Structural engineers often use the terms “dead load” and “live load.” Understanding the difference between these two types of loads is important to maintaining the stability and structural integrity of steel structures. These terms help to understand how to construct a custom steel structure system.
In this article, Xinguangzheng will discuss Live Load Vs Dead Load in detail to help you better understand these terms.
Table of Contents
Live load vs dead load
When designing a steel structure, you need to know about many types of structural loads. There are generally three types of structural loads: vertical loads, horizontal loads, and longitudinal loads. Each load type can be subdivided into more types. Today we will discuss live loads and dead loads. Both of these loads are considered to be larger vertical loads.
Dead load
The first vertical load to consider is the dead load. These loads are always inside the building and do not move. In most cases, dead loads are forces exerted on the building structure by fixed walls, structural elements, or permanent equipment. In most cases, this category includes all beams, roofs, supports, walls, and other things. Unless there are any changes to the building structure, the dead load will remain the same.
Characteristics of Static Loads
- Fixed Weight: Static loads do not change over time unless there are changes to the building structure.
- Permanent: Static loads consist of the weight of building components and built-in parts of the structure.
- Vertically Distributed: Gravity pulls static loads vertically downward, exerting constant pressure on building components.
Examples of Dead Loads
- The dead weight of structural building components, such as walls, bricks, beams, and columns
- Fixed installations, such as HVAC systems, pipes, and electrical wiring
- Materials used to lay floors, such as acrylic, tiles, and wood panels
- Roofs and their coverings
- The exterior of a building, such as paint, plaster, and siding
Before moving any live loads into a building, it is important to find out what the dead load is. When people estimate dead loads, they often forget to include fixtures such as HVAC, plumbing systems, elevators, etc. Therefore, these things are still very important and can have a huge impact on your calculations.
Live Load
Live load is also known as imposed load. It refers to temporary or moving loads on a building caused by people, furniture, cars, and other short-term factors. As live loads can change over time, they can exert dynamic forces on a building. Engineers need to take this into account for safety and design reasons.
The size and position of live loads can change over time. This is because they are influenced by how the building is used and who lives there. Therefore, the floor should always be able to withstand evenly distributed heavy objects or concentrated heavy objects. In practice, the floor does not bear the maximum load at any time. This means that you can be more creative when planning columns, load-bearing walls, pier supports, and even foundations.
Characteristics of Live Loads
- Variable Amplitude: The magnitude of a live load depends on the number of people using the structure and the weight they carry. For example, residential floors are subject to different loads than commercial floors.
- Not Permanently Fixed: Live loads change as people walk around and engage in different activities.
- Dynamically Distributed: Live loads can act at different locations and move within the structure. This causes the forces acting on the various parts of the structure to vary.
Examples of Live Loads
- People living and working in residential and commercial buildings and their furniture
- Cars and trucks on roads, parking lots, and bridges
- Warehouses for storage and goods
- Tools and machines in industrial buildings
- In winter, snow accumulates on roofs.Also often referred to as snow load
The Difference Between live vs dead loads
- Nature: A dead load is a weight that remains in one position. A live load is a weight that moves.
- Size: A dead load is usually greater than a live load, as it includes the weight of the structure itself. A live load includes any temporary loads that are applied to the structure.
- Relationship to Time: A dead load remains the same. A live load, however, changes depending on the number of people and activities in the building.
You need to know the values of the live and dead loads before you start building anything. This is because these values also change the construction costs. This is because you may need to use different materials than originally envisaged. In the long term, this can increase construction costs. This is important if you need to use concrete instead of steel or wood.
To calculate the steel structure load value, you need to know the load limits and allowable loads for the region where the building is located. Usually, these values are the same as those in the International Residential Code.
Of course, you should also check the local building codes before starting construction. You may need to know the specific standards for dead and live loads. What is feasible in one part of the country may not be feasible in another. You need to pay attention to any nuances, as they may determine whether the building can pass inspection.
Factors to Consider When Selecting the Building Code to Be Followed for the Project
What Is the Type of Use of the Building?
Different uses of a building require different values for the structural loads to be considered. Metal workshop building may have a lot of machinery and therefore require higher values for the live loads to be considered. A building for storing hay or other animal feed would require significantly lower values. The structural engineer therefore needs to consider the use of the building when designing the building structure.
What Materials Can Withstand Static Loads?
Many houses are built with wood. However, most commercial buildings can be built with steel, concrete, or wood. However, for larger buildings, it is best to use steel structures. This is because steel structures offer many advantages. These include high strength, low weight, short construction periods, cost-effectiveness, and great design flexibility.
What Is the Design of Live Loads?
The structural engineer must understand the live load requirements of the structure being built. This helps you decide what materials to use when building. After all, the live load of a home is very different from that of a steel structure shopping mall. It is also important to remember that different rooms will have different live loads. It is helpful to know the purpose of each room before construction begins.
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What You Need to Do to Use the Span Tables
- Examine your plan to find the span and distance between each point.
- Check the code to determine the limits for dead load, live load, snow load, and even deflection.
- Select the appropriate span table.
- Match your design conditions to the ranges in the table to find the smallest Fb and E numbers.
- Select the grade from the list of numbers in the design value table.
- Calculate the compression perpendicularity based on the design values in the table.
- Make sure that the numbers you have selected in steps 5 and 6 are correct and ultimately match.
Some Live Load Values From the International Residential Code
- Exterior balconies 60
- Decks 40
- Garages for passenger cars 50
- Attics with no storage 10
- Sleeping rooms 30
- Rooms other than sleeping 40
It is important to remember that these are the minimum live loads that should be evenly distributed in these areas. If you do not use the correct live and dead load values, then any building may become unsafe. If buildings are constructed to withstand both dead and live loads, then they may collapse over time. Furthermore, people will not be able to live safely where the rules for live and dead loads are not followed.
Many people think that buildings are stable no matter what material they are made of. But if you don’t use the right materials to withstand live and dead loads, then any building can become dangerous and uninhabitable. For example, we have made this detailed introduction to what materials should be chosen for a steel warehouse.So if you want to build your home properly in the future, you should learn more about live and dead loads.
Because nowadays people put more things in buildings than ever before. So you need to make sure that they are safe and won’t cause any part of the building to collapse. In the past, you may not have given much thought to live and dead loads. Now is the time to learn as much as you can about them. By following these principles, you will build something safer in the future than ever before.
Summary
When constructing a building structure, structural engineers take both live and dead loads into account. This ensures that the structure is safe and will not collapse. Dead loads tell us about the strength and stability that the overall structure needs to achieve. Live loads, on the other hand, influence the design and thus the way in which it is used. To compensate for unknown factors and changes in live loads, the design process should include an appropriate safety factor.
In summary, the concepts of dead and live loads are very important in structural engineering. The permanent weight of a building and its components is called the “dead load”. Variable short-term loads that people impose on a building are called “live loads”.
