Design of Structural Components

Design of Structural Components: A Licensing Exam Guide

Whether you’re preparing for the Architectural PE, the Civil PE, or another engineering licensing exam, understanding the design of building structural components is essential. These elements form the backbone of most structures, and exam questions often test your ability to analyze, design, and apply relevant codes to real-world scenarios. This post provides a comprehensive overview of the primary structural components found in buildings and offers insights into design approaches, code references, and typical exam considerations.

1. Introduction to Building Structural Systems

A building’s structural system ensures that all applied loads—such as gravity, wind, seismic forces, and occupancy loads—are safely transferred to the foundation and ultimately to the ground. The structural system is generally divided into two subsystems:

• Gravity Load-Resisting System (GLRS): Transfers vertical loads like dead load, live load, and snow load.
• Lateral Load-Resisting System (LLRS): Resists horizontal forces due to wind or seismic activity.

The primary components of these systems include beams, columns, slabs, walls, and foundations. Each has unique design considerations and is governed by specific codes and standards.

2. Beams and Girders

Function

Beams support vertical loads and transfer them to columns or load-bearing walls. Girders are larger beams that support other beams.

Design Considerations

• Flexural Strength: Governed by bending moment capacity:
  φMn ≥ Mu
• Shear Capacity: Ensure:
  φVn ≥ Vu
• Deflection Limits: Common limit:
  Δ ≤ L / 360

Code References

• AISC 360 (Steel)
• ACI 318 (Concrete)
• NDS (Timber)

Exam Tips

• Know moment and shear diagrams for various beam load conditions.
• Be familiar with composite steel-concrete systems.

3. Columns

Function

Columns carry axial loads and sometimes bending. They transmit loads from beams or slabs to the foundation.

Design Considerations

• Axial Strength: φPn ≥ Pu
• Slenderness Effects: Buckling depends on:
  K·L / r
• Interaction Diagrams: For combined axial and bending loads.

Code References

• AISC 360 (Steel)
• ACI 318 (Concrete)
• NDS (Wood)

Exam Tips

• Use Euler’s buckling formula for long columns.
• Understand braced vs. unbraced frame behavior.

4. Slabs and Decks

Function

Slabs distribute loads to beams or directly to columns in flat-slab systems.

Design Considerations

• One-Way vs. Two-Way Slabs: Based on aspect ratio Llong/Lshort
• Punching Shear: Critical around columns
• Reinforcement Design: Positive and negative moment regions

Code References

• ACI 318 (Concrete)
• ASCE 7 (Load combinations)

Exam Tips

• Edge conditions (e.g., cantilevers) affect moment distribution.
• Understand diaphragm action in steel decks.

5. Shear Walls and Braced Frames

Function

These lateral systems resist wind and seismic forces.

Design Considerations

• Shear Strength: Must handle in-plane forces
• Coupling Beams: Aid stiffness and ductility
• Ductility and Detailing: Crucial under seismic loading

Code References

• ACI 318 (Concrete shear walls)
• AISC 341 (Seismic steel design)
• ASCE 7 (Seismic design criteria)

Exam Tips

• Know R-values, Cd, and Ω₀ from ASCE 7
• Understand load path and anchorage

6. Foundations

Function

Foundations transfer building loads to the soil.

Types

• Shallow Foundations: Spread footings, mats
• Deep Foundations: Piles, drilled shafts

Design Considerations

• Bearing Capacity: Must exceed applied stress with safety factor
• Settlement: Often governs more than strength
• Soil-Structure Interaction: Important in advanced exams

Code References

• ACI 318 (Concrete foundations)
• IBC and ASCE 7 (Geotechnical)
• AASHTO or FHWA (for bridges)

Exam Tips

• Be fluent in allowable bearing pressure calculations
• Identify uplift or lateral control in deep foundations

7. Load Combinations and Design Philosophies

Design relies on Limit States Design, using LRFD or ASD.

Typical Load Combinations (ASCE 7)

• Strength: 1.2D + 1.6L + 0.5(Lr, S, or R)
• Seismic: 1.2D + 0.5L + E
• Wind: 1.2D + 0.5L + 1.6W

Exam Tips

• Memorize key load combinations
• Know which combination controls for each case

8. Material-Specific Notes

• Steel: AISC 360, understand compact sections, bolts, and welds
• Concrete: ACI 318, focus on development length and seismic detailing
• Timber: NDS, consider moisture, duration, and slenderness

9. Practice Problem Strategy

• Interpret the structural role
• Identify governing loads
• Apply correct code equations
• Check all limit states
• Sketch and annotate on scratch paper

10. Final Thoughts

The design of building structural components is a cornerstone of structural engineering practice—and a major focus of licensing exams. Mastering these elements involves not just memorizing formulas, but understanding why components behave as they do, how loads flow, and how to apply codes with confidence.

Approach your study with an organized strategy:

• Start with component behavior and loading
• Reinforce with code-specific practice
• Drill with realistic problems under timed conditions

When exam day comes, you won’t just be solving equations—you’ll be designing safe, efficient, code-compliant buildings.