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HomeMy WebLinkAboutTAPESTRY - FDP240016 - SUBMITTAL DOCUMENTS - ROUND 2 - Supporting Documentation (3) Evaluation of Loading on Sewer Pipe Colorado Iron & Metal Salvage Yard Project Name: Tapestry Project Location: 903 Buckingham Street Fort Collins, Colorado Presented by: Magnum Geo-Solutions, LLC Project No. 25-1831-0000 Prepared For: Hartford Acquisitions, LLC 4801 Goodman Street Timnath, CO 80547 January 17, 2025 Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Design Report Magnum Doc. E-LT001.2 Magnum Project No. 25-1831-0000 Table of Contents 1.0 Introduction ........................................................................................................... 3 2.0 Background Information & Design Loads ............................................................. 3 3.0 Calculations .......................................................................................................... 3 4.0 Impact from Falling Material ................................................................................. 4 5.0 Standard Limitations ............................................................................................. 5 Appendix A Calculations Appendix B Reference Documents Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Design Report Magnum Doc. E-LT001.2 Magnum Project No. 25-1831-0000 1.0 Introduction Per your request, staff from Magnum Geo-Solutions have reviewed the proposed sewer trench backfill details for the Tapestry project on Buckingham Street. The proposed sewer line is planned to cross beneath an active industrial site (Colorado Iron & Metal). Where the pipe will cross the site, there is a granular, all-weather surface along with piles of scrap steel, and the equipment to handle it. It is understood that the City of Fort Collins utility department has concerns with the integrity of the pipe when heavy industrial equipment is driven over the top of the pipe and its fill. 2.0 Background Information & Design Loads Civil engineering plans for the site indicate that there will be a minimum of 36 inches of cover over the proposed pipe (Figure 1). Heavy equipment is expected to traverse over the trench on a regular basis. For analysis, the following documents were referenced (and attached to this report):  “Burial Depths for PVC Pipe), by the North American Pipe Corporation  “Burial Depth Guidance for PVC Pipe” by Westlake Pipe & Fittings”  “Highway Live Loads on Concrete Pipe” by the American Concrete Pipe Association” The first two documents reference the Modified Iowa Formula for analysis of pipe stresses and deflections. The formula was used in this analysis. For the design load case in the salvage yard, a large loader with a full bucket was utilized. It has a larger load on a relatively small footprint. For calculations, the required backfill material is CDOT Class 67 aggregate, which can be considered a Class II soil in the design literature. Moderate compaction (85% to 95%) was considered. As reference for the design calculations, the values were compared to verbiage in the “Burial Depths for PVC Pipe”. That document indicates that for highway loads, “the minimum depth of bury for PVC pipe with traffic loading is twelve inches from the top of the pipe to the bottom of the flexible road surface.” The document goes on to say that, “for light to medium aircraft loadings of up to 320,000 pounds gross weight the minimum depth of bury is two feet.” As noted above, our minimum depth of bury is 36 inches. 3.0 Calculations Using the design loader and the Modified Iowa Equation, it was determined that the maximum pipe deflection is approximately 1.7%, which is well below the 7.5% limit referenced by the PVC pipe industry. (Refer to the attached calculations). Even if assuming a burial depth of 20 feet (to represent the scrap steel piles), the calculated pipe deflection is less than 2.5%. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Design Report Magnum Doc. E-LT001.2 Magnum Project No. 25-1831-0000 4.0 Impact from Falling Material It is understood that there is some concern that dropped / falling material in the yard would penetrate the soil cover over the pipe and damage the pipe. While no readily available equations could be found to model this impact, the following were used as frames of reference:  From a geotechnical standpoint, compacted gravel would normally have a blow count in excess of 10 blows per foot. That means that a 140-pound hammer driving a steel shaft into the ground would need at least 10 blows to reach a foot of depth.  Online test data published by “Frontiers in Earth Science” describes the penetration depth of an object depending on its velocity. For an object traveling at 7 meters per second (23 feet per second, the tested penetration is approximately 0.09 meters (<4 inches). Figure 1: Proposed Pipe Backfill Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Design Report Magnum Doc. E-LT001.2 Magnum Project No. 25-1831-0000 For the penetration testing, if extrapolated to 35 feet per second (equivalent to dropping an object 20 feet), the penetration would be on the order of 6 inches. The caveats to this is that the test utilized spherical objects. Nevertheless, the depth of penetration is relatively shallow. 5.0 Standard Limitations This work was prepared with the level of skill and care ordinarily used by engineers practicing in this area, on this type of project, at this time. No warranty is given, express or implied. If you have any questions, please feel free to contact us at 970.635.1851. Respectfully, MAGNUM GEO-SOLUTIONS, LLC Wayne Thompson, PE Senior Engineer Attachments: Calculation Package (4 pages) “Burial Depths for PVC Pipe), by the North American Pipe Corporation “Burial Depth Guidance for PVC Pipe” by Westlake Pipe & Fittings” “Highway Live Loads on Concrete Pipe” by the American Concrete Pipe Association” Figure 2: Test Results for Penetra on of Falling Objects Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 1/20/2025 Design Report Magnum Doc. E-LT001.2 Magnum Project No. 25-1831-0000 APPENDIX A Calculations Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 HABITAT FOR HUMANITARY UTILITY COVER MAGNUM Project No: 25-1831-0000 Origin Date: 1/17/2025 Calcs By: DDE Checked By: WT PROJECT INFORMATION PREPARED FOR: Hartford Acquisitions, LLC ADDRESS: Buckingham Street CONTACT: Jamie Thorpe CITY, STATE: Fort Collins, CO PHONE: 719.244.6088 NOTE:ENGINEER'S STAMP TABLE OF CONTENTS: DateRevision Description By Approved MA G N U M - R E V A . C A L C H A B I T A T F O R