What Steel Structure

As a breakthrough technology in the field of modern construction, steel structure is widely used around the world today. Its outstanding advantages make it an indispensable part of construction projects. From skyscrapers towering over city skylines to large bridges spanning rivers, steel structures are everywhere, giving our cities a solid backbone.

Its strength and stability make it a solid barrier against natural disasters such as wind and earthquakes, providing safe and reliable living and working spaces. In addition, steel structures’ outstanding plasticity and flexibility have allowed designers to put their ideas into practice and create many iconic architectural works.

It gives the building a sense of beautiful lines and structure and dramatically shortens the construction period, providing a solid guarantee for the efficient progress of the project. Therefore, it is not an exaggeration to say that steel structure has become a key driving force in the field of modern architecture, providing unlimited design possibilities for architects and, at the same time, bringing unprecedented development opportunities to society.

Advantages of Steel Structures

Steel structures have become an integral part of the modern construction industry due to their exceptional strength and stability, as well as their outstanding flexibility and malleability. With abundant design space, it is also a safer, more stable, and flexible building.

Strength and Stability

Steel structure stands out for its excellent strength and stability and has become one of the preferred materials for modern construction projects. In the face of natural disasters, steel structures show unrivaled resistance to wind and earthquakes. Its high degree of toughness and load-bearing capacity enables steel structures to maintain the stability of buildings under extreme conditions, thus protecting the lives and properties of people.

Flexibility and malleability

he steel structure has fantastic flexibility and plasticity, which can be adapted to different design and construction requirements. Whether it is a high-rise building, a bridge, a sports stadium, or an industrial facility, steel structures can respond to different scenarios in various shapes and sizes. Its customizability and adaptability allow engineers to find the optimum balance between creativity and practicality to create architectural works with unique characteristics.

Through proper design and fabrication, steel can be machined into various shapes to meet a particular project’s needs. This flexibility makes steel an efficient building material and brings unprecedented design freedom to the construction industry.

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Types of Steel for Steel Structures

The steel used in steel structures is usually based on specific project needs and design requirements, so there are many different specifications and types. Below are some of the standard structural steel specifications and their characteristics:

Plain Carbon Structural Steel: Q235, Q345: These are the two types of ordinary carbon structural steel specified in Chinese standard GB/T 700. Q235 is usually used for general engineering structures, while Q345 has higher strength and durability and is commonly used for more demanding projects.

Alloy structural steel:20Cr, 40Cr, 65Mn: These steels contain a certain proportion of alloying elements to improve their strength, hardness, and wear resistance and are suitable for some special engineering needs.

Low alloy high strength structural steel: Q420, Q460, Q550: With high strength and toughness, they are usually used for large-span bridges, high-rise buildings, and other projects.

Weathering steel: Corten steel (ASTM A242, A588), with good weather resistance, commonly used in outdoor buildings and bridges, can reduce maintenance costs.

Stainless Steel:304, 316: Commonly used in unique environments, such as marine environments or where corrosion resistance is required.

Hot rolled steel sheets: SS400, A36: Usually used to manufacture steel structural components, such as beams and columns.

Cold rolled steel plates: DC01, DC04: Used on some occasions that require high surface quality and dimensional accuracy.

H-beam, angle, channel: These are standard steel structural members used to erect building frames and support structures.

Pipes: Welded steel pipe, seamless steel pipe: commonly used for piping, bearing, and other parts in steel structure.

Steel Structures Types

Types of Steel Rigid Frame Structures

Steel rigid frame is a structure commonly used in building and bridge projects, characterized by high stiffness and stability in the horizontal direction. The following are some common types of steel structure stiffeners:

Planar rigid frame (2D rigid frame)

Planar stiffeners consist of horizontal beams and vertical columns that can resist horizontal loads in the plane (e.g., wind loads or seismic forces) but have a weaker response to loads in the vertical direction. Planar stiffeners are suitable for most building structures.

Spatial Rigid Frame (3D Rigid Frame)

The spatial rigid frame is characterized by high horizontal and vertical stiffness and can resist loads in all directions. It consists of horizontal beams, vertical columns, and diagonal rods and is usually used for high-rise buildings and large-span structures.


A truss is a structure composed of multiple rods and is usually used in projects such as bridges and flyovers with large spans and buildings requiring large openings.

Rigid Frame

The rigid frame is a wooden structure composed of horizontal beams and vertical columns, which can effectively resist horizontal and vertical loads. It is usually used in building projects that require high stability and rigidity.

Frame Structure

The frame structure combines beams, columns, and lateral bracing to provide high stability and stiffness. It is widely used in multi-story and high-rise buildings

Giant truss

Giant truss is usually used in building or bridge projects with vast spans and can provide excellent load-bearing capacity and stability due to its structural characteristics. Advantages of Steel Structures

Steel frame structure

Span and Column Spacing for Steel Buildings

The length and width of a steel building refer to the dimensions of the building in the plan. At the same time, span and column spacing are two important dimensional parameters that play a crucial role in design and construction.


