Load Combinations

During solution the model is loaded with a combination of factored Load Categories and/or Basic Load Cases, both of which are defined on the Basic Load Cases Spreadsheet. These combinations, load factors, and other parameters are defined on the Load Combinations Spreadsheet. Most standard load combinations are included in the program. See Solution to learn how to solve load combinations.

Click on image to enlarge it

Add Load Combinations Manually

To add Load Combinations manually:

From the ‘Home’ ribbon, click on the Load Combinations icon.
Enter load combinations by pairing loads in the BLC fields with factors in the Factor fields.

Add Auto-Generated Building Code Combinations

To add auto-generated building code combinations:

From the ‘Home’ ribbon click on the Load Combinations icon.
Click on the button at the top of the spreadsheet.
On the ‘Gravity’ tab, choose the Load Combination Region and Load Combination Code from the drop down lists.
Choose the desired Notional Load options.
Choose the desired Roof Live Load options.
Click the Generate button.
Click on the Wind tab and choose the desired Wind Load options.
Click the Generate button.
Click on the Seismic tab and choose the desired Seismic Load options.
Click the Generate button.
Modify the generated combinations and options in the spreadsheet as necessary.

Note:

The generated building code combinations are made up of Load Categories and Factors. Loads that are not assigned to these categories will not be included in the combinations upon solution.
All generated combinations are added and marked for the envelope solution. You can remove combinations from the envelope after adding them.
You can specify P-Delta options and SRSS combinations for each combination after you have added them.
Verify the Wind/Seismic ASIF (allowable stress increase factor), and the Timber CD settings on the Design tab for combinations after you add them.
You can save any preferred load combinations as the default by clicking the Save As Defaults button on the Window Toolbar.

Solve Load Combinations

Click on image to enlarge it

Solve Single Load Combinations

To solve a single load combination:

On the ‘Home’ ribbon, click the Solve icon.
Choose the Single Load Combination from the drop down list.
Click the Solve button.

Solve Multiple Load Combinations

To solve multiple load combinations:

On the ‘Load Combinations’ spreadsheet, check the Solve checkbox for each combination to be solved.
On the ‘Home’ ribbon, click the Solve icon.
Choose the Envelope or Batch option.
Click the Solve button.

Note:

The Envelope solution is where all combinations with a checkmark in the Solve field are solved simultaneously. The Maximum and Minimum results of these solutions are listed, along with the number of the controlling load combination for each solution result.
The Batch solution is where all combinations with a checkmark in the Solve field are solved simultaneously. All results of these solutions are listed.

Load Combinations Spreadsheet

The Load Combinations Spreadsheet records the combinations of loads for solution. It can be accessed by choosing Load Combination on the from the ‘Explorer’ panel under ‘Data Entry’.

Click on image to enlarge it

Combinations Tab

The first column, Description, is strictly for your reference. Enter any descriptive label you wish and it will be displayed with the results when the combination is solved.

The next three columns are for options that apply to each load combination.

The P-Delta entry is used to enable an analysis of member secondary effects. See P-Delta Analysis for more information.

The Solve checkbox is used to indicate which combinations should be included in batch or envelope solutions. See Solution for more information.

Note: Per Section C1 of Chapter C (Design for Stability) of the AISC 15th Edition steel code, a factor of 1.6 will be applied to all load combinations for which a P-Delta analysis is to be performed (and for which the Hot Rolled box is checked on the Design tab) whenever 'AISC 15th: ASD' is selected on the Codes tab of the Model Settings Dialog. This factor is applied prior to conducting the P-Delta analysis and the results are subsequently divided by a factor of 1.6.

The SRSS entry is used to combine response spectra results by the Square Root of Sum of Squares. See SRSS Combination of RSA Results for more information.

