DuraFuse Moment Frame Connection

The requirements for the analysis and design of the DuraFuse moment frame connection have been comprehensively implemented, with close coordination with the engineers at DuraFuse Frames. The connection is assigned using the Assign – Beams – Frame Beam Connection Types command. The influence of the connection on the joint and frame stiffness is automatically determined and applied in the analysis. The requirements of AISC 360-10 and AISC 360-16 have been implemented for the basic steel design checks, and the requirements of AISC 341-10 and AISC 341-16 have been implemented for the seismic design checks of the connection, columns, and beams. Pertinent panel zone shear check and strong column – weak beam requirements from AISC 358 are also implemented.

Frame Beam Connection Types

The Assign – Beams – Frame Beam Connection Types command is used to assign special connection types to Frame beam ends. These include Springs, Custom stiffnesses, Reduced Beam Sections (RBS), SidePlate, and DuraFuse. The dialog has been reorganized to list each separate type and its associated data on separate tabs. It has been enhanced such that it is more versatile in assigning these connections to one or both ends of the beam, and a Clear assignment command has been added, replacing the need to “assign” no connection type.

User-specified Demand/Capacity Limits

In the Steel Beam and Steel Column modules the user can now specify the limit on the Demand/Capacity ratio used in the design of steel beams and columns, using the Criteria – Demand/Capacity Limits command. Previously the program designed to a ratio limit of 1.0. This now allows the user to specify lower values, resulting in designs of members with an extra margin of capacity for future changes in loads, for example. Separate values can be specified for steel beams, steel joists, and C-Beams, with limits for both strength and deflection.

Framing Check

In the Steel Beam module, the Reports – Framing Check command creates a report that lists all of the beams that are supported by a shallower beam, listing the beam size, the supporting beam size, the location, and the reaction. This command has been enhanced; it now highlights all beams that have been included in that report so that they can easily be located. Use the View – Show Designs command to show the sizes, and then use View/Update or the Assign – Beam Size command to change beam sizes if desired. A Show Beams with Framing Check Warnings button has been added to the tool bar to invoke this command. Select this button to turn off the highlighting.

Connection Check

In the Steel Beam module, the Reports – Connection Check command creates a report that lists all of the beams that have reactions that exceed the capacity of the typical connection for that size, based on a table of capacities created by the user. The report lists the location of the beam end, the beam size, the reaction, and the capacity given in the table. This command has been enhanced; it now highlights all beams that have been included in that report so that they can easily be located. Use the View – Show Designs command to show the sizes, and then use View/Update or the Assign – Beam Size command to change beam sizes if desired. A Show Beams with Connection Check Warnings button has been added to the tool bar to invoke this command. Select this button to turn off the highlighting.

Selection with Intersect Line

In the Modeler several of the Beam commands have been enhanced to allow selection of beams using the Intersect Line command. With this command a line is drawn across one or more beams; the modeling action is then applied to all of the beams that that line crosses. For example, to delete an entire bay of beams invoke the Layout – Beams – Delete command, select Intersect Line, and draw a line across the beams to be deleted.

Story Data

In v16.01 the ability to generate story labels was implemented. This feature has been enhanced such that the story ‘remembers’ how its story data was created; if you select a story in Story Data dialog, the Use fields or Generate fields are automatically filled in based on how that story’s data was originally created. This makes it easier to make changes or to generate additional stories’ data.

Data Check Enhancement

If Story Data has been defined, the Data Check only performs a check on those layout types included in the Story Data. Previously if no Story Data had been defined, the Data Check would not perform any checks on any layout types. This has been modified; if there is no Story Data, the Data Check performs the checks on all layout types. This is convenient in the early stages of modeling because it allows you to perform Data Checks on the layouts even before they have been assigned to stories.

ACI 318 Moment Magnification

ACI 318 requires that the effects of both large and small P-delta be considered. To account for those, the Code allows the use of amplified 1^st-order moments. In Section 6.6.4.5.1 of ACI 318-14, the magnification factor, d, is given as an amplifier for the 1^st-order moments along the length of the member. Eq. (6.6.4.5.2) defines the calculation of d. That equation includes a Pc term, the critical buckling load, which is defined in Eq. (6.6.4.4.2). That equation includes the effective length factor, k. Section 6.6.4.4.3 indicates that “for nonsway members, k shall be permitted to be taken as 1.0, and for sway members, k shall be at least 1.0.” That is, for sway members k shall be calculated from the nomograph given for Sway frames in Fig. R6.2.5.1(b), for example, or by some similar means. In the Concrete Column module, the program used the k value determined from that nomograph when calculating the value of d used to amplify the moments in the design of sway frame columns. This was unnecessarily conservative. Based on communication with the ACI 318 committee (which has acknowledged that the current terminology is unclear) the program has been changed to always use k=1.0 in the equation for Pc in the calculation of the magnification factor, d, for sway frame columns. The rationale for using k=1.0 is that d is an amplifier of non-sway moments. So whether the frame is a sway frame or a nonsway frame, a value of k=1.0 can be used in the calculation of the amplifier on the non-sway moments.