H U M A N I T Y U T I L I T Y C O V E R - H A R T F O R D A C Q U I S I T I O N S . x l s x SANITARY SEWER DEFLECTION CALCULATION PACKAGE PAGE NO. 1. Live Load Calculation 2 2. Sanitary Sewer Pipe Deflection Check 3 3.4Limitations Copyright © 2009 thru 2021 Magnum Geo-Solutions, LLC - All Rights Reserved PHONE: 970.635.1851 WEB: www.magnumgeo.com ADDRESS: 138 E. 4th Street, Suite E, Loveland, CO 80537 Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 1/20/2025 HABITAT FOR HUMANITARY UTILITY COVER MAGNUM Project No: 25-1831-0000 Origin Date: 1/17/2025 Calcs By: DDE Checked By: WT Fill Material Select Granular Fill Vehicle Tire Type Vehicle Operating Weight 78,264 lb Tire Load, P Recommended Tire Pressure 69 psi Tire Contact Area 283.6 in² Tire Width, a 33.5 in Tire Contact Length, b 8.5 in Pipe Depth, H 3 ft Tire Spread a 10.2 ft Tire Spread b 4.2 ft Tire Spread Area, A 42.6 ft² Impact Factor, IM 0.206 Average Pressure Intensity, W' 3.8 psi As a conservative estimate, consider a loader with excessive weight on front wheel, plus full bucket Load in Bucket 50000 lbs Bucket Distance from front wheels 9 feet Wheel Base 12.5 feet Reaction at Front Wheels 125132 lbs Reaction at Rear Wheels 3132 lbs Reaction per Wheel 62566 lbs Average Pressure Intensity, W' 12 psi Extreme Case used for design VEHICLE LIVE LOAD CALCULATION Cat 982 XE Wheel Loader Bridgestone 875/65R29 19,566 lb/tire MA G N U M - R E V A . C A L C H A B I T A T F O R H U M A N I T Y U T I L I T Y C O V E R - H A R T F O R D A C Q U I S I T I O N S . x l s x IM = 33(1.0 - 0.125H)/100 Spread a = a + 4 + 1.15H Spread b = b + 1.15H W = P(1 + IM)/A Copyright © 2009 thru 2021 Magnum Geo-Solutions, LLC - All Rights Reserved PHONE: 970.635.1851 WEB: www.magnumgeo.com ADDRESS: 138 E. 4th Street, Suite E, Loveland, CO 80537 Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 HABITAT FOR HUMANITARY UTILITY COVER MAGNUM Project No: 25-1831-0000 Origin Date: 1/17/2025 Calcs By: DDE Checked By: WT Pipe Deflection per Modified Iowa Equation PVC Pipe Diameter 8 in PVC Pipe Thickness Class SDR35 PVC Pipe Stiffness, PS 46 psi Overburden Soil Unit Weight 135 pcf Depth to Top of PVC Pipe 3 ft Vertical Soil Pressure, P 2.8 psi Pressure on pipe due to weight of soil Bedding Constant, K 0.1 Recommended in "Burial Depth Guidance" document Deflection Lag Factor, DL 1.0 1.0 used to represent transient load of equipment Pipe Bedding Material Bedding Material Class II Modulus of Soil Reaction, E'2,000 psi (85% to 95% Compaction) Live Load, W'12.31 psi extreme case (Modified Iowa Equation) Delflection % 1.17 % ≤ 7.5 % OK MA G N U M - R E V A . C A L C H A B I T A T F O R H U M A N I T Y U T I L I T Y C O V E R - H A R T F O R D A C Q U I S I T I O N S . x l s x SANITARY SEWER PIPE DEFLECTION CALCULATION Coarse-Grained Soils with Little or No Fines Deflection % = = .. Copyright © 2009 thru 2021 Magnum Geo-Solutions, LLC - All Rights Reserved PHONE: 970.635.1851 WEB: www.magnumgeo.com ADDRESS: 138 E. 4th Street, Suite E, Loveland, CO 80537 Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 HABITAT FOR HUMANITARY UTILITY COVER MAGNUM Project No: 25-1831-0000 Origin Date: 1/17/2025 Calcs By: DDE Checked By: WT MA G N U M - R E V A . C A L C H A B I T A T F O R H U M A N I T Y U T I L I T Y C O V E R - H A R T F O R D A C Q U I S I T I O N S . x l s x LIMITATIONS The design(s) contained in this document may be based upon information provided by other parties. Magnum Geo cannot be responsible for the accuracy, completeness or applicability of any such information, nor do we warrant the fitness of this submitted design based upon such information for the intended purpose. Should any of the assumptions used to develop this conceptual design be incorrect, or should project conditions be found to vary from those assumed, the Engineer of Record should contact Magnum Geo-Solutions immediately so that appropriate modifications can be made in the design. Copyright © 2009 thru 2021 Magnum Geo-Solutions, LLC - All Rights Reserved PHONE: 970.635.1851 WEB: www.magnumgeo.com ADDRESS: 138 E. 4th Street, Suite E, Loveland, CO 80537 Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Design Report Magnum Doc. E-LT001.2 Magnum Project No. 25-1831-0000 APPENDIX B Reference Documents Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Burial Depths for PVC Pipe Questions are often asked regarding the maximum depth of bury for PVC pipe, especially PVC sewer pipe. The short answer to the question of how deep can you bury PVC pipe is “really deep” because the pipe is not the limiting factor; it is the quality and installation of the embedment material. FLEXIBLE AND RIGID CONDUIT THEORY PVC pipe is classified as a flexible conduit. Ductile iron pipe is also considered to be a flexible conduit. Concrete and clay pipe are classified as rigid conduits. The difference between the two classifications is this: flexible conduits bend without breaking in response to soil and traffic loads. As these loads come to bear, the flexible conduit deflects in the vertical direction and extends in the horizontal direction and becomes slightly elliptical in shape. In this way the vertical soil and traffic loads are transferred horizontally to the embedment material at the sides of the pipe. Rigid conduits rely on their structural strength to resist the same loading. Once a maximum load is reached the conduit will fail. This has led to the use of terms such as “crush strength” or “crush rating” for those materials. Because flexible and rigid conduits react differently under load, the terms crush strength and crush rating do not apply to flexible conduits such as PVC pipe. PVC pipe in and of itself will not support very much load without deflecting. As such it is reliant upon the quality of the embedment material and the compaction of that material to control the amount the pipe deflects. The “stiffer” the embedment the more support provided for the pipe. The amount that a buried flexible pipe will deflect can be calculated with the Modified Iowa Equation. This empirical equation and the soil values that are used with it were derived through extensive testing and evaluation. More information about flexible conduit theory, the Modified Iowa Equation, and soil and embedment values and their use with PVC pipeline design can be found in the Uni-Bell PVC Pipe Association technical report UNI-TR-1-97 entitled “Deflection: The Pipe/Soil Mechanism”. MAXIMUM DEFLECTION The maximum recommended vertical deflection for PVC pressure pipe (AWWA C900, AWWA C905, ASTM D2241…) is 5% and for solid wall sewer/drain pipe (ASTM D3034, ASTM F679, ASTM D2729…) it is 7 ½%. Please note that deflections in excess of these amounts will not cause the pipe to fail. These values were determined by applying a safety factor of 4:1 to in-soil deflection test results. The tests indicated that PVC pipe becomes and remains elliptical in shape at in-soil deflections of up to 30%. Deflections of more than 30% result in inverse curvature of the pipe but no structural failure. In fact the standards to which PVC pipe is made require that deflection tests to 40% of the inside diameter (or a deflection of 60%) be run on a routine basis to confirm the quality and integrity of the produced material. The following photographs show the testing of a piece of eight inch, DR18 AWWA C900 PVC pipe before testing and at the required 40% deflection. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Burial Depths for PVC Pipe The requirements of the different standards are that, after the test, “There is no evidence of splitting, cracking, or breaking” of the sample. (AWWA C900-97, Section 4.3.3.4) CALCULATING PIPE DEFLECTION It is possible to obtain a computer program based on the Modified Iowa Equation free of charge from The Uni-Bell PVC Pipe Association (http://www.uni-bell.org/unidown.html). This program can be used to calculate pipe deflections for a variety of installation conditions and pipe stiffness values. It was used to perform the following calculations for ASTM D3034 and ASTM F679 pipe bedded in a class II material as defined by ASTM D2321 and compacted to 95% Proctor density. The calculated values are independent of the pipe size because the pipe stiffness value is the same for all. Notice that with quality embedment and compaction the calculated deflections of the SDR35 and SDR26 pipes are nearly identical and are approximately one-third of the recommended maximum value at a depth of sixty feet. These values can be compared to the same pipe and bedding material but with a compaction of 85% Proctor density. It can be seen from these comparisons that the quality of the embedment plays a much greater role in the deflection of the pipe than does the stiffness value. Even with a looser compaction on the backfill the calculated deflection at sixty feet is within the recommended maximum value of 7.5%. TRAFFIC LOADS Traffic loads can be incorporated into these calculations and they are much more of an issue with shallow depths of bury than deep. What’s more, at depths of 10 feet or more an H20 traffic load can be considered to have a negligible affect on the pipe. The minimum depth of bury for PVC pipe with traffic loading is twelve inches from the top of the pipe to the bottom of the flexible road surface. For light to medium aircraft loadings of up to 320,000 pounds gross weight the minimum depth of bury is two feet. These depths assume a minimum 95% Proctor density with grade I or grade II embedment. Special attention should be given to the selection, placement, and compaction of shallow bury flexible pipes underneath rigid road surfaces to prevent excessive cracking of the road surface. SUMMARY The combination of the pipe stiffness and the soil stiffness enables PVC pipe of all sizes to be utilized at significant depths of bury in a very efficient and economical manner through the use of common, attentive installation techniques. Thickness Class Pipe Stiffness, lb/in2 Bury Depth- Deflection Bury Depth-40ft, % Deflection Bury Depth-60ft, % Deflection SDR35 46 0.88 1.76 2.63 SDR26 115 0.83 1.67 2.50 E’=3000 lb/in2 Thickness Class Pipe Stiffness, lb/in2 Bury Depth- Deflection Bury Depth-40ft, % Deflection Bury Depth-60ft, % Deflection SDR35 46 2.46 4.91 7.37 SDR26 115 2.13 4.27 6.40 E’=1000 lb/in2 Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 www.westlakepipe.com TECHNICAL BULLETIN ©2022 Westlake Pipe & Fittings All rights reserved PI-TB-009-US-EN-0522.1 www.westlakepipe.com Westlake Pipe & Fittings PVC PIPE AS A FLEXIBLE CONDUIT PVC pipe is considered a flexible pipe, which means that the pipe is designed to transfer external loads to the surrounding soil. The amount of deflection that PVC pipe will experience due to loading when buried depends largely on the soil stiffness of the bedding material. For PVC pipe, pipe stiffness is the ability of a particular pipe to resist deflection under load. It is measured in lbf/in2 and depends on the pipe dimension ratio (DR) and the PVC material properties (specifically the Modulus of Elasticity). When considering resistance to deflection, the pipe stiffness (pipe property) and the soil support (compaction, soil material properties) must be considered. At shallow depths, live loads (i.e. traffic) will influence the external load on the pipe. As the depth of burial increases, live loads influence the load less and the weight of soil contributes more to the external load. MODIFIED IOWA EQUATION Pipe Deflection is estimated using the Modified Iowa Formula, which takes into account the support provided by the surrounding soil conditions and pipe properties. Further explanation for this equation can be found in the PVC Pipe Association’s Handbook of PVC Pipe Design and Construction, Chapters 6 & 7. Deflection % = ∆Y = (DL KP + KW') 100 D 0.149PS + 0.061E' Where DL = Deflection Lag Factor, Dimensionless Factor to for long-term deflection. K = Bedding Constant, Dimensionless Accommodates the response of the buried flexible pipe to the reaction of the load force derived from the bedding under the pipe. P = Vertical Soil Pressure due to Prism Load, psi This is the product of the unit weight of the soil over the pipe multiplied by the depth of cover. W' = Live Load, psi - This is the load on the buried pipe from sources such as highway or railway traffic. E' = Modulus of Soil Reaction, psi - This is an empirical value, assigned to a pipe bedding condition which takes into account the soil classification and the degree of com- paction of the bedding. DEFLECTION PERCENTAGE LIMITS The performance limit for buried PVC pipe is considered to occur when the external loading on the pipe results in a reverse curva- ture of the pipe, which occurs at approximately 30% deflection. The PVC pipe industry suggests a maximum vertical ring deflec- tion of 7.5% the original base inside diameter, which provides a 4:1 safety factor to account for manufacturing tolerances, Modified Iowa Equation accuracies, and uncertainties in choosing constants and factors. This maximum threshold value is reflected in ASTM D3034 and ASTM F679. Some utility owners and engi- neering firms choose to use an even more restrictive value