The next eight pairs of columns (BLC, Factor) are for defining what loads are to be part of the combination, along with factors for each. Select load categories from the drop down lists in the Category columns of the spreadsheet. The following are the entries you can use in the BLC field:

Entry	Description
Number	Entering a number includes that particular Basic Load Case, I.e. enter “3" for BLC 3
Category	Enter a category code such as DL, LL, etc to include all loads in that category
Lnn	Enter “Lnn” to nest the loads from another combination, where “nn” is the number of the other combination, i.e. “L3" means include all loads from load combination 3.
Mnn	Use this entry to include a moving load where “Mnn” is the moving load tag from the moving load spreadsheet
Sn	Includes response spectra results for the global direction “n”, I.e. enter “SX” to include response spectra results calculated in the global X direction, “SY” for global Y , etc.
Tn	Use this entry to include a time history load where “Tn” is the time history load tag from the Time History Loads spreadsheet

There are also a number of BLC Prefixes that can be included in your load combinations. You can have these generated by the LC Generator or you can click on the triple dot button in the BLC cell to select them manually. Rho, SDS, and Omega (Ω) are defined in the Seismic tab of the Model Settings, and SF is accessed from the RSA Scaling Factor button within the Load Combination spreadsheet. They are explained below:

Prefix	Description
SF	Scaling Factor - applied to RSA results
ρ (Rho)	Redundancy factor - applied to EL loads for seismic load combinations (or RSA results) Note: If ELX and ELZ used, the ρ from the X and Z direction will be used directionally. If EL is used, the ρ from the X direction will be used and the Z direction will be disregarded. If ELY is used, the ρ from the Z direction will be used and the X direction will be disregarded.
SDS	Spectral Response Acceleration Parameter for Short Periods - applied to DL for seismic load combinations
Ω (Om)	Overstrength Factor - applied to EL loads for seismic load combinations (or RSA results) Note: If ELX and ELZ are used, the Ω from the X and Z direction will be used directionally. If EL is used, the Ω from the X direction will be used and the Z direction will be disregarded. If ELY is used, the Ω from the Z direction will be used and the X direction will be disregarded.
CL	Capacity-Limited Forces - applied to EL loads for seismic load combinations for vertical braced frame seismic design (e.g. SCBF, BRBF as VBrace). The program will conduct capacity-limited design for beams and columns using braces' capacity-limited forces in lieu of the applied seismic loads.

In the Factor column, enter a multiplier to be applied to the loads being included.

You can also use the button in the BLC cell to help you specify the loads. Choose from load categories, basic load cases,or spectral results or moving loads from the drop-down lists.

Click on image to enlarge it

Notice the Seismic Options and RSA Options that are described in the Prefix table above. For additional advice on this topic, please see the RISA Tips & Tricks website: www.risa.com/post/support. Type in Search keywords: Seismic Factors.

Design Tab

Click on image to enlarge it

The first field, the Description, is strictly for the user's reference. Enter any descriptive label you wish and it will be displayed with the results when the combination is solved.

The ASIF column is used to set the allowable stress increase factor used for both the AISC: ASD code checking and ACI 530 ASD (masonry allowable stress design). See Allowable Stress Increase regarding its usage for Hot Rolled Steel.

The CD factor is the load duration factor and is only necessary for NDS timber design using ASD (see Load Duration Factor). Note: this is KD for Canadian (CSA O86) wood design.

The lambda factor is the time effect factor and is only necessary for NDS timber design using LRFD (see Time Effect Factor).

The Service check box is used in the following applications:

Cracked Concrete Section Properties: Per the provisions of ACI 318-14 Section 6.6.3.2.2 (ACI 318-11 Section R10.10.4.1) the cracked section properties of beams, columns and walls can be multiplied by a factor of 1.43 for service level loads (<= 1.0*Ig). All concrete members and walls apply this factor when the Service box is checked. Note that this 1.43 factor does not apply to masonry walls. Masonry wall stiffness is NOT dependent on this check box.
Story Drift: The story drift results are broken up by each lateral direction into Service and Strength load combinations. These tabs can be seen in the Story Drift results spreadsheet.
Member Deflections: The first two tabs of the Member Deflections spreadsheet provide deflection and deflection ratio results for Service and Strength load combinations.

