# PIP STE03350 2008 Vertical Vessel Foundation Design Guide

TECHNICAL CORRECTION December 2008 Process Industry Practices Structural PIP STE03350 Vertical Vessel Foundation Design Guide PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES In an effort to minimize the cost of process industry facilities, this Practice has been prepared from the technical requirements in the existing standards of major industrial users, contractors, or standards organizations. By harmonizing these technical requirements into a single set of Practices, administrative, application, and engineering costs to both the purchaser and the manufacturer should be reduced. While this Practice is expected to incorporate the majority of requirements of most users, individual applications may involve requirements that will be appended to and take precedence over this Practice. Determinations concerning fitness for purpose and particular matters or application of the Practice to particular project or engineering situations should not be made solely on ination contained in these materials. The use of trade names from time to time should not be viewed as an expression of preference but rather recognized as normal usage in the trade. Other brands having the same specifications are equally correct and may be substituted for those named. All Practices or guidelines are intended to be consistent with applicable laws and regulations including OSHA requirements. To the extent these Practices or guidelines should conflict with OSHA or other applicable laws or regulations, such laws or regulations must be followed. Consult an appropriate professional before applying or acting on any material contained in or suggested by the Practice. This Practice is subject to revision at any time. © Process Industry Practices PIP, Construction Industry Institute, The University of Texas at Austin, 3925 West Braker Lane R4500, Austin, Texas 78759. PIP member companies and subscribers may copy this Practice for their internal use. Changes, overlays, addenda, or modifications of any kind are not permitted within any PIP Practice without the express written authorization of PIP. PRINTING HISTORY September 2004 Issued September 2007 Technical Correction December 2008 Technical Correction Not printed with State funds TECHNICAL CORRECTION December 2008 Process Industry Practices Page 1 of 31 Process Industry Practices Structural PIP STE03350 Vertical Vessel Foundation Design Guide Table of Contents 1. Introduction..................................2 1.1 Purpose ............................................. 2 1.2 Scope................................................. 2 2. References ...................................2 2.1 Process Industry Practices................ 2 2.2 Industry Guides and Standards......... 2 3. Definitions ....................................2 4. Design Procedure ........................3 4.1 Design Considerations ...................... 3 4.2 Vertical Loads.................................... 3 4.3 Horizontal Loads................................ 4 4.4 Load Combinations............................ 4 4.5 Pedestal............................................. 5 4.6 Anchor Bolts ...................................... 6 4.7 Footing Design .................................. 8 APPENDIX Figures, Tables, and Example.....................................12 Figure A - Potential Concrete Failure Areas AN for Various Configurations ....... 13 Figure B - Foundation Pressures for Octagon Bases ................................ 15 Table 1 - Octagon Properties .................. 16 Table 2 - Foundation Pressures for Octagon Bases ................................ 21 Example - Vertical Vessel Foundation Design.............................................. 22 PIP STE03350 TECHNICAL CORRECTION Vertical Vessel Foundation Design Guide December 2008 Page 2 of 31 Process Industry Practices 1. Introduction 1.1 Purpose This Practice provides guidelines and recommended procedures for engineers analyzing and designing vertical vessel foundations. 1.2 Scope This Practice addresses isolated foundations supported directly on soil. Pile-supported footings are not included in this Practice. 2. References Applicable requirements of the latest edition of the following guides, standards, and regulations in effect on the date of contract award should be considered an integral part of this Practice, except as otherwise noted. Short titles are used herein where appropriate. 