Span refers to a building or structure’s horizontal distance between two pivot points (e.g., columns or walls). In structural steel buildings, span is often used to describe the length of a beam or truss and can also be used to describe the size of the main span of a bridge.

The span directly affects the stability and load-carrying capacity of the structure. Larger spans require more robust materials and structural design, so span size significantly impacts the project’s cost and complexity.

Column spacing

Column spacing is the horizontal distance between the centers of two adjacent columns inside a building. In steel structure buildings, the size of column spacing affects the layout and use of the internal space of the building and also affects the stability and load-bearing capacity of the structure.

Reasonable setting of column spacing is the key to ensuring the reasonable use of space inside the building. Larger column spacing can provide greater spatial freedom but will also impact the structure’s stability and, therefore, needs to be weighed in the design process.

For example, if considering the design of a warehouse, its length can be expressed as the distance between two opposing walls, while its width can be defined as the distance between two adjacent columns. In this way, the designer can determine the most appropriate span and column spacing according to the expected functional and structural requirements, thus achieving an optimal layout of the building’s internal space.

Span And Column Spacing For Steel Buildings

Roof Slope

Roof slope refers to the degree of inclination or the angle between the roof surface and the horizontal plane. It is an essential parameter in architectural design, which directly affects the appearance of the Roof, its drainage performance, and stability in the event of natural disasters such as snow and rain.

The slope of a roof is usually expressed as “/12”, which is the number of feet of vertical rise per unit of horizontal distance. For example, if a roof is said to have a slope of “4/12”, the Roof rises vertically by 1 foot while advancing horizontally by 4 feet.

Here are some common types of roof slopes

Flat Roof (0/12): virtually no slope; the Roof is entirely flat and is suitable for some modern building designs, but drainage needs to be considered.

Low-slope roofs (1/12 – 3/12): this slope is suitable for commercial buildings and some modern residential designs and usually requires measures to ensure drainage.

Medium Slope Roofs (4/12 – 6/12): this is a standard range of residential roof slopes, providing good drainage and some flexibility in design.

Steep-slope roofs (7/12 and above): this pitch is commonly used in traditional houses and provides good drainage performance but requires more care in structural design.

Therefore, when selecting the type of steel building, consideration should be given to the different architectural designs and functional requirements, and the corresponding type of metal building roof slope should be selected. Choosing the proper roof slope will ensure that the Roof can remain stable under various natural conditions and will also affect the overall appearance and style of the building.

Steel frame structure Roof Slope

Steel Eave Height

Eave height is the vertical distance between the top edge of a building and the ground. In the case of steel buildings, the choice of eave height affects the building’s appearance, functionality, ventilation, and maintenance. Here are some of the advantages, cost implications, and determinants of eave height:


Visual Impact: Higher eave heights can make a building appear more grand and imposing, enhancing the overall visual impact.

Ventilation: Higher eaves height improves ventilation inside the building, facilitating airflow and improving indoor comfort.

Accommodate Functional Needs: Higher gable heights can provide more space to accommodate equipment goods or specific functional needs, such as ample equipment storage, production lines, etc.

Accommodate Large Vehicles or Equipment: Higher eave heights can accommodate taller vehicles or large equipment for industrial buildings.

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Cost Implications

Construction Material Costs: Higher gable heights require more steel and other structural materials, which can increase the cost of construction materials.

Construction Costs: Higher eave heights increase the height of the building, which may require additional construction equipment and workforce, thus increasing construction costs.

Maintenance Costs: Higher eave heights may make future maintenance and cleaning more difficult, affecting maintenance costs.

Determining factor

Functional Requirements: Different functions require different heights; e.g., industrial buildings may require higher elevations to accommodate large equipment, while commercial buildings may focus more on appearance and comfort.

Building design and style: The style and character of the building design will influence the choice of eave height; for example, modern techniques may focus more on a clean, airy look, whereas traditional styles may take higher eave heights into account.

Budgetary constraints: The budget is an important consideration and will directly impact the materials and construction resources available for the building.

Regulations: Local building regulations and standards may also place specific requirements and restrictions on eave heights.

Steel Bracing

Bracing in steel structures is an essential structural element that supports, stabilizes, and resists external forces in a building. The designer will choose the appropriate type of bracing according to the specific building structure and engineering requirements and arrange it in the structure reasonably to ensure the stability and safety of the building. Below are some common steel bracing styles and their functions:

Diagonal Bracing

Diagonal braces are diagonal rods or lines connected in the structure, usually connected between beams and columns, trusses, and other structural elements to form an “X” shape. They can effectively transfer the horizontal and vertical loads of the structure to the foundation, improving the system’s overall stability and reducing the risk of structural distortion.

