Precautions for installation of steel structure space frame in autumn and winter

 1. According to the average temperature specification, the data map of the installation sequence of the steel components is compiled, and the installation is carried out in strict accordance with the sequence during construction.

2. When assembling the space frame components, expand and assemble from the inside to the outside according to the order specified by the process, and do a test to determine the shrinkage value of the weld that needs to be reserved during the assembly at low temperature.

3. When the steel components are made at normal temperature and installed at low temperature, the shrinkage of the components should be fully considered according to the difference in ambient temperature, and technical measures to adjust the deviation should be taken during construction.

4. The columns and main beams installed at negative temperature should be corrected immediately. After the correct position correction, they should be permanently fixed immediately. The components installed on the same day should form a stable space system.

5. When the high-strength bolted joint is installed, the friction surface of the component shall not have snow and ice, and shall not be in contact with dirt, oil and other stolen goods.

6. When using steel cables to hoist steel components, anti-slip spacers should be added, and the gusset plates that are lifted at the same time as the components, and the fixtures and other items that the installer needs to use are securely tied with ropes.

7. When the steel structure space frame is installed on site, it is necessary to build a protective shed in case of rain and snow or when the wind speed is above 6m/s.

Installation steps of the lower chord of the flat steel space frame structure

 1. Familiarize with the drawings before installation, recheck the size and quantity of each component to be installed, and place each component in the order of installation to facilitate the installation of the steel space frame structure.

2. Before installation, check the quality of the threaded fasteners, clean the screw holes and threaded fasteners, and screw them in after they are clean. The high-strength bolts should be tightened in place to ensure that the downward deflection of the entire space frame structure is not affected.

3. According to the numbered positions of the rods and balls on the drawing, install the lower chord balls and rods in the first span to form a longitudinal plane grid, and tighten the high-strength bolts.

4. After installing the support in the first span, align the axis and centerline of the column top. Use a level to correct the elevation if there are errors.

5. Arrange the temporary fulcrums according to the required elevation of the bottom chord to ensure the elevation position of the bottom string.

The temporary fulcrum can be made of on-site scaffold steel pipes, so that the lower chord grid of the first span can pass through the temporary fulcrum.

SAFS Steel Structure Official Website: https://www.safsteelstructure.com/

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What regulations should be complied with when lifting or jacking the space frame structure

 When lifting or jacking the space frame structure, the following requirements should be met:

The construction shall be carried out in accordance with the regulations of the construction organization design.

Steel pipe welders on the construction site shall pass the all-position welding procedure qualification and welder examination of the welded ball joints and steel pipe connections before they can participate in the construction.

The hoisting method should be determined comprehensively according to the stress and structural characteristics of the space frame, under the requirements of quality and schedule, and combined with the local construction technical conditions.

 

The selection of the position and number of lifting points for the hoisting of the grid shall comply with the following requirements:

It should be consistent with the force condition when the space frame structure is in use or the members must meet the force requirements after checking;

The reaction force at the lifting point should be less than the load capacity of the lifting equipment;

The load of each lifting equipment should be close.

After the hoisting method is selected, the reaction force of the hoisting point, the internal force and deflection of the members, the stability of the supporting column and the horizontal thrust of the space frame under wind load should be checked separately during the construction phase of the space frame, and reinforcement measures should be taken if necessary. .

All welds of the welded joint space frame shall be visually inspected and recorded. For the butt welds of the tie rods and balls of the large and medium-span steel pipe space frame, non-destructive inspection shall be conducted, and the number of samples shall not be less than 20% of the total number of welds. The quality standards shall comply with the current national standard "Code for Acceptance of Steel Structure Engineering Construction Quality" 》(GB50205) the requirements for level 2 welds.

Picture taken from: https://www.safsteelstructure.com/

The benefits of steel structure design for the present and the future

 The benefits of steel structure design can be seen from both the present and the future. The advantage of steel structure design for the present is that it can spend less cost to get the maximum value. Because the steel structure design is generally used in social public buildings. The large-scale use of steel structure design is equivalent to saving money for the country, and it is also a way to enhance the country's comprehensive national strength. After all, the money saved is a lot. The money can then be used for other infrastructure construction. Of course, saving money is only one of the many benefits of steel structure design for contemporary times.

The advantage of steel structure design for the future is that it allows future generations to see the crystallization of our wisdom. This is just like the situation where we sincerely sigh after seeing many things left over from history. The younger generations will invent many other new things, but they will still be proud of the design of the steel structure built by their ancestors. No matter how the future develops, the emergence of steel structure design is an advancement in society and productivity. The thoughts and concepts of these steel structure designs are worthy of scrutiny and have been verified by history. Therefore, steel structure design is a real wealth for people in the future.

