ENERCALC Version 5.8 - Non-Current Retired Version

Plywood Shear Wall

This program provides complete design and analysis of shear walls constructed of plywood sheathing over wood studs. Plywood can be applied to one or both sides, and you can specify up to five applied lateral loads and five vertical loads to the wall.

Applied lateral loads can be from uniform forces (diaphragm connection) or concentrated loads (collector load transfer). Additionally, a concentrated moment can be applied to the wall, allowing you to transfer moments from upper level wall sections to the current wall.

Vertical loads can be applied as uniform or concentrated, and will act to stabilize the wall for overturning. You can use the concentrated load entries to apply end uplift/compression forces from a wall above to the current section.

Values which can be specified for the wall construction are; plywood thickness, plywood grade, nail size, number of sides applied, stud spacing, sill thickness, and seismic factor. All of these values will be used to determine allowable shear capacity and nail spacing of the wall sheathing, sill bolting requirements, and wall uplift provisions.

Also provided by this program is the ability to design a supporting footing. The footing length, width, and thickness can be modified to achieve acceptable soil pressures, shearing stresses, overturning stability, and bending reinforcement requirements.

Basic Usage

• | Lateral Loads can be specified by the user, and are applied to the top of the wall. Uniform loads are applied from an attached diaphragm, and Concentrated loads due to transfer of collector forces (drag struts). A Moment can also be applied to transfer reactions from a wall section above to the current wall. |

• | Vertical Loads allow you to apply uniform floor loads, concentrated beam loads, and uplift/compression loads due to end reactions from a wall above. |

• | Design Data specifies all values affecting the plywood sheathing selection. Thickness, grade, number of sides, and nail size all affect the program's selection of required nailing. Wall Length, Height, and Weight are used to calculate unit shear, lateral wall weight, and moments created by lateral loads applied at the top of the wall. |

• | The Summary section provides the results of the wall design, giving plywood thickness, nailing, allowable and actual shear values, uplift, check values and end hold down requirements, and footing design data. |

• | Footing Analysis is where you can define the footing width, thickness, and projection beyond the end of the wall. |

• | Refining the Wall and Footing Design is simply a matter of recalculating the worksheet and refining wall construction and footing sizes. |

Unique Features

• | This program has all the capabilities to design an entire plywood shear wall/footing assembly in one pass. The what-If ability can quickly modify the design criteria and give the user many design options and resulting calculations quickly. |

• | The footing design capability of the program can quickly determine the proper size footing to satisfy soil pressure and overturning requirements, normally a very tedious procedure. |

Assumptions & Limitations

• | Allowable plywood shear wall values are taken from UBC Table 23-I-K-1 for Structural I and II. The program assumes two times the allowable value for one side is allowed, when both sides are sheathed. |

• | All loads are considered to be applied at the top of the wall. |

• | ACI equation 9-3 is used for footing analysis and design. |

• | All lateral loads are considered short term and ACI load factors are applied accordingly. |

Example

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.

Data Entry Tabs

This set of tabs provides entries for all input in this calculation. 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.). A recalculation is performed after any entry data is changed. After each data entry you can view the results on the right-hand set of tabs.

General Tab

The data in this section defines the material parameters used in determining the necessary nail spacing for the shear wall. YOU enter Plywood Grade, Thickness, Nail Size, and Number of Sides Applied, and the program determines the allowable shear values from its internally stored UBC 25-K table. The nail spacing and allowable shear values are given.

Wall Length

Enter the desired wall length to be used for the analysis. This length will be used to determine the shear per foot from lateral loads for design purposes, the wall weight, and will be carried through to the section for footing design.

Wall Height

The wall height entered will be used to determine overturning moments on the wall for uplift calculations and overall stability moments. All lateral loads are applied at this height above the top of footing. Also, this height is used to calculate the wall weight for vertical loads.

Wall Weight

Enter the actual weight of the wall here. This weight is not used to contribute lateral seismic loads, only vertical loadings for uplift, soil pressure, and overturning calculations.

Ht/Width

Ratio Wall height divided by wall length.

Sheathing Data

# Plywood Layers

Enter either 1" or 2" to indicate whether one or both sides of the wall will have plywood sheathing.

Plywood Grade

Select Structural I = 1" or Structural II = 2". These values should conform to the values allowed in the UBC.

Nail Size

Enter 6, 8, or 10" to indicate the penny size of the nails to be used.

Sheathing Thickness

This represents the nominal thickness of sheathing used on one or both sides. Enter this thickness in decimal form. These thicknesses should be only those which are available in UBC Table 23-I-K-1.

Stud Spacing

Enter the stud spacing which will be used as the sheathing attachment. The program checks whether stud spacing is 16" or less for some sheathing combinations to determine if higher values may be used. See the footnotes of Table 25-K for further information on which combinations are applicable.

End Post Dimension

This information will be used to determine the Simpson (or equivalent) connector to be called out for resisting uplift.

Seismic Factor For Wall Wt

Enter the seismic factor to be applied to the wall's weight for calculating that lateral force.

Nominal Sill Thickness

This program stores bolt values from UBC Table 23-I-K-1, and uses UBC code section 2311.2, paragraph 2, which states Allowable shear values used to connect a wood member to concrete or masonry are permitted to be determined as one-half the tabulated double shear values for a wood member twice the thickness of the member attached to the concrete or masonry.

