How to control the quality of bolted connection construction of steel structure engineering? The high-strength bolt connection project is also one of the most important sub-items of steel structure engineering, and it is also one of the weak links in the current construction quality, mainly in:​

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(l) Some high-strength bolts are shoddy (replace high-strength bolts with ordinary refined bolts);

(2) The surface treatment of high-strength bolts does not meet the requirements of the specification, including surface treatment, leveling and closeness, and quality of bolt holes;

(3) The tightening of high-strength bolts is not carried out according to the specifications. For example, the initial tightening and final tightening are completed at one time, no torque wrench is required, and it is entirely based on subjective estimates.

In order to ensure the construction quality of the high-strength bolted connection project, the supervising engineer must have a high sense of responsibility. While urging contractors to improve quality awareness, strengthen quality management, and implement quality assurance measures, work methods such as side-by-side supervision and parallel inspection are actively adopted. Only in this way can the construction quality of the high-strength bolted connection project be under strict control.

Introduction of four major systems in large-span steel structure engineering buildings

How many systems are there in large-span steel structure engineering buildings? Steel structure engineering is a direct reflection of the current level of construction in the construction industry. Therefore, both in industry and commerce, steel structure engineering has developed rapidly, and steel structure engineering has also attracted much attention. At present, in the field of steel structure engineering, there are mainly four kinds of structural models, the specific categories are as follows.

Image from SAFS Steel Structure Engineering Company.

1. Cold-formed thin-walled steel system. In this system, steel structural members are cold-formed with thin steel sheets into C-shaped and Z-shaped members, which can be used alone or in combination. However, self-tapping screws are used for the connection between components, and the stiffness of the joints is not easy to guarantee. It has poor lateral force resistance and is generally only used in residential buildings or villas with 1-2 floors.

2. The frame system. This kind of steel structure project is set up with steel frame both vertically and horizontally, and the doors and windows can be set flexibly to provide large bays. Therefore, it is widely used in multi-storey steel structure houses.

3. Frame support system. Under this system, steel structure engineering generally has multiple lateral force resistance systems. Beam-column connections and column foot connections can be designed as hinged semi-rigid connections. The construction structure is simple, the foundation mainly bears the axial force, and the size is small.

4. Frame-shear wall system, mainly used in low-rise residential buildings. Currently, it is widely used.

These four steel structure systems also constitute the main structural system of steel structure engineering. It also plays an excellent role in promoting the development of steel structure engineering.

Specific inspection items and methods for steel structure spherical space frame

The specific inspection items of the steel structure spherical space frame mainly include the following five aspects. SAFS steel structure will introduce the specific details to you:

1. The first is the inspection of raw materials. Check the factory certificate, test report, etc. of the material, and you can also sample for re-inspection.

2. Ultrasonic flaw detection is mostly carried out by sampling method when testing welds. If unqualified, sampling test is required.

3. The tensile and compressive bearing capacity testing is similar to the welding seam testing. Three pieces are randomly selected from each batch for tensile and pressure testing.

4. The surface of the welded ball needs to be checked with an arc-shaped die and a steel ruler. Spot check 5% of nodes according to various specifications, and require no less than 5 pieces of each type.

5. The detection of the thinning of the wall thickness of the finished ball is similar to the detection of the surface of the welded ball, but the method used is an ultrasonic thickness gauge, and the extraction method is the same.

The above are the specific inspection items of SAFS steel structure spherical space frame. If you want to know more details, please submit a message below.

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Steel structure sun sheds are widely used

In our daily life, the application of steel structure sunshade is more and more extensive. Why do so many builders like to use steel structure to build buildings? SAFS steel structure shares the following 6 points with you:

1. The strength of this building is very high, because most of the main body of the steel structure sun shed uses steel as the raw material for production and installation, so when it is used, the age will be increased accordingly.

2. We all know that steel is more prone to rust, and in order to reduce this situation, the steel structure sun shed has been treated with anti-rust treatment on the frame.

3. In order to make the shed feel brighter, the strength of the shed roof is strengthened, and the feet are firmly welded.

4. It has good impact resistance. Because of the stability of the structure, the steel structure sun shed can be well adapted to bad weather.

