HomeMy WebLinkAboutKiddie Research Light pole base 03132023.pdfEdward C. Robison, PE
14 DEC. 2022
Rev’d 31 JAN 2023
Rev’d 13 March 2023
Oak Hills Construction
901 Algona Blvd. North, Suite A
Algona, WA 98001
SUBJ: KIDDIE RESEARCH DAYCARE
1025 N 36TH ST, RENTON, WA
LIGHT POST BASES
The project requires the installation of light posts on concrete bases. The project plans don’t
specify the depth of the post bases. The design is based on compliance with the applicable
requirements of the 2018 International Building Code as adopted by Washington State and the
AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and
Traffic Signals Fifth Edition.
Based on the the attached design calculations the the recommended post base size is:
For 40’ poles: Pier depth = 3’-3” x 3’-6” diameter: SF = 3.2 (requires plan variance)
Pier depth = 5’-0” x 3’-0” diameter: SF = 10.5
For 18’ poles: Pier depth = 3’-0” x 2’-6” diameter: SF = 6.8 (requires plan variance)
Pier depth = 4’-0” x 2’-6” diameter: SF = 14.0
Those depths that are less than the minimum required by the City of Renton and thus require a
variance approval. As shown these footing sizes will provide a safety factor greater than 2.5 as
required by the AASHTO manual.
Calculations Page
Loading 2
Soil parameters used in design 3
Depth calculations 3 - 4
Safety factors 5
If you have any questions please e-mail me at elrobison@narrows.com.
Edward Robison, P.E.
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98329 fax 253-858-0856
email: elrobison@narrows.comSTATEOFWASHIN
G
T
ON29129REGIST ERE D
Sealed 13 March 2023
Kiddie Research Light Post Base Page ! of !2 5
DESIGN LOADING:
Luminaire weight = 100#
Arm length 10’
Ice loads = 3 psf on surface
Wind loads:
AASHTO
F = qhGCfAs
V = 100mph for location
Kz = 1.04 AASHTO Table 3-5 40’
height
G = 1.3
Cd = 0.5 AASHTO Table 3-6 for
generally round surfaces
vpz = 0.00256KzGV2IrCd =
0.00256*1.04*1.3*1002*1.0*0.5 =
17.3 psf
Total wind load
On post:
12” average diameter
Wp = 1’*40’*17.3 = 692#
on luminaire Conic shape
Wl = 2’*2’*(2/3)*17.3 = 46.1#
on arm:
Wa = 0.5’*10’*17.3 = 86.5#
Combined moment on the post
base:
Group Load:
I DL
II DL + W
III DL + Ice + 1/2W
IV Fatigue - not applicable for
this application
M = D + W
M = (100*10’) +
692*20’+(64.1+86.5)*35’
20,111’#
V = 692+64.1+86.5 = 843#
As ice load is so small relative to
wind it is trivial case.
Edward C. Robison, P.E.
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98329 fax 253-858-0856
email: elrobison@narrows.com
SHEET NO.:
OF
REVISION DATE BY DESIGNED BY:
DRAWN BY:
APPROVED BY:
ISSUE DATE:
02-26-2020
JOB NO.:
TENW #6002
DRAWING FILE NO.:
DRAWING NO.:
DMA
DMA
EMS 2
KIDDIE RESEARCH DAYCARETENW
Transportation Planning | Design | Traffic Impact & Operations
11400 SE 8th Street, Suite 200, Bellevue, WA 98004
Office (425) 889-6747
Transportation Engineering NorthWest
Project Contact: Danielle Allen , E.I.T.
