Exploring Static Load vs Dynamic Load: Key Concepts for Structural Stability
Static vs. dynamic load - both are key aspects for maintaining the safety and stability of buildings. Both these loads play an important role in the design and construction of a structure. Here is everything you should know about static and dynamic load, and their impact on infrastructures.
Understanding Static Load vs Dynamic Load
The structural system of a building must support two both static and dynamic loads. Whether you are a seasoned professional or an inhabitant, here is all you need to know about both types of loads and their importance:
What Is Static Load?
A static load is a constant load that doesn’t change over time. Also called a fixed load, it must have a specific magnitude, direction, and location that doesn’t change. Static loads are applied slowly to a structure until they reach their highest point, without quickly changing in strength or position. Here are some of the major types of static loads:
Dead loads
These are static loads that act vertically downward on an infrastructure. They include the load of the structure itself, as well as the load of non structural building elements, fixtures, and equipment that are permanently attached.
Live Loads
Live loads refer to any moving or movable loads on a structure. These can be a result of occupancy, accumulated snow & water, or moving equipment. Live loads usually act vertically downward. However, they can also exert horizontal forces depending on the nature of the moving load.
Occupancy loads
Occupancy Loads arise from the weight of people, furniture, stored materials, and other similar stuff within a building. Structures have to follow several building codes to limit these loads for different uses and types of occupancy.
Snow loads
These are the forces exerted by the weight of accumulated snow on a roof. Snow loads can vary based on geographic location, the size and slope of the roof, its shape, and overall roof design.
Rain loads
The rain loads occur because of the accumulation of water on a roof. These can occur due to the roof's shape, deflection, or blockages in the drainage system.
Settlement Loads
Settlement loads are created when a portion of the supporting soil subsides. This leads to differential settlements in the foundation of a structure and as a result, settlement loads occur.
Ground Pressure
Ground pressure refers to the horizontal force that the soil exerts against a vertical retaining structure.
Water pressure
Water pressure refers to the hydraulic force exerted on the foundation system of a structure, including footings, walls, slabs, piers, etc.
Thermal stresses
These refer to the compressive or tensile forces in objects. These occur when materials are restricted from expanding or contracting as temperatures change.
Impact loads
These are short-duration kinetic loads that occur because of moving vehicles, falling objects, or equipment and machinery vibrations. Impact loads are technically dynamic. However, the building codes classify them as static for the purpose of design and safety calculations.
What Is Dynamic Load?
Dynamic loads are forces that are applied quickly and suddenly to a structure. They can vary in strength and location every time they occur (even when occur during the same event). The two main types of dynamic loads are wind loads and earthquake loads. Here is all you need to know about them and their impact:
Wind Loads
Winds coming from any horizontal direction may exert forces on a structure called wind loads. Buildings and all their components should be designed to bear the pressure of wind-induced sliding, uplift, and overturning.
Wind exerts both positive pressure (pushing against the building) and negative pressure (suction pulling away from the building). Therefore, make sure that your structural designs are capable of resisting wind-induced forces.
Flutter is another impact caused by wind loads. It refers to the rapid oscillations of flexible structures, such as cables or other membranes. Structures that experience flutter more often include tall, slender buildings or those with unusual shapes and lightweight structures. Engineers usually use wind funnel testing or computer modeling to control the impact of flutter on structures.
Seismic Loads
A structure experiences seismic load because of the ground moving during an earthquake. These forces can impact a structure by causing it to shake, rock, or twist.
To calculate seismic loads, considering the earthquake's parameters at the building’s location is important. Other vital factors to consider include natural frequency, building materials, and quality of construction.
Need any more information about static vs. dynamic loads? Feel free to reach out to us at Principal Built Engineering. We are here to help you with any questions or concerns about dynamic & static load capacity, load analysis, and structural design.
Conclusion
Knowing about dynamic load vs static load and their impact is important to maintain the safety and stability of structures. Both play a critical role in the design and analysis of buildings. The above guide gives comprehensive information on how different forces impact a building structure. Static loads, such as dead loads and live loads, are constant forces acting on a structure. On the contrary, dynamic loads, including wind and seismic forces, highlight the need for adaptability in design to accommodate sudden changes. Understanding what is the difference between a static and dynamic load for both professionals and residents. After all, this helps in maintaining safe and resilient structures.