The type of steel building structures includes the portal rigid steel frame, frame structure, truss structure, and grid structure. The advantages and disadvantages of different structural systems vary, and the forms of stress are also different.
The portal steel frame comprises a hot-rolled or welded section steel, cold-formed C/Z steel, and steel pipe as the main force-bearing components and adopts a light roof and wall structure. The Portal frame is the most common form of the light steel structure.
The rigid portal frame is a structure in which beams and columns are rigidly connected. It has the characteristics of simple structure, lightweight, reasonable stress, simple construction. Therefore, it is widely used in industrial, commercial, agricultural, and Institutional Buildings.
The steel frame structure is composed of steel beams and columns that can withstand vertical and horizontal loads. Columns, beams, bracing, and other members are rigidly or hingedly connected to form a flexible layout and create a larger space. It is widely used in a multi-story, high-rise, and super high-rise buildings, commercial office buildings, conference centers, and other buildings.
The steel truss structure is made up of several rods hinged at both ends of each rod. It can be divided into plane truss and space truss. According to the parts section, it can be divided into tube truss and angle steel truss. The truss is generally composed of the upper chord, lower chord, vertical rod, diagonal web, and inter-truss support. The amount of steel used in trusses is less than that of solid web beams, the structural weight is lighter, and the rigidity is greater.
The advantage of the steel truss is that it is used to form more significant members with smaller cross-sections. It is often used in roofs, bridges, TV towers, mast towers, marine oil platforms, and tower corridors of industrial and civil buildings.
The grid structure comprises many rods according to a specific rule, with small space stress, lightweight, high rigidity, and excellent seismic resistance. It is used as a gymnasium, exhibition hall, aircraft hangar.
Steel structure workshops are divided into light steel workshops and heavy steel workshops. The workshop’s structural system is mainly composed of steel columns, wind columns, parapet columns, roof steel beams, crane beams, inter-column bracing, horizontal roof bracing, wall girt, roof purlins, tie bar, and other components. The primary structure is the portal steel frame, which can be single-span, multi-span, or multi-story, with an economic span of about 24-30m.
The portal steel frame’s particular nodes include column foot node, beam, column to beam node, roof beam node, column and roof bracing, tie beam connection node, and gutter bracket.
For the steel frame structure, with the increase of the number of layers and height and bearing a large vertical load, the lateral resistance (wind load, earthquake action, etc.) requirements become the primary bearing characteristics of the frame.
The steel frame structure system is generally divided into frame structure, frame bracing structure, frame shear wall structure, and frame tube structure.
Frame structure: The frame is composed of columns and beams, which bear vertical and lateral forces. Steel columns generally use H-shaped steel, box-shaped steel columns, or steel tube concrete columns.
Frame bracing structure: The frame is composed of columns and beams, and bracings are provided between the columns to resist lateral forces.
Frame shear wall structure: similar to the frame bracing structure, except that the bracing is replaced with a shear wall to resist lateral forces.
The shear wall is generally a concrete slab or steel plate, or a steel-concrete composite structure with better lateral stiffness than bracing and is more flexible in layout, suitable for higher building structures.
Frame tube structure: The structure is generally composed of a reinforced concrete core tube and an outer ring steel frame.
The system form uses pure steel frames in the horizontal direction and arranges an appropriate number of vertical inter-column bracing in the longitudinal direction to strengthen the longitudinal rigidity, reduce the amount of steel used in the frame, and form a larger space.
Common nodes of steel frame structure include column foot node, beam to column node, beam to beam node, the node of column joint, bracing node, beam-on-column node, etc.
The truss is a structure formed by a plurality of rods hinged connected at each rod’s end and divided into a plane truss and a space truss. The sectional form of the parts includes tube truss, H-shaped steel truss, box-shaped truss, angle steel truss, etc. The truss is generally composed of upper chords, lower chords, vertical rods, web rob, and bracing between truss. The amount of steel used for the truss is less than that of the H beam, the structure has a lighter weight, and the rigidity is greater. It is widely used in high-rise buildings, large-span structures, and bridges.
The grid is a spatial structure formed by connecting multiple rods with nodes in a specific grid form. There are many types of grids, which are classified according to different standards. The different composition methods are divided into cross-truss system grids, triangular cone system grids, quadrangular cone system grids, and hexagonal cone system grids. The flat grid is mainly composed of chords, diagonal webs, intermediate nodes, support nodes, etc.
The steel structure building uses advanced design and processing technology and large-scale production methods so that the cost can be greatly reduced. Simultaneously, due to the simple and rapid installation, it saves many construction costs and enables enterprises or developers to put into production more quickly.
Traditional reinforced concrete buildings have a high civil construction cost and a long construction period. The cost is susceptible to unpredictable factors, such as natural disasters, construction in winter and rainy seasons, and rising material prices.
The steel structure building can be delivered and installed quickly. The installation is expected to be completed within four or five months after the contract is signed, and it is basically not affected by winter construction.
The construction speed of traditional reinforced concrete structures is slow, and the construction period can reach 8-10 months or longer.
The weight of the steel structure building is usually only equivalent to 1/6 of its design bearing capacity. The weight of components is much lighter than that of reinforced concrete components.
In traditional reinforced concrete buildings, the structure’s weight is often equal to its designed load-bearing capacity, and the prefabricated components are heavy, which requires high equipment for lifting.
Due to the lightweight of the steel structure building, the reaction force at the bottom of the column is small, saving many foundation treatment costs.
Traditional reinforced concrete buildings have complicated foundation treatment due to their complex self-weight. More than half of the total structure cost will be used for the foundation in poor soil quality.
Steel structure buildings have large deformations before destruction, which is easy to detect and avoid. Simultaneously, due to the lightweight and the joints’ mechanical properties, the steel structure has the excellent seismic performance.
Traditional reinforced concrete buildings are based on the material properties of concrete. Compared with light steel structures, reinforced concrete buildings are more prone to brittle failure, and their seismic performance is significantly lower than steel structure buildings.
The interior space of the steel structure building is spacious, with a span of up to 60m. It can be expanded and rebuilt relatively easily, and various industrial pipelines can be flexibly laid out.
The span of traditional reinforced concrete buildings is limited, and prestressing technology must be used to achieve a span of more than 15m. The internal space layout is limited, and there are many columns and large space waste. After its completion, it is more difficult to persuade its structure. The structural design is more complicated to cooperate with other professions.
Bolts can connect the steel structure building, and it can be easily disassembled, transferred, and assembled easily without much expense, and has strong mobility. There is basically no possibility of movement in traditional reinforced concrete buildings.