2.1 Process Industry Practices PIP – PIP STC01015 - Structural Design Criteria – PIP STE05121 - Anchor Bolt Design Guide – PIP STE03360 - Heat Exchanger and Horizontal Vessel Foundation Design Guide – PIP STF05121 - Fabrication and Installation of Anchor Bolts 2.2 Industry Guides and Standards American Concrete Institute ACI – ACI 318/318R-05 - Building Code Requirements for Structural Concrete and Commentary American Society of Civil Engineers ASCE – ASCE/SEI 7-05 - Minimum Design Loads for Buildings and Other Structures ASTM International ASTM – ASTM F1554 - Standard Specification for Anchor Bolts, Steel, 36, 55, and 105-ksi Yield Strength 3. Definitions For the purposes of this Practice, the following definitions apply engineer The engineer who pers the structural design stability ratio The ratio of the resisting moment to overturning moment about the edge of rotation TECHNICAL CORRECTION PIP STE03350 December 2008 Vertical Vessel Foundation Design Guide Process Industry Practices Page 3 of 31 owner The party who has authority through ownership, lease, or other legal agreement over the site, facility, structure or project wherein the foundation will be constructed 4. Design Procedure 4.1 Design Considerations 4.1.1 The engineer should review and verify project design as based on applicable codes, corrosion allowances for anchor bolts, anchor bolt types, and any special requirements dictated by the owner. 4.1.2 For very tall or heavy vessels, sufficient capacity cranes may not be available for erection. The engineer should determine whether additional loading may be imposed on the foundation during erection. 4.2 Vertical Loads 4.2.1 Dead Loads 4.2.1.1 The following nominal loads should be considered as dead loads when applying load factors used in strength design. a. Structure dead load Ds - Weight of the foundation and weight of the soil above the foundation that are resisting uplift. Pedestal dead load Dp is a part of Dsrepresenting the weight of the pedestal used in the calculation of tension in pedestal dowels. b. Erection dead load Df - Fabricated weight of the vessel generally taken from the certified vessel drawing c. Empty dead load De - Empty weight of the vessel, including all attachments, trays, internals, insulation, fireproofing, agitators, piping, ladders, plats, etc. d. Operating dead load Do - Empty dead load of the vessel plus the maximum weight of contents including packing/catalyst during normal operation e. Test dead load Dt - Empty dead load of the vessel plus the weight of test medium contained in the system. The test medium should be as specified in the contract documents or as specified by the owner. Unless otherwise specified, a minimum specific gravity of 1.0 should be used for the test medium. Cleaning load should be used for test dead load if cleaning fluid is heavier than test medium. Whether to test or clean in the field should be determined. Designing for test dead load is generally desirable because unforeseen circumstances may occur. 4.2.1.2 Eccentric vessel loads caused by large pipes or reboilers should be considered for the applicable load cases. PIP STE03350 TECHNICAL CORRECTION Vertical Vessel Foundation Design Guide December 2008 Page 4 of 31 Process Industry Practices 4.2.2 Live Loads L 4.2.2.1 Live loads should be calculated in accordance with PIP STC01015. 4.2.2.2 Load combinations that include live load as listed in Tables 3 and 4 of PIP STC01015 will typically not control any part of the foundation design. 4.3 Horizontal Loads 4.3.1 Wind Loads W 4.3.1.1 Wind loads should be calculated in accordance with PIP STC01015. 4.3.1.2 The engineer is responsible for determining wind loads used for the foundation design. Comment Loads from vendor or other engineering disciplines without verification should not be accepted. 4.3.1.3 When calculating or checking wind loads, due consideration should be given to factors that may significantly affect total wind loads, such as the application of dynamic gust factors or the presence of spoilers, plats, ladders, piping, etc., on the vessel. 4.3.2 Earthquake Loads E 4.3.2.1 Earthquake loads should be calculated in accordance with PIP STC01015. 4.3.2.2 The engineer is responsible for determining earthquake loads used for the foundation design. Comment Loads from vendor or other engineering disciplines should not be accepted without verification. 4.3.2.3 For skirt-supported vertical vessels classified as Occupancy Category IV in accordance with ASCE/SEI 7-05, Section 1.5.1 and Table 1-1, the critical earthquake provisions and implied load combination of ASCE/SEI 7-05, Section 15.7.10.5, should be followed. 4.3.3 Other Loading 4.3.3.1 Thrust forces caused by thermal expansion of piping should be included in the calculations for operating load combinations, if deemed advisable. The pipe stress engineer should be consulted for any thermal loads that are to be considered. 4.3.3.2 Consideration should be given to process upset conditions that could occur and could increase loading on the foundation. 4.4 Load Combinations The vertical vessel foundation should be designed using load combinations in accordance with PIP STC01015. TECHNICAL CORRECTION PIP STE03350 December 2008 Vertical Vessel Foundation Design Guide Process Industry Practices Page 5 of 31 4.5 Pedestal 4.5.1 Concrete pedestal dimensions should be sized on the basis of standard available s for the project. When ination is not available, octagon pedestal dimensions should be sized with pedestal faces in 2-inch increments to allow use of standard manufactured s. The following criteria should be used to determine the size and shape for the pedestal. 