![]() The user should verify that this force can be resisted. Surface Restraint Force : When surface restraint has been specified, the lateral force acting at the surface is given. This number is then multiplied by the load duration factor to get the final allowable pressure at the base. It equals the maximum allowable passive pressure multiplied by the load duration factor.Īctual Base of Embedment : The allowable passive pressure (after application of the load duration factor) is multiplied by the footing depth, compared with the limiting soil pressure value, and the smaller value used. of Embedment : This represents the maximum allowable pressure at the base of embedment, and is given only for poles with lateral restraint at the ground surface. S3 = Allowable lateral bearing pressure at base of embedmentĪllow. H = Height of point of load application, ft.ī = Diameter or width of footing or pole, ft. Required Depth : Based on the formulas to follow, the minimum required embedment depth is calculated to satisfy allowable soil pressures. This number is then multiplied by the load duration factor to get the final allowable pressure at 1/3 embedment. 1/3 Embedment : The allowable passive pressure (after application of the load duration factor) is multiplied by 1/3 the pole embedment, compared with the limiting value, and the smaller value used. It is calculated using a modified version of the formula used to calculate depth of embedment.Īllow. Considering the applied loads, pole footing dimensions, and calculated length of embedment, the actual lateral pressure at 1/3 of embedment depth is given here. S1 = Allowable Lateral passive pressure at 1/3 embedment * LDFĪctual 1/3 Embedment : This is the location of maximum lateral pressure for non-restrained footings. Required Depth : Based on the 19.7 formulas shown on the next page, the minimum required embedment depth is calculated to satisfy allowable soil pressures. This force is simply the sum of point and distributed lateral loads applied to the pole. This moment results from applying both point and concentrated loads to the pole (above soil) at their respective distances above the soil surface The program will combine both loading's and use the resultant moment and shear force at the ground surface. Two types of loads may be entered concentrated load applied at some point above the ground, or a partial length uniform lateral load. The program will iterate (solving the indeterminate equations) until the minimum embedment depth is determined. When ground surface restraint is present, the lateral pressure value that will govern the design will be at the base of embedment. When specifying a restrained footing, you must assure yourself that the final force required to be restrained at the top can be provided. A Restrained footing indicates that a concrete slab or other rigid element only allows rotation of the top of the footing without translation. Specify whether the footing is free at the ground surface or restrained and cannot rotate. Width is measured perpendicular to force direction. If the pole is specified as square, the dimension entered is multiplied by 1.41 to arrive at an equivalent width dimension for calculations.Įnter the width or diameter of the footing, and specify whether a round or rectangular footing is used. Use this section to specify whether the pole is round or square. This number will then be used as the allowable pressures used to determine footing embedment. The load duration factor will be applied to the allowable lateral passive pressures. Maximum allowable passive pressure regardless of depth, and load duration factor to be used to increase the allowable pressures. Regardless of maximum value entered in the next entry the allowable pressure will not be raised when the depth of embedment is below 12'-0". For example, at 4'-0" below the surface allowable lateral pressure entry of 150 psf/ft would be able to resist 150 * 4 = 600 psf. This value will be increased per foot of vertical embedment depth. ![]() The allowable lateral force the soil can withstand. This tab contains all the date entry items for this calculation. After each data entry you can view the results on the right-hand set of tabs. A recalculation is performed after any entry data is changed. ![]() While you are entering data and switching between these tabs you can view the desired resulting information on the tabs on the right-hand side of the screen (calculated values, sketches, diagrams, etc.). This set of tabs provides entries for all input in this calculation. ![]() The data entry for this example is shown in the screen captures that accompany the Data Entry Tabs and Results & Graphics Tabs sections to follow. When surface restraint is specified, the restraint is assumed to be rigid and able to resist lateral reactions. ![]()
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