In this blog post, we will learn about What is Live load, with detailed explanation from all angles, so that you can a very good grip on this topic,
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Table of Contents
What is Live load? (Definition)
Live load can be defined as the load on a structure that is not permanently applied and can change in magnitude and position, such as loads from occupants, furniture, vehicles, or environmental factors like wind and snow. Live-loads are typically transient and are accounted for in the structural design to ensure safety and stability
For Example :-
Imagine you have a big, strong table. Some days, you put toys on it. On other days, you might put books, or maybe you climb on it for fun. All these things – toys, books, and even you – are like live-loads.
They’re not always there, and they can move around or change. The table has to be strong enough to hold all these things, even if they’re heavy or if they change. So, a live-load is just stuff that comes and goes on something strong like a table or a building.
Now you understand what is live load, you might doubt what the opposite of such kind of load is called. I’m I, right?
Yes, The load which does not change its magnitude and position with respect to time is called a dead load.
Why is it important to understand, What is live load?
Understanding live-load is important because it helps make buildings, bridges, and other structures safe and strong. Here’s why:
- Safety: Live-loads like people walking, cars driving, or furniture moving can change over time. If a structure isn’t designed to handle these, it could bend, crack, or even collapse.
- Durability: Designing for live-loads ensures that structures last a long time without damage, even when they are used in different ways.
- Comfort: When live-loads are considered, floors won’t shake too much when people walk, and bridges won’t bounce when cars pass by, making them feel steady and reliable.
- Legal Requirements: Engineers need to follow rules and codes that define live-loads to ensure public safety and avoid costly mistakes
What are the Live load units?
The units of live-load depend on the system of measurement being used:
- SI System (Metric Units):
- Live loads are typically measured in kilonewtons per square meter (kN/m²).
- For example, a floor in a building might be designed for a live-load of 3 kN/m², which means the floor can safely hold 3 kilonewtons of load per square meter of area.
- Imperial System (US Customary Units):
- Live-loads are typically measured in pounds per square foot (psf).
- For instance, a roof might be designed for a live-load of 40 psf, meaning it can hold 40 pounds of load for every square foot of its area.
These units represent the intensity of the load over a specific area and are used by engineers to calculate and ensure a structure’s safety and stability.
What is the formula for live load?
There is no single universal formula for live-load because live-loads vary depending on the type of structure and its use. However, live-loads are typically determined based on building codes and standards such as ASCE 7, IS 875 (Part 2), or other local codes.
These standards provide recommended values or formulas for live-loads based on the type of occupancy or usage of the structure. For example:
General Formula for Live Load:
The live-load (L) is calculated as: L=Load Intensity×Area
- Load Intensity is the specified live-load per unit area (e.g., in kN/m² or psf).
- Area is the surface area where the load is applied.
Example:
If a floor has a live-load intensity of 4 kN/m² and the area is 50 m²,
then: L= 4×50 =200 kN
For Beams or Structural Elements:
For beams or members, live-load is often distributed as a uniformly distributed load (UDL) or a point load, and structural analysis is used to calculate the effects on bending, shear, and deflection.
Important Note:
The live-load values are usually provided directly by standards for different cases, such as:
- Residential buildings: 2-3 kN/m².
- Offices: 4 kN/m².
- Roofs: 0.75-1.5 kN/m², etc.
Always refer to the specific building code or standard relevant to the project for accurate live-load requirements.
What are live load types:
Here are the following different types of live loads
- Uniformly Distributed Live Load (UDL)
- Concentrated or Point Live Load
- Impact Load
- Roof Live Load
- Environmental Live Load
- Crowd Load
- Seismic Live Load
- Special Loads
List of Live Load examples with standard values
Table showing typical live-load values according to various standards like IS 875 (Part 2) (India), ASCE 7 (USA), and similar international codes. These values may vary slightly depending on the specific standard or country.
| Type of Occupancy/Use | Live Load (kN/m²) | Live Load (psf) |
|---|---|---|
| Residential Buildings | ||
| Bedrooms | 2.0 | 40 |
| Living Rooms | 2.0 | 40 |
| Balconies | 3.0 – 4.0 | 60 – 80 |
| Office Buildings | ||
| Light work areas (e.g., meeting rooms) | 2.5 | 50 |
| General office space | 3.0 – 4.0 | 60 – 80 |
| Corridors (access to rooms) | 4.0 | 80 |
| Commercial Buildings | ||
| Retail stores | 4.0 – 5.0 | 80 – 100 |
| Shopping malls | 5.0 | 100 |
| Restaurants | 3.0 – 4.0 | 60 – 80 |
| Educational Buildings | ||
| Classrooms | 3.0 | 60 |
| Libraries (Reading areas) | 4.0 | 80 |
| Libraries (Book storage) | 7.5 | 150 |
| Hospitals | ||
| Wards and rooms | 2.0 – 3.0 | 40 – 60 |
| Operating rooms | 3.0 | 60 |
| Corridors (accessible by heavy equipment) | 4.0 – 5.0 | 80 – 100 |
| Assembly Areas | ||
| Theaters, cinemas, churches | 3.0 – 5.0 | 60 – 100 |
| Gymnasiums | 5.0 | 100 |
| Stadiums | 5.0 – 6.0 | 100 – 120 |
| Industrial Buildings | ||
| Light industrial floors | 5.0 – 7.5 | 100 – 150 |
| Heavy industrial floors | 10.0+ | 200+ |
| Roofs | ||
| Accessible roofs | 1.5 – 3.0 | 30 – 60 |
| Non-accessible roofs | 0.75 – 1.5 | 15 – 30 |
| Roofs with equipment | 2.0 – 4.0 | 40 – 80 |
Notes:
- These values are typical recommended minimums and may need adjustment based on local building codes, design considerations, or specific use cases.
- Dynamic factors (e.g., vibrations, impact loads) may apply to live loads in some cases, such as for gym floors or stadiums.
- Always refer to the governing standard (e.g., IS 875, ASCE 7, Eurocode) for precise values and conditions.
