Live load is essential in every structural design and is produced by the use and occupancy of a building. It is often called a probabilistic load or imposed load. To ensure structure stability, live load needs to be defined in every building project by a structural engineer.
It helps them ensure that the building can withstand such heavy loads or the design needs to be adjusted to accommodate the load. Read on to understand what live load is, the importance of calculating live load and its examples, which are explained in detail below:
What is Live Load?
Live load refers to the variable loads produced by the use and occupancy of a building. It includes the weight of furniture, office equipment, people, cars, etc. The value of each building’s live loads is defined by the standard codes of practice, and this is the reason to estimate the usage of any structure before the design is executed. This way, the loads can be calculated in a standard manner and the errors are reduced.
Components of Live Loads
Live loads are moving loads that can be estimated with some important components, such as:
Occupants: It defines the number and weight of the people and their belongings like clothing, bags, accessories, etc.
Furniture: All movable furnishings like chairs, cabinets, tables, and beds
Storage: inventory, tools, equipment, and other items stored in factories, warehouses, etc.
Vehicles: Vehicles include buses, cars, trucks, and bikes that may be parked near or on the structure. Examples are bridges and parking garages.
Wind and snow: Forces by wind and snow created on the exterior surface of the wall or structure
Other Temporary Loads: It refers to the loads that are temporarily produced on a structure, including construction equipment, crowds of people, and other factors.
Importance of Live Load in Structural Design
Live loads are dynamic and can vary significantly over time and location. The accurate estimation of load ensures the safety and durability of a structure. Here are some of the key reasons why live loads are crucial in structural design:
Safety and Structural Integrity: Every structural design is aimed to withstand both live loads and dead loads. Sometimes, insufficient consideration of live loads causes potential failures that can lead to injury or loss of life. To prevent excessive damage or deformation of structures, careful evaluation, calculation and design are vital.
Functional Requirements: The type and intensity of the live load are typically based on the use and occupancy of the structure. Adhering to the building codes and standards ensures that the structure is completely safe and secure from all kinds of potential damages. If it is a warehouse, high live load capacity is required to tolerate heavy loads of materials and equipment, while a residential building requires less live load capacity, which includes only the weight of furniture, appliances, and occupants.
Structural Performance: Repeated application of live loads causes excessive vibration that affects the functionality of a structure. Planning for adequate design factors helps mitigate these issues in advance.
Examples of Live Loads
Areas used for domestic and residential activities: bedrooms, kitchens, and toilets in hotels; rooms made in residential houses and buildings; bedrooms and wards in hospitals.
Shopping Areas: refers to department stores and general retail shops.
Storage Areas: Areas that are highly susceptible to accommodating goods, like industrial areas.
Areas where people may congregate: Areas susceptible to large crowds with fixed seats and tables like dining halls, cinemas, theaters, conference rooms, concert halls, stands, railway platforms, etc.
Live Load Direction
In general, the live load is applied to a horizontal element like stairs, slabs, flat roofs, and balconies. Here, the load gets transferred vertically downwards from the structure to the foundation.
In inclined surfaces, the live load acts vertically downwards, but the load gets distributed along the slope of the inclined surface. It is then transferred to the supporting horizontal or vertical supports such as beams or columns.
How is Live Load Calculated?
For any structural design, calculating the maximum live load is important to avoid costly mistakes and fatalities. It may greatly vary in each situation, for example, a stadium, a single-family house, and a school. Regardless of the exact calculation, being aware of the minimum live loads that every structure can withstand will save you.
In particular, live loads are determined by a variable part, daily usage and occupancy. If you want to simply use the calculation method, calculate live loads as uniform loads (as defined by Indian Standard codes) and apply it over the area of the structure.
Elements to Consider When Calculating Live Load
Most importantly, live load is not static and uniform. When the forces are applied, the structure may feel extra load, and it must be considered in calculations. Some of the key factors essential to be taken into account and are listed below:
- Vibration
- Amount of Movement
- Material wear
- Impact
- Fluid dynamics
Final Thoughts
Structural elements are susceptible to carrying multiple varying loads, whereas live load is important to calculate before the design is commenced. Hopefully, this article has explained everything in detail, which may be useful when dealing with any residential or commercial building works.