of 5% deflection, yielding a 6:1 safety factor. It is important to note that flow area of partially full gravity sewer pipe is slightly reduced as the pipe is forced from a circle into an ellipse. If this small change is a concern, we recommend a more detailed analysis be undertaken. MINIMUM BURIAL DEPTH ASTM D2321, Standard Practice for Underground Installation of Thermoplastic Pipe for Sewers and Other Gravity-Flow Applica- tions, Section 7.6 states: “The minimum depth of cover should be established by the engineer based on an evaluation of specific project conditions.” “The minimum depth of cover should be established by the engineer based on an evaluation of specific project conditions.” “In the absence of an engineering evaluation, the following minimum cover requirements should be used. For embed- ment materials installed in accordance with Table 3, provide cover (that is, depth of backfill above top of pipe) of at least 24 in. or one pipe diameter (whichever is larger) for Class I embedment, and a cover of at least 36 in. or one pipe diam- eter (whichever is larger) for Class II, III, and IV embedment, before allowing vehicles or construction equipment to traffic the trench surface, and at least 48 in. of cover before using a hydrohammer for compaction.” The Unibell PVC Pipe Association Handbook of PVC Pipe, Section 7.8.3 states: “A minimum cover height of 12 in. is recommended for PVC (SDR35) pipe subjected to highway loads of up to 18 kip axle. To prevent cracking of the road surface, special attention should be given to the selection, placement, and compaction of backfill material around shallow buried flexible pipe (such as PVC pipe)…” BURIAL DEPTH GUIDANCE FOR PVC PIPE () Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 www.westlakepipe.com TECHNICAL BULLETIN ©2022 Westlake Pipe & Fittings All rights reserved PI-TB-009-US-EN-0522.1 www.westlakepipe.com Westlake Pipe & Fittings CALCULATOR • The Uni-Bell PVC Pipe Association has developed the “Buried Pipe Design” software which calculates the expected amount of deflection for a particular burial situation based on the Modified Iowa Formula. This is available free of charge from their website (https://www.uni-bell.org/resources/technical-library/software). SOIL SUPPORT TABLE The modulus of soil reaction, E', is the value assigned to the bedding conditions for a PVC pipe installation. The E' value includes the Bedding Material soil type and the degree of compaction specified for the bedding. The following table shows estimated values for E' for different soil/compaction conditions: SOIL TYPE – PIPE BEDDING MATERIAL E' FOR DEGREE OF COMPACTION OF BEDDING, PSI Description Class Dumped Slight <85% Proctor <40% Relative Density Moderate 85-95% Proctor 40%-70% Relative Density High >95% Proctor >70% Relative Density Fine-Grained Soils (LL>50): Soils with medium to high plasticity, CH, MH, CH-MH V No data available, consult a geotechnical engineer or use E’=0 Fine-Grained Soils (LL<50): Soils with medium to no plasticity, CL, ML, ML-CL, with less than 25% coarse-grained particles IV 50 200 400 1,000 Fine-Grained Soils (LL<50): Soils with medium to no plasticity, CL, ML, ML-CL, with more than 25% coarse-grained particles Coarse-Grained soils with fines: GM, GP, SW, SP, contain more than 12% fines III 100 400 1,000 2,000 Coarse-Grained Soils with Little or No Fines: GW, GP, SW, SC, contain less than 12% fines II 200 1,000 2,000 3,000 Crushed Rock I 1,000 3,000 3,000 3,000 BURIAL DEPTH GUIDANCE FOR PVC PIPE Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 www.westlakepipe.com TECHNICAL BULLETIN ©2022 Westlake Pipe & Fittings All rights reserved PI-TB-009-US-EN-0522.1 www.westlakepipe.com Westlake Pipe & Fittings PIPE CLASS SELECTION TABLE The table below shows the thinnest class of gravity sewer pipe that can be used with a particular burial depth and E' and assuming a maximum deflection of 7.5% and H20 Highway Live Loading. THINNEST CLASS OF GRAVITY SEWER PIPE WHEN SUBJECTED TO H2O HIGHWAY LIVE LOADING (MAXIMUM DEFLECTION PERMITTED OF 7.5%) Depth of Cover (ft) Bedding Soil Modulus, E' (psi) 200 400 1,000 2,000 3,000 1 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 2 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 5 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 10 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 15 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 20 SDR26 / PS115 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 25 SDR26 / PS115 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 30 DR21/PS224 SDR26 / PS115 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 35 DR21/PS224 SDR26 / PS115 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 40 DR21/PS224 DR21/PS224 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 45 DR18/PS364 DR21/PS224 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 50 DR18/PS364 DR21/PS224 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 55 DR18/PS364 DR18/PS364 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 60 DR18/PS364 DR18/PS364 SDR35 / PS46 SDR35 / PS46 SDR35 / PS46 65 DR14/PS815 DR18/PS364 SDR26/ PS115 SDR35 / PS46 SDR35 / PS46 70 DR14/PS815 DR18/PS364 DR21/PS224 SDR35 / PS46 SDR35 / PS46 75 DR14/PS815 DR14/PS815 DR21/PS224 SDR35 / PS46 SDR35 / PS46 Assumptions: DL=1.0, K=0.1, Backfill Weight=120 lb/ft3, Live Load=H20 Highway BURIAL DEPTH GUIDANCE FOR PVC PIPE Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 www.westlakepipe.com TECHNICAL BULLETIN ©2022 Westlake Pipe & Fittings All rights reserved PI-TB-009-US-EN-0522.1 www.westlakepipe.com Westlake Pipe & Fittings DEFLECTION PERCENTAGE TABLES The following 3 tables show the expected amount of pipe deflection for a specific burial depth, E', pipe class, and H20 Highway Live Loading based on values calculated using the Modified Iowa Equation. For values that exceed 7.5%, a stiffer class of PVC pipe must be used or the bedding soil conditions must be improved. PIPE DEFLECTION (%) FOR GRAVITY SEWER PIPE AT VARIOUS DEPTHS AND BEDDING CONDITIONS SUBJECTED TO H20 HIGHWAY LIVE LOADING Depth of Cover (ft) Bedding Soil Modulus, E' (psi) 200 400 1,000 2,000 3,000 SDR35 PS46 SDR26 PS115 SDR35 PS46 SDR26 PS115 SDR35 PS46 SDR26 PS115 SDR35 PS46 SDR26 PS115 SDR35 PS46 SDR26 PS115 1 7.0 4.5 4.3 3.2 2.0 1.7 1.0 1.0 0.7 0.7 2 3.8 2.5 2.3 1.7 1.1 0.9 0.6 0.5 0.4 0.4 5 3.1 2.0 1.9 1.4 0.9 0.8 0.5 0.4 0.3 0.3 10 4.4 2.8 2.7 2.0 1.2 1.1 0.6 0.6 0.4 0.4 15 6.6 4.3 4.0 3.0 1.8 1.6 1.0 0.9 0.7 0.6 20 8.7 5.7 5.3 4.0 2.5 2.1 1.3 1.2 0.9 0.8 25 10.9 7.1 6.7 5.0 3.1 2.7 1.6 1.5 1.1 1.0 30 13.1 8.5 8.0 6.0 3.7 