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Sign footings must be calculated before construction begins. Failure to calculate these footings may cost you time and money, especially if you order too much concrete or not enough.
How to Calculate Sign Footing
The method for estimating sign footings has been simplified by the construction industry to include the average do-it-yourselfer. You can expect to complete this task is to 30 minutes, depending on the size and scope of the project. Multiply the length times the width of the footer to determine the square footage. If the footer has more than four sides, then keep the sections separated.
For example, if your sign footer is in the shape of a T or an L, then separate the sections on paper by labeling them. This will help you in case you need to make changes to one section. If you have a section that is 4 feet by 6 feet, then multiply to get 24 square feet. Record this on your paper. Add all square footages together to get total square feet. Record this calculation under total square feet on your paper. For example, if you have a footing that several sections of, say 24, 28, and 48 square feet, then add them together.
Multiply the total square footages times the thickness of the footer. Because the calculations are in feet, convert your footing thickness--if it is less than one foot--into feet. Divide the thickness by For example, if your footer is 8 inches thick, then divide that by 12 inches to get. If you have a footer that is 16 inches thick, then that means that your footer is 1'4". Convert the 4 inches into feet to get.
Now your footer is 1. Multiply 1. Convert cubic feet into yards in order to determine the amount of yards that your sign footer will require. Divide the total cubic footage by 27, which is the equivalent of one cubic yard. Dividing Round up to the nearest yard to get 3 yards of concrete for your footer. Pin Share Tweet Share Email. Step 1. Step 2. Step 3. Step 4. Miller; Show Comments.Log In. However, I think as engineers, we owe it to our clients to give them a safe, economical and code compliant desings.
If wind load calculations yield less than 30 PSF pressure, why not use the lower pressure? That is the rational for my statement number 2 above.
I've only done a few signs, but many monopoles and many flagpoles - the tallest at this point is feet. The company I consulted for basic wind speed was mph, bare pole, no mater where the site was. But I'm seeing higher wind speeds for Florida did only a few there and I believe that they are real wind speeds.
One thing that I didn't mention before is to require shop drawings and depending how you are putting the sign together, whether you will require special inspection. RE: Foundation design of a sign to handle windload Lufti, I understand your point about providing economical designs. I work directly for a company that designs, details, fabricates and sells billboard structures to owners. Long before I started in the business, someone I've been told the Outdoor Advertising Association determined that 30 PSF was the minimum wind load to be used for design.
Many municipalities throughout the country have zoning ordinances that require a minimum load of 30 PSF for outdoor advertising structures. I'm guessing that these all came from the same place many years ago. I would hate to provide a structure designed for ASCE 7 loads only to find out after erection that there is some law in rural Arkansas that requires a minimum of 30 PSF. Obviously, the wind pressure can change incredibly for different parts of the country. I believe that we're providing the owners with what the industry wants.
There are many shops similar to our that provide similar products. If we were providing over-engineered and in turn over-priced structures, the market would go elsewhere. Regards, John RE: Foundation design of a sign to handle windload azcat, I agree with your explanation. Codes are intended to provide minimums.
Many municipalities do require over and above the code minimums. If that is the case, by all means, engineers must follow the ordinances. No one should design to ASCE without first checking for local requirements. My point is as I started above, 30 PSF by itself, as a blanket requirement is not meaningful, at least in my opinion.
I face this with Cooling Tower suppliers. They tell me that their towers will support 30 PSF! In some areas in Florida that would not corresponds to the code prescribed wind speed with all applicable factors. I am glad to see a healthy exchange of ideas and opinions. This is what this forum is all about. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.
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Already a Member? Join your peers on the Internet's largest technical engineering professional community. It's easy to join and it's free. Register now while it's still free! Already a member?POLEFDN is a spreadsheet program written in MS-Excel for the purpose of analysis of a pole foundation assuming the use of a rigid round pier which is assumed free unrestrained at the top and subjected to lateral and vertical loads.
Specifically, the required embedment depth, the maximum moment and shear, the plain concrete stresses, and the soil bearing pressures are calculated. Since there is not a universally accepted method for pole foundation analysis, this program offers up five different methods of determining embedment length for pole foundations.
The "Pole Fdn Czerniak " worksheet is the primary method emphasized in this program, since it provides the most detail in overall analysis. However, it does yield the most conservative embedment depth results of all the methods presented. ST2, PaperMarch This program will handle both horizontally as well as vertically applied loads.