The next seven check boxes designate which load combinations should be used for the code checking of each material type. The example shown uses one set of Load Combinations for the NDS wood design, and another for the ACI concrete design. Member results (Forces, Stresses, Torsion) will only be reported for a members if it’s material type has been checked for that load combination. Member results for general material will be shown for all load combinations. For example when using steel and wood in your model, you can design your steel for one set of load combinations and your wood for another.

The last check box for Connection defines:

If this LC should be used in designing hot-rolled steel connections with RISAConnection.

Load Combinations with RSA Results

The results from response spectra analyses in the X, Y, and Z direction can also be included in the load combinations. Remember, when you perform a response spectra analysis (RSA), you specify in which global direction the spectrum is applied. RISA-3D will retain the three RSA solutions (one for each direction) simultaneously.

Click on image to enlarge it

To include the RSA results for a particular direction in a load combination, enter "Sn" in the BLC field, where n is the global direction. Suppose you wanted to include X direction RSA results, you would enter SX in the BLC field. You would enter SY for Y direction and SZ for Z direction RSA results. Also be sure to put the RSA Scaling Factor for the RSA results in the Factor field. You can have more than one RSA entry in a load combination.

Note:

Remember that RSA results are typically unsigned (all positive) and you should provide some means of accounting for this. The figure above uses two combinations for each RSA result, one with a positive factor and the other with a negative factor to capture the maximum deflections, stresses and forces. See Unsigned (All Positive) Results for more information.
If you have to combine 2 or 3 different spectra results with many static load combinations, it is convenient to put all the spectra results (SX, SY, and SZ) and factors in one load combination and nest that combination in other combinations. You must set the RSA SRSS flag on each load combination for it to be performed.

SRSS Combination of RSA Results

This is used to cause orthogonal RSA results in the combination to be summed together using an SRSS (Square Root of Sum of Squares) summation. This gives a good approximation of MAXIMUM responses but it also causes all the RSA results to be positive.

You can choose from the options by clicking on the button. The entry is “+” or “-” to indicate whether the combined RSA results are to be added (+) or subtracted (-) from the other loads in the combination.

Note:

This flag is used to combine different spectra that are acting in different directions. This is different than the modal combination method that combines results for one direction and is specified in the Response Spectra settings.
This method was only approved for use in the 1997 UBC and is no longer noted as an appropriate method in the current codes.

Load Combinations with Capacity-Limited (CL) Design

The capacity-limited design forces for braced frames (e.g. SCBF, BRBF as VBrace) can also be included in the load combinations. For capacity-limited design, the expected strengths of braces will be used in lieu of the applied earthquake loads for columns and beams design in vertical braced frames. The columns and beams will be designed to resist the expected strength of the braces to ensure braces yield first to dissipate energy during an earthquake event (e.g. Tne + Pne for BRBF, Tne + Pne or Tne + 0.3Pne for SCBF).

Click on image to enlarge it

To include the capacity-limited (CL) design considerations for a particular direction in a load combination, enter "ELn-CL" in the BLC field, where n is the global direction. Suppose you wanted to consider brace capacity-limited forces for braced frames in the X direction, you would enter ELX-CL in the BLC field.

