Example
A 2×10 Douglas Fir-Larch #2 beam spans 10 ft + 10 ft (two spans, pinned interior support). Uniform dead 15 plf, live 60 plf. Check capacity per NDS 2024. CD = 1.0 for D+L. L/360 deflection.
How StructSuite solves this
Use StructSuite's free beam design calculator: select Floor Joist, Design per NDS. Enter spans [10, 10], supports (pinned-pinned-pinned). Add uniform load segments, assign D and L. StructSuite runs beam analysis, applies NDS 2024 Eq 3.3-1, 3.4-2, size factor CF, deflection check. Two-span reduces midspan moment vs simple span.
Steps
- Step 1: Select member type
Design consideration: Two-span continuous reduces midspan moment vs simple span (M = wL²/8 vs wL²/24 at interior for equal spans). Negative moment at interior support often governs. Beam/girder carrying joists—single member, no Cr.
In StructSuite: In the "Select member type" section at the top, click the Floor Joist card.
- Step 2: Select design method
Design consideration: NDS for multi-span, point loads, or when IBC tables don't apply. Equal spans: interior support gets 1.25× simple-span moment. Unequal spans: longer span drives design. CD from load type.
In StructSuite: In the "Select design method" section, click the "Design per 2024 NDS (National Design Specification for Wood Construction)" card.
- Step 1: Geometry & Configuration
Design consideration: Two 10 ft spans: interior support critical for negative moment. Longer interior span increases negative moment. Pinned interior = no moment restraint; fixed would reduce moment but uncommon for wood. Adding third span changes distribution.
In StructSuite: Open the Geometry section. In the beam schematic, enter span lengths: 10, 10. For each support, use the support type dropdown to select: Pinned, Roller, Pinned. NDS 2024 Eq 3.3-1, 3.4-2 for flexure and shear.
- Step 2: Load Definition (ASCE 7-22 / NDS 2024)
Design consideration: 75 plf total (15+60) on 10 ft: M_positive ≈ 470 ft-lb; M_negative ≈ 940 ft-lb at interior. Negative moment at support often 2× positive—design for it. Tributary from joists: 16 in. o.c. → 1.33 ft; 10 ft beam → ~7–8 joists.
In StructSuite: Open the Loads section. Add load items with these exact values: D 15 plf; L 60 plf. For each uniform load: set Type (D, L, Lr, S), enter the plf value in Uniform (plf). For point loads: set category Point, enter magnitude (lb) and position (ft). Include self-weight. NDS 2024 Table 2.3.2 sets CD.
- Step 3: Material & Section
Design consideration: CF for 2×10 from NDS Table 4A. No Cr (single beam). Wet service if exposed. Deflection L/360; check both midspan and support. Larger depth improves negative-moment capacity; may need 2×12 for 14+ ft spans.
In StructSuite: Open the Materials section. In Product category select the type; in Species select Douglas Fir-Larch; in Grade select No. 2; in Size select 2×10. Open Design Parameters: set Wet service (CM) to No; set Repetitive member to No; select Deflection limit. NDS 2024 §4.3.
Live design (pre-filled)
The form below is the real StructSuite module with example data loaded. Display only—values cannot be changed.
Select member type
Select design method
Floor Joist — Design per 2024 NDS
National Design Specification for Wood Construction