The URL can be used to link to this page

Home My WebLink AboutBridge Abutment Assessment for BLD2008-00318 - BLD Engineering / Geo-tech Reports - 3/20/2008 116 Envirotech Engineering March 20, 2008 74 NE Hurd Road, Doug Neyhart Belfair, WA 98528 2297 Tahuya River Road Tahuya,Washington Reference: Bridge Abutment Assessment for property located at 2297 Tahuya River Road in Tahuya,Washington Dear Mr.Neyhart, Envirotech Engineering (Envirotech) completed a site visit on March 14, 2008, followed by this structural assessment of two existing reinforced concrete bridge abutments located at 2297 Tahuya River Road in Tahuya,Washington. The abutments will hold a prefabricated bridge with an approximate span of 82 feet. The bridge will have a dead load of about 46,000 pounds. The accompanying abutment details depict construction information for this project. The owner provided all construction information for the existing abutments. Envirotech verified abutment dimensions and assessed soil conditions during the site visit. The structural analysis provided herein is based on owner provided information and the aforementioned field verification by Envirotech. This assessment is structural,and does not assess hydraulics or river dynamics. Earth Pressures Baclfill material:compacted SP, SW, SP-SM,or SW-SM Assume Active earth pressures. H= 10 ft height of wall y„.= 140 psf soil unit weight yw=62.4 psf water unit weight �=32° angle of intemal friction c= 100 psf cohesion 8=2/3�=21.3° angle of wall pressures Ko= 1-sin+=0.31 at-rest earth pressure coefficient Kh=3/4Ko=0.23 earthquake earth pressure coefficient Resultant Pressures R,= 1/2y,,,bWKo=224 psf Lateral earth pressure from soil R. 1/2yJf=3120 psf Lateral earth pressure from water P,=3/8y,,,0Kh=599 psf Lateral earth pressure from earthquakes R,,=gHKo=307 psf Lateral earth pressure from surcharges R=R,+Rw+R,+R,=4251 psf @ 3.83ft from the base of the wall RH=R cos S=3960 psf Resultant horizontal earth pressure Rv=R sin S= 1546 psf Resultant vertical earth pressure Rv1=69 psf vertical component of resultant active earth pressure used to counteract sliding Rm= 176 psf horizontal component of resultant active earth pressure used to counteract sliding OFFICE: 360-275-9374 CELL: 360-689-6045 FAX: 360-275-4789 EMAIL: envirotech@geotechnicalinfo.com Vertical Loads Bridge dead weight=46,000 lb; 23,000 lb per abutment Snow Load=25 psf; 12,300 lb per abutment Live Load=45,000 lb per abutment Sliding and Overturning EWi=64101b sum of vertical weights on retaining wall EWix;=26686 ft-lb sum of vertical moments on retaining wall Rs,=(y,%+Rv+Rv,+Rv+-W)tan S+cB=5967 Resistance against sliding RH=3960 Sliding forces Rs,/RH>FS 1.51 > 1.5 o.k.against sliding yWixi+Rvxv+Rv,xv, =32606 Resistance against overturning Rhys= 15167 Overturning forces (EWixi+Rvxv+Rv,xvl)/Sys-RH,yxl)>FS o.k.against overturning 2.1> 1.5 Wall Analysis f =3500 psi concrete compressive strength M„=wH2/6=21256 lb-ft Ultimate moment fy=60 ksi yield stress of rebar X=0.Id=0.825 in w= 1.4*R=5952 psf force of earth A.=Mj�fy(d-X)=0.404 si Steel area t= 16 in wall thickness at base k=fyA� 0.85f =8.14 si Concrete area H= 10 ft Ma=Aefy(d-X)=283 k-ft Nominal moment d=8.25 in critical depth �M„=21.3 k-ft Design moment As2=A,(M„/M„)=0.404 si New Steel Area Use A.=0.404 si Flexural Steel: #4 bars @ 5.8 in.O.C. required Used Two#4 bars @ 6.0 in.O.C. o.L A.=0.0018bt=0.3456 si Temperature Steel:#4 bars @ 6.82 in.O.C. Used Two#4 bars*6.0 in. O.C. o.k. Wall Foundation h=24 in footing thickness K=[q„(B-t)2]/8=75572 in-lb B=84 in footing width Ao=M„/�fy(d-X)=0.0751 si d= 19.88 in effective footing depth k=fyA� 0.85f;= 1.515 si P„= 1.4D+1.7L+soil= 105461b/in factored loads X=Ao/2b=0.0631 in q„=P„/B= 126 psi load per unit length A,=Md�fy(d-),)=0.0678 si v„=(gjd)[(B-t)/2)-d] =89.23 psi shear stress A.