Note:

Proper seismic design rules (e.g. SCBF, BRBF) are needed for frame members so the program can include capacity-limited (CL) design considerations. No CL considerations will be done for members with incorrect seismic design rules. The SCBF or BRBF braces must be assigned as vertical brace (VBrace) in order to run the CL Load Combinations.
If both standard lateral loads and capacity-limited (CL) forces are specified in the same load combination, the non-CL lateral loads will be ignored. This is based on our understanding of the code requirement for CL design that the applied lateral loads in CL design shall be replaced by the brace CL forces. The program will not consider both standard lateral loads and CL forces during analysis for the same load combination.
The capacity-limited (CL) design procedure applies to only column and beam design in braced frames. When an CL LC is solved, the program replaces braces with brace capacity-limited forces in frames that are eligible for CL design (e.g. frames specified with proper seismic design rules). Since the braces are removed during the CL design process, hidden boundary conditions are added in the lateral directions at beam ends in the braced frames to avoid frame instability. The lock of beam ends in lateral directions will not be an issue for CL design because this design process only applies to columns and beams. The brace CL forces will be transferred to adjacent columns and beams properly for their CL design. However, there are limitations due to the added hidden boundary conditions. Currently no beam axial load redistribution is considered among braced beams in the same frame line due to the added boundary conditions. Also no unbalanced beam axial load is considered for frames with braces connected to beam ends directly (e.g. diagonal braced frames). The unbalanced beam axial load is considered for V and Inverted-V braces. The display of the hidden boundary conditions can be turned on by going to the File -> Application Settings -> Output, and selecting the checkbox "Display seismic capacity-limited boundary conditions".
Users can display capacity-limited (CL) forces after solutions. The program requires solutions to determine and display the CL forces of braces. If users display the forces under CL load combinations before solutions, the CL forces will be displayed as the associated standard seismic forces. For example, ELX-CL will be displayed as ELX loads before solution. After solution it will be displayed as the brace expected strength forces for braced frames in the X direction.

Click on image to enlarge it

Limitations

The analysis consideration per AISC 341-2016 F2.3c of progressive yielding and buckling of the braces for multi-tiered braced frames is not included in the current implementation of capacity-limited (CL) design.
The exceptions under AISC 341-2010 F2.3 are not fully considered in program. This is due to the program not having enough information to determine if these exceptions apply. Users need to use their judgment to check if these exceptions apply to their structure. The only exception the program partially considers is the AISC 341-2010 F2.3 Exception 2a. Per this exception the program will perform SCBF column design using the lesser of the forces determined from load combinations using the amplified seismic loads or the CL loads. However, the program cannot automatically remove compression braces in the model. The users need to modify the models accordingly if they need to consider this exception.
Unbalanced forces for beams are only considered for V and Inverted-V braced frames. This is due to the added hidden lateral boundary conditions for frame instability during capacity-limited (CL)design. No unbalanced beam axial load can be considered for frames with braces connected to beam ends directly (e.g. diagonal braced frames) because the unbalanced axial loads will go into the boundary conditions directly. Also, for the same reason the program currently does not consider any redistribution of beam unbalanced axial loads among beams in the same frame line.

Load Combinations with Moving Loads

Moving loads are included in your analysis by referencing them on the Load Combinations spreadsheet. For example, to reference moving load number “n” you would enter “Mn” in one of the BLC fields, and then also enter the corresponding BLC factor. The moving load numbers are shown for each moving load on the Moving Loads spreadsheet.

Click on image to enlarge it

Nesting Load Combinations

You are allowed only 10 BLC's per load combination, which may not be enough. For this reason you can define "combinations of load combinations". This means if you need more than 8 BLC entries in a single combination, you can define the needed BLC's and self-weights over several load combinations and then pull these combinations together into another load combination.

Click on image to enlarge it

Entering "Lnn" in the BLC field means include all the BLC entries (with their factors) from Load Combination "nn". For example, say Load Combination 4 has "L1" entered for one of its BLC's. This specifies to include all the BLC's (with their factors) entered in Load Combination 1 as part of Load Combination 4 (this includes self-weight and RSA entries as well). The flags for Load Combination 1 (i.e. Solve, PDelta, and SRSS entries) apply only to Load Combination 1 and will not be used when Load Combination 4 is solved.

Also, the factor we enter with the "Lnn" entry will be applied to the BLC factors entered for LC nn. Thus, if we enter "L1" with a factor of "0.9", we're including 90% of the BLC entries of Load Combination 1.

