(Global) Model Settings

The Model Settings may be accessed through the menu or toolbar buttons highlighted below.

The Model Settings are settings specific to the model which is currently open. The information stored here is retained with the model, and will be retained even if the model is opened on a different computer.

You may save any of the settings in the Model Settings as the default setting, such that new models you create will begin with the settings that you saved as Defaults. To do this, simply enter the information that you want to save and click the Save as Defaults button.

Description

The entries under the Description tab are used to enter descriptive information such as a title for the particular model being defined, the name of the designer and a job number. The title may then be printed at the top of each sheet of the output, and on the graphic printouts of the model. Note that for any of these tabs, you can click on Save as Defaults and then your settings will be saved the next time you open the program.

The Checked By field is intended for the model reviewer to initial upon completion of a model review. Their initials will then be printed on each sheet of the output.

The Notes field is intended for information about the model that may be useful for the engineer or reviewer to refer to.

Solution

The entries under the Solution tab are used to control settings that affect the general solution of the model.

Members

Number of Sections controls how many places you receive reported member force, stress, torsion, and deflection results. This only affects the amount of data displayed in the results spreadsheets, and has no effect on the solution of the model or the code checks. See Printing and Member Results for more information.

Number of Internal Sections controls how many places along each member the software calculates and stores results such as deflections and code checks. The member force diagrams displayed in the model view and the detail plot are also drawn from these results. Increasing this value means that the program will make more "cuts" along the beam's length, which means it is more likely to hit the theoretical maximum and minimum values for code checks.

Note:

• Number of Sections cannot exceed 20. Also, Number of Internal Sections cannot be less than twice the Number of Sections. If unacceptable values are entered for either of these fields the program will automatically reset them to acceptable values.

Check the Shear Deformation box if shear deformation considerations are to be included in the model solution. See Member Shear Deformations for more information.

Wall Panels

The Mesh Size is the base mesh size that is used when wall panels solved. If there is a constraint smaller than this mesh size, the mesh will be refined to accommodate this constraint. You can see the mesh size graphically on the wall panels when you solve your model.

Note: The mesh size is also used for plate sub-mesh for RISAFloor Concrete floor Semi-Rigid diaphragms.

Include P-Delta for Walls is used to enable P-Delta analysis for wall panels. Even if this box is checked the P-Delta analysis will only be performed on load combinations which have P-Delta enabled.

The Increase Nailing Capacity for Wind option will automatically increase the shear capacity of wood wall and diaphragm panels by 1.4 for all load combinations that contain wind loads. Load combinations that have both wind and seismic loads acting simultaneously will not receive this increase.

Wall Optimization

The Wall Design option defines whether you want to automatically iterate the solution for masonry and wood walls.

The Iterations option defines how many automatic iterations will occur.

Note:

• This automatic iteration procedure will only happen for Batch or Envelope solutions. This is because we do not want to update your wall panel thicknesses if you are only solving a DL combination. In that case the program would then downsize your panel unnecessarily.
• For more information on masonry wall optimization see the Masonry Wall - Design topic.
• For more information on wood wall optimization see the Wood Wall - Design topic.
• Concrete wall design will be done automatically and the selections here will not affect this design. This is because concrete wall reinforcement changes will have very little effect on the stiffness of the walls.
• The program will stop the iteration procedure if the results from the previous solution match the results from the current solution.

Advanced

The P-Delta Tolerance is used to adjust the tolerance used to determine convergence of the P-Delta analysis. Be sure to enter this value as a percentage! The default for this is ½ of 1 percent (.5%). See P-Delta Analysis to learn more about this.

The Convergence Tolerance is used to set how close a subsequent solution must be to the previous solution for a mode to be considered converged. See Dynamic Analysis for more information.

The Gravity Acceleration is used to convert loads into masses for the purpose of a dynamic analysis.

The Merge Tolerance is used as the maximum distance 2 joints can be apart and still be merged together. It is also used when scanning for crossing members and for unattached joints along the spans of members.

The Dynamics Solver options allow you to choose between the Standard Solver, the Accelerated Solver and a Ritz Vector solution. Refer to the Solution topic for a more details.

• The accelerated solver uses an accelerated sub-space iteration with a Lanzcos starting vector.  The accelerated solver is the default and should produce solution in a fraction of the time that the standard solver would take to produce them.
• The Standard Solver uses a simple sub-space iteration to solve for the natural frequencies.  This solver has been used for years and the accuracy of the results is very well established. It has been included only for comparative / verification purposes.
• The Ritz Vector solution does not solve for true mode shapes and natural frequencies. However, it is generally the best choice when running a response spectra analysis. The use of Load Dependent Ritz vectors provides a more accurate response spectra analysis for the same number of modes.

Codes

The settings under the Codes tab control which design code is used for code checks for each material type.

The HR Steel entry indicates which code is to be used for the design of hot rolled steel. For more information see Hot Rolled Steel Design.