Horizontal bracing

Horizontal braces are steel rods or members connected horizontally to the structure, usually between columns or at the top of trusses. They can resist horizontal forces and prevent lateral displacement of the system, thus maintaining the stability of the structure.

Vertical Bracing

Vertical braces are steel rods or members attached vertically to the structure, usually at the top and bottom of the building. It prevents the system from deformation and vibration in the vertical direction and ensures the vertical stability of the structure.


A truss is a structure of multiple rods, usually used to support large-span structures such as bridges and flyovers. Through its particular structural form, it can effectively transfer loads to the foundation while maintaining the stability and strength of the system.


X-braces are diagonal rods connected to the structure in a cross-woven manner, usually in the external frame of the building, forming an “X” shape. They can effectively improve the structure’s overall stability and are particularly suitable for resisting lateral loads such as earthquakes.


A mast is a vertical structure usually used at the top of a high-rise building as part of the structure. It can provide additional support to prevent lateral displacement of high-rise buildings under conditions such as wind loads.

Steel bridge support arm

Structural Steel Connections

When it comes to structural steel connections, there are several common ways in which they play a vital role in building construction. Below is a description of each type of connection:

Bolted connection

A bolt connection is a standard and reliable connection usually used to connect the members of a steel structure, such as between a beam and a column. This connection uses bolts to hold the members together, usually through pre-designed holes.

The advantage of the bolted connection is that it is easy to dismantle, allowing the structure to be dismantled and altered if required. At the same time, it provides a high degree of accuracy and tightness, ensuring the stability and strength of the connection.

Welded connections

A welded connection is a way of permanently joining two members by melting their contact surfaces. Welding is usually used for structural components that require higher strength and stability, such as trusses, braces, etc.

The advantage of a welded connection is that it provides a solid relationship and usually has a better appearance and overall structural performance. However, welded connections are not easily dismantled and may be more complex than bolted connections when parts of the structure need to be disassembled or replaced.

Riveted connections

A riveted connection is similar to a bolted connection, but it uses rivets (a rivet is a metal rod held in place by a rivet cap at each end) instead of bolts. Riveted connections were more common in the past but are now generally replaced by welded or bolted connections.

Structural Steel Bolt Links

Pin connection

A pinned connection uses one or more pins to join two members together. This type of connection is often used where a degree of removability is required, as the pins can be removed relatively easily.

Fastener connection

A fastener connection is a method of joining members using specially designed fasteners. This type of connection is usually used for smaller structures such as steel plate bridges.

Structural Steel Design

Structural steel design is an engineering design area involving steel as the primary structural material. It includes the following significant aspects:

Structural analysis

During the design phase, the engineer first conducts a structural analysis to determine the static and dynamic loads to which the building is subjected. These loads may come from wind, rain, snow, earthquakes, use loads, and other factors. By analyzing the effects of these loads, the engineer can calculate the forces and moments, etc., that the structure needs to withstand.

Component Selection

Based on the structural analysis results, the engineer will select the appropriate type, gauge, and size of steel to meet the structural requirements. This may cover various members such as beams, columns, trusses, etc.

Connection Design

Connections in a steel structure are crucial as they determine the stability and safety of the entire system. Engineers will design suitable connections, including bolted connections, welded connections, etc.

Material Selection and Specification

According to the structural requirements and design specifications, engineers will select suitable steel materials and determine their specific specifications, strength, and other parameters.

Load Calculation and Structural Design

Based on the load analysis results, the engineer carries out the structural design and determines the size of the members, cross-section shape, and other parameters to ensure the safety and stability of the structure.

CAD Drawing and 3D Modelling

Engineers will use computer-aided design (CAD) software to draw structural drawings, including plans, sections, and elevations. 3D modeling software will also be used to create a 3D model of the structure for more intuitive analysis and review.

Construction Drawing Design

Upon completion of the design phase, the engineer will generate detailed construction drawings, including information such as specific dimensions of components, connection methods, material specifications, etc., for the constructor’s reference.

Codes and Standards Compliance

Engineers must follow national or regional building codes and standards when designing steel structures to ensure the system meets safety and quality requirements.


The steel structure is widely used in modern construction as an essential construction engineering material with superior strength, stability, and plasticity. Its key advantages include Excellent wind and earthquake resistance/Flexible and malleable design features/Making it one of the top choices for all construction projects.

By choosing the correct steel specification and using the right connections, engineers can design a steel structure that meets safety standards, is stable and reliable, and is, therefore, safe to operate and use for the long term. During the design process, engineers need to make comprehensive use of professional knowledge in structural mechanics, mechanics of materials, and other aspects and use computer-aided design software to ensure that the design and construction of steel structures are in the best condition.

If you are looking for a reliable steel structure contractor, KAFA will be your first choice. Contact us today, and let’s work together to create a safe, stable, and efficient steel structure project for your project.

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