Do steel structure and steel space frame have to do fire protection?

Whether steel structure and steel space frame are painted with fire-retardant coating should be determined according to the fire risk category. The "Code for Fire Protection Design of Buildings" explicitly stipulates that Category D and E are not necessary to be painted, but Category C and above must be. Steel as a building material has some unavoidable defects in fire protection. Its mechanical properties, such as yield point, tensile strength and elastic modulus will drop sharply due to the increase in temperature. Therefore, it is very necessary to make steel space frame and steel structures for fire protection. Steel structures and stainless steel space frame usually lose load-bearing capacity at a temperature of 450 to 650°C, and then they occur great deformation that would result in the bend of columns and beams. This excessive deformation will make the steel unusable. Generally, the fire protection limit of unprotected steel structure is about 15 minutes. The length of this time is also related to the speed at which the component absorbs heat. To make steel structure materials overcome the shortcomings of fire protection in practical applications, it is necessary to carry out fire protection treatment. The purpose is to increase the fire protection to the limit specified in the design code. There are various methods to prevent the deformation and collapse of the steel structure in the fire. The key is to adopt different methods according to different situations, such as using heat insulation and fireproof materials to prevent frame from direct burning, reducing the speed of heat transfer to delay the time of temperature rise and strength weakening. But no matter what method is adopted, the principle is the same.

How to reasonably reduce the engineering construction and processing cost of space frame structure

How to reduce the engineering construction and processing cost of space frame structure？ Let’s take a look.

First, we can pay attention to the size of the entire project. Although the space is fixed, we can reduce the size of the entire project by reducing the amount of coverage. Once the entire size is reduced, then the price of our project is definitely lowered accordingly, which we believe everyone can understand.

Second, if the size of the grid cannot be changed, then we can focus on its design. There are generally three different design schemes, and the material costs used are different, such as the triangular vertebral design. Compared with the quadrangular pyramid design, the material cost is much more.

Third, in addition to choosing a relatively simple design with less materials, we can also save in the materials of the entire product, such as thinning the inner wall of the stainless steel pipe to make the material of the entire steel pipe If it is reduced, a considerable amount of expenditure can be saved.

No matter what method of price reduction is, it’s all based on engineering safety.

Hoisting steps of steel space frame structure

     The connection point of the steel space frame structure is a key step to connect the components of the junction and transmit the load. The development of an effective connection point design plan is crucial to the safety factor of the steel space frame structure, the production and installation, the construction schedule and the project budget. Immediate hazard. The connection points of the space frame are divided into internal connection points and rubber bearing connection points. The design plan and structure should comply with the requirements of effective support, reliable force transmission, simple structure, and convenient manufacturing and installation. Frame connection points are divided into several categories, each of which is electric welded thick steel plate connection point, electric welded hollow ball connection point, anchor bolt ball connection point, immediate intersecting connection point and welded pipe connection point.

The lifting steps of the steel space frame:

     1. Side-by-side high and low-span roof hoisting: be sure to install the high-span first and then the low-span, which is beneficial to the flatness of the high- and low-span steel beams.

     2. Side-by-side installation of large span and small span: be sure to install the large span first, and then install the small span. To

     3. Installations with larger side-by-side rooms and fewer rooms: first hoist the larger room, and then hoist the smaller room. To

     4. Hoisting of prefabricated components under most engineering construction conditions, the longitudinal prefabricated components are hoisted first, and then the plan view prefabricated components are hoisted, that is, the comprehensive installation method is selected for lifting. The layout of the hoisting machine and the line of operation of the space frame: the installation of the space frame should integrate the structural characteristics of the project, site conditions, and the working half of the crane on the spot, and carry out the layout of the hoisting machinery and equipment and the line of operation beforehand. The overall planning of the crane makes full use of the high efficiency of the crane to ensure the orderly development of the lifting.

Large span, light weight, various shapes and beautiful appearance of space frame structure

Space frame structure is widely used as the roof structure of gymnasiums, exhibition halls, clubs, theaters, cafeterias, conference rooms, station hall, aircraft hangars, workshops, etc.

It has the characteristics of high industrialization, light weight, good stability and beautiful appearance. 

There are 6 advantages of the space frame： 

1. Large span-suitable for roofs of large space structures;

2. Space force-give full play to the strength of steel;

3. Light weight-saving steel;

4. Good earthquake resistance-hinged to the building, it is not easy to damage after being stressed;

5. Fast construction-short production period and shorter on-site construction time.

6. Beautiful structure-the structure itself has a modern flavor, full of boldness and beauty. 

Our company has been committed to space truss processing, design, production and construction for many years, and has been engaged in the design, processing, and construction of a number of large-scale grids in China. The understanding of the concept of Chinese green buildings has been at the forefront of space truss companies.

Our philosophy is that the designed space truss should not only be practical, but more importantly, it must be green enough to effectively save resources and achieve the best construction purpose.