Note: These “combinations of load combinations” can only be nested to one level; i.e. the load combs referenced with the Lnn entries may not themselves have Lnn entries.

ASIF Factors for Wind / Seismic Load Combinations

Entering a value/factor in the field labeled ASIF (Allowable Stress Increase Factor) indicates that the load combination should be treated as a wind/seismic load combination.

Click on image to enlarge it

If AISC 9th Edition ASD code checking is selected, the allowable stress increase factor entered in this field is applied to this load combination.

If LRFD code checking is selected, then any value of ASIF greater than 1.0 will indicate that the seismic provisions for the WF compactness checks are to be used (Table 8-1, p. 6-317 of the 2nd ed. LRFD).

P-Delta Load Combinations

The P Delta field is used to perform a P-Delta calculation for that load combination. You can choose from the options by clicking on the button. A blank field indicates no P-Delta analysis, Y indicates that a P-Delta analysis is to be performed for the combination.

Click on image to enlarge it

You can also perform a compression only P-Delta analysis. Invoke this option by putting a C in the P Delta field. See P-Delta Analysis for more information.

Note:

P-Delta analysis is normally required for LRFD based code checks. If this is not desired, you can change the setting by selecting Application Settings on the Tools menu and clicking the Solution and Results tab.
P-Delta analysis is not performed on plates.

If P-Delta was not included in the load combination spreadsheet (PDelta column is blank) but is required by code, the following message will display upon solution.

This warning means that the solution was run but the members requiring P-Delta will not provide any design results. In order to bypass this warning to see results without P-Delta, you can turn off the "Enforce code required P-Delta analysis" option in the Application Settings. An example of when this would be a recommended work flow is when investigating model instabilities. Once you are ready to view full design results for your model, it is recommended to turn this requirement back on.

Click on image to enlarge it

Timber Design Load Duration Factor

For Wood design, the load duration factor (CD) is entered in the CD field on the row that the particular CD factor applies to. Different load combinations would have different CD factors. For example, per the NDS code, a load combination that had only dead load, would have a CD factor of "0.9", while another combination that was comprised of dead load plus wind load would have a CD factor of "1.6".

The CD factor will only be applied to wood code checks on wood members. "Wood" members are those members whose material properties are defined on the Wood tab of the Material Properties Spreadsheet.

Note:

See Table 2.3.2 in the NDS 2018 code for the CD factors to be applied for typical loads. Note that the CD factor used for a load combination should be for the load with the shortest load duration in that load combination.
When the Canadian CSA O86 Wood design code is selected, these entries will all change to "KD". See Table 5.3.2.2 of the CSA O86-14 code for direction on what factors to enter.

Generate Building Code Combinations

Major portions of the load combinations that are specified by building codes are included and can be applied to the model for solution. These combinations can be inserted by selecting the button from thetop of the Load Combinations spreadsheet. This opens the ‘Load Combination Generator’ window, shown in the following image.

The LC Region refers to the various regions supported by the program (U.S., Canada, India, British, et cetera).

The LC Code refers to the actual code used to build the load combinations. For the United States, there are a number of different codes that could be used to build load combinations. If the only option is Sample, that means that no load combinations have been input for that region. See Customizing the Load Combination Generator for more information on how to add or edit combinations for that region.

Gravity Options

The first tab in the Load Combination Generator window is Gravity. This tab contains Roof Live Load and Notional Load Options.

The LC Region refers to the various regions supported by the program (U.S., Canada, India, British, et cetera).

These settings, changed on any of the three tabs, automatically update on the remaining tabs. Thereby making it easy to simply move through the tabs, selecting the options you require, without having to re-select the region and code data on each.

Click on image to enlarge it

Beam Deflection Options

The Generate Deflection LCs will automatically place 3 load combinations first that match DL, LL and DL + LL.