5. The appearance is simple and elegant, because the steel has good toughness, so it can well meet the needs of users when designing. The finished product designed is also in line with the aesthetics of the public.

6. Simple installation. Because most of this raw material is produced by factories, it can be installed quickly after mastering the corresponding technology during construction.

Xuzhou SAFS Steel Structure Engineering Co., Ltd.

Two elements of quality control of steel space frame structure processing

                1. Steel structure blanking control

Before cutting, the cleanliness, flatness, cutting size, section roughness, verticality, notch depth and groove angle of the steel surface meet the requirements; the surface of assembly and welding needs to be treated.

Setting out: The assembly of various components and parts, and the assembly of pre-assembled components require professional setting out workers to accurately stakeout on the machined surface and assembly large template. After setting out, it must be checked by an inspector to ensure that the geometry and angle of the component machining are accurate.

The drilling template, the connecting plate after drilling, and the gusset plate correspond to the body reference line; strictly control the eccentricity of the hole, the offset of the hole distance, the hole distance, the roundness and perpendicularity, and the surface quality of the hole wall and hole edge. In order to ensure the accuracy and quality of drilling, when using die drilling, a setting out worker must set out a line to mark the reference axis and the center of the hole.

2. Steel structure assembly control

Strength, rigidity, levelness and related fixtures of work platforms and tire frames; dimensions of details and special tires; parts material, number, size, machining accuracy, quantity, surface treatment of connections and welds; datum planes , datum line, cross center line and assembly position line of parts; assembly position, direction, angle, concentricity, verticality, camber, groove angle, blunt edge, gap, gasket seal and joint dislocation of parts; Assembly sequence and method, additional welding shrinkage and machining allowance; size, length, spacing, location and surface quality of tack welding.

Component assembly: Component assembly refers to spot welding positioning and fixing before submerged arc welding. Before assembly, the small material should be corrected, and the setting out personnel should draw the center line and positioning line. After passing the inspection, spot welding is fixed, and after inspection, it is delivered for formal welding.

Article source: https://songmoon0115.medium.com/two-elements-of-quality-control-of-steel-space-frame-structure-processing-26f89f8dd97a

Maintenance of steel structure space frame industrial plant

The steel structure space frame industrial plant has the advantages of beautiful design, diversified body shapes, bright colors, high factory production of steel components, low engineering cost, short capital construction period, simple installation and construction, and flexible layout. Steel has the advantages of light weight, easy design and calculation, recyclability and other advantages, so that steel structures are used in large quantities in contemporary industrial plants. At the same time, the maintenance of the steel structure workshop is very important in the later use. SAFS briefly introduces the maintenance and maintenance methods of the steel structure workshop in the later period of use.

The picture project is selected from: https://www.safsteelstructure.com/application-center/

The following are three maintenance methods for steel structure space frame industrial plant maintenance:

1. The steel structure workshop is the entire connection of the structural parts. Electric lighting equipment and wires cannot be directly tied to the steel components. It is necessary to set up wire pipes or wire groove blocking devices to avoid electric shock;

2. The steel structure components should be repainted and maintained every 3 years to prolong the overall appearance and service life of the steel structure workshop;

3. After the installation of the steel structure space frame workshop is completed, the owner cannot change the structure without permission, cannot remove any bolt components, and cannot add or reduce partition walls.

If it is necessary to change, it should be negotiated and agreed with the steel structure manufacturing company before the change

Advantages and disadvantages of steel structure space frame connection

 1. Welding

Advantages: strong adaptability to geometric frame shapes and simple structure. Without weakening the section, automatic operation can be realized, the connection has good airtightness and high structural rigidity.

Disadvantages: high material requirements, reduced bearing capacity of welding residual stress and residual deformation compression components, welded structure is more sensitive to cracks, and the problem of low temperature cold brittleness is obvious.

2. Riveting

Advantages: reliable force transmission, good toughness and plasticity, easy quality inspection, and good resistance to dynamic loads.

Disadvantages: complex structure, expensive steel and labor.

3. Ordinary bolt connection

Advantages: easy loading and unloading, simple equipment.