The vertical load may have an associated eccentricity which results in an additional overturning moment which is always assumed to add directly to the overturning moment produced by the horizontal load. This program assumes that the top of the pier is at or above the top of the ground surface level.
This program assumes that the actual resisting surface is at or below the ground surface level. This accounts for any weak soil or any soil which may be removed at the top. The "Pole Fdn Czerniak " worksheet assumes that the rigid pier rotates about a point located at a distance, 'a', below the resisting the surface.
The "Pole Fdn Czerniak " worksheet calculates the "plain" unreinforced concrete stresses, compression, tension, and shear in the pier. The respective allowable stresses are also determined based on the strength f'c of the concrete. This is done to determine if steel reinforcing is actually required. However, whether minimum reinforcing is to be used or not is left up to the user. The respective allowable passive pressures at those locations are determined for comparison.
However, it is left up to the user to determine the adequacy. Since all overturning loads are resisted by the passive pressure against the embedment of the pier, this program assumes that the pier acts in direct end bearing to resist only the vertical loading.
The bottom of pier bearing pressure is calculated, which includes the self-weight of the pier, assumed at 0. Beam on Elastic Foundation Analysis. BOEF is a spreadsheet program written in MS-Excel for the purpose of analysis a finite length beam with free ends supported continuously on an elastic foundation. Rectangular Spread Footing Analysis. FOOTINGS is a spreadsheet program written in MS-Excel for the purpose of analysis of rigid rectangular spread footings with up to 8 total piers, and for either uniaxial or biaxial resultant eccentricities.
Concrete Slab on Grade Analysis. A total of 10 votes cast and 0 users reviewed the software. AllPile is a Windows-based analysis program that handles virtually all types of piles, including steel pipes, H-piles, pre-cast concrete piles, auger-cast piles, drilled shafts, timber piles, jetted piles, tapered piles, piers with bell, micropiles minipilesuplift anchors, uplift plate, and shallow foundations.
GEO5 is a suite of programs for geotechnical analysis. The software package includes individual programs that are closely linked to each other and run in the same environment. Dartis Lab is a geotechnical software for easily processing lab test data.
RE Shoring Wall is state-of-the-art software for designing shoring systems using current industry standards and methods. PileSuite is a powerful suite of software products for deep foundation analysis and design for both onshore and offshore projects. DartisLog is a bore log software that will help users to create soil borehole logs specially adjusted for the Geotechnical Engineer.
All software and resources in the CESDb. All downloadable or viewable content available on CESDb. You agree that you bear sole responsibility for your own decisions to download or use any of the software listed. BOEF Version Thank you. Your comment will appear after moderationLog In.
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Students Click Here. Related Projects. I am looking for some sign post foundation resources. I would like to understand how to approach the process.When it comes to freestanding sign structures, footings are critical, helping to transfer the load of the structure to the foundation while also increasing stability. There are three main types of footings that are used. In this blog, you will learn some of the major benefits of each footing, an overview of their complexities, and when best to use them.
Best for large structures such as taller freeway or highway signs 70 to feet-tall, but can fit all size needs. For large structures, a round footing involves the highest amount of labor, requiring equipment such as caisson drills, which are costly, and a heavy rebar cage and corrugated sleeve to prevent the hole from collapsing; allows for virtually unlimited diameter and depth capabilities. Requires stable soil conditions and low water table.
Column diameter depends on overall width and height of a sign, but can be as small as 4 inches up to 2-feet. Require the least amount of labor because of the way they are dug—excavated with a track excavator or backhoe. Vertical footings are ideal for tight areas, especially in commercial applications when working within curbs in parking lots. Relies on lateral soil bearing instead of vertical bearing Spread footings rely on vertical bearing pressure. Rebar not required if you go direct burial in most circumstances.
Spread footings rely solely on vertical soil bearing pressure and require greater surface area. Best for larger signs—feet high or taller. Column diameter are determined similarly like block and vertical footings—by overall width and height of a sign, 1 foot to 3 feet in diameter.
Good for poor soil conditions and high water table, but requires rebar mats on the top and bottom; soil stabilization may also be required by adding gravel or replacing several feet of soil and compacting every foot on the size. Spread footings are shallow, but its bottom must still to go below frost line. Where poor soil conditions are present, engineer may require structural pilings to be driven into stable ground depending on the size of structure and vertical loads to be exerted directly into soil area below footing.
There is an alternate spread type that includes a concrete pier on top of a spread footing. The pier on top of the spread is used to get the bottom of the spread down to the frost level instead of making the entire spread the total height to grade 36 inches or more. The spread is placed down low and is 12 to 18 inches thick, then a square pier is formed to the top of the spread footing and tied together through rebar coming out of the footing.