Click on image to enlarge it

This will match the Typical design rule from the default Member Design Rules - Deflection tab inputs.

Click on image to enlarge it

Notional Load Options

The Notional Load Options allow the user to specify how complex the load combinations including notional loads should be.

When None is selected, the program will not generate any Load Combinations that include the NL load category.

The 2D Only option is used to indicate that only the most basic notional load category (NL) will be used.

The X and Z option is used to indicate that the program should generate separate notional load combinations for each horizontal direction (NLX and NLZ).

When the Reversible box is checked, the program will generate every notional load combination twice. Once with a positive load factor, once with a negative load factor.

For additional advice on this topic, please see the RISA Tips & Tricks website: www.risa.com/post/support. Type in Search keywords: Notional Loads.

Roof Live Load Options

The Roof Live Load Options lets you specify how complex the load combinations including roof live loads should be.

Check the checkbox next to RLL (Roof Live Load), SL (Snow Load), and/or RL (Rain Load) to indicate that the selected load categories are to be included in the generated load combinations.

Wind Options

The second tab of the Load Combination Generator is the Wind tab. This tab contains Wind Load Options.

Click on image to enlarge it

Wind Load Options

The Wind Load Options specify how detailed the generated wind load combinations should be.

When None is selected as the wind load option, the program will not generate any Load Combinations that include wind load categories.

The 2D Only option generates only the most basic wind load category (WL).

The X and Z option generates separate wind load combinations for each horizontal direction (WLX and WLZ when Y is set at the vertical axis).

The X and Z w/ Ecc option generates all possible wind load combinations that include partial / eccentric wind loading (WLX, WLXP1, WLXP2, et cetera) per Case 2 from Figure 27.3-8 in the ASCE 7-16.

The X and Z w/ Ecc, Quart option generates all possible wind load combinations per Cases 2, 3 and 4 from Figure 27.3-8 in the ASCE 7-16. For additional advice on this topic, please see the RISA Tips & Tricks website: www.risa.com/post/support. Type in Search keyword: Quartering.

The Reversible option generates two combinations for each wind load, one with positive load factors and one with negative load factors.

The Generate Semi-Rigid Diaphragm Loads option generates wind loads for BLC's using windward and leeward direction loads prescribed by the ASCE 7-16 (WLX+Z, WLX-Z, WLZ+X, WLZ-X).

Seismic Options

The third tab of the Load Combination Generator is the Seismic tab. This tab contains Seismic Load Options.

Click on image to enlarge it

Seismic Load Options

The SeismicLoad Options specify how complex the generated seismic load combinations should be.

When None is selected as the seismic load option, the program will not generate any Load Combinations that include the EL load category.

The 2D Only option is used to indicate that only the most basic seismic load category (EL) will be used.

The X and Z option is used to indicate that the program should generate separate seismic load combinations for each horizontal direction (ELX and ELZ).

The X and Z w/ Eccentric option is used to indicate that the program should generate all possible seismic load combinations that include eccentricities (ELX, ELX+Z, ELX-Z, et cetera).

The X and Z RSA option will use the spectral seismic loads (SX, SY, SZ) instead of the regular earthquake loading (ELX, ELY, ELZ).

If you have selected the X and Z, X and Z w/ Eccentric, or X and Z RSA option, you will also have the ability to include non-orthogonal seismic loads. Simply check the Include Non Ortho (100% + 30%) checkbox to include these loads per the Orthogonal Combination Procedure of section 12.5.3.1(a) of the ASCE 7-16.

When the Reversible box is checked, the program will generate every seismic load combination twice. Once with a positive load factor, once with a negative load factor.

Check the Include ρ checkbox if you want to include the redundancy factor in your seismic load combinations. This factor is set in the Seismic tab of Model Settings.

Check the Include Ev (vertical) checkbox if you want to include the vertical seismic load effect in your seismic load combinations. This value is calculated per equation 12.14-6 of the ASCE 7-16 using the S_DS value set on the Seismic tab of Model Settings.