The concrete column design report was enhanced to show both the value of k used in the calculation of the sway moment magnification factor, d_s, and the value of k (1.0) used in the calculation of the nonsway moment magnification factor, d.

In addition to ACI 318-14, this change was likewise made to the program in the implementation of ACI 318-08 and ACI 318-11 (the moment amplifier was not implemented in earlier versions).

Coupling Beams and Asymmetric Reinforcement

The ability to assign reveals and separate clear cover values on the primary and secondary faces of concrete walls was implemented in v17.00. This results in wall reinforcement that is asymmetrically placed. The asymmetric placement of reinforcement has now been implemented in shear wall coupling beams.

Stress Contours

Stress contours can be displayed for walls and diaphragms with the Process – Results – Stress and Force Contours command. Contours for in-plane stresses, out-of-plane shear, internal forces, plate moments, and plate transverse shear can be displayed.

Associated with this, two new reports are now available: Wall Internal Forces and Stresses Summary and Diaphragm Internal Forces and Stresses Summary. They are invoked using the Reports – Internal Forces and Stresses Summary menu item.

In order for the contour display and reports to be available, the options to Store stresses and internal forces for Walls and for Diaphragms must be selected in the Criteria – General command.

Response Spectra Scale Factors for Plus and Minus Eccentricity

In the Loads – Load Cases command for response spectra load cases, scale factors can be specified, typically used to scale the response spectra forces down to the code-level base shears. Previously, only one scale factor value could be specified in each orthogonal direction, even if there was a plus-eccentricity and a minus-eccentricity load case in each direction; that is, the same scale factor was applied to both the plus-eccentricity and a minus-eccentricity load cases. This has now been modified; now if there is both a plus-eccentricity and a minus-eccentricity load case, distinct scale factors can be specified for each load case. This enhancement has been made to the following response spectra load case dialogs: generic Response Spectra, ASCE 7-16, UBC 97, AS 1170.4, NBC of Canada, and IS 1893.

ASCE 7 Appendix D Wind Case Exemption

Figure 27.3-8 of ASCE 7-16 indicates the set of wind load cases that must be considered; it groups the load cases into four Cases. Two of those cases, Case 2 and Case 4, require that a torsional moment be applied. When all four Cases are expanded to account for each orthogonal direction, there are twelve load cases that must be analyzed. Appendix D of ASCE 7-16 lists conditions under which the structure is exempt from the torsional cases (Case 2 and Case 4). For example, buildings that are torsionally regular under wind load, and buildings controlled by seismic loads (with some restrictions), are exempt from the torsional cases. In the Loads – Load Cases command, the load case generator for ASCE 7-16 wind now includes an option, Exempted from Torsional Cases 2 and 4 per Appendix D. Before selecting this option the engineer should verify that it is applicable. When the option is selected, the number of wind load cases generated is reduced to four, rather than the twelve cases generated when that option is not selected.

Torsional Irregularity Report

The Drift report, available using the Process – Results – Drift – At Control Points command, has been enhanced to include a new section, TORSIONAL IRREGULARITY DATA. For the seismic and response spectra load cases in a given direction, the program determines the load case with the largest difference in drift between two Control Points, and the Load Case, Drift and Coordinate of the first Control Point, Drift and Coordinate of the second Control Point, the ratio of the larger of those two drift values divided by the smaller (Max/Min), and the ratio of the larger of those two drift values divided by the average of the two (Max/Ave) are listed for each level. This provides an easy way of identifying if a level is torsionally irregular. Values for Max/Min and Max/Ave are both listed because some Codes base their definition of torsional irregularity on one, some on the other. ASCE 7 defines a torsional irregularity to exist when the maximum drift is more than 1.2 time the average, and an extreme torsional irregularity to exist when the maximum drift is more than 1.4 times the average, so those designing to ASCE 7 should use the values listed in the last column of that report, Max/Ave, to determine if the structure is torsionally irregular. The National Building Code of Canada also uses Max/Ave, with a limit of 1.7. India IS 1893 uses the ratio of the maximum drift to the minimum drift (Max/Min), with a limit of 1.5.