3.2 1.9 1.8 1.3 1.2 35 15.3 9.9 9.3 7.0 4.3 3.7 2.3 2.1 1.5 1.5 40 17.5 11.4 10.7 8.0 4.9 4.3 2.6 2.4 1.8 1.7 45 19.7 12.8 12.0 9.0 5.5 4.8 2.9 2.7 2.0 1.9 50 21.9 14.2 13.3 10.0 6.1 5.3 3.2 3.0 2.2 2.1 55 24.1 15.6 14.7 11.0 6.8 5.9 3.6 3.3 2.4 2.3 60 26.2 17.0 16.0 12.0 7.4 6.4 3.9 3.6 2.6 2.5 65 28.4 18.5 17.3 13.0 8.0 6.9 4.2 3.9 2.9 2.7 70 30.6 19.9 18.7 14.0 8.6 7.5 4.5 4.2 3.1 2.9 75 32.8 21.3 20.0 15.0 9.2 8.0 4.9 4.5 3.3 3.1 Assumptions: DL=1.0, K=0.1, Backfill Weight=120 lb/ft3, Live Load=H20 Highway BURIAL DEPTH GUIDANCE FOR PVC PIPE Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 www.westlakepipe.com TECHNICAL BULLETIN ©2022 Westlake Pipe & Fittings All rights reserved PI-TB-009-US-EN-0522.1 www.westlakepipe.com Westlake Pipe & Fittings PIPE DEFLECTION (%) FOR CIOD PRESSURE PIPE AT VARIOUS DEPTHS AND BEDDING CONDITIONS SUBJECTED TO H20 HIGHWAY LIVE LOADING Burial Depth (ft) 200 400 1,000 2,000 3,000 DR14 PS815 DR18 PS364 DR14 PS815 DR18 PS364 DR14 PS815 DR18 PS364 DR14 PS815 DR18 PS364 DR14 PS815 DR18 PS364 20 1.2 2.5 1.1 2.1 0.9 1.4 0.7 0.9 0.5 0.7 25 1.6 3.1 1.4 2.6 1.1 1.8 0.9 1.2 0.7 0.9 30 1.9 3.8 1.7 3.2 1.4 2.2 1.0 1.4 0.8 1.1 35 2.2 4.4 2.0 3.7 1.6 2.5 1.2 1.7 1.0 1.2 40 2.5 5.0 2.3 4.2 1.8 2.9 1.4 1.9 1.1 1.4 45 2.8 5.6 2.6 4.8 2.1 3.3 1.5 2.1 1.2 1.6 50 3.1 6.3 2.9 5.3 2.3 3.6 1.7 2.4 1.4 1.8 55 3.4 6.9 3.1 5.8 2.5 4.0 1.9 2.6 1.5 1.9 60 3.7 7.5 3.4 6.4 2.7 4.3 2.1 2.8 1.6 2.1 65 4.1 8.2 3.7 6.9 3.0 4.7 2.2 3.1 1.8 2.3 70 4.4 8.8 4.0 7.4 3.2 5.1 2.4 3.3 1.9 2.5 75 4.7 9.4 4.3 7.9 3.4 5.4 2.6 3.5 2.1 2.6 Assumptions: DL=1.0, K=0.1, Backfill Weight=120 lb/ft3, Live Load=H20 Highway BURIAL DEPTH GUIDANCE FOR PVC PIPE Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 www.westlakepipe.com TECHNICAL BULLETIN ©2022 Westlake Pipe & Fittings All rights reserved PI-TB-009-US-EN-0522.1 www.westlakepipe.com Westlake Pipe & Fittings PIPE DEFLECTION (%) FOR IPS PRESSURE PIPE AT VARIOUS DEPTHS AND BEDDING CONDITIONS SUBJECTED TO H20 HIGHWAY LIVE LOADING Burial Depth (ft) 200 400 1,000 2,000 3,000 DR21 PS224 DR21 PS224 DR21 PS224 DR21 PS224 DR21 PS224 20 3.7 2.9 1.8 1.1 0.8 25 4.6 3.6 2.2 1.3 1.0 30 5.5 4.3 2.6 1.6 1.2 35 6.4 5.0 3.1 1.9 1.3 40 7.3 5.8 3.5 2.1 1.5 45 8.2 6.5 4.0 2.4 1.7 50 9.1 7.2 4.4 2.7 1.9 55 10.1 7.9 4.9 2.9 2.1 60 11.0 8.7 5.3 3.2 2.3 65 11.9 9.4 5.7 3.5 2.5 70 12.8 10.1 6.2 3.8 2.7 75 13.7 10.8 6.6 4.0 2.9 Assumptions: DL=1.0, K=0.1, Backfill Weight=120 lb/ft3, Live Load=H20 Highway REFERENCES: ASTM D3034. Standard Specification for PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings. May 2016. ASTM F679. Standard Specification for Poly(Vinyl Chloride) (PVC) Large-Diameter Sewer Pipe and Fittings. March 2015. AWWA C900. AWWA C900-16: Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4"(100mm) through 60"(1,500mm) ASTM D2241. Standard Specification for Poly(Vinyl Chloride)(PVC) Pressure-Rated Pipe (SDR Series), Uni-Bell PVC Pipe Association. Handbook of PVC Pipe Design and Construction. 5th Ed. Chapters 6 & 7. This Technical Bulletin is published for general informational purposes only and is not intended to imply that these materials, procedures, or methods, are suitable for any particular job or should be relied on by the user. Materials, procedures, or methods may vary according to the particular circumstances, local building code requirements, design conditions, or statutory and regulatory requirements. While the information in this Technical Bulletin is believed to be accurate and reliable, it is presented without guarantee or responsibility on the part of Westlake Pipe & Fittings. User is solely responsible for usage of any material, procedure, or method contained herein. BURIAL DEPTH GUIDANCE FOR PVC PIPE Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Highway Live Loads on Concrete Pipe Foreword Thick, high-strength pavements designed for heavy truck traffic substantially reduce the pressure transmitted through a wheel to the subgrade and, consequently, to the underlying concrete pipe. The pressure reduction is so great that generally the live load can be neglected. In 1926, Westergaard presented a paper summarizing the results of an extensive study of the effects of loading conditions, subgrade support, and boundary conditions on concrete pavements(1). These results formed the basis by which Westergaard developed a method to calculate the stresses in concrete slabs. Based upon the work of Westergaard and others, the Portland Cement Association, (PCA), developed a method to determine the vertical pressure on buried pipe due to wheel loads applied to concrete pavements(2). The PCA method is presented in the American Concrete Pipe Association, ACPA, “Concrete Pipe Handbook” (3) and “Concrete Pipe Design Manual”(4). Intermediate and thin thicknesses of asphalt or flexible pavements do not reduce the pressure transmitted from a wheel to the pavement subgrade to any significant degree. For these pavements, there is no generally accepted theory for estimating load distribution effects, and, therefore, these pavements should be considered as unsurfaced roadways. Design of Highway Loads in the US often follows the American Association of State Highway and Transportation Officials, AASHTO, critieria. The AASHTO LRFD Bridge Design Specifications specifies the applicable highway loads and their distribution through the soil. This Design Data addresses the method of determining the live load pressure transmitted through unsurfaced roadways to circular, elliptical and arch concrete pipe in accordance with the criteria of the AASHTO LRFD Bridge Design Specifications . IntroduCtIon To determine the required supporting strength of concrete pipe installed under intermediate and thin thicknesses of asphalt or flexible pavements, or relatively shallow earth cover, it is necessary to evaluate the effect of live loads, such as highway truck loads, in addition to dead loads imposed by the soil and surcharge loads. LIve Loads If a rigid pavement or a thick flexible pavement designed for heavy duty traffic is provided with a sufficient buffer between the pipe and pavement, then the live load transmitted through the pavement to the buried concrete pipe is usually negligible at any depth. If any culvert or sewer pipe is within the heavy duty traffic highway right-of-way, but not under the pavement structure, then such pipe should be analyzed for the effect of live load transmission from an unsurfaced roadway, because of the possibility of trucks leaving the pavement. dead Loads Various methods for analyzing soil dead loads, which have been developed over the