Disadvantages: The bolts should not be sheared when the accuracy is low. When the bolt precision is high, the processing and installation are complicated and the price is relatively high.

4. High-strength bolt connection

Advantages: The friction type shear deformation is small, the elastic performance is good, and it is more suitable for the structure of the follow-up load. The bearing capacity of the pressure bearing type is higher than that of the friction type, and the connection is compact.

Disadvantages: The treatment of the friction surface, the installation process is slightly complicated, and the cost is slightly higher. The shear deformation of the pressure-bearing connection is large, and it cannot be used in the structure that bears the dynamic load.

The geometric structure content is selected from: https://www.safsteelstructure.com/

Xuzhou SAFS Steel Structure Engineering Co., Ltd.

Space Frame Structure Engineering

 1. The quality of the steel structure space frame project is affected by many factors. The quality of the steel is one of the most important aspects. It directly affects the use time of the space frame. Therefore, the choice of space frame building materials is very important. , to avoid buying inferior products.

2. Under the background that the state advocates energy saving and recyclable materials, the space frame residential building will show a trend of geometric development. Among them, steel plates, hot-rolled H-beams, steel pipes, and cold-formed steels are the main products, and products with steel strength of Q345 and Q235 are the first choice of customers.

3. The space frame structure is generally composed of roughly the same lattice or smaller sized units (repeated). Often used in roof structures. The joints of plate space frame and double shell space frame made of steel mainly include cross plate joint, welded hollow ball joint and bolt ball joint.

Space frame structure engineering is a new type of energy-saving and environmentally friendly building system, known as "green building". Space frame engineering has huge development space due to its light weight, high strength, good seismic performance, and the advantages of recycling and comprehensive use.

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Techniques and details of high-altitude bulk loading of space frame roof structures

The space frame roof structure installation adopts high-altitude bulk, so it is necessary to set up an installation platform. In order to improve the construction progress, a scaffolding platform is adopted. The platform surface should be between 0.3 and 0.8m from the bottom chord of the space frame, and the space frame steel bar should be placed on the ground according to the construction sequence, and hoisted to the installation platform in sequence. Each lifting should not exceed 0.5 tons, and the lifting equipment should be hydraulic crane on site. After the components are lifted to the platform, they should be placed according to the installation position immediately to prevent the components from being stacked together. Before the installation of the grid, Before installation of each space frame,in addition to the careful inspection of the steel bar and bolt balls during production, the number check of the steel bar and the bolt balls and the inspection of the external dimensions should be carried out to match the positive and negative deviations of the steel bar and bolt balls.

Generally speaking, there are two main ways to install the space frame roof structure, one is the direct splicing of steel bar, and the other is a small unit installation. During the installation process, the above two methods can be combined and constructed at the same time, and the high-strength bolts must be in place when tightening. The multi-pass tightening method is adopted. After the bolts are tightened, the set screws are tightened. Finally, all the joints and the redundant bolt holes on the node ball are filled tightly with an oil brush, and two coats of anti-rust paint are applied.

Image credit: safsteelstructure.com

How to Control the Installation Deviation of the Bolt Ball Space frame

        There are generally deviations in the installation of the bolt ball space frame. How to reasonably control deviations during installation and avoid deviation accumulation? SAFS steel structure Engineering Company has organized three ways for your reference:

1. The embedded parts should be leveled and the axis of the spring should be leveled to ensure that the rubber bearings meet the installation requirements under the design standards. Properly dispose of embedded parts that do not meet the conditions.

2.  Prevent the overall space frame from settling before forming. Give enough grid support points on the actual operating platform.

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

3. After each unit or multiple units are installed, the grid must be checked and recorded step by step to prevent deviations in the processing and production process from accumulating during installation. If it is found that the deviation accumulation is too large in the whole process of the installation, which affects the subsequent installation, it is necessary to stop the installation, analyze the reasons, and make rectifications in time.

For large-span space frames, when installing a single-span, the bolts cannot be tightened at one time, so as to adjust the deviation of the rubber bearing caused by the accumulation of deviations or the insufficient support of the scaffolding platform in the later stage. Adjusting the height of the platform support can be adjusted with a jack, but the strength and stability of the scaffolding must be ensured.