Note:

• If the AISC 360 code is selected (either ASD or LRFD), the Adjust Stiffness menu will appear. The options in this menu control the stiffness reduction provisions listed in the code. See Hot Rolled Steel - Design for more information on how the reduction is calculated and applied.
• If the EN 1993-1-1:2005 (Eurocode) is selected, the National Annex menu will appear. If you select "None" the design will be performed per the generic Eurocode specifications. If you select a National Annex from the list then the provisions relating to that specific National Annex will also be considered in the design. Where the National Annex and the generic Eurocode differ, the National Annex provisions are used. See the Hot Rolled Steel - Design topic for more information on the differences in design.

The CF Steel entry indicates which steel code is to be used for the design of cold formed steel. For more information see Cold Formed Steel Design.

The Wood entry indicates which wood code is to be used for the design of wood, including wood walls and structural composite lumber. For more information see Wood Design.

Note:

• The temperature menu is used to calculate the temperature factor (C_t) for the NDS code design. This factor is used in the design of wood members for all editions of the AF&PA code.  See NDS-2012, Section 2.3.3 for more information.
• This selection is ignored for the CSA O86 code design. Rather than applying a separate temperature factor, the CSA O86 code suggests that the designer apply the wet properties reduction factor when the member is subject to prolonged exposure to temperatures higher than 50°C (122°F). See Chapter 11 (Reference Information) of the Wood Design Manual (2010) for more information.

The Concrete entry indicates which concrete code is to be used in the design of concrete members and walls. For more information see Concrete Design.

Note:

• ACI 318-08 and ACI 318-11 behave identically in the program, as there were no relevant changes between these two editions of the code.

The Masonry entry indicates which masonry code is to be used for the design of masonry walls. For more information see Masonry Design.

Note:

• If the UBC 1997 ASD code is chosen, there is an option for whether the construction of the wall is subject to special inspection. This affects some values in design under that code.

Concrete

The entries under the Concrete tab contain options related to the analysis and design of concrete members.

The Shear Tie Options allow you to control the Number of Shear Regions that will be used when detailing a beam or column span. It also allows you to specify the increment that you'd like the program to use when increasing or reducing the spacing of the shear ties.

The Concrete Stress Options allow you to choose what type of stress block to consider in your analysis. The options are the constant Rectangular Stress Block and the Parabolic Stress Block. See Parabolic vs. Rectangular Stress Blocks for more information.

Check the Used Cracked Sections box if you want to modify the member and wall stiffnesses by the Icr Factor as described in both the Concrete - Design and Wall Panels topics.

Check the Bad Framing or Unused Force Warnings check box to see force warnings on the detail report or bad framing warnings in the Warning Log.

Checking the Minimum 1 Bar Dia Spacing box will allow a minimum spacing of one bar diameter between parallel bars. Otherwise, RISA will default to a two bar diameter or one inch clear spacing, whichever is greater, to allow for lap splices and continue to maintain adequate spacing between parallel bars.

The Concrete Rebar Set allows you to choose from the standard ASTM A615 (imperial), ASTM A615M ("hard" metric, i.e. #8M is an 8mm bar), prENV 10080 (Euro), CSA G30.18 (Canadian), and AS/NZS 4671:2001 (Australian/New Zealand) reinforcement standards.

The Include Welded Wire Reinf. (ASTMA1064) in Slab Design allows you to design a slab using Welded Wire Reinforcement.

Note:

• Users shall choose the correct material in the Materials Spreadsheet to account for ASTM A1064 steel.

• Welded wire reinforcement is only available for

• Only ASTM A1064 deformed bar sizes are available.

The Minimum % Steel for Columns allows you to choose the minimum percentage of reinforcement steel to be used in a concrete column section. The percentage entered will be multiplied by the gross area of the column section to determine the minimum amount of reinforcement required in each column. It should be noted that the minimum percentage allowed by ACI 318-14 Section 10.6.1.1 (ACI 318-11 Section 10.9.1) is 1%.

The Maximum % Steel for Columns allows you to choose the maximum percentage of reinforcement steel to be used in a concrete column section. The percentage entered will be multiplied by the gross area of the column section to determine the maximum amount of reinforcement allowed in each column. It should be noted that the maximum percentage allowed by ACI 318-14 Section 10.6.1.1 (ACI 318-11 Section 10.9.1)1 is 8%.

The Elevated Slab Design Option is only visible when you have elevated slabs. This option offers a choice between two methods, namely the Construction method and the Theoretical method, for the design of the slab rebar. The Construction method, which is the default method employed by the program for a significant period, determines the design of the slab based on an integer number of rebar. This method operates under the assumption that if the strip width divided by rebar spacing is not an integer, an additional rebar will be provided to guarantee the presence of a rebar at each end of the design strip. On the other hand, the Theoretical method is a new method added later that enables the program to calculate the rebar area based on the average value, where the rebar area equals As (single rebar) multiplied by the Strip Width divided by Spacing. However, it is crucial to note that this method may not always result in an integer number of rebar so unlike the Construction method, the results for Theoretical method will have no info of rebar amount.

Note:

Concrete cover for beams and columns is specified under Design Rules under the Concrete Rebar tab.Concrete cover for beams and columns is specified under Design Rules under the Concrete Rebar tab.