4.5.1.1 Face-to-face pedestal size should be no less than the largest of the following BC 9 inches Equation 1a BC 8 BD for Grade 36 anchor bolts Equation 1b BC 12 BD for high-strength anchor bolts Equation 1c BC SD 9 inches - BD Equation 1d BC SD 7 BD for Grade 36 anchor bolts Equation 1e BC SD 11 BD for high-strength anchor bolts Equation 1f where BC bolt circle, inches BD bolt diameter, inches SD sleeve diameter, inches 4.5.1.2 Pedestals 6 ft and larger should be octagonal. Dimensions for octagon pedestals are provided in Table 1. Octagons highlighted in gray in Table 1 have faces in 2-inch increments. 4.5.1.3 Pedestals smaller than 6 ft should be square, or round if s are available. 4.5.2 Anchorage - It is normally desirable to make the pedestal deep enough to contain the anchor bolts and to keep them out of the footing. Consideration should be given to anchor bolt development and foundation depth requirements. Pedestal size may need to be increased to provide adequate ANfor anchor bolts when additional reinforcement for anchor bolts is not used. 4.5.3 Pedestal reinforcement - The pedestal should be tied to the footing with sufficient dowels around the pedestal perimeter to prevent separation of the pedestal and footing. Development of reinforcing steel should be checked. 4.5.4 Dowels - Dowels should be sized by computing the maximum tension existing at the pedestal perimeter attributable to overturning moments. Conservatively, the following ulas may be used. More exact tension loads may be obtained by using ACI 318 strength design ology. Tension, Fu 4Muped/[NdDC] – 0.9[Deor DoDp]/NdPIP STE03350 TECHNICAL CORRECTION Vertical Vessel Foundation Design Guide December 2008 Page 6 of 31 Process Industry Practices Equation 2 De or Do nominal empty or operating vessel weight. Use empty weight for wind loads. Use empty or operating for earthquake loads depending on which condition is used to calculate Muped.As required tension/design stress Fu/φfy Equation 3 where Fu maximum ultimate tension in reinforcing bar Muped maximum factored overturning moment at base of pedestal, calculated by using load factors in load combinations for uplift cases in Table 4 “Loading Combinations and Load Factors - Strength Design” of PIP STC01015 Nd number of dowels assumed; should be a multiple of 8 DC dowel circle diameter assume pedestal size minus 6 inches DeDp nominal empty weight of vessel and pedestal weight DoDp nominal operating weight of vessel and pedestal weight φ strength reduction factor 0.90 fy yield strength of reinforcing steel 4.5.5 Minimum pedestal reinforcement should be as follows Octagons 6 ft - 0 inch to 8 ft - 6 inches 16, 4 verticals with 3 ties at 15-inch maximum Octagons larger than 8 ft - 6 inches to 12 ft - 0 inch 24, 5 verticals with 4 ties at 15-inch maximum Octagons larger than 12 ft - 0 inch 5 verticals at 18-inch maximum spacing with 4 ties at 15-inch maximum 4.5.6 Top reinforcement - A mat of reinforcing steel at the top of the pedestal should be provided. Minimum steel should be 4 bars at 12-inch maximum spacing across the flats in two directions only. 4.5.7 Ties - See minimum pedestal reinforcement, Section 4.5.5, this Practice. 4.6 Anchor Bolts See PIP STE05121 for anchor bolt design procedures. The nomenclature in the following sections is from PIP STE05121. 4.6.1 Conservatively, the maximum tension on an anchor bolt may be determined using the following ula. More exact tension loads may be obtained by using ACI 318 strength design ology. TECHNICAL CORRECTION PIP STE03350 December 2008 Vertical Vessel Foundation Design Guide Process Industry Practices Page 7 of 31 Nu 4Mu/[NbBC] - 0.9Deor Do/NbEquation 4 where Nu factored maximum tensile load on an anchor bolt Mu factored moment at the base of the vessel, calculated using load factors in load combinations for uplift cases in Table 4 “Loading Combinations and Load Factors - Strength Design” of PIP STC01015 Nb number of anchor bolts BC bolt circle diameter Deor Do nominal empty or operating vessel weight. Use empty weight for wind loads. Use empty or operating for earthquake loads, depending on which condition is used to calculate Mu. 4.6.2 For most cases, there is no shear on the anchor bolts because the load is resisted by friction caused primarily by the overturning moment. If friction cannot resist the load, the bolts should be designed to resist the entire shear load, or other s may be used to resist the shear load. The friction resistance can be calculated using the following ulas Pu Mu/LA 0.9Deor Do/2 Equation 5 Vf μPuEquation 6 where Pu factored compression force at top of pedestal LA