Calculation of Bolt Ball

     The process of the bolt ball involves the angular position of chord member and web member and the size of corresponding bolt hole. Chord members are cross orthogonal, and the positions of web members are controlled by two sets of angles. One set is the intersection angle between the horizontal projection position of web member and chord member, and the other set is the angle of intersection between web member and its projection plane.

     The bolt ball can be calculated according to the size and thickness of the space frame provided by the design drawing.

Significance of bolt ball calculation:

1. Check the accuracy of the bolt ball processing drawing provided by the design.

2. Provide bolt ball processing drawings for lofting and guide processing.

3. Manually calculate whether there is overlap between the members.

4. When there is an angle of intersection between chord member and support, it can provide guidance for the processing factory to weld supports and support ribs.

The curtain wall is the external maintenance wall of the building

 We know that the curtain wall of steel structure building is actually the building's outer wall envelope structure, although it does not bear load, but relative to the main structure, it has a certain displacement ability or its own deformation ability.

It is a light decorative wall commonly used in modern large high-rise buildings. It consists of a panel and a supporting structural system. Decorative curtain wall basically has adornment effect, let us have a further understanding.

How to distinguish between walls and decorative curtain walls:

The glass curtain wall belongs to the maintenance structure and plays a basic role of enclosure. Decorative curtain wall: can be regarded as a building component, do not need to exist.

The definition of glass curtain wall is as follows: Building curtain wall: a building exterior wall or decorative structure composed of supporting structural system and panels, which has a certain displacement capacity compared with the main structure and does not share the role of the main structure. Glass curtain wall: Building curtain wall with glass as panel material.

hether the glass curtain wall is the key depends on whether the glass structure and the main structure of the whole building have a certain displacement capacity and do not share the role of the main structure. If the glass-supported foundation comes from the main body of the building, such as a steel structure supporting glass or aluminum alloy supported by columns, beams or walls of the main building, it cannot be called a glass curtain wall.

The curtain wall of the steel structure building can be understood as the external maintenance wall of the building. If there is a requirement of indoor heat preservation and waterproof, insulating glass or bonded glass should be used. Fire prevention and other measures should be taken between the floors. But if the decorative curtain wall does not have such a requirement, the decorative curtain wall is actually mainly based on the block, as long as beautiful, generally using glass or bonded glass, generally no inter-layer fire prevention facilities.

Method of winter construction of space frame

 If the space frame is constructed in the cold winter, we should pay attention to what the installation matters are. Today, I will briefly introduce it to my friends.

1. Before the installation of the space frame, the surface of the component should be cleared of ice, snow and dew, but the coating should not be damaged.

2. When assembling the space frame components, remove the rust, burr, soil, oil, snow and ice and other debris left in the joint 50mm, and keep the joint dry and without residual moisture.

3. Anti-skid spacers should be added when the cable is used to hoiste the network frame members. The node plates that are hoisted at the same time with the members should be bound firmly with ropes for the fixtures and other objects needed by the installers.

4. The electrode used under negative temperature shall not be exposed for more than 2 hours, and more than 2 hours shall be rebaked. The number of roasting electrodes shall not exceed 3 times.

5. When the space frame member is installed at positive temperature, the shrinkage of the member should be considered according to the difference of the ambient temperature, and technical measures should be taken to adjust the deviation in the construction.

Listen to me to introduce so much is there more understanding of the space framework, if you still do not understand or want to understand, you can open the contact information to find me.

In-depth analysis of space frame structure and space frame accessories

In recent years, the spatial structure of the world has been greatly developed. Space frame accessories and space frame structure are a kind of spatial space frame structure. The so-called "space frame structure" is relative to the "planar structure", it has the characteristics of three-dimensional function, and the space frame structure is also the expansion and deepening of the planar structure. In the development of the space frame structure, it is welcomed by people for its efficient stress performance, novel and beautiful form and fast and convenient construction. Especially in large-span, large-space stadiums, convention and exhibition centers, cultural facilities, transportation hubs and even industrial plants, space frame structures are used.

The cross-sections of space frame accessories and space frame structures should be determined according to strength and stability calculations. In order to reduce the calculated length of the compression rod and increase its stability, measures such as adding sub-rods and supporting rods can be adopted. The joints of the plate space frame and double-shell space frame made of steel mainly have three forms: cross plate joints, welded hollow spherical joints and bolted spherical joints. The cross plate node is suitable for the space frame fittings and space frame structure of the section steel rod. The connection between the rod and the node plate is connected by welding or high-strength bolts. Hollow ball joints and bolted ball joints are suitable for the grid structure of steel pipe rods. The nodes of the single-layer shell-type grid should be able to withstand bending internal forces. In general, the steel consumption of the nodes accounts for 15-20% of the steel consumption of the entire steel space frame structure.

