Structural loads are the fundamental forces, deformations, or accelerations applied to a structure or its components. These loads include dead load, live load, wind load, seismic load, and increasingly complex types like flood load and thermal load expansion. Whether designing a small house or a skyscraper, understanding these loads is essential to ensure safety, resilient design, and structural integrity.
Structural loads are foundational to modern buildings. Engineers use codes like ASCE SEI 7, NSCP, and IS 875 to model and resist lateral, gravity, thermal, and flood loads. Tools like ETABS and STAAD.Pro, combined with performance-based design and real-time data, shapes the future of safer, smarter, and climate-adaptive buildings.
This article examines the various types of structural loads, their calculation methods, and their practical applications in real-world scenarios.
It also highlights key building standards like ASCE SEI 7-16, ASCE SEI 7-22, NSCP 2015, and IS 875. If you’re a civil engineer, architecture student, or someone interested in how buildings resist gravity load, lateral load, and extreme forces, this guide is for you.
What Are Structural Loads on Buildings?
Structural loads are internal or external forces applied to a building’s elements—such as beams, columns, and foundations—that directly affect performance-based design. These can include gravity loads, construction loads, or lateral loads, among others, and are influenced by factors such as occupancy, location, material, and environmental conditions.
Main Types of Structural Loads
Dead Load (Permanent Static Load)
Dead load includes the self-weight of the structure and all permanently installed components like walls, columns, and roofing.
Typical values:
Residential: 2–3 kN/m²
Commercial: 4–5 kN/m²
Referenced in IS 875 Part 1 and ASCE 7-16.
Live Load (Imposed Load)
Live loads depend on occupancy type and include people, furniture, and movable items.
Typical values:
Residential: ~2 kN/m²
Offices: ~3–4 kN/m²
Live load reduction is considered in the design for large-area floors.
Wind Load
Wind load acts both vertically and laterally. It’s crucial in tall structures, canopies, and facades. Calculations refer to:
ASCE 7-16, IS 875 Part 3, ASCE 7 Wind Loads, and BS 6399
MWFRS methods are used for whole-building analysis
Exposure Category C impacts wind design
CFD simulations assist modern assessments
Seismic Load
Generated by ground motion, seismic loads vary by region and soil type. Consider:
Base shear, modal analysis, and ductile detailing
ASCE SEI 7-16, ASCE SEI 7, NSCP Seismic Provisions, and IS 1893
Risk category and building occupancy category determine design intensity
Snow Load
Important in colder regions, snow load is calculated using:
ASCE 7-05, ASCE 7-10, ASCE 7-16
Refer to the Snow Load Calculation Chart for drift and density factors
Rain Load / Ponding Load
Flat roofs must be checked for water accumulation from blocked drainage systems. Refer to ASCE 7-16 for provisions.
Temperature Load
Thermal load expansion can lead to cracks or displacement, especially in bridges and metal structures.
Settlement Load
Differential foundation settlement induces internal stress. Soil reports help anticipate this.
Blast and Impact Loads
These loads affect military, industrial, and high-security structures. Specialised materials and design methods are used.
Flood Load
Newer codes, such as ASCE SEI 7-22, include flood load criteria for flood-prone areas.
How to Calculate Structural Loads?
1. Dead Load Calculation
- Use unit weights from IS 875 Part 1
- Includes slabs, finishes, and permanent equipment
2. Live Load Calculation
- Based on use/occupancy
- Refer to IS 875 Part 2, ASCE 7-10, and live load reduction techniques
3. Wind Load Calculation
- Uses data from ASCE 7-02 Wind Loads, ASCE 7 Wind Loads, and IS 875 Part 3
- Requires defining exposure categories, height, and terrain
4. Seismic Load Calculation
- Defined in ASCE 7-16, NSCP 2015, and IS 1893
- Factors: seismic zone, soil profile, importance factor, risk category
Load Combinations
As per ASCE SEI 7-16:
- 1.4D
- 1.2D + 1.6L + 0.5(Lr or R)
- 1.2D + 1.0W + 1.0L + 0.5(Lr or R)
- 0.9D ± 1.0W or ± 1.0E (seismic or uplift cases)
Real-World Applications and Case Studies
Burj Khalifa Wind Load Analysis
- Resists lateral loads up to 240 km/h using a buttressed core
- Wind tunnels + CFD simulations used for optimisation
Seismic Zone IV – Residential Structure (India)
- Used base isolation and performance-based design
- Followed IS 1893, NSCP, and ASCE SEI 7-16
Snow Design in Cold Regions
- Followed ASCE 7-10 Commentary and ASCE 7-05
- Adjusted for building occupancy category and roof slope
Design Standards & Building Codes
ASCE SEI 7 Series
- ASCE SEI 7-05, 7-10, 7-16, 7-22
- Include provisions for wind, snow, earthquake, flood, and construction loads
- Explained in ASCE 7-10 Commentary
NSCP (Philippines)
- Local seismic/wind zoning integrated
- Uses similar combinations as ASCE
IS 875 (India)
Eurocode EN 1991 (EU)
BS 6399 (UK)
Advanced Tools for Load Analysis
Structural Software
- STAAD.Pro, ETABS, SAP2000, RAM Structural System
- Simulate wind, seismic, and construction load scenarios
Load Span Tables and Charts
- Beam/partition span guides
- Use the Snow Load Calculation Chart for cold climates
Common Mistakes in Load Estimation
- Ignoring load combinations
- Underestimating lateral loads on canopies
- Missing importance factor in seismic design
- Using outdated codes like ASCE 7-02
FAQs
What’s the difference between dead and live loads?
Dead loads are permanent (walls, roof). Live loads are movable (furniture, people). Live load reduction is applied for large areas.
Which code is used for wind load in the US?
ASCE 7-16, ASCE 7-02 Wind Loads, and ASCE 7 Wind Load Provisions.
How are snow loads determined?
Use ASCE 7-05 and Snow Load Calculation Chart. Consider density, drift, and roof exposure.
What software calculates seismic loads?
STAAD.Pro, ETABS, and SAP2000 handle seismic base shear and modal analysis.
Is ASCE 7-05 still valid?
It is outdated. Use ASCE SEI 7-16 or the latest ASCE SEI 7-22.