Picture from: https://www.safsteelstructure.com/

Introduction and installation of interval space frame structures

     The interval space frame structure is a new type of space structure system developed form the open-web space frame structure system. The structure system is composed of the open-web space frame layer and the space frame or space truss supporting the open-web space frame vertically arranged alternately. When the span of the space frame structure is large, the height of the space frame is increased accordingly. Therefore, for a large-span structure, the space of the open-web space frame layer can be used as a separate building layer. This kind of open-web space frame in not only a structural layer but also a building layer, but also has a large spanning ability. This make the new structural system have the architectural function of large and small spaces intersecting each other, which overcomes the previous large space standing at the bottom or top of the building. Some architecture limitations are particularly suitable for large span high-rise buildings.

The composition of different structures makes the structure have different stress characteristics. Based on the ordinary interval space frame structure, we analyzed and studied the addition of oblique webs around the grid, the unequal spacing of the grid grid, and the support of the grid as the space. The internal force distribution and deformation of different types of interval space frame structures such as trusses under vertical and horizontal loads. At the same time, the internal force and deformation changes of the structure when the floor is involved in work and prestressing are further analyzed, and the conclusions of the analysis and calculations It provides a theoretical reference for the selection and design of the structure in engineering design.

After studying the force characteristics of the structure under the vertical load in detail, based on the flexibility method of the cross beam system considering the shear deformation and the layering method of the multi-layer frame under the vertical load, interval vierendeel grid structures method is proposed. The simplified analysis method of the open-web grid structure has made a great improvement to the simplified method proposed by some scholars in the past. This method has higher calculation accuracy and is especially suitable for the preliminary design of the structure.

For interval space frame structures, the usual concept is that the structural system has poor collapse resistance under strong earthquakes. Through the analysis of the natural vibration characteristics of different types ofinterval space frame structures, the stiffness of the space frame and the rigidity of the supporting structure are revealed The impact of the change of the structure on the natural frequency and mode shape of the structure. The response spectrum method has studied the seismic performance of the structure under three-dimensional one-dimensional excitation and simultaneous excitation in the three directions of the earthquake. The internal force and deformation of the structure under the action of the earthquake are obtained, and the response spectrum method is used for seismic design. Type interception order. Time history analysis method is used to study the linear elastic response of jump-story grid structure under frequent earthquakes and the elastoplastic response under rare earthquakes. The elasto-plastic response of the structure under rare earthquakes shows that the structural system can meet the design principle of “no collapse in large earthquakes” under the conditions of selecting appropriate cross-sections and reinforcement ratios. The analysis results of the response spectrum method and the time history method are compared, which can guide the seismic design of this new type of structural system.

Reasons for loosening of space frame bolts in gas station

A gas station is a place where gasoline is added to motor vehicles. The appearance must be more conspicuous and appealing to consumers.Gas stations with good appeal can attract a large number of customer resources and increase profits for gas stations.The shape design of the gas station using the space frame structure is generally very neat and simple. The canopy and the column constitute the main body of the structure.The area around the canopy is usually decorated with aluminum slabs and light box cloth. The upper plan is usually covered with color steel plates, and the lower plan is set for lighting fixtures. Ceiling are not required. If suspended ceilings are required, aluminum gussets are generally used. Many gas station space frame have loosening of space frame bolts during the installation period or a period of time after installation. There are many factors that lead to this type of situation.All of us must deal with it according to specific circumstances.

Picture taken from: https://www.safsteelstructure.com/

1. Installation by non-professional staff: The space frame construction team is still not professionally trained, and feels that it is caused by tightening the sleeve. Many non-professional staff, who have not undergone professional training, seem to be tightened, but in fact they are not tightened in time. Perhaps the construction site has not been able to deal with the problem in time, but it will loosen after a period of application, which is very dangerous.

2.  After the roof installation was completed, the sleeve was loosened after delivery, the rubber support was rusted, and the components were damaged. After this problem occurs, it will seriously harm the installation of the space frame design scheme. The bearing structure is changed. It is very easy to cause safety hazards and safety accidents.

If you have any of the above problems, I suggest to stop and repair it in all directions.Each component of the space frame is carefully inspected, and repairs are carried out purposefully. In serious cases, it must be disassembled and installed again, and painted again.

The space frame structure has a small steel content, and the parts are all prefabricated components of the factory. The installation is convenient and the construction period is very short, which is more suitable for rushing to the construction period.

What is the H-beam commonly used in steel structure workshops?

Steel structure workshop H-shaped steel is a kind of economical section and high-efficiency section with more optimized cross-sectional area distribution and more reasonable strength-to-weight ratio. Because the section and the English letter "H" is the same name. H beam has been widely used for its advantages of strong bending resistance, simple construction, cost saving and light structural weight. H-shaped steel is mainly used in industrial factory, civil construction, municipal engineering, etc., and light H-shaped steel is very suitable for the manufacturing of containers, mobile houses, and various garages.

1. The expression method of hot-rolled H-beam:

H-beams are divided into three types: wide-flange H-beams (HK), narrow-flange H-beams (HZ) and H-beam piles (HU).