Updated SidePlate Table

The table used in conjunction with the analysis and design of the SidePlate moment connection has been updated. The stiffness properties for the SidePlate MF (R=3) connection type have been increased based on recent full-scale testing and FEA modeling. This results in increased frame stiffness and reduced lateral drifts when compared to previous versions.

Revised SidePlate Biaxial Interaction Check

SidePlate has updated their procedures for checking the strength of HSS columns used in biaxial framing configurations. In the biaxial strength interaction equation used when checking HSS columns with the SidePlate connection for frame beams framing into both axes of the column, the value of Mpc has been modified to use ZxFyRy. Previously, Mpc used M*pc = Zx(Fy-Pu/Ag), which is the nominal flexural strength of the column used in the Strong Column – Weak Beam checks.

Frame Beam Connection Type Assignment

Previously, if a connection type was assigned to a beam in RAM Frame using the Assign – Beams – Frame Beam Connection Type command, and then that beam was subsequently changed to a Gravity beam, the connection assignment remained and was displayed in the graphics, and couldn’t be deleted without changing the beam back to a Frame beam. If the column was also changed to Gravity, the program would crash during analysis. The Data Check in the Modeler and the analysis in RAM Frame have been enhanced to automatically delete these assignments.

Archive Database

Previously in the Manager there was a File – Zip Model command. It provided a way of saving a model database as a .zip file; it also included the ability to select which RAM Frame and RAM Concrete results files to include in the .zip file. This was of limited use because the results files quickly become outdated when new versions of the program are released; if the file is subsequently opened in a newer version of the program, the program ignores those results. This command has been replaced with a File – Save as Archive command. When invoked, the Save as Archive dialog will appear, with File name listed as the current database name plus the version number (e.g., “_v17_01”) plus the date (e.g., “_03-27-20”). The user can modify this file name any way they want before saving. The file extension will be .rss (which means it can be opened by the program without the need to change the extension name). The archived database will only include the model files, it will not include any of the analysis or design results files. This results in a minimally sized model file, suitable for archiving.

Reset Model Status

In very rare cases it may be desirable to reset the model’s analysis and design status to force the program to reanalyze. A File – Reset Status command has been implemented. When invoked, a notification will be given that this change will “require that the model be totally reframed and redesigned”. The model status will be changed, and the analysis and design results will be discarded. The Status lights next to each of the design modules on the Manager screen will then display as red. This command will rarely, if ever, be necessary, but may be useful if the analysis and design results appear to be out of sync with the model.

Data Extractor

The Data Extractor is invoked using the Post-Processing – Extract Data command; it provides a powerful means of extracting model, design, and analysis results data. It has been enhanced:

• Additional data has been added, and can now be extracted:
  • Gravity Loads on beams, columns, and walls
  • Deck data
  • Joint data (which beams frame into which columns)
  • Story Drift (user must define the drift points in RAM Frame)
  • RAM Frame General Criteria
  • Timestamp of export, model name and units written out to RAM Manager Criteria
• When the RAM Structural System is installed it now creates a Templates folder, under the Reports folder (typically at C:\ProgramData\Bentley\Engineering\RAM Structural System\Reports\Templates). Templates are saved in this folder; templates can easily be shared by copying them to the Templates folder.
• Three sample templates are now included and installed in the Templates folder:
  • CriteriaOnly: This template contains the selections from several of the analysis and design criteria dialogs.
  • GeometryOnly: This template contains the model geometry data.
  • FrameAnalysisResults: This template contains the frame model geometry and the analysis results from RAM Frame.

These templates are included as simple examples of what can be done with templates. They can be customized to suit your needs (save them to a different name), or new templates created.

C-Beam dt and Do Increment

A minor adjustment was made to the design of Castellated and Cellular C-Beams. The user specifies the increment to be used when the program is determining the best value of dt for castellated beams and Do for cellular beams. However, the starting value of dt and Do initially used in the iterative process is set based on certain parameters, and if that starting value of dt or Do is not an even multiple of the increment value specified by the user, the final dt or Do value was not an even multiple of the specified increment value. This change will have a minor impact on the final design, if any.

Concrete Beam Elevation DXF

Reinforcement splices are shown in the DXF output of the Concrete Beam Elevations. However, previously the splice was merely symbolic, to indicate a splice; it was not drawn to scale. This created some confusion. The splice is now drawn to scale, to its proper splice length.