Structural System - Load-bearing Cold-Formed Steel (CFS) stud-wall building
Lateral Force Resisting System - Flat-strap X-braced shear walls (diagonal tension-only straps)
Number of stories - 6
Story heights - First story 11 ft 6 in (registration, lobby, breakfast areas); typical upper stories (2-6) 9 ft 8 in; total height ~59 ft 10 in
Analysis procedure - ELF; SDC C (SDS = 0.48 g, SD1 = 0.20 g, Site Class D, Risk Category II, Ie = 1.0)
Design standards - AISI S100, AISI S240, AISI S400, ASCE 7
Project - Mid-rise hotel

## Material Properties
- CFS structural members: **ASTM A1003 / A653**, **Fy = 50 ksi**
- Flat straps: **Fy = 50 ksi** (ASTM A1008 / A1011), expected-strength factor Ry = 1.1
- Floor system: proprietary composite steel deck with 3 in. deep concrete topping on open-web CFS floor trusses
- Screws: **ASTM C1513** self-drilling, self-tapping

## Gravity Loads
| Load Type | Magnitude |
|------------|-----------|
| Floor Dead Load | 55 psf (3 in. concrete topping on composite deck + open-web CFS trusses) |
| Roof Dead Load | 20 psf |
| Cladding Load | 15 psf (perimeter facade) |
| Floor Live Load | 40 psf (hotel guest rooms) + 15 psf partition allowance; reducible per Sec. 4.7 |
| Roof Live Load | 20 psf (Lr; reducible per Sec. 4.8) |

### Additional Notes
- Wind loads - V = 115 mph (Risk Cat II), Exposure C
- Studs are continuously braced by sheathing about the weak axis / torsion; strong-axis unbraced length = clear story height.

## Member Design Requirements
- Stud thickness steps down with height; lower-story studs not lighter than stories above.
- Lower-level exterior studs are blocked / back-to-back built-up sections (agent to determine fastener schedule per AISI S240).
- Track sizing to match stud depth/thickness (agent to determine).

## Building Plan Geometry
- Building length / width: 204 ft (E-W) x 68 ft (N-S), double-loaded central corridor
- X-bracing bay locations: 8 X-braced bays x 12 ft-0 in per exterior long wall per story PLUS 8 x 12 ft-0 in per corridor wall per story (corridor 6 ft wide, centered); N-S: 3 X-braced bays x 10 ft-0 in per end wall PLUS five interior party-wall braced lines at 34 ft o.c. (5 bays x 12 ft-0 in per line) -- all stacked over height. Floor trusses span ~13.6 ft between party bearing walls (12-in-deep trusses cannot span the 31-ft unit depth)
- Consider these section-size groups (agent to determine the actual CFS sections; designations and thicknesses are the design output):

Story	Exterior Bearing-Wall Studs	Floor Trusses	Flat Straps (X-brace)	Stud Spacing (per source)
1	A (back-to-back)	C	D	12 in. o.c.
2	A (back-to-back)	C	D	12 in. o.c.
3	A (back-to-back)	C	D	12 in. o.c.
4	B	C	D	16 in. o.c.
5	B	C	D	16 in. o.c.
6	B	C	D	16 in. o.c.

(Story groups 1-3 (lower) and 4-6 (upper) are taken from the source. Open-web CFS floor trusses are ~12 in. deep at 24 in. o.c., constant over height; strap sizes step down in two groups, stories 1-3 and 4-6.)

- Drift target - 0.020 h_sx (ASCE 7 Table 12.12-1, all other structures; 6 stories)

## Lateral Strap-Bracing Design (CFS)
- Flat steel straps configured in an "X" pattern on designated bracing bays, designed as a tension-only system.
- Strap width and thickness: agent to determine (capacity per AISI S100 tension yield, T_n = Fy*Ag).
- Boundary studs (chords/posts) at bracing-bay ends sized for gravity plus the vertical component of the expected strap force.

## Connections
- Strap bracing: flat straps welded or screwed to **10-gauge (137 mil) gusset plates**, connected to boundary studs with No. 12-16 self-drilling screws (ASTM C1513); connection sized for the expected strap force Ry*Fy*Ag (screw shear, tilting/bearing, net-section rupture per AISI S100 Chapter J).
