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Building Loading 101: What are Loads and How Do they Affect my Pre-Engineered Metal Building?

When it comes to constructing durable and versatile structures, pre-engineered metal buildings have gained significant popularity in recent years. These modern marvels offer exceptional strength, cost-effectiveness, and quick assembly. However, one crucial aspect of their design that ensures their structural integrity is the consideration of loads and the implementation of robust bracing systems.

girts, purlins and I-beams are shown in the process of being erected as an orange front loader moves gravel below.
A pre-engineered metal building project begins to be erected

In this blog post, we will delve into the world of pre-engineered metal buildings, exploring the various loads these structures are subjected to and how they are skillfully braced to accommodate these forces. Whether you're an aspiring architect, an engineering enthusiast, or simply curious about the intricacies of construction, this guide will provide you with valuable insights into the impressive engineering behind these structures.

From static to dynamic loads, such as dead loads, live loads, wind loads, and seismic forces, pre-engineered metal buildings are engineered to withstand a wide range of stressors. Understanding these loads and the strategies employed to distribute and resist them is vital for ensuring the safety and stability of these structures in various environments.

Moreover, we will explore the purpose and importance of bracing systems within pre-engineered metal buildings. These systems play a critical role in enhancing the overall structural integrity by effectively redistributing loads, mitigating potential deformations, and increasing the building's resistance to lateral forces.

By shedding light on the science behind load capacities and bracing, we aim to provide a comprehensive understanding of how pre-engineered metal buildings are designed to withstand the harshest conditions and maintain their durability over time.

So, if you've ever marveled at the strength of a metal building or wondered how these structures can withstand the forces of nature, join us and our partners over at the Metal Building Manufacturers Association (MBMA) on this enlightening journey as we uncover the secrets behind load capacities and bracing in pre-engineered metal buildings.

First off, let's go over the basics. Here's a quick refresher on some of the terminology that you will encounter when discussing a metal building (2:36 min)

Now that we have a basic understanding of the vernacular associated with these building systems, let's take a look at how loads such as wind move longitudinally (along the ridge), laterally (across the ridge) or vertically through a metal building.


Transverse Wind Loads:

Transverse wind loads refer to the horizontal forces exerted by wind perpendicular to the walls of a metal building. These loads can pose a significant challenge to the structural integrity of the building, especially in regions prone to high winds or extreme weather conditions. Therefore, it is crucial to account for these transverse wind loads during the design and construction of metal buildings. (1:54 min)

To effectively address transverse wind loads, engineers employ several strategies and techniques:

  1. Building Codes and Standards: Building codes provide specific guidelines and standards for designing structures, including metal buildings, to withstand wind loads. These codes consider factors such as the location of the building, local wind speeds, terrain, and building height to determine the required wind resistance. Compliance with these codes ensures that the building meets minimum safety requirements.

  2. Wind Load Calculations: Engineers use wind load calculations based on established engineering principles to determine the magnitude of transverse wind forces acting on a metal building. These calculations consider factors like wind speed, exposure category (which accounts for the building's surroundings), and building dimensions to assess the anticipated wind pressure.

  3. Structural Design and Bracing: Metal buildings are designed with structural systems that efficiently distribute and resist wind loads. This involves integrating elements like rigid frames, roof systems, and bracing systems. Rigid frames, typically made of steel, provide robust support and resistance to bending moments induced by transverse wind forces. Additionally, bracing systems, such as diagonal bracing or portal frames, are strategically placed to improve the building's overall stability and stiffness, minimizing deflections caused by wind loads.

  4. Cladding and Roofing Considerations: The selection and installation of cladding and roofing materials play a vital role in withstanding transverse wind loads. These elements should be designed and installed to resist uplift forces and prevent the ingress of wind-driven rain. Adequate fastening systems, sealants, and joints are crucial to ensuring the integrity of the building envelope and reducing the risk of wind-related damage.

By considering building codes, performing wind load calculations, conducting wind tunnel testing when necessary, implementing robust structural design and bracing systems, and choosing appropriate cladding and roofing materials, metal buildings can effectively account for transverse wind loads. These measures ensure the safety, durability, and long-term performance of the structure in the face of strong winds and adverse weather conditions.

Longitudinal Wind Loads:

Longitudinal wind loads, also known as along-wind or parallel wind loads, are the horizontal forces exerted by wind along the length or parallel to the walls of a metal building. These loads act in the direction of the wind flow and can significantly impact the structural integrity of the building. Here's a quick demonstration of this. (1:41 min)

To ensure the building's stability and resistance to longitudinal wind loads, specific considerations and design approaches are employed:

  1. Wind Load Calculations: Similar to transverse wind loads, wind load calculations are essential for determining the magnitude of longitudinal wind forces on a metal building. These calculations take into account factors such as wind speed, building height, exposure category, and the dimensions and shape of the building. By considering these parameters, engineers can assess the anticipated wind pressure acting along the length of the building.