Loads Tab

This program allows the user to apply lateral loads to the top of the wall, and have these lateral loads transformed to a per foot shear on the wall for design calculations. Both uniform and concentrated lateral loads are allowed, giving you the ability to model diaphragm and drag strut loadings.

Overburden Load over Footing

This is a uniform load resting over the wall footing. It is applied over the entire footing....even where there might be a wall area present.

Vertical Loading

The user can also apply vertical loads to the wall to account for vertical floor, roof, beam, or column loads. These loads are included in overturning and soil pressure calculations.

Point Load & X-left

The user can enter up to three concentrated loads applied to the wall. Enter the distance from the left side of the wall to where the loads is applied.

Uniform....& X-left, X-Right

The user can also enter up to two partial or full length uniform loads to the wall. X-Left indicates the distance from the left side of the wall to the beginning of the load. X-Right indicates the distance from the left end of wall to the end of the load.

Lateral Shear Applied To Wall

This input item represents the uniform shear force applied to the top of the wall. Uniform indicates the load is applied to the wall along its entire length (such as a load transferred to the wall from a horizontal diaphragm).

Strut Force Applied @Top Of Wall

The user can also apply a concentrated load at the top of the wall height. This strut force is provided to apply collector loads (drag struts) to the wall.

Moment Applied to Top of Wall

When you have a wall on the level above that must have its lateral forces and overturning moment transferred to the wall below (i.e. wall being designed), you can enter the moment here and it will be included in the calculations for uplift at the end of the wall and for footing calculations. Positive sign ( + ) applies the moment to the wall in a clockwise direction (increasing soil pressure at the right side of the wall). To apply the vertical components at the end of the wall on the story above, use the Point Load entry of the Vertical Loads section.

Footing Tab

Footing Dimensions

Past Left Edge of Wall

Enter the distance from the left edge of wall to the left end of the footing here. Modifying this value will alter soil pressure and overturning stability. A non-zero value will be the projection of the footing beyond the edge of the wall.

Wall Length

The Wall Length previously entered is automatically transferred to this cell, and used as the basis of determining footing calculations (considering left and right footing projecting lengths).

Past Right Edge of Wall

Enter the distance from the left edge of wall to the left end of the footing here. Modifying this value will alter soil pressure and overturning stability. A non-zero value will be the projection of the footing beyond the edge of the wall.

Footing Length

This is the summation of wall length and the distance the footing projects beyond ends of the wall.

Footing Width

Enter the footing width to be used is calculations of soil pressure and stability.

Footing Thickness

Enter the footing thickness to be used to calculate of soil pressure and stability.

Concrete Weight

Enter the concrete density to be used to calculate the added vertical load due to the footing weight. If you wish to omit the automatic inclusion of footing weight in soil pressure calculations, set this value to zero.

Rebar Cover

Enter the distance from the bottom of the footing to edge of the reinforcing.

f'c

Compressive strength of concrete.

Fy

Tension yield strength of reinforcing.

Min As %

Enter the absolute minimum reinforcing area ratio here. The actual required reinforcing area is calculates as follows:

• | The required steel percentage is calculated by first finding the required steel area due to bending moments: % Req'd = (1/m) * (1-[1-(2*m*Ru)/Fy)½ ]½ |

• | If this percentage is greater than 200/Fy then it is compared to your Min. As % value, and the maximum used. |

• | If it's less than 200/Fy, it is multiplied by 1.33 and again compared to 200/Fy. The minimum of those two values is then compared to your Min. AS % value and the larger used |

• | The actual area required is equal to the As% value calculated previously multiplied by the footing width and (Footing Thickness - Rebar Cover). |

Results & Graphics Tabs

This set of tabs provides the calculated values resulting from your input on the "Data Entry Tabs". Because a recalculation is performed with each data entry, the information on these tabs always reflects the accurate and current results, problem sketch, or stress/deflection diagram.

Results / Summary Tab

Wall Summary

This gives a complete summary of all values calculated for the shear wall.

Footing Summary

This gives a complete summary of all values calculated for the footing.

Soil Pressures

Using the lateral loads and vertical loads (including footing weight), the actual soil pressures are given. The program automatically checks cases where the resultant is outside the kern as well as inside.

Moments

Calculated moments in the footing taken at the face of the wall.

Shears

Calculated one-way shear stresses in the footing at a distance (footing thickness - rebar cover) from the end of the wall. Allowable shear equals 2.0 * f'c½

Overturning

Overturning Moment : Total overturning moment acting on the footing/wall system, taken about the bottom/outer edge of the footing (lateral weight of the footing is ignored).

Resisting Moment : Total overturning moment acting on the footing/wall system, taken about the bottom/outer edge of the footing (lateral weight of the footing is ignored).

Factor of Safety : Total Resisting Moment/Total Overturning moment. It is recommended that this value be greater than or equal to 1.5.

Results / Simpson Hold Down

Sketch Tab

This tab provides a sketch of the beam with loads and resulting values shown. Using the [Print Sketch] button will print the sketch in large scale on a single sheet of paper.

Printing Tab

This tab allows you to control which areas of the calculation to print. Checking a box will signal that the information described by the item will be printed. However, if there is no information in for a particular selection it will not be printed. So these checkboxes are best described as "If this particular area of the calculations contains data then print it".

Sample Printout Page 1

Sample Printout Page 2