 

The expression method is: height H width B web thickness t1 wing plate thickness t2, such as H-beam Q235, SS400 200200812, it is expressed as a wide flange H-beam with a height of 200mm, a width of 200mm, a web thickness of 8mm, and a wing plate thickness of 12mm. The grade is Q235 or SS400.

Advantages of hot rolled H-beam:

H-shaped steel is a new type of steel for economic construction. H-shaped steel has economical and reasonable cross-section shape and good mechanical properties. During rolling, each point on the cross-section extends more uniformly and has low internal stress. Compared with ordinary I-beams, it has the advantages of large section modulus, light weight, and metal saving, which can make buildings The structure is reduced by 30-40%; because the legs are parallel inside and outside, and the ends of the legs are right-angled, they can be assembled into components, which can save welding and riveting work by up to 25%. It is often used in large buildings (such as factory buildings and high-rise buildings) that require large intercepting capacity and good cross-sectional stability, as well as bridges, equipment foundations, and supports.

The Hot-rolled H-beams can reasonably allocate the height-to-width ratio of the cross-section size according to different purposes, and have excellent mechanical properties and superior use performance.

2. Welding H-beam production process

Steel plate-automatic slitting-assembly-automatic submerged arc welding-flaw detection-flange correction-web correction-end surface processing-sand blasting and rust removal-painting. The automatic submerged arc welding production line is controlled by a microcomputer to ensure the dimensional accuracy of the H-shaped steel produced, and the quality of the welds meets the national standards. The steel structure building has a simple and lightweight structure, which expands the internal space of the building, saves steel, and has a short installation period. The roof and walls are made of color profiled steel plates, which makes the building more beautiful.

H-beam weight (2*b*t2+h*t1-2*t1*t2)*7.85*L/1000000

H-beam surface area (4*b-2*t1+2*h)*L/1000

The above is the H-beam commonly used in steel structure workshops.

Five support methods of space frame structure

The support methods of the space frame structure include peripheral support, point support, combination of peripheral support and point support, two-sided and three-sided support, etc.

As the roof of a large-span building, the space frame structure should firstly meet the requirements of the building layout and the use function of the building. This structure has greater spatial rigidity and is more sensitive to the rigidity and stability of the supporting member. From a mechanical point of view, the support of the frame structure can be divided into two types: rigid support and elastic support.The former means that there is no vertical displacement under load, there can be horizontal displacement, or no horizontal displacement. It is generally suitable for the space frame to be directly placed on a column, wall, or reinforced concrete beam with greater rigidity;The latter generally refers to the situation where the free side of the three-sided support space frame is equipped with anti-beam support, truss support, and cable support.

When it is not allowed to set up columns on one or both sides of the space frame at the expansion end of industrial plants, hangars, hull workshops, gymnasiums, etc., the space frame needs to be designed in a form that supports three sides and one side is free. Mixed support is suitable for large steel column industrial plants, warehouses, exhibition halls and other buildings.

Reasons for bolt loosening after installation of space frame structure

When the space frame structure is installed, or a period of time after installation, the high-strength bolt sleeves of the space frame structure are loosened. There are many reasons for this situation, we need to analyze and deal with the specific situation:

1. Installation by undocumented workers: space frame workers have not received professional training, and they feel that they are tightening the sleeve. Many non-professional workers have not dealt with it well, and may not find the problem in time on the spot. However, it is very dangerous to loosen after a period of use.

2. After the roof panel was installed, the sleeve was loosened, the support was rusted, and the rod was damaged during use. These will seriously affect the carrying capacity of the space frame design, change the force structure, and cause hidden danger accidents.

For the above two problems, I personally suggest to stop using it and check and repair all aspects. In particular, each component of the space frame must be carefully checked and repaired in a targeted manner. The serious problems must be disassembled and reinstalled, and then repainted.

Picture from: safsteelstructure.com

How to inspect the steel structure space frame engineering coatings

In modern society, people's living standards have been greatly improved, and their tastes are getting higher and higher. There are also certain regulations for the aesthetics of engineering buildings. There are also certain regulations for common coatings for large-scale engineering buildings. Now let’s introduce how to test the construction coatings for steel structure space frame engineering. 

Inspection quantity: 10% of the number of prefabricated components shall be sampled for inspection, and similar prefabricated components shall not be less than 3.

Inspection method: check with a gray knife.

Do not miscoating, leakage coating, coating should not molt and rust.

Inspection quantity: all

Inspection method: vision inspection

                                          Picture from: safsteelstructure.com

Steel structure space frame inspection method: check the quality standard certification materials, Chinese label and test report of the product.

The types, specifications, characteristics, and quality of raw materials such as steel structure fireproof coatings, paints, paint thinners and epoxy curing agents should comply with the current standards of our country's product implementation standards and design plans.

The anti-rust treatment of the surface of the steel frame structure before painting shall comply with the relevant laws, regulations, specifications and design plans of the current standards. The surface of the treated stainless steel plate shall not have rust, weld bead, weld slag, oil stain, dust, water and burrs, etc. When the design scheme is not specified, the derusting grade of the steel frame structure surface should meet the requirements.