KW-06011061
Description : Existing Foundation, Single Story Foundation
Title Block Line 1
You can change this area
using the "Settings" menu item
and then using the "Printing &
Title Block" selection.
Title Block Line 6
Project Title:
Engineer:
Project ID:
Printed: 17 JAN 2021, 1:19PM
Project Descr:
File = C:\Users\yanng\Dropbox\KENCOL~1\2021PR~1\879MIL~1\879 Miller Ave Cupertino.ec6 .
Software copyright ENERCALC, INC. 1983-2018, Build:10.18.12.30 .
Load Combination Support 1 Support 2
Vertical Reactions Support notation : Far left is #1
+D+H 2.733 2.733
+D+L+H 3.483 3.483
+D+Lr+H 2.733 2.733
+D+S+H 2.733 2.733
+D+0.750Lr+0.750L+H 3.295 3.295
+D+0.750L+0.750S+H 3.295 3.295
+D+0.60W+H 2.733 2.733
+D+0.70E+H 2.733 2.733
+D+0.750Lr+0.750L+0.450W+H 3.295 3.295
+D+0.750L+0.750S+0.450W+H 3.295 3.295
+D+0.750L+0.750S+0.5250E+H 3.295 3.295
+0.60D+0.60W+0.60H 1.640 1.640
+0.60D+0.70E+0.60H 1.640 1.640
D Only 2.733 2.733
Lr Only
L Only 0.750 0.750
S Only
W Only
E Only
H Only
.Shear Stirrup Requirements
Between 0.00 to 0.90 ft, PhiVc/2 < Vu <= PhiVc, Req'd Vs = Min 11.4.6.1, use #3 stirrups spaced at 7.000 in
Between 0.92 to 6.58 ft, Vu < PhiVc/2, Req'd Vs = Not Reqd 11.4.6.1, use #3 stirrups spaced at 0.000 in
Between 6.60 to 7.49 ft, PhiVc/2 < Vu <= PhiVc, Req'd Vs = Min 11.4.6.1, use #3 stirrups spaced at 7.000 in
.
Location in Span (ft)Load CombinationMax. "-" Defl (in) Location in Span (ft) Load Combination Span Max. "+" Defl (in)
Overall Maximum Deflections
+D+L+H 1 0.0073 3.750 0.0000 0.000
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