SCBF Brace-to-Brace Connection

References

Seismic Design Manual

Details

An alternative design for Example 5.3.8 at Joint JT/1 of Figure 5-11 in the reference is presented here in this example. Example 5.3.8 used separate gusset plates for each brace, while this example uses continuous “chevron type” gusset plates for the top and bottom braces as shown in Figure 5-29 in the reference. This is a common arrangement for this situation, and the example provides and admissible internal force distribution that differs from the distribution used for the four separate gusset plates. All braces are ASTM A500 Grade B round HSS and the beam is an ASTM A992 W27x114. For the connection, ASTM A36 plate material and 70-ksi electrodes are used.

Refer to the figure in the reference for additional details.

Results

Table 1. Comparison with AISC Seismic Design Example 5.3.9
Parameter RAM Connection Reference Difference
Brace Interface Forces H1 (kips)1 -159.8 -160 < 1%
V1 (kips)1 -159.8 -160 < 1%
H2 (kips)1 217.1 217 < 1%
V2 (kips)1 217.1 217 < 1%
H1 (kips)2 388.9 389 < 1%
V1 (kips)2 388.9 389 < 1%
H2 (kips)2 -314 -314 none
V2 (kips)2 -314 -314 none
Upper Gusset Nu (kips) 57.28 57 < 1%
Vu (kips) -376.9 -377 < 1%
Mu (kip·ft) -5,145 -5,160 < 1%
Gusset capacity (kips) 869.4 869 < 1%
Lower Gusset Nu (kips) 74.95 75 < 1%
Vu (kips) 702.9 703 < 1%
Mu (kip·in) 9,594 9,630 < 1%
Gusset capacity (kips) 1,377 1,380 < 1%

Input

The following data is input into the New Joint dialog:

Joint Data tab:
  • Joint = CVR
  • Actual members / Upper gusset = yes
  • Actual members / Lower gusset = yes
  • Beam/Section = W 27x114
  • Beam/Material = ASTM A992 Gr50
  • Upper right brace / Section = HSS_SQR 6x6x5_16
  • Upper right brace / Material = A500 GrB Rectangular
  • Upper left brace / Section = HSS_SQR 6x6x5_16
  • Upper left brace / Material = A500 GrB Rectangular
  • Lower right brace / Section = HSS_RND 6.875x0.500
  • Lower right brace / Material = A500 GrB Rounded
  • Lower left brace / Section = HSS_RND 6.875x0.500
  • Lower left brace / Material = A500 GrB Rounded
The following data can be added after the Seismic Parameters option is set in the Connection Design Configuration dialog:
  • Braced frame system = SCBF
Loads tab:
  • Braces / Upper right brace = 307 kips
  • Braces / Upper left brace = -226 kips
  • Braces / Lower left brace = 550 kips
  • Braces / Lower right brace = -444 kips

Select the Gusset Connections/CVR connection type.

The following data is input into the Connection Pad:

General Information group:
  • Design criteria / Dimensions calculation = Manual
Members group:
  • Upper right brace / Additional geometric data / Minimum distance to other members, Le = 8 in.
  • Upper right brace / Additional geometric data / Left distance, Le1 = 1 in.
  • Upper right brace / Additional geometric data / Right distance, Le2 = 1 in.
  • Upper right brace / Additional geometric data / Length on beam, LH = 23 in.
  • Upper left brace / Additional geometric data / Minimum distance to other members, Le = 8 in.
  • Upper left brace / Additional geometric data / Left distance, Le1 = 1 in.
  • Upper left brace / Additional geometric data / Right distance, Le2 = 1 in.
  • Upper left brace / Additional geometric data / Length on beam, LH = 23 in.
  • Lower right brace / Additional geometric data / Minimum distance to other members, Le = 10 in.
  • Lower right brace / Additional geometric data / Left distance, Le1 = 1 in.
  • Lower right brace / Additional geometric data / Right distance, Le2 = 1 in.
  • Lower right brace / Additional geometric data / Length on beam, LH = 25.5 in.
  • Lower left brace / Additional geometric data / Minimum distance to other members, Le = 10 in.
  • Lower left brace / Additional geometric data / Left distance, Le1 = 1 in.
  • Lower left brace / Additional geometric data / Right distance, Le2 = 1 in.
  • Lower left brace / Additional geometric data / Length on beam, LH = 25.5 in.
Interfaces group:
  • Upper gusset / General / Thickness, tp = 0.875 in.
  • Upper gusset / General / Material = A36
  • Upper gusset / Directly welded / Weld size to beam (1/16s in), D = 5
  • Upper right brace / Gusset-to-Brace connection / Length on toe, Lt = 15 in.
  • Upper right brace / Gusset-to-Brace connection / Length on heal, Lh = 15 in.
  • Upper right brace / Gusset-to-Brace connection / Weld size (1/16s in), D = 4
  • Upper left brace / Gusset-to-Brace connection / Length on toe, Lt = 15 in.
  • Upper left brace / Gusset-to-Brace connection / Length on heal, Lh = 15 in.
  • Upper left brace / Gusset-to-Brace connection / Weld size (1/16s in), D = 4
  • Lower gusset / General / Thickness, tp = 1.25 in.
  • Lower gusset / General / Material = A36
  • Lower gusset / Directly welded / Weld size to beam (1/16s in), D = 8
  • Lower right brace / Gusset-to-Brace connection / Length on toe, Lt = 25 in.
  • Lower right brace / Gusset-to-Brace connection / Length on heal, Lh = 25 in.
  • Lower right brace / Gusset-to-Brace connection / Weld size (1/16s in), D = 4
  • Lower left brace / Gusset-to-Brace connection / Length on toe, Lt = 25 in.
  • Lower left brace / Gusset-to-Brace connection / Length on heal, Lh = 25 in.
  • Lower left brace / Gusset-to-Brace connection / Weld size (1/16s in), D = 4