Structural System - Steel Special Concentrically Braced Frame (SCBF)
Frame type - Perimeter SCBF (braced bays on all four faces; see Braced-Frame Layout)
Number of stories - 6
Story heights - All stories 12 ft; mean roof height 72 ft (6 @ 12 ft)
Analysis procedure - Equivalent Lateral Force (ELF); SDC D (derived from SDS/SD1, Risk Category II)
Design standards - AISC 360, AISC 341, ASCE 7-22
Source - FEMA P-2192-V1, 2020 NEHRP Provisions Design Examples (Example Six-Story Building, Figure 7-7)

## Material Properties
- Structural steel (W-shapes): **ASTM A992**, **Fy = 50 ksi**
- Braces (HSS): **ASTM A500 Grade C**, **Fy = 50 ksi**
- Gusset plates: **ASTM A572 Grade 50**

## Seismic Design Parameters
- Risk Category II, Importance Factor Ie = 1.0
- SDS = 1.2 g, SD1 = 0.70 g (ASCE 7-22 Section 11.4.4)
- Seismic Design Category: D (derived - SDS >= 0.50 g and SD1 >= 0.20 g for Risk Category II)
- Steel SCBF: R = 6, Overstrength Omega0 = 2; Cd = 5 (Cd per ASCE 7-22 Table 12.2-1 for SCBF; not stated in brief)
- All seismic forces are at strength level.

## Gravity / Seismic Weights
| Load Type | Magnitude |
|------------|-----------|
| Floor Dead Load (floor + ceiling) | 80 psf (includes 10 psf interior partitions) |
| Roof Dead Load (roof + ceiling) | 40 psf |
| Cladding Load (exterior wall) | 20 psf |
| Floor Live Load | 50 psf (office; partitions already included in the dead load, not added to LL); reducible per ASCE 7-22 Sec. 4.7 |
| Roof Live Load | 20 psf (Lr; reducible per Sec. 4.8) |

### Diaphragms
- Floors (2nd-6th): concrete-filled steel deck (treat as rigid diaphragm).
- Roof: bare steel deck (treat as flexible / semi-rigid diaphragm).

## Building Plan Geometry (from Figure 7-7)
- Plan: 5 bays @ 30 ft = 150 ft (length, X-direction) by 4 bays @ 30 ft = 120 ft (width, Y-direction).
- Regular orthogonal column grid at 30 ft each way: 6 column lines (X) x 5 column lines (Y) = 30 columns.
- Mean roof height 72 ft (6 stories @ 12 ft).

### Braced-Frame Layout (text rendering of Figure 7-7 plan + Elevation A-A)
- Steel SCBF located on all four perimeter frame lines; interior framing is gravity-only.
- Braced bays are placed symmetrically about each wall's centerline:
  - Long walls (150 ft, 5 bays - North and South): two braced bays flanking the center bay.
  - Short walls (120 ft, 4 bays - East and West): the two central bays.
  - Corner bays are NOT braced.
- Vertical configuration (Elevation A-A): two-story-X bracing, stacked over the six stories (three two-story X modules up the height).

## Member Sizing (agent to determine; section designations are the design output)

Story	Brace	Braced-Frame Beam	Braced-Frame Column
1	A	D	G
2	A	D	G
3	B	E	H
4	B	E	H
5	C	F	I
6	C	F	I

(Grouped by the two-story-X brace modules: stories 1-2, 3-4, 5-6. 

- Consider one size for all gravity beams and one size for all gravity columns outside the braced frames (agent to determine).
- Column splices at two-story intervals. Column unbraced length = clear story height.
- Base fixity - pinned column bases (typical for SCBF).
- Beam-to-column connections outside the brace work points - pinned / simple-shear (SCBF gravity framing).
- Drift target - allowable story drift 0.020 h_sx (ASCE 7-22 Table 12.12-1, Risk Category II).

## Brace Connections (SCBF, per AISC 341)
- Brace-to-frame gusset plates (ASTM A572 Gr. 50) with a "2t" linear fold-line clearance (t = gusset thickness) to permit out-of-plane brace buckling.
- Gusset-to-beam and gusset-to-column welds designed by the Uniform Force Method (UFM).
- Brace and frame member width-to-thickness ratios: highly ductile limits per AISC 341 Table D1.1.
