1.4 CoreBrace in RAM Frame_c2s

7/28/2019 1.4 CoreBrace in RAM Frame_c2s

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CoreBraceTM Buckling Restrained Braces in

RAM Structural SystemCoreBrace buckling restrained brace shapes are now available in the RAM Structural

System. This feature allows the engineer to conveniently assign CoreBrace shapes tobuckling restrained braces in the RAM model.

To model, analyze and design buckling restrained braces using CoreBrace shapes, do the

following:

Select the CoreBrace Master Steel TableA Master Steel table, COREBRACEAISC.TAB, is now available containing the CoreBrace

brace shapes. This table is a duplicate of the RAMAISC.TAB table that contains all of theAISC shapes for beams, columns and braces, with the addition of the CoreBrace shapes. To

select this Master Steel table select the CriteriaMaster Steel Table command and selectCOREBRACEAISC from the list of tables. Note that this table can be edited and updated if

necessary as explained in the RAM Manager manual.

Create the model, including bracesCreate the model in the Modeler. Typically

Fy for the braces is specified a value in therange of 38 to 46 ksi. CoreBrace can assist

the engineer in determining the appropriatevalue to use.


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Assign sizes to the braces

Brace sizes can be assigned either with the Layout BracesAssign Size command inElevation View in the Modeler or with the AssignBracesSize command in RAM Frame.

The CoreBrace shapes are listed under the Flat Bar shapes. Select the desired size from the

list and assign it to the braces in the model.

In the 3D View CoreBraces are drawn as square braces, scaled to the size of the casing.

Specify the braces as Buckling Restrained BracesIn RAM Frame use the AssignBracesBuckling Restrained command to specify the

braces to be BRBs; at that time an Axial Stiffness Multiplier, as determined by the engineer,is assigned to each brace.


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In the analysis performed by RAM Frame the braces lengths are based on centerlinedimensions; the purpose of the Axial Stiffness Multiplier is to take into account the increased

stiffness resulting from the true joint dimensions and the size of the connection. Byincreasing the brace stiffness with this Multiplier, a more realistic analysis is obtained.

CoreBrace can assist the engineer in determining the appropriate values to use.

Analyze the modelIn RAM Frame, analyze the model using the ProcessAnalyze command.

Perform a Code Check

In the RAM FrameSteel Standard Provisions mode, select the desired steel design code(e.g., AISC 360-05 ASD or LRFD), generate the corresponding load combinations (either

automatically or manually) and then perform a code check using the ProcessMemberCode Checkcommand. A code-check is performed per the Standard provisions of the

specified Code for the load combinations that have been generated.

With the View/Update command the user can select any brace of interest, view the resultsincluding the interaction equation, and can select and investigate other CoreBrace sizes.


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If the currently assigned size is not acceptable, different sizes can be investigated, and whenthe desired CoreBrace size is determined, it can be saved back to the brace using the Update

Database command. In this way the engineer can quickly arrive at the optimum sizes. Ofcourse, if the Axial Stiffness Multiplier is different for the new brace size, the user would

have to reassign that value.

The design results can be viewed:

Note that since it is a Buckling Restrained Brace, the axial capacity is based on the tensile

capacity of the section, regardless of whether the brace is in tension or compression.

In addition to the standard provisions of the steel specification, there are additional seismicrequirements per AISC 341, but those provisions are not currently checked by the program

for Buckling Restrained Braces.Bentley Systems, Inc. 9/22/09

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1.4 CoreBrace in RAM Frame_c2s