What is a load on structure?

Civil engineers primarily deal with beams in their day-to-day applications. A beam is a structural member that resists shear loadings. There are various types of beams such as cantilever beam, simply supported beam, and over the hanging beam. All these beams have a different end and loading conditions.

A civil engineering structure is composed of various members and links joined together. The loads act at the joins in a structure. Depending upon the loading conditions, a structural member may act as beams or trusses. The building must have a proper load-bearing capacity to ensure the safety of both living and non-living entities. Non-living entities cover all the non-structural members such as adjacent buildings and properties. A proper load calculation is very crucial in civil engineering for structural members under various loading conditions, as it gives an insight into the critical area that needs to be improved to avoid failure.

Live loads

The structural civil engineering members are always subjected to change in loading conditions continuously. One of the primary loads that act on the civil engineering members is the live loads. Live loads arise from people walking, and the movement of objects inside the building structure. These live loads vary in nature, both in direction and magnitude, and are repeatedly applied to the same spot. To design a building, the American Society of Civil Engineers prescribes criteria for minimum permissible of live loads in a structural member. Apart from people, loads such as wind load, seismic load, and temperature loads also form a part of live loads for a building. The live loads can be either a point live load or linearly varying live loads. In the case of uniformly distributed loads, a single live load that is equivalent to the load's distribution is applied for calculation purposes. For the analysis of a building composed of live loads from fluids and other external agents, accurate concepts from subject backgrounds should be applied to solve the problem of the deformation caused for these live loads.

Dead loads

Dead loads are the immovable permanent and static loads in a building. The magnitude of dead loads does not change with respect to time. The weight of the beams and columns itself forms a part of the dead load. The primary dead load of a building is the weight of structural elements and members of the building. Apart from these, furniture, tables, and other equipment inside the building that majorly does not change its position with time can be counted as dead loads. A beam with cantilever conditions usually remains under the action of dead loads as they are used in buildings to support the vertical loads from the buildings. A similar explanation of dead loads can be provided for simply supported beams.

Wind loads

Winds loads are major concerns for tall buildings and skyscrapers. Wind loads induce different aerodynamic forces on the buildings. Having a poor aerodynamically designed building may fail under the influence of wind loads. A proper building to withstand wind loads must have a lower value of the coefficient of drag. The coefficient of drag is proportional to the drag force that the building experiences under wind loads. Wind loads are always dynamic loads. A dynamic load is a load that exerts its influence due to kinetic energy.

Snow loads

Snow loads are periodic loads that a building experiences due to the downward pressure exerted by snow or ice. For a certain volume of water, the weight exerted by the snow or ice is more than the weight of the water. Water has a peculiar property of expansion under the fusion process, so when volume increases, its mass also increases. Hence, building design with snow load consideration is of utmost importance. The roof floor system should be specially designed that minimize water accumulation and through the inclusion of heating elements over the surface, the snow load can be minimized to great extent. Other structural changes, such as separate channels and passageways, that can be built for grounding snow load safely out of the buildings can also be an effective way.

Earthquake loads

Seismic forces induce earthquake loads to the buildings. In that case, the material of the building must possess enough strength to withstand the earthquake loads. Proper reinforcement must be provided with the inclusion of tuned mass dampers that suppress vibrations induced to the building by causing a braking effect, known as damping. In addition, the earth pressure should also be calculated during building design, so that the foundations remain strong even during high seismic loads.

Loads on trusses and columns

Trusses are structural members where different individual members are interconnected through joints. These joints may be bolted, pin-jointed, or welded. In the trusses, the loads always act at the joints. The effects of such loads lead to deformations and the development of internal stresses. The loading conditions also cause moments in the whole structure. Side supports of bridges, telephone towers, and the surrounding of a typical cricket all are examples of trusses. These kinds of structures are subjected to tensile loadings, compressive loadings, and bending moments.

Columns are the members that support vertically compressive loads. The foundations of the building are the columns that withstand the whole load of the building. After a critical load, known as Euler's critical load, these members start to buckle. A civil engineer must consider the buckling criteria to design a column for a building.

Context and Applications

The topic is extensively taught in various engineering and applied science degree courses such as:

• Bachelors in Science (Physics)
• Bachelors of Technology in Civil Engineering
• Bachelors of Technology in Mechanical Engineering
• Masters of Technology in Civil Engineering
• Masters of Technology in Mechanical Engineering

Practice Problems

1. Which of the following loads are supported by a cantilever beam?

1. Lateral loads
2. Vertical loads
3. Shear loads
4. All of these

Correct option- d

Explanation: A cantilever is a structural member that supports lateral loads, vertical loads, and shear loads.

2. Which of the following is also known as aerodynamic load?

1. Loads exerted by liquids
2. Seismic loads
3. Wind loads
4. Snow loads

Correct option- c

Explanation: Wind loads are exerted by winds on the buildings, they induce aerodynamic forces.

3. Which of the following loads is supported by columns?

1. Shear loads
2. Vertical loads
3. Bending moments
4. None of these

Correct option- d

Explanation: A column is a structural member that supports vertically compressive loads.

4. Which of the following is a primary dead load of a building?

1. Loads from structural members
2. Loads from moving objects
3. Loads from walking peoples
4. All of these

Correct option- a

Explanation: A building experiences a dead load from its structural members as the weight of the beams and columns itself.

5. Which of the following is an example of a truss?

1. Foundation of a building
2. Side supports of a bridge
3. Mobile tower
4. Both b and c

Correct option- d

Explanation: Structural members such as mobile towers and sides of a bridge are examples of trusses.