Design

The Design tab checks the model's own members with the forces of the combinations you choose, analysed with the second-order method you choose. Nothing is checked against a fixed section or a demo load.

Steel design (AISC 360, LRFD) #

Design setup #

Design ▸ Design setup has four pages. Everything is saved with the model and undoable.

Method: LRFD (ϕRn against the §2.3 combinations) or ASD (Rn/Ω, AISC 360-16 §B3.2, against the §2.4 combinations), the second-order method and its options, the model-wide K and the utilization colour bands:

Method	What the design job does
First order	Linear analysis of every design combination; the B1 member amplifier (App. 8 §8.2.1) on members in compression when on. Sway effects are not included.
P-Δ	Geometric-stiffness P-Δ analysis of every design combination (ASD combinations at 1.6× and scaled back).
Direct analysis method	AISC 360-22 Ch. C: 0.8 EI and EA, τb (per member or with additional notional load), notional loads Ni = 0.002 Yi (automatic: gravity-only combinations), P-Δ; K = 1 (Lc = L) for every member.
B1-B2	Approximate second-order analysis (App. 8): B2 per story with RM (0.85 moment frames, 1.0 braced).

Combinations: the design combinations (default: every LRFD combination). Only these are analysed and enveloped for design.
Member parameters: per member the role (beam, column, brace, or automatic from the slope), K, Lb (unbraced length for lateral-torsional buckling; blank = member length), Cb (AISC 360 F1; blank = 1.0, conservative), Lcx and Lcy (effective lengths for flexural buckling about the strong and weak axes; blank = K·L). Set values for the whole selection at once, or per row.
Design groups: named sets of members with shared role and lengths. A member's own values override its group; the group overrides the model-wide values.

Run and results #

Design ▸ Run steel design runs the job, colours the members by utilization and opens the Design table in the bottom panel:

one row per member: section, role, length, ratio, status, governing check, clause and combination;
sort by any column, filter by text, status (over capacity, not certified, OK) and role, download CSV;
a click selects the member and shows its detail: the parameters used (K, Lb, Cb, Lc) and every check with demand, capacity, ratio, clause, combination and the engine's step-by-step detail.

The checks: D2 tension, E3 / E4 compression (E7 slender elements), F2 / F3 / F5 strong-axis flexure with Lb and Cb, F6 weak-axis flexure, G2 shear and the H1-1a / H1-1b interaction. Hover a clause for what it checks.

Not certified #

When the engine cannot compute a capacity conservatively for a section (for example a slender element whose dimensions are unknown, or Pr ≥ Pe1 so no B1 can be formed), the check is not certified. A not-certified member is shown with its own status and is never counted as passing: check it by hand or use a section the engine can check.

Optimize #

Design ▸ Optimize members finds the lightest catalogue W-shape whose every check is certified and at most the target ratio (default 0.95), for the selected members, a design group or all members, with the same combinations and second-order method. Review the table (current → proposed, ratio), untick any change, then Accept: all changes are one undo step. The member forces come from the current analysis: run the analysis and design again after accepting, because the stiffness changed.

Size a beam #

Design ▸ Size a beam lists every W-shape that passes F2, G2 and an L/360 live-load deflection check for Mu, Vu, span, Lb, Cb, Fy and optional depth and weight limits; Demands from member takes Mu, Vu and L from the analysis envelope of the selected member. Assign puts the section on the member (undoable).

Composite beam (AISC 360 Ch. I) #

Span, W-shape, Fy, beam spacing, deck rib height and orientation, concrete above the deck, f'c, unit weight, stud diameter, studs per side (blank = full composite), factored load and service live load. Results: ϕMn vs Mu, stud count and composite ratio, effective width, lower-bound inertia, live-load deflection and floor frequency, with the engine's worked summary.

Concrete (ACI 318-19) #

Beam: b, d, As, stirrups Av at s, f'c, fy, λ; Mu and Vu. Checks §22.3 flexure (ϕ from εt, §21.2), §9.6.1 minimum steel, maximum steel (εt ≥ 0.005), §22.5 shear.
Column: Ag, Ast, f'c, fy, Pu; for slenderness Ig, r, k, Lu, βdns, M1, M2 and transverse loading. Checks §22.4 axial strength and the §6.6.4 moment magnification.
Shear wall: lw, thickness, hw, ρl, ρt, f'c, fy, λ, ϕ; Pu, Mu, Vu. Checks §11.5.4 in-plane shear, §11.6 minimum reinforcement, §11.5.3 axial force and flexure.

Wood (NDS) #

Beam: b, d, Fb, Emin, Le, adjustment factors CD, CM, Ct, CF (blank = size factor from d), Ci, Cr, Cfu; M. Checks §3.3 bending with CL (fully braced when Le = 0).
Column: b, d, Fc, E, Emin, Le, KcE, c, factors; P. Checks §3.7 compression with CP.

Enter ASD-level demands for wood and masonry.

Masonry (TMS 402-16) #

Wall strip: thickness and width (computes Ag, Sg, r, In), effective height, f'm, Em, eccentricity, P, M. Checks §8.2 axial and flexural stresses, the unity check Eq. 8-11 and the ¼Pe buckling limit Eq. 8-16.

Seismic design (AISC 341-22) #

Design ▸ Seismic (AISC 341):

Special moment frame (§E3): beam and column W-shapes, Fy, Fu, Ry, clear span, Puc, gravity shear, column shear, connection type (RBS with a, b, c; WUF-W; others with sh), joint layout, doubler plate. Checks strong column / weak beam (Eq. E3-1), panel-zone shear and thickness, continuity plates.
Special concentrically braced frame (§F2): brace shape, material (Ry from Table A3.2), Lc, element and b/t, Pu, Tu, the tension-brace share of the lateral force. Checks slenderness, width-to-thickness (λhd), strength and the force distribution, and gives the capacity-limited brace forces for the connections.
Eccentrically braced frame link (§F3): link W-shape, Fy, e, Vu, Pr, Mp, link rotation. Checks the link class, shear strength, length limit and rotation.

System R, Cd, Ω0 gives the ASCE 7-22 Table 12.2-1 factors and the Table 12.12-1 drift limit for the system, risk category, structure type, ρ and SDC.

Story drift and wind drift #

Design ▸ Story drift (ASCE 7-22 §12.12, §12.8.7, Table 12.3-2): choose the solved case or combination with the seismic loads, the direction, Cd, Ie, ρ and the risk category, then Fill from the analysis: the stories come from Model ▸ Grid lines & stories (or the node elevations), δx and δxe from the analysis, V and P from the loads above each story (editable). The check gives Δ = Cd·δxe/Ie against Δa, θ against θmax, and the vertical irregularities.

Design ▸ Wind drift: a service-level wind result, the total (H/400) and story (h/600) limits.

Direct analysis method helper #

Design ▸ DAM helper computes the notional loads Ni for a list of story gravity loads, τb for Pr and Py, and the Δ2nd / Δ1st ratio. The direct analysis method itself is a second-order method in Design setup.