After a century of continuous development of the space frame structure, in terms of structural form, in addition to the space frame and the reticulated shell, the membrane structure, the tensioned overall system, the open and closed roof, and the foldable structure are all new members of the space structure. In the early twentieth century, steel materials provided conditions for the development of grid structures, and subsequent aluminum alloys made the rods of the grid lighter. In recent years, composite materials, especially a large number of new building materials have been developed, which has had a strong impact on the development of space structures. In terms of material application, due to the continuous improvement of steel varieties and strength, more and more space structures use section steel, steel pipes, steel rods, cables and even cast steel products. To a large extent, the space structure has become a "spatial steel structure". With the advent of modern computers, some new theories and analysis methods, such as finite element method, nonlinear analysis, dynamic analysis, etc., have been widely used in space structure, and the calculation and design of space structure have become more convenient and accurate. The spatial structure is now ever-changing and diverse. It can be said that spatial structure has become one of the most important and active areas of contemporary architectural structure. 

Five requirements for temporary fulcrum for space frame installation

      1. During the installation of the steel space frame, the requirements for the temporary fulcrum are very high. The fulcrum and the elevation of the fulcrum should be arranged before installation. The temporary fulcrum should make the grid support uniform force and the force of the space frame members should be consistent. Pay attention to the stability of the foundation (scaffolding) of the temporary fulcrum, and pay attention to prevent the fulcrum from sinking.

2. the support of the temporary fulcrum is very good to use a jack, so that it can be adjusted gradually during the installation process. Note that the adjustment of the temporary fulcrum should not be the adjustment of a certain point, but also consider the uniform force of the surrounding space frame. Sometimes this local adjustment will deform and bend individual rods. 

3. When disassembling the temporary fulcrum, it should be noted that several groups of fulcrums should be lowered synchronously. During the descending process, the descending range should not be too large, it should be gradually divided into sections and stepped down proportionally, or with equal steps of no more than 100mm method to remove the support point.

4. When installing and welding the welded spherical space frame, the deformation of welding shrinkage should be considered, especially the overall hoisting space frame and strip space frame. After installation on the ground, the welding deformation and shrinkage value should be mastered before welding. Because when the steel space frame is welded, the welding points (heating surface) are all on the upper side of the plane space frame, so it is very easy to deform the structure due to unidirectional heating.

The general deformation law is that after the space frame is welded, the four peripheral supports will gradually tilt up freely. If the deformation is large, the arching degree of the original plan will be offset. If arching is not considered, the welding will produce a large deflection value, which will affect the quality requirements for acceptance. Therefore, one-way heating deformation factors should be taken into consideration when constructing the welded ball space frame.

5. Pay attention to the force of the support after the space frame is installed. Some supports are allowed to be welded, some should be free ends, and some need to be limited, so the construction of the space frame supports should  strictly follow the design requirements. 

What should be paid attention to when making and installing the space frame structure pull rod

 According to the actual situation of the ground of the space frame installation construction site, there is no need to deal with the bottom of the pull rod.

 

1. The structure of the pull rod

The single-leg pull rod consists of an independent steel pipe, a base, a pulley block and a winch. The pull rod is made of steel pipe, and the top is pulled with a wind rope, which is fixed on the frame beam and column, and all the wind ropes must be tightened. 

The top and bottom of the pull rod are respectively equipped with a pulley block and a guide pulley block, and the wringing mill is used to lift heavy objects. The cable wind rope and the steel wire rope of the pulley block shall be calculated and determined. The top of the pull rod is welded with a head steel plate with holes, and a clamping plate is set to tie the cable wind rope. A cantilever plate is set close to the top to hang a hoisting tackle. The lower part of the pull rod is supported on a square timber. To prevent displacement, it must be anchored with a rope.

 

2. Fabrication of the drawing rod of the steel space frame. The steel pipe used for the lifting and drawing rod of the space frame is transported to the construction site, the assembly site is selected, the length measurement and appearance inspection of the steel pipe are carried out, and the assembly and welding of the drawing rod is started. Use bright-colored paint to number and identify the pull rods, which is convenient for unified management. After the assembled pull rod is re-tested and calibrated, install the pulley block and the steel wire rope, pay attention to the running direction of the rope, and install and arrange the cable wind rope. After all the assembled pull rods are checked, they can be put in place.

3. For the installation of the drawing rods of the steel space frame, a square timber is placed at the bottom of the drawing rods. The pull rod can be lifted and placed in a designated position by a car crane, and at the same time, the corresponding cable wind rope is stretched and fixed. The lower end of the cable wind rope is fixed on the steel column to ensure the correct position, clear direction and firm fixation. The lower part of the pull rod is provided with a bottom tie rope corresponding to the upper part, and the outer end is tied to the surrounding steel column, and the bottom of the pull rod is firmly connected and fixed to prevent horizontal lateral movement.

 

4. Take protective measures for the connection between the steel wire rope of the space frame structure and the building. First, the section of the steel pipe with a diameter of 89mm is divided into three, and then the cut steel pipe is placed at the corners of the building to protect the building from damage and wire rope damage due to broken wires. There are no less than four fixed buckles for the steel wire rope, which are required to be firm and reliable without looseness.