years, are presented in the ACPA “Concrete Pipe Technology Handbook”(7). surCHarge Loads A common type of surcharge load is additional soil fill placed after the pipe has been installed for a period of time. If the surcharge load is a building or other surface load, the resultant uniformly distributed load can be converted to an equivalent height of fill, and then evaluated as an additional soil load. When concrete pipe has been installed underground, the soil-structure system will continually show an increase in load capacity. Data on concrete pipe, which have been removed from service and tested, indicate an increase in concrete strength and an increase in load carrying capacity of 10 to 40 percent. Settlement and consolidation will improve the soil structure surrounding the pipe, which also improves load carrying capacity. LIve Loads The AASHTO design loads commonly used in the past were the HS 20 with a 32,000 pound axle load in the Normal Truck Configuration, and a 24,000 pound axle load in the Alternate Load Configuration (Figure 2). The average pressure intensity caused by a wheel load is calculated by Equation 3. The AASHTO LRFD design loads are the HS 20 with a 32,000 pound axle load in the Normal Truck Configuration, and a 25,000 pound axle load in the Alternate Load Configuration (Figure 2). Design Data 1 1American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 IMPaCt FaCtors The AASHTO LRFD Standard applies a dynamic load allowance to account for the truck load being non- static. The dynamic load allowance, IM, is determined by Equation 1: IM = [1]100 33(1.0 - 0.125H) where: H = height of earth cover over the top of the pipe, ft. Load dIstrIButIon The surface load is assumed to be uniformly spread on any horizontal subsoil plane. The spread load area is developed by increasing the length and width of the wheel contact area for a load configuration as illustrated in Figure 3 for a dual wheel; in Figure 4 for dual wheels of two trucks in passing mode; and in Figure 5 for two dual wheels of two Alternate Load configurations in passing mode. On a horizontal soil plane, the dimensional increases to the wheel contact area are based on height Figure 1 aasHto wheel Load surface Contact area (Foot Print) table 1 LrFd wheel surface Contact area Figure 2 aasHto wheel Loads and wheel spacings table 2 LrFd wheel Contact area dimensional Increase Factor 16000 lb. HS 20 Load12500 lb. LRFD Alternate Load 1.67 ft.(20 in.) 0.83 ft.(10 in.)b a HS 20 Load LRFD Alternate Load 4000 lb.4000 lb. 6 ft. 6 ft.6 ft.4 ft. 14 ft. 14 ft. to 30 ft. HS 20 Load 4000 lb.4000 lb. 16000 lb.16000 lb.16000 lb.16000 lb. 12500 lb.12500 lb. HS 20 & LRFD Alternate Loads 12500 lb.12500 lb. 16000 lb.16000 lb. 6 ft.14 ft. 4 ft. The HS 20, 32,000 pound and the Alternate Truck 25,000 pound design axle are carried on dual wheels (Figure 1). The contact area of the dual wheels with the ground is assumed to be a rectangle (Figure 1), with dimensions presented in Table 1. a(width), ft(in.)b(length, ft(in.) 1.67(20)0.83(10) soil type dimensional Increase Factor LRFD select granular 1.15H LRFD any other soil 1.00H 2American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 of earth cover over the top of the pipe as presented in Table 2 for two types of soil. As indicated by Figures 3, 4 and 5, the spread load areas from adjacent wheels will overlap as the height of earth cover over the top of the pipe increases. Live load will also dissipate through the concrete pipe itself resulting in an effective length that resists this load as demonstrated in Figure 7. The effective supporting length of pipe is: Le = L + 1.75(3/4Ro) [2] where: RO = outside vertical rise of pipe, feet The governing wheel load configuration is thus table 3 LrFd Critical wheel Loads and spread dimensions at the top of the Pipe a combination of the overlap in live load pressures distributed through the soil, as well as any instance where the effective lengths from adjacent tires overlap within the pipe itself as shown in Figure 8. These conditions have been summarized in Table 3. At shallow depths, the maximum pressure will be developed by an HS 20 dual wheel, since at 16,000 pounds it applies a greater load than the 12,500 pound Alternate Load (Figures 2 and 3). At intermediate depths, the maximum pressure will be developed by the wheels of two HS 20 trucks in the passing mode, since at 16,000 pounds each, the two wheels apply a greater load than the 12,500 pounds of an Alternate Load wheel (Figures 2 and 4). At greater depths, the maximum pressure will be developed by wheels of two Alternate Load configuration trucks in the passing mode, since at 12,500 pounds each, the four wheels apply the greatest load (50,000 pounds) (Figures 2 and 5). desIgn MetHod The design method encompasses 4 steps. 1. Obtain the following project data: Pipe shape, size and wall thickness. Height of cover over the concrete pipe, and type of earth fill. LRFD or other criteria. 2. Calculate the average pressure intensity of the wheel loads on the soil plane on the outside top of the pipe. 3. Calculate the total live load acting on the pipe. 4. Calculate the total live load acting on the pipe in pounds per linear foot. vehicle traveling Perpendicular to Pipe H, ft P, lbs spread a, ft spread b, ft Figure Live Load distribution of 1.15 x H for select granular Fill H + 1.15DO < 2.05 16,000 a + 1.15H b + 1.15H 3 2.05 - 1.15DO < H < 5.5 32,000 a + 4 + 1.15H b + 1.15H 4 5.5 < H 50,000 a + 4 + 1.15H b + 4 + 1.15H 5 Live Load distribution of 1.0 x H for other soils H + 1.30DO < 2.30 16,000 a + 1.00H b + 1.00H 3 2.30 - 1.30 DO < H < 6.3 32,000 a + 4 + 1.00H b + 1.00H 4 6.3 < H 50,000 a + 4 + 1.00H b + 4 + 1.00H 5 vehicle traveling Parallel to Pipe Live Load distribution of 1.15 x H for select granular Fill H < 2.03 16,000 a + 1.15H b + 1.15H 3 2.03 < H < 5.5 32,000 a + 4 + 1.15H b + 1.15H 4 5.5 <H 50,000 a + 4 + 1.15H b + 4 + 1.15H 5 Live Load distribution of 1.0 x H for other soils H < 2.33 16,000 a + 1.00H b + 1.00H 3 2.33 < H < 6.3 32,000 a + 4 + 1.00H b + 1.00H 4 6.3 < H 50,000 a + 4 + 1.00H b + 4 + 1.00H 5 Figure 3 spread Load area - single dual wheel a Spread a H ft. b Spread b Directi o n o f T r a v e l Spread Load Area Wheel Load Area 3American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Figure 4 spread Load area - two single dual wheels of trucks in Passing Mode Figure 5 spread Load area - two single dual wheels of two alternate Loads in Passing Mode a 4.0 ft. Spread a a H ft. b b 4.0 ft. Sprea d b Directi o n o f T r a v e l Distributed Load Area WheelLoad Areas Wheel Load Areas 1.67 ft . 