SE Exam cheat sheet

Gravity combinations (ASCE 7 §2.3): LRFD 1.2D + 1.6L + 0.5(Lr or S or R); ASD D + L; roof-dominant case 1.2D + 1.6(Lr or S or R) + (L or 0.5W).

Live load reduction (ASCE 7 §4.7.2): L = L0(0.25 + 15/√(KLL·AT)), AT in ft²; KLL = 4 for columns, 2 for beams and one-way slabs; floor 0.50 L0 minimum for one floor, 0.40 L0 for two or more.

Reduction is not permitted where L0 exceeds 100 psf (except for members supporting two or more floors) or for passenger-vehicle garage live loads.

Snow: pf = 0.7 Ce Ct Is Pg; Cs reduces load on sloped roofs; balanced plus unbalanced/drift surcharge cases must both be checked.

Composite beam horizontal shear: V' = min(AsFy, 0.85f'cAc); number of shear studs = V'/Qn with φ = 0.90.

Beam flexure: Zx,required = Mu/(φFy) with φ = 0.90; compare unbraced length Lb to Lp (full plastic) and Lr (onset of elastic lateral-torsional buckling).

Compression members: KL/r preferably ≤ 200; Fe = π²E/(KL/r)²; Fcr = 0.658^(Fy/Fe)·Fy when KL/r ≤ 4.71√(E/Fy), otherwise Fcr = 0.877Fe.

Deflection limits (IBC Table 1604.3): floor live load L/360, roof live load L/240, roof total load L/180; stucco or plaster ceilings L/360 under total load.

Load path: slab → beams → girders → columns → footing; ASCE 7 requires a continuous path with connections capable of resisting the calculated forces.

Seismic base shear V = CsW with Cs = SDS/(R/Ie); Cs need not exceed SD1/(T·R/Ie) for T ≤ TL, and shall not be less than 0.044 SDS Ie (and not less than 0.01).

Equivalent lateral force vertical distribution: Fx = CvxV, Cvx = wx hx^k / Σ wi hi^k; k = 1.0 for T ≤ 0.5 s, k = 2.0 for T ≥ 2.5 s, linearly interpolated between.

Period: Ta = Ct hn^x from ASCE 7 Table 12.8-2 (Ct = 0.028, x = 0.8 steel moment frames; 0.016, 0.9 concrete moment frames; 0.020, 0.75 other systems); the computed period is capped at CuTa.

Story drift: δx = Cd δxe / Ie; allowable Δa = 0.020 hsx for Risk Categories I and II, 0.015 for III, 0.010 for IV.

P-delta: θ = PxΔIe/(Vx hsx Cd); θ ≤ 0.10 allows second-order effects to be ignored; θ must not exceed 0.5/(βCd) and never 0.25.

Torsion: include accidental eccentricity equal to 5 percent of the dimension perpendicular to the applied force; amplify by Ax = (δmax/δavg)², bounded 1.0 to 3.0, when 1.2 < δmax/δavg ≤ 1.4.

Wind: qz = 0.00256 Kz Kzt Kd Ke V² (psf, V in mph); p = qGCp − qGCpi; GCpi = ±0.18 enclosed, ±0.55 open or partially enclosed; Kd = 0.85 for buildings; G = 0.85 for rigid structures.

Diaphragm design force: Fpx = (ΣFi/Σwi)·wpx, bounded by 0.2 SDS Ie wpx ≤ Fpx ≤ 0.4 SDS Ie wpx.

Overstrength combinations (ASCE 7 §12.4.3): (1.2 + 0.2SDS)D + Ω0E + L + 0.2S and (0.9 − 0.2SDS)D + Ω0E; redundancy factor ρ = 1.3 by default, 1.0 only where §12.3.4.2 conditions are satisfied.