Instability analysis of steel space frame structure

 1. The steel space frame structure is divided into overall instability and local instability. Most of the overall instability is caused by local instability. When the slenderness ratio of the compression part or the bending part exceeds the allowable value, the stability will be lost. It is affected by many objective factors, such as load changes, initial defects of steel, and different supporting conditions etc.. Support is often ignored by designers or builders, which is also one of the reasons for the overall instability.

2. Due to the different positions of the hoisting points, the force of the pipe of the steel truss or space frame structure may change, resulting in instability; the overturning, collapse or deformation of the scaffold is mostly caused by insufficient connecting rods and no support.

Therefore, when designing the steel space frame structure, it should be designed by technical personnel with rich work experience. It should not be taken lightly and try to avoid the above-mentioned hidden dangers. Our company has more than 10 years of rich experience in the field of steel structure, professional and technical personnel, professional equipment, and won the trust of many customers.

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How to avoid deformation of bolt ball space frames

   The bolt ball space frame uses the bolted ball as the node between the steel rods, which plays the role of support and leverage. The bolted ball space frame is usually used outdoors, and it will be deformed due to some external factors. So how should we avoid the deformation of the bolt ball space frame?

1. The front page needs to be tied up during transportation, and some more support points should be added. Try to choose wood for padding, so as to avoid deformation of columns, beams, tie rods and other connecting parts during transportation.

2. Use two-point hoisting when loading and unloading the bolted ball net frame. If the bolt ball net frame is too long, a pole can be used and the lifting point can be appropriately increased.

3. When the bolted ball space frame is stacked, the number of stacked layers can be reduced. At the same time, it is necessary to appropriately increase the supporting points to prevent the bolted ball space frame from being deformed by compression.

Connectors such as bolted ball space frames often experience extrusion and deformation. In order to reduce the occurrence of these situations, you can learn more about the above information. Only in this way can the deformation of the connecting parts be avoided and reduced, and the utilization rate of the bolted ball space frame can be improved.

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7 advantages of space frame structure

 Most of today's industrial warehouses are built with a space frame structure. Why does the space frame structure have such magic to attract these owners? I have summarized 7 advantages to share with you:

1. Anti-earthquake disaster and anti-storm: the anti-seismic level is above level 8, and it can withstand level 11 storm (wind force 140km/h).

2. Anti-rust treatment and anti-corrosion: light steel structures generally use hot-dip galvanized steel plates and V-type connectors as the frame. Good rust resistance, high compressive strength and long service life. No distortion, no deformation, no erosion, firm structure. The design scheme of the steel structure has a service life of 50 years.

3. Safety and fire prevention.

4. Thermal insulation: The thermal insulation function is further improved. Building environmental protection and energy saving can reach 65%, exceeding the national regulations on building environmental protection and energy saving.

5. Protect the ecological environment.

6. Good sound insulation performance: meet the sound insulation requirements of workshops.

7. Space frame steel structure industrial warehouse are widely used in outdoor spaces: power plants, cement plants, clinker plants, etc. will build coal storage, cement or clinker warehouses.

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Roof panel installation steps of steel structure space frame

1. Check whether the purlins are installed correctly, and whether the steel prefabricated components are sprayed or not;

2. Before installation, according to the layout diagram of corrugated steel plate, classify and stack according to the type and specification. The corrugated steel plate faces upwards, the lap edge faces the installed roof edge, and is placed along the steel roof truss beams and laid manually;

3. The steel structure grid roof panel is laid at the eaves of the roof. In the whole process of installation, the straightness of the cornice line is used as the benchmark, and the positioning of the pull line is checked. The dislocation difference between the ends of the two adjacent panels should not be greater than 8 mm, and the slope of the roof panel is perpendicular to the datum point of the cornice;

4. Start from one side of the roof,put the first piece of roof board installation and location line.Pave the first corrugated steel plate, and fix it with screws after inspection;

5. After the first corrugated steel plate is fixed in place, install the next corrugated steel plate. When installing, place its lap edge on the front corrugated steel plate accurately. In order to ensure the installation position is accurate, clamp it with the previous corrugated steel plate with a tooling fixture, fix both sides of the corrugated steel plate, and then fix it with screws;

6. The length of the longitudinal lap of the corrugated steel plate is not less than 250mm, the lap joint is located at the purlin of the roof, the lap joint is sealed with glue and a row of waterproof rivets, and then fixed with screws;

7. Install the corrugated steel plate in place using the above method. For every 4 pieces of corrugated steel plate installed, check the flatness on both sides of the profiled steel plate. If there is any deviation, adjust it immediately and accurately measure the total width of the fixed profiled steel plate. , measure it once on both the upper and lower sides to ensure that no fan shape appears in the installation part of the corrugated steel plate;

8. After installing a certain number of roof bottom plates, start the installation of roof panel supports, and fix the supports and steel purlins with screws. Then lay insulation cotton, and ensure that the insulation cotton is installed tightly;

9. The installation of the steel structure space frame roof panel is basically the same as that of the thermal insulation cotton. When a piece of thermal insulation cotton is installed, a roof panel is installed. The installation method of the roof panel is the same as that of the roof bottom plate.

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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.

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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.

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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.

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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.

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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.