The pier is then brought up to grade to save concrete where anchor bolts are typically set to accept the sign. As you can see, selecting the right footing for your sign structure is no simple undertaking. However, choosing the right footing greatly depends on soil conditions, space available, the size of the structure, and budget. July 20, Three Footings Used For Freestanding Signs When it comes to freestanding sign structures, footings are critical, helping to transfer the load of the structure to the foundation while also increasing stability.
Round Footings Also known as augered or caisson footing. Small structures can be supported by columns with diameters of 4 inches to 12 inches.
Please enable it or visit HappyBrowser.Need more? Ask Us a Question. This module determines actual soil pressures and required depths for pole footings primarily supporting lateral loads. Such footings are commonly called "flagpole footings".
Click here for a video:. Cases with and without lateral restraint at the ground surface are allowed. Evaluation of actual and allowable pressures is in accordance with the IBC Section entitled "Embedded posts and poles". General Data Tab. Pole Footing Shape. Use this section to specify whether the pole is round or rectangular assumed square. Enter the width or diameter of the pole footing.
Width is measured perpendicular to force direction.
If the pole is specified as rectangular, the module will multiply the value entered for footing width 1. Restraint at Ground Surface. Specify whether the footing is free at the ground surface or restrained and cannot translate. A restrained footing indicates that a concrete slab or other rigid element prevents translation of the pole footing at the ground surface, but does not prevent rotation.
When specifying a restrained footing, you must assure yourself that the final force required to provide the restraint can actually be developed by the restraining construction.
When ground surface restraint is present, the lateral pressure value at the bottom of the pole will govern the design. Operation Mode. This setting provides an option to select from two different modes of operation as follows:. Calculate Minimum Depth : In this mode, the module will iterate to determine the minimum embedment depth required to make the actual lateral soil pressure lower than the allowable soil pressure.
How to Calculate Sign Footing
Find Lateral Pressure for Given Depth : In this mode, the module will calculate the lateral earth pressures caused by the specified pole size, embedment depth and applied loads. When this option is selected, a Pole Footing Embedment Depth input field will appear as shown below:. Allowable Pressure Limit. Two options are provided as indicated below:. Limit only by "Max. Passive" : Solves for a design that allows the passive pressure to approach the value specified in the Allowable Lateral Passive Pressure field below limited to the value specified in the Maximum Lateral Pressure Limit field.
When the Limit only by "Max. Passive" option is selected, the solution will progress as follows:. When the Use limit of 12 ft per IBC option is selected, the solution will progress as follows:. Allowable Lateral Passive Pressure. The allowable lateral passive pressure that the soil can withstand. This value is entered as pounds per square foot per foot of embedment depth.
Maximum Lateral Pressure Limit. This value is used to specify an upper limit on the Allowable Lateral Passive Pressure, so that it does not increase in an uncontrolled manner as the embedment depth increases. This value is entered as pounds per square foot.John W.
AndrewP. Course Outline. This course highlights the requirements for determining the embedment depths required and foundation pressures for pole foundations for signs, flagpoles, light poles and pole framed buildings in accordance with Section and Paragraph The course is designed to help architects and structural engineers become familiar with the design criteria for pole foundations.
A copy of the International Building Code is required for this course. This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials. Learning Objective. Intended Audience. Benefits to Attendee. The Attendee will learn how to determine the embedment depths and foundation pressures for many pole type structures, including signs, flagpoles, light poles and pole framed buildings.
These pole foundations may be more efficient and easier to install than conventional spread footings in many applications. Course Introduction. Poles foundations are commonly used for sign, flagpole and light pole foundations and pole framed buildings.
A design criteria for pole foundations is indicated in Section and Paragraph This criteria applies to vertical poles considered columns embedded in either earth or in concrete footings in the earth and used to resist lateral loads. The backfill in the annular space around a column that is not embedded in a concrete footing shall be clean sand thoroughly compacted by tamping in layers not exceeding 8 inches in depth. Course Content. Pole Foundation Design with Spreadsheet.
Please click on the above underlined hypertexts to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As You may need to download Acrobat Reader to view and print the document. Course Summary. This course covered the requirements for determining the embedment depths required and foundation pressures for pole foundations for signs, flagpoles, light poles and pole framed buildings in various types of soil in accordance with the International Building Code.
Related Links and References. Q uiz. Once you finish studying the above course contentyou need to take a quiz to obtain the PDH credits. Print this page.