Phase IV · Research Methodology · Week 7
Structural Engineering Methodology
Work a structural or bridge project from system definition through loads, analysis, member design and validation.
Preliminary work only. Calculations, models and estimates produced here are student coursework for proposal development. They are not sealed engineering documents and do not replace professional engineering judgment.
Structural Engineering Methodology
Work a structural or bridge project from system definition through loads, analysis, member design and validation.
Learn
Learning objectives
- Define the structural system and load path
- Develop load cases and combinations
- Plan member, connection and serviceability checks
Engineering guidance
Load path first, member sizes second. A member size without a load path is a guess.
FE Civil connection
Structural Analysis
Handbook §7 — Analysis of statically indeterminate structures (placeholder)
- Which load combination controls uplift on a hangar frame?
- How is tributary area used to size a girder?
- What controls lateral-torsional buckling?
Technical methodology planner
Plan Chapter 3 against the exact equations, standards, data sources and design checks you will execute in Capstone II.
Write
Structural methodology workflow
0/26 completeCode and standard reference panel
| Combination | Typical governing case |
|---|---|
| 1.4D | Governs for storage/vault loading with negligible live load. |
| 1.2D + 1.6L + 0.5(Lr or S or R) | Typical gravity-controlled floor/roof combination. |
| 1.2D + 1.6(Lr or S or R) + (L or 0.5W) | Roof live/snow controlled case. |
| 1.2D + 1.0W + L + 0.5(Lr or S or R) | Wind combined with reduced live and roof loads. |
| 1.2D + 1.0E + L + 0.2S | Seismic combined with live and snow. |
| 0.9D + 1.0W | Net uplift/overturning check under wind. |
| 0.9D + 1.0E | Net uplift/overturning check under seismic. |
Tributary area and beam demand calculator
wD = D × tributary width = 60 psf × 6 ft = 0.360 klf
wL = L × tributary width = 40 psf × 6 ft = 0.240 klf
wu = 1.2wD + 1.6wL = 1.2(0.360) + 1.6(0.240) = 0.816 klf
Mu = wuL²/8 = 0.816(24)²/8 = 58.8 kip-ft
Vu = wuL/2 = 0.816(24)/2 = 9.8 kip
RC beam flexural capacity (ACI 318)
a = Asfy / (0.85f'cb) = 4.412 in
Mn = Asfy(d − a/2) = 289.4 kip-ft
φMn = 0.9 × 289.4 = 260.5 kip-ft
ρ = As/(bd) = 1.16%
φMn vs Mu: 260.5 ≥ 58.8 kip-ft — adequate
Steel W-section flexural check (AISC 360)
Mn = ZxFy = 64.7 × 50 / 12 = 269.6 kip-ft
φMn = 0.9 × 269.6 = 242.6 kip-ft
φMn vs Mu: 242.6 ≥ 58.8 kip-ft — adequate (compact section, Lb ≤ Lp assumed)
Deflection limit check
Limit
Δlimit = L/360 = (24 ft × 12)/360 = 0.800 in
Δactual = 0.600 in ≤ 0.800 in — Pass
Column axial capacity screening (AISC 360 E3)
KL/r = 14 × 12 / 1.51 = 111.3
Fe = π²E/(KL/r)² = 23.1 ksi
Fcr = 0.658^(Fy/Fe)·Fy = 20.2 ksi
Pn = FcrAg = 232.6 kip
φPn = 0.9 × 232.6 = 209.3 kip
Preliminary design summary
| Design item | Value | Basis |
|---|---|---|
| Factored moment demand Mu | 58.8 kip-ft | Tributary-area gravity beam calc |
| Factored shear demand Vu | 9.8 kip | Tributary-area gravity beam calc |
| RC beam φMn | 260.5 kip-ft | b=12 in, d=21.5 in, As=3.0 in² |
| Steel W-section φMn | 242.6 kip-ft | Zx=64.7 in³, Fy=50 ksi |
| Deflection check | Pass | L/360 = 0.800 in limit |
| Column φPn | 209.3 kip | KL/r = 111.3 |
Reflection
Do your demand and capacity checks reference the correct ASCE 7 / ACI 318 / AISC 360 provisions, and are units consistent throughout?
Learning objectives
- Define the structural system and load path
- Develop load cases and combinations
- Plan member, connection and serviceability checks
Engineering guidance
Load path first, member sizes second. A member size without a load path is a guess.
FE Civil connection
Structural Analysis
Handbook §7 — Analysis of statically indeterminate structures (placeholder)
- Which load combination controls uplift on a hangar frame?
- How is tributary area used to size a girder?
- What controls lateral-torsional buckling?
Technical methodology planner
Plan Chapter 3 against the exact equations, standards, data sources and design checks you will execute in Capstone II.