4.0 ft. Spread a a H ft. b = .83 f t . Sprea d b Directi o n o f T r a v e l Distributed Load Area WheelLoad Areas Wheel Load Areas 4American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Project data Pipe shape and internal dimensions are shown on the project plans. Complete information on dimensional details are included in ASTM Specification C 14 for nonreinforced circular concrete pipe(8), C 76 for reinforced concrete circular pipe(9), C 506 for reinforced concrete arch pipe(10) and C 507 for reinforced concrete elliptical pipe(11). Internal size, wall thickness and outside dimensions are presented in Tables 6, 7 and 8 for circular, arch and elliptical pipe respectively. The minimum earth cover over the concrete pipe can be obtained from the project plans. The type of fill material required under, around and over the concrete pipe will be noted on the project plans or detailed in the contract documents. A decision regarding whether the AASHTO LRFD or other criteria will be used should be obtained from the project authority. average Pressure Intensity The wheel load average pressure intensity on the subsoil plane at the outside top of the concrete pipe is: w = [3]A P(1 + IM) where: w = wheel load average pressure intensity, pounds per square foot P = total live wheel load applied at the surface, pounds A = spread wheel load area at the outside top of the pipe, square feet IM = dynamic load allowance From the appropriate Table 3, or 4, select the critical wheel load and spread dimensions for the height of earth cover over the outside top of the pipe, H. The spread live load area is equal to Spread a times Spread b. Select the appropriate dynamic load allowance, using Equation 1. total Live Load A designer is concerned with the maximum possible loads, which occur when the distributed load area is centered over the buried pipe. Figure 6 illustrates the dimensions of the spread load area, A, related to whether the truck travel is transverse or parallel to the centerline of the pipe. The total live load acting on the pipe is : where: WT = total live load, pounds w = wheel load average pressure intensity, pounds per square foor (at the top of the pipe) Figure 6 spread Load area dimensions vs direction of truck Spread a Pipe Pipe Centerline Di r e c t i o n o f T r a v e l Direction of Travel Spr e a d a Spread b Sp r e a d b L = dimension of A parallel to the longitudinal axis of pipe, feet For vehicles traveling perpendicular to the pipe, L = spread a For vehicles traveling parallel to the pipe, L = spread b S L = outside horizontal span of pipe, DO, or spread wheel load area, A, transverse to the longitudinal axis of pipe, whichever is less, feet total Live Load in Pounds per Linear Foot The total live load in pounds per linear foot, WL, is calculated by dividing the Total Live Load, WT, by the Effective Supporting Length, Le (See Figure 7), of the pipe: where: WL = live load on top of pipe, pounds per linear foot L e = effective supporting length of pipe (see Equation 2 and Figure 7), feet WT = wLSL [4] WL = [5]Le WT 5American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Figure 7 effective supporting Length of Pipe L Wheel Surface Contact Area Pipe Centerline4 3R0 R0 Le = L + 1.75(3/4Bc) H Figure 8 Load spread through soil and Pipe 4 ft 3/4 RO H RO table 4 summary of LrFd Live Loads Calculated in examples example d, in Load soil Fill H, ft P, lbs Live Load, plf 1 30 Perpendicular Select Granular 2 32,000 3,272 2 30 Parallel Select Granular 2 16,000 2,162 3 30 Perpendicular Other Soil 2 32,000 3,407 4 30 Perpendicular Select Granular 6 50,000 855 eXaMPLes Four Example calculations are presented on the following pages to illustrate the four steps of the Design Method, and the effect of varying the depth of fill and the type of fill. The live loads per linear foot calculated in the four Examples are summarized in Table 4. 5 6American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 eXaMPLe 1 given: A 30-inch diameter, B wall, concrete pipe is to be installed as a storm drain under a flexible pavement and subjected to AASHTO highway loadings that run perpendicular to the pipe. The pipe will be installed in a trench with a minimum of 2 feet of cover over the top of the pipe. The AASHTO LRFD Criteria will be used with Select Granular Soil. Find: The maximum live load on the pipe in pounds per linear foot. solution: 1. Review project data. A 30-inch diameter, B wall, circular concrete pipe has a wall thickness of 3.5 inches, therefore the outside diameter of the pipe, DO, and Ro are 3.08 feet. The height of earth cover is 2 feet. Use AASHTO LRFD Criteria with Select Granular Soil Fill. 2. Calculate average pressure intensity of the live load on the plane at the outside top of the pipe. From Table 3, the critical load, P, is 32,000 pounds from two HS 20 single dual wheels in passing mode, and the Spread Area is: A = (Spread a)(Spread b) A = (1.67 + 4 + 1.15 x 2)(0.83 + 1.15 x 2) A = (7.97)(3.13) A = 24.9 square feet From Equation 1: I.M. = 33(1.0 - 0.125H)/100 I.M. = .2475 (24.75%) From Equation 3: w = P(1 + IM)/A w = 32,000(1 + .2475)/24.9 w = 1,603 lb/ft2 3. Calculate total live load acting on the pipe. From Equation 4: WT = wLSL Since the truck travels transverse to pipe centerline. L = Spread a = 7.97 feet Spread b = 3.13 feet DO = 3.08 feet, which is less than Spread b, therefore SL = 3.08 feet WT = 1603 x 7.97 x 3.08 = 39,300 pounds 4. Calculate live load on pipe in pounds per linear foot. Ro = 3.08 feet From Equation 2: Le = L + 1.75(3/4Ro) Le = 7.97 + 1.75(.75x3.08) = 12.01 feet WL = WT/LeWL = 39,300/12.01 = 3,272 pounds per linear foot eXaMPLe 2 given: Same as Example 1, except the live load runs parallel to the pipe. Find: The maximum live load on the pipe in pounds per linear foot. solution: 1. Review project data. A 30-inch diameter, B wall, circular concrete pipe has a wall thickness of 3.5 inches, therefore DO and RO are 3.08 feet. Height of earth cover is 2 feet. Use AASHTO LRFD Criteria with Select Granular Soil Fill. 2. Calculate average pressure intensity of the live load on the plane at the outside top of the pipe. From Table 3, the critical load, P, is 16,000 pounds from an HS 20 single dual wheel, and the Spread Area is: A = (Spread a)(Spread b) A = (1.67 + 1.15 x 2)(0.83 + 1.15 x 2) A = (3.97)(3.13) A = 12.4 square feet From Equation 1: I.M. = 33(1.0 - 0.125H)/100 I.M. = .2475(24.75%) From Equation 3: w = P(1 + IM)/A w = 16,000(1 + .2475)/12.4 w = 1,610 lb/ft2 3. Calculate total live load acting on the pipe. From Equation 4: WT = wLSL Since the truck travels parallel to pipe centerline. 