  2. Building Shape and Orientation: The shape and orientation of the metal building play a significant role in its response to longitudinal wind loads. Buildings with streamlined shapes, such as gable or curved roofs, are more aerodynamic and tend to experience reduced wind pressures compared to buildings with complex shapes. Additionally, aligning the building in a manner that minimizes the building's exposure to prevailing winds can help mitigate the impact of longitudinal wind loads.

  3. Structural Design and Framing Systems: The structural design and framing systems of a metal building are crucial for withstanding longitudinal wind loads. Rigid frames, which are common in metal building construction, provide strength and stability by resisting bending moments induced by wind forces. These frames are typically designed to have adequate stiffness to limit deflections caused by longitudinal wind loads and maintain the building's overall stability.

  4. Shear Walls and Bracing: To enhance the resistance of metal buildings to longitudinal wind loads, shear walls and bracing systems are incorporated into the structural design. Shear walls, which are vertical elements made of steel or other materials, are strategically placed along the length of the building to distribute wind loads and reduce lateral displacements. Bracing systems, such as diagonal bracing or portal frames, are also utilized to improve the overall stiffness and rigidity of the building, minimizing the effects of wind-induced vibrations.

  5. Cladding and Roofing Considerations: The cladding and roofing materials used in a metal building play a crucial role in withstanding longitudinal wind loads. These elements should be properly secured and installed to resist uplift forces and prevent wind-driven rain from penetrating the building envelope. Adequate fastening systems, sealants, and joint designs are essential to ensure the integrity and weather resistance of the building.

By incorporating wind load calculations, optimizing building shape and orientation, employing robust structural design and framing systems, incorporating shear walls and bracing, and selecting appropriate cladding and roofing materials, metal buildings can effectively account for longitudinal wind loads. These measures help ensure the building's stability, minimize structural deflections, and enhance its overall resistance to the forces exerted by wind along its length.

Gravity Loads:

Gravity loads refer to the vertical forces exerted on a metal building due to the weight of its own structural components, as well as the weight of any occupants, equipment, and other live loads. These loads include dead loads and live loads, and they play a fundamental role in the structural design and stability of a metal building. (1:38 min)

Here's how gravity loads are typically accounted for in a metal building:

  1. Dead Loads: Dead loads are the permanent and self-weight of the building's structural elements, including columns, beams, roof systems, walls, and other components. These loads remain constant over time and are relatively predictable. Engineers carefully calculate the dead loads based on the weight of the materials used, taking into account factors such as steel sections, concrete slabs, roofing materials, insulation, and other permanent fixtures. By accurately estimating the dead loads, designers ensure that the building's structural elements are appropriately sized and capable of supporting their own weight.

  2. Live Loads: Live loads represent temporary loads that can change over time and are associated with the occupancy and use of the building. Examples of live loads include people, furniture, equipment, and other movable objects. The magnitude of live loads varies depending on the intended function of the space within the metal building. Building codes provide guidelines for determining the required live loads for different areas of the building, such as storage areas, offices, or assembly spaces. Engineers incorporate these load requirements into the design process to ensure that the building's structural elements can safely support the anticipated live loads.

  3. Load Combinations: In addition to considering dead loads and live loads separately, engineers also account for various load combinations to ensure the building's overall stability. Load combinations involve considering the simultaneous occurrence of multiple loads, such as dead load combined with live load, wind load, or seismic forces. Building codes provide specific load combinations based on the type of structure and the applicable design standards. By considering these load combinations, engineers can design the metal building to withstand the most critical and realistic load scenarios.

  4. Structural Analysis and Design: To account for gravity loads, structural engineers utilize advanced analysis techniques and computer simulations to evaluate the behavior of the metal building under various load conditions. These analyses consider factors such as member sizes, material properties, and connection designs to ensure that the structural elements can safely resist the applied loads. Engineers use structural design codes and standards to determine the appropriate member sizes and configurations, ensuring that the metal building can support the anticipated gravity loads while maintaining safety and structural integrity.

By accurately calculating dead loads and live loads, considering load combinations, and conducting rigorous structural analysis and design, metal buildings can effectively account for gravity loads. This ensures that the structural elements are designed and constructed to safely support the weight of the building and any additional loads imposed on it during its intended use.

Overall, the "Pre-Engineered" in Pre-engineered Metal Building System means that every member of your metal building is engineered to account for the loading or movement detailed above. We at Peak Building Systems love getting into the weeds about this in order to better design and deliver structures that are made for every environment under the sun. We proudly stand behind every building we provide because we take the time to verify all of these loads before the steel ever touches your jobsite. Want to get into the weeds with us? Contact us today by clicking the button below or calling us at 720-282-5074.

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