(min)=0.0018bh=0.5184 si 2of3 concrete shear strength v�=2(f�)'� = 100 psi vo<0.85v, depth o.k. use A.=0.5184 A No of#6 bars per foot=1.17(Flexural);#6 bar spacing=10.23 in Used#6 rebar at 6"spacing o.k. AS =0.0018Bh=3.63 si spacing too close A.(min)=0.0018 si Spacing(max)=5h or 18 in= 18 in Temperature Steel:#6 bars @ 18 in.O.C. Used#6 rebar at 6"spacing o.k. Bearing Capacity/Settlement Qall=(cNc+(gamma)DNq+0.5(gamma)Bng)/F.S. allowable bearing capacity =(100psf(35.5)+ 120pcf(0ft)(23.2)+0.5(120pcf)(7)(22.0))/3=4263 psf q„= 1465 psf Qall> q■ Bearing Capacity o.k. These types of soils settle immediately upon loading,with virtually no consolidation or secondary settlements. Total settlement is estimated to be less than 1.0 inch,with a differential settlement of less than 0.5 inch.This is based on foundations constructed per the retaining wall design detail. Settlement o.k. Envirotech is pleased to submit this engineering analysis. If you have any questions or need additional information,please contact Michael Staten at 360-275-9374. Best Regards, Envirotech Engineering �j,CLYDF S ~G O WAsy��T9T� 0" ��r/STCR� CSS�UNALENVl EXPIRES JAN 10,20W Michael Staten Project Manager 3of3 i 82FTt f R•r 12FTt a ' .e'• s. . 4 �''••• C '•' > . 4 v 44.. .,. �! � ] �4 12' 7FT BRIDGE ABUTMENT (TYP) PROJECT/ LOCATION RETAINING WALL DESIGN y CLY'o PLAN VIEW DOUGw xj�T9� TAHUY1A, WASHINGTON ROAD CONTRACTOR, OUG NEYHART ,d 2297 TAHUYA RIVER ROAD TAHUYA, WASHINGTON 0. 43W DRAWN BY, DATE, S I NCS 03/20/08 ENGINEER, REVISIONS, t� CS DESIGNED BY, DATE, ENVIRDTECH ENGINEERING 1 N r " SIGNAL Nichael Staten, P.E. 03/20/08 74 NE HURD ROAD SHEET BELFAIR, WASHINGTON 98528 PHONE, (360) 275-"74 EXPIRES T Q 0 FAX, (360) 875-4789 SHEET I OF 2 I 16 IN--{ (2) 12'x12'xi6' BLOCKS, ONE ON EACH END OF ABUTMENT FOR LATERAL SUPPORT OF BRIDGE, NOTES: STRUCTURALLY TIED TO WALL WITH STEEL REINFORCEMENT 1, RETAINING WALLS CALCULATED USING ACTIVE EARTH PRESSURES. 0 2. RETAINING WALLS ARE LIMITED TO 10 FEET. d, 3. SLOPING EARTH RETENTION (BACKFILL) IS NOT PERMITTED, 4, FOOTING SUBGRADES ARE DENSE UNDISTURBED SOIL. 5, ALL CONCRETE IS 7-SACK. 6. YIEL60 7. CON REINFORCEMENT OVER STEEL FOR STEEL MUSTNBEHAI MINIMUMI OF 1.5 #4 REINFORCEMENT STEEL COMPACTED GRAVEL, ' INCHES FOR WALLS, AND 3 INCHES FOR FOOTINGS. HORIZONTAL 2 6 IN O.C. ° SAND, SAND WITH SILT S. BRACES AND TIE-DOWNS, IF USED, SHOULD HAVE A (TYP) e • :OR GRAVEL WITH SILT.•' CORROSIVE RESISTENT COATING, BACKFILL 9,BACKFILL SHOULD BE COMPACTED TO A MEDIUM RELATIVE DENSITY (80%-85%). #4 REINFORCEMENT STEEL 10, ALL WORK IS EXPECTED TO BE IN ACCORDANCE WITH VERTICAL e 6 1N O,C, ' c PROPRIATE IBC, STATE AND LOCAL CODES. (TYP) 11, ALTHOUGH NOT REQUIRED, 4' WEEP HOLES AT 4 FEET O,C, ARE SUGGESTED, CONCRETE RETAINING WALL AND FOOTING, 3500 psi e 10,0 FT f 4 d Ills 3 FT MIN 24 I1 N 3/4' REINFORCEMENT STEEL 28 IN (VERTICAL) 8 6 IN O.C. 3/4' REINFORCEMENT STEEL PROJECT/ LOCATIODM (TEMPERATURE) B 6' O.C, RETAINING WALL DESIGN (2) 30' STEEL REINFORCED CONCRETE �ti CLYI�FS DOUGPILES BENEATH FOOTING. STRUCTURALY WAS J+ 2297 NEYHART kj 9 2297 TAHUYA RIVER ROAD 7 FT TIED TO FOOTING �� TAHUYA, WASHINGTON IOPTABUIMMUWAM-WrAM Q' O CONTRACTOR, Z19UG NEYHART NOTTO WAM 2297 TAHUYA RIVER ROAD at i TAHUYA, WASHINGTON 43U45 DRAWN BYt DATEi MCS 03/20/08 ENGINEER, REVISIONS, ss G DESIGNED BY, DATEt SCRTPTEN T Te IQ Michael Staten P.E. 03/20/08 ENVIROTECH ENGINEERING ` NAL 74 NE HURD ROAD SHEET BELFAIR, WASHINGTON 98528 coo F PHONE, (360r275-9374 IR_S j QIF FAX, (360) 275-4789 SHEET 2 OF 2