7American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Spread a = 3.97 feet L = Spread b = 3.13 feet BC = 3.08 feet, which is less than Spread a, therefore SL = 3.08 feet WT = (1603)3.08 x 3.13 = 15,500 pounds 4. Calculate live load on pipe in pounds per linear foot. Ro = 3.08 feet Le = L + 1.75(3/4Ro) Le = 3.13 + 1.75(.75x3.08) = 7.17 feet WL = WT/LeWL = 15,500/7.17 = 2,162 pounds per linear foot eXaMPLe 3 given: Same as Example 1, except use AASHTO LRFD Criteria with Other Soils Fill. Find: The maximum live load on the pipe in pounds per linear foot. solution: 1. Review project data. A wall B 30-inch diameter circular concrete pipe has a wall thickness of 3.5 inches, therefore the outside diameter of the pipe, DO, and Ro are 3.08 feet. Height of earth cover is 2 feet. Use AASHTO LRFD Criteria with Other Soils Fill. 2. Calculate average pressure intensity on the plane at the top of the pipe. From Table 3, the critical load, P, is 32,000 pounds from two HS 20 single dual wheels in passing mode, and the Spread Area is: A = (Spread a)(Spread b) A = (1.67 + 4 + 1.00 x 2)(0.83 + 1.00 x 2) A = (7.67)(2.83) A = 21.71 square feet From Equation 1: I.M. = 33(1.0 - 0.125H)/100 I.M. = .2475 From Equation 3: w = P(I + IM)/A w = 32,000(1 + .2475)/21.71 w = 1,839 lb/ft2 3. Calculate total live load acting on the pipe. From Equation 4: WT = wLSL Since the truck travels transverse to pipe centerline. L = Spread a = 7.67 feet Spread b = 2.83 feet DO = 3.08 feet, which is greater than Spread b, therefore SL = 2.83 feet WT = 1,839 x 7.67 x 2.83 = 39,900 pounds 4. Calculate live load on pipe in pounds per linear foot. Ro=3.08 feet From Equation 2: Le = L + 1.75(3/4Ro) Le = 7.67 + 1.75(.75 x 3.08) = 11.71 feet WL = WT/LeWL = 39,900/11.71 = 3,407 pounds per linear foot eXaMPLe 4 given: Same as Example 1, except minimum depth of fill is 6 feet. Find: The maximum live load on the pipe in pounds per linear foot. solution: 1. Review project data. A wall B 30-inch diameter circular concrete pipe has a wall thickness of 3.5 inches, therefore the outside diameter of the pipe, DO, and Ro are 3.08 feet. Height of earth cover is 6 feet. Use AASHTO LRFD Criteria with Select Granular Soil Fill. 2. Calculate average pressure intensity at the outside top of the pipe. From Table 3, the critical load, P, is 50,000 pounds from two single dual wheels of two Alternate Load Configurations in the passing mode, and the Spread Area is: A = (Spread a)(Spread b) A = (1.67 + 4 + 1.15 x 6)(0.83 + 4 + 1.15 x 6) 8American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 A = (12.57)(11.73) A = 147.45 square feet From Equation 1: I.M. = 33(1-0.125H)/100 I.M. = 0.0825 From Equation 3: w = P(1 + I.M.)/A = 50,000(1 + 0.0825)/147.45 w = 367 lb/ft2 3. Calculate total live load acting on the pipe. WT = wLSL Since the truck travels transverse to pipe centerline. L = Spread a = 12.57 feet Spread b = 11.73 feet DO = 3.08 feet, which is less than Spread b, therefore SL = 3.08 feet WT = 367 x 12.57 x 3.08 = 14,200 pounds 4. Calculate live load on pipe in pounds per linear foot. Ro = 3.08 feet From Equation 2: Le = L + 1.75(3/4Ro) Le = 12.57 + 1.75(0.75x3.08) = 16.6 feet WL = WT/LeWL = 14,200/16.6 = 855 pounds per linear foot table 6 dimensions of Circular Concrete Pipe wall a wall B wall C Internal Minimum Minimum Minimum diameter, wall wall wall inches thickness, thickness, thickness, inches inches inches 12 1-3/4 2 - 15 1-7/8 2-1/4 - 18 2 2-1/2 - 21 2-1/4 2-3/4 - 24 2-1/2 3 3-3/4 27 2-5/8 3-1/4 4 30 2-3/4 3-1/2 4-1/4 33 2-7/8 3-3/4 4-1/2 36 3 4 4-3/4 42 3-1/2 4-1/2 5-1/4 48 4 5 5-3/4 54 4-1/2 5-1/2 6-1/4 60 5 6 6-3/4 66 5-1/2 6-1/2 7-1/4 72 6 7 7-3/4 78 6-1/2 7-1/2 8-1/4 84 7 8 8-3/4 90 7-1/2 8-1/2 9-1/4 96 8 9 9-3/4 102 8-1/2 9-1/2 10-1/4 108 9 10 10-3/4 114 9-1/2 10-1/2 11-1/4 120 10 11 11-3/4 126 10-1/2 11-1/2 12-1/4 132 11 12 12-3/4 138 11-1/2 12-1/2 13-1/4 144 12 13 13-3/4 150 12-1/2 13-1/2 14-1/4 156 13 14 14-3/4 162 13-1/2 14-1/2 15-1/4 168 14 15 15-3/4 174 14-1/2 15-1/2 16-1/4 180 15 16 16-3/4 table 7 dimensions of arch Concrete Pipe Minimum equivalent Minimum Minimum wall round size, rise, span, thickness, inches inches inches Inches 15 11 18 2-1/4 18 13-1/2 22 2-1/2 21 15-1/2 26 2-3/4 24 18 28-1/2 3 30 22-1/2 36-1/4 3-1/2 36 26-5/8 43-3/4 4 42 3-15/16 5-1/8 4-1/2 48 36 58-1/2 5 54 40 65 5-1/2 60 45 73 6 72 54 88 7 84 62 102 8 90 72 115 8-1/2 96 77-1/4 122 9 108 87-1/8 138 10 120 96-7/8 154 11 132 106-1/2 168-3/4 10 table 7 dimensions of elliptical Concrete Pipe equivalent Minor Major Minimum wall round size, axis, axis thickness, inches inches inches inches 18 14 23 2-3/4 24 19 30 3-1/4 27 22 34 3-1/2 30 24 38 3-1/4 33 27 42 3-3/4 36 29 45 4-1/2 39 32 49 4-3/4 42 34 53 5 48 38 60 5-1/2 54 43 68 6 60 48 76 6-1/2 66 53 83 7 72 58 91 7-1/2 78 63 98 8 84 68 106 8-1/2 90 72 113 9 96 77 121 9-1/2 102 82 128 9-3/4 108 87 136 10 114 92 143 10-1/2 120 97 151 11 132 106 166 12 144 116 180 13 9American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5 Technical data herein is considered reliable, but no guarantee is made or liability assumed. references 1. Westergaard, H.M., “Stresses in Concrete Pavements Computed by Theoretical Analysis”, Public Roads, April, 1926. 2. “Vertical Pressure on Culverts Under Wheel Loads on Concrete Pavement Slabs”, Portland Cement Association, 1944. 3. “Concrete Pipe Handbook”, American Concrete Pipe Association, 1998. 4. “Concrete Pipe Design Manual”, American Concrete Pipe Association, 2000. 5. “Standard Specifications for Highway Bridges”, American Association for State Highway and Transportation Officials. 6. “LRFD Bridge Design Specifications”, American Association for State Highway and Transportation Officials. 7. “Concrete Pipe Technology Handbook”, American Concrete Pipe Association, 1993. 8. ASTM Standard C 14, “Specification for Concrete Sewer, Storm Drain, and Culvert Pipe”, American Society for Testing and Materials. 9. ASTM Standard C 76, “Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe”, American Society for Testing and Materials. 10. ASTM Standard C 506, “Specification for Reinforced Concrete Arch Culvert, Storm Drain, and Sewer Pipe”, American Society for Testing and Materials. 11. ASTM Standard C 507, “Specification for Reinforced Concrete Elliptical Culvert, Storm Drain, and Sewer Pipe”, American Society for Testing and Materials. 10American Concrete Pipe Association • www.concrete-pipe.org • info@concrete-pipe.org dd 1 (07/09)© 2009 american Concrete Pipe association, all rights reserved. Docusign Envelope ID: AB59BF1D-8917-444D-BBF5-524E0913EBD5