Phone: 425-250-0584
KIDDIE RESEARCH, LLC
1025 N 36TH ST.RENTON, WA 98056KIDZRESEARCH@HOTMAIL.COMYING CHIAO CHEN
02-26-2020 ILLUMINATION PLAN
2
IL-02
T-411101TRO-41-4111
Kiddie Research Light Post Base Page ! of !3 5
FOUNDATION DESIGN:
3’ DIAMETER ROUND PIER
Soil strength based on geotechnical report for the project from Mud Bay Geotechnical Services,
LLC:
Geotechnical Engineering Design Report: 3123 Sunset Blvd NE Renton, WA prepared by Carson
AuYeung and Livia Chen, sealed by Chris J. Heathman, P.E. on 03/18/2019.
Allowable bearing pressure based on section 4.2.1 = 3,500 psf
Lateral resistance on the pier based on the ultimate passive earth pressure:
Kpult = 1,185 psf
Reduce by safety factor of 2.5 per AASHTO manual (1.5 specified in report).
Kpdes = 1,185/(2.5) = 474 psf (use 590 psf)
Cohesive strength = 0
Check required pier depth based on AASHTO formula C13-7
L3- 2VFL/(KpγD) - 2MF/(KpγD) = 0
Use iterative process to find L to satisfy the equation using Kpγ = 474 psf
Edward C. Robison, P.E.
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98329 fax 253-858-0856
email: elrobison@narrows.com
Kiddie Research Light Post Base Page ! of !4 5
Minimum pier length as required by the City of Renton Standard Detail is 5’ - requires variance
CHECK FOR 18’ TALL POSTS:
Loading:
Wp = 1’*18’*17.3 = 311#
M = (100*10’) + 311*9’+(64.1+86.5)*16’ = 6,161’#
V = 311+64.1+86.5 = 462#
Minimum pier length as required by the City of Renton Standard Detail is 4’
MF VF Kpγ = Diameter
20111 843 474 3.5
Trial length L3 2VFL/(KpγD)2MF/(KpγD)∆
1 1 1.016 24.245 -24.261
2 8 2.033 24.245 -18.277
3 27 3.049 24.245 -0.294
3.125 30.517578125 3.176 24.245 3.097
3.25 34.328125 3.303 24.245 6.781
5 125 5.081 24.245 95.674
MF VF Kpγ = Diameter
6161 462 474 2.5
Trial length L3 2VFL/(KpγD)2MF/(KpγD)∆
1 1 0.780 10.398 -10.178
2 8 1.559 10.398 -3.958
2.25 11.390625 1.754 10.398 -0.762
2.333 12.698260037 1.819 10.398 0.481
2.4167 14.114588665463 1.884 10.398 1.832
3 27 2.339 10.398 14.262
Edward C. Robison, P.E.
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98329 fax 253-858-0856
email: elrobison@narrows.com
Kiddie Research Light Post Base Page ! of !5 5
Determine maximum load for revised base size:
Find by trial and error:
35’ poles
SF = 2.5*25730/20111 = 3.2 (42” diameter x 3’3” depth)
SF = 2.5*84660/20111 = 10.5 (36” diameter x 5’0” depth)
18’ pole
SF = 2.5*16660/6161 = 6.8 (3’ diameter x 3’ depth)
SF = 2.5*34548/6161 = 14.0 (3’ diameter x 3’ depth)
MF VF Kpγ = Diameter
25730 843 474 3.5
Trial length L3 2VFL/(KpγD)2MF/(KpγD)∆
3.25 34.328125 3.303 31.019 0.007
MF VF Kpγ = Diameter
84660 843 474 3
Trial length L3 2VFL/(KpγD)2MF/(KpγD)∆
5 125 5.928 119.072 -0.000
MF VF Kpγ = Diameter
16660 843 474 3
Trial length L3 2VFL/(KpγD)2MF/(KpγD)∆
3 27 3.557 23.432 0.011
MF VF Kpγ = Diameter
34548 843 474 2.5
Trial length L3 2VFL/(KpγD)2MF/(KpγD)∆
4 64 5.691 58.309 0.000
Edward C. Robison, P.E.
10012 Creviston DR NW 253-858-0855
Gig Harbor, WA 98329 fax 253-858-0856
email: elrobison@narrows.com