The Capacity-Limited (CL) LC Options for Braced Frames will generate capacity-limited design forces based on brace expected strength. The generator will use the overstrength load combinations per LC code selected, and replace the overstrength seismic forces with CL forces. The Include Non Ortho (100%+100%) checkbox is provided as an additional option for Capacity-Limited Braced Frames in order to meet the requirements for columns that are common to intersecting frames per AISC 341-16 D1.4a.

Check the Add Notional Loads to Seismic Load Combinations checkbox if you want to include notional loads applied as lateral seismic loads per the ASCE 7 and AISC codes.

The Save as Defaults button can be used to establish the current load combination generator settings as the defaults for future use. Clicking the Generate button will generate load combinations in the Load Combinations Spreadsheet based on the selected options.

Load Combination Generator - General Notes

The following loads are not generally included in the standard combinations but can be added by editing the combinations in the spreadsheet or by modifying the source document itself. For more information, see Customizing the Load Combination Generator below:

Category Code	Description
SX, SY, SZ	Response Spectra Results
TL	Long Term Load
HL	Hydrostatic Load
FL	Fluid Pressure Load
PL	Ponding Load Category
EPL	Earth Pressure Load
OL#	Other Load Categories

Note:

The standard combinations are made up of Load Categories and Factors. Loads that are not assigned to these categories will not be included in the combinations upon solution.
Some load categories do not occur in all of the design codes. Loads placed in categories that are not part of the standard combinations will not be included in the solution of these combinations.
All combinations added from the drop down list are added to the envelope solution. You can remove combinations from the envelope after adding them.
Verify the Wind/Seismic ASIF settings for combinations after you add them.
After you add the combinations, verify the settings for the wood design Load Duration factor, CD/KD.
You can specify P-Delta options and SRSS combinations for each combination after you have added them.
See Editing Spreadsheets - Inserting, Deleting and Clearing Cells for quick ways to edit or add combinations.
When a new installation is performed the program will back-up any existing XML files that contain load combination data rather than overwriting them. The back up copies will be given the extension BAK.

Customize the Load Combination Generator

The Load Combinations for each region are contained in an XML file which can be opened and edited using a standard spreadsheet program. An example of on of these XML files is shown below:

Click on image to enlarge it

The name of the file itself becomes the name of the Load Combination Region that appears in the Load Combination Generator. Each XML file has a series of "worksheets" and the name of each worksheet will be the name of the Load Combination Code that appears in the Load Combination Generator. You can add, edit or modify these documents to completely customize the available load combinations.

Note: When the program is updated for new versions, the existing XML files will be "backed up" and saved with a '.bak' extension while the new XML files in the update will replace them. If any customizations were made to the XML files, they can be retrieved from the back ups.

The first row of each sheet is reserved for the column headers. The recognized column headers are as follows: Label, Solve, pDelta, SRSS, ASIF, CD, ABIF, Service, Hot Rolled, Cold Formed, Wood, Concrete, Masonry, Footings, Aluminum, and Stainless,. In addition, there will be multiple pairs of BLC & Factor headers.

Other than Label and the BLC / Factor pairs, you can omit columns. If a column is omitted, the default values will be used for those entries. The order of the column labels is optional except for pairs of BLC and Factor. For the program to correspond the Factor with correct BLC, the user should always provide BLC label PRIOR to the corresponding Factor. You can insert blank columns or columns with other labels than described above. In those cases, the program omits those undefined columns.

Note:

As shown in the above example, the wind and seismic loads should be entered as WL and EL in order for them to be "expanded" using the Wind Load Options and Seismic Load Options.
The program will read these files from the directory specified from clicking the 3D Button Application Settings File Locations.
SX, SY, and SZ are not valid BLC that can be used within the Load Combination Generator spreadsheet. A response spectra analysis must be done first within RISA-3D.