What are the basic requirements for winter construction of steel structure engineering

Some people are not very clear about this. There are many aspects of the construction specifications of steel structure engineering, and the following is an introduction to some for you to understand. Code for design of steel structure GB50017-2003 Code for seismic design of buildings GB50011-2001 Code for construction and acceptance of steel structure engineering GB50205-2001 Code for welding of steel structures in buildings JGJ81-2002 Technical code for steel structures of high-rise civil buildings JGJ 99-98 Code for design, construction and acceptance of high-strength bolted connections of steel structures JGJ82-91 Quality inspection and evaluation standards for steel structure engineering GB50221-95 Test method for the quality of galvanized layer of steel products GB T trace pipe coffee is unique to sweep the damage 1839-93 High-strength large hexagon bolts, hexagonal head nuts, washers and technical conditions for steel structures GB T1228-1231-91 Technical conditions for torsional shear high-strength bolt connection pairs for steel structures GB T3632-3633-95 Metal tensile test methods GB 228-87 Steel mechanical and process performance test sampling regulations GB2975-82 Metal tensile test specimens GB6397-86 Brinell hardness test method for metal GB231-84 Impact test method for welded joints GB-2650 Tensile test method for welded joints GB-2651 Test method for bending and flattening of welded joints GB-2653 Through the above introduction, I believe that you will not be at a loss for this problem.

It is a must for steel structure personnel to know these things, and this knowledge is essential in their work.

General provisions. 1. When the production and installation of steel structures are carried out at negative temperature, the steel structure production process regulations and installation and construction organization design documents should be prepared in accordance with the requirements of negative temperature construction.

2. The steel ruler and measuring tools used in the production and installation of the steel structure should be the same as the steel ruler and measuring tools used by the civil engineering unit, and should be identified by the same accuracy level. Civil structures and steel structures should take different measures to adjust the difference of temperature expansion coefficient.

3. When the steel components are made at positive temperature and installed at negative temperature, technical measures should be taken to adjust the deviation accordingly during construction.

4. The welders who participate in the construction of negative temperature steel structures should be trained in negative temperature welding technology and should obtain a certificate before they can participate in the negative temperature welding work of steel structures. The positioning spot welding work should be carried out by the welder who has obtained the positioning spot welding certificate.

<>2.Winter Shi prepares for the work of Pei Bu.

Winter Construction Deployment:

1) Construction arrangement:

Before entering the winter, the preparations required by the winter construction plan should be implemented, and the equipment, materials, energy, and tools should be gradually entered, and the materials, equipment, and facilities on the site should be arranged and erected according to the winter construction plan. Establish and improve the safety and fire prevention system, temperature measurement system and quality inspection system.

This project uses on-site mixing concrete. The maintenance method of concrete transported soil adopts the integrated heat storage method. Concrete pouring below 5 floors, personnel preparation:

1) For admixture personnel, temperature measurement and insulation personnel and heating management personnel, etc., specially organize technical disclosure, learn relevant knowledge within the scope of work, and clarify responsibilities.

2) Set up full-time personnel to listen to the radio of the meteorological station throughout the day to collect future medium and long-term weather forecast information in a timely manner.

3) The temperature measurement work is responsible for the technical group, the tester is responsible for the implementation, the quality inspection team is responsible for checking the implementation, and the tester with Zhensui will feedback the temperature measurement results to the data clerk every day, and the data clerk will sort it out into the data in a timely manner. The construction party arranges special personnel to carry out on-site temperature measurement. (See attached diagram on page 15 for management system).

Preparation of winter materials;

Before entering the winter, equipment, materials, energy, and tools should be gradually entered according to the plan, and various insulation materials and heating materials should be formulated in detail.

Main construction insulation material schedule:

Preparation of thermal and logistical materials:

The hot water used for stirring concrete on site is heated by an iron electric heating box, and a special person is arranged to measure and control the water temperature.

Set up a temporary boiler room in the on-site office for heating the living area and office area, strengthen the insulation of houses, doors and windows, and purchase warm clothes, bedding, shoes and hats, gloves, etc. in time to ensure that workers are fed, warm, and sleep well, and ensure that workers have enough energy to put themselves into work.

<>a).Winter construction measures.

1.The winter construction of steel structure production and installation is strictly implemented in accordance with the relevant winter construction regulations of steel structure.

2.When the positive temperature of the steel component is made and the negative temperature is installed, the shrinkage of the component should be considered according to the difference of the ambient temperature, and the technical measures to adjust the deviation should be taken in the construction.

3.The welders who participate in the construction of negative temperature steel structures should be trained in negative temperature welding technology, pass the examination, and obtain the corresponding certificate.

4.The steel and related connecting materials used at negative temperature must be accompanied by a quality certificate, and the performance meets the requirements of the design and product standards.

5.The electrode used at negative temperature shall not be exposed for more than 2 hours, and the electrode shall be re-baked after more than 2 hours, and the number of electrode baking shall not exceed 3 times.

6.The flux is baked as specified before use so that its moisture content does not exceed.

7.The high-strength bolts used at negative temperature must have product certification, and the re-inspection of torque coefficient and axial force should be carried out at negative temperature.

8.The paint used in the steel structure at negative temperature shall not use water-based paint.

9.When the component is unloaded, the shrinkage margin should be reserved, and the welding shrinkage and compression deformation should be coordinated with the shrinkage deformation generated by the steel at negative temperature.

10.When the components are assembled, they are assembled from the inside to the outside according to the order specified in the process, and the test is done to determine the shrinkage value of the weld that needs to be reserved during the negative temperature assembly.

11.When assembling components, remove rust, burrs, mud, oil, ice and snow and other debris left within 50mm of the joint, and keep the joint dry without residual moisture.

12.Multi-layer welding should be used when welding steel plates above 9mm at negative temperature, and the weld should be welded layer by layer from bottom to top, and each weld should be welded at one time. It is strictly forbidden to start the arc on the welded base metal.

13.When the steel structure is installed on site, in case of snow or wind speed above 6ms, a protective shed will be erected.

14.The unqualified weld is eradicated and rewelded, and the welding is carried out in accordance with the provisions of the steel structure welding process at negative temperature.

15.When the ambient temperature is lower than 0, the brushing process test should be carried out before the anticorrosive coating is applied, and the rust, oil, burrs and other materials on the surface of the component must be cleaned up during the painting, and the surface must be kept dry. Painting work should not be carried out in snow or when there is thin ice on the components.

16.In winter, anti-skid measures are taken when transporting and stacking steel structures, and the component stacking site is flat and solid, without puddles, and the ground is free of freezing. When the components of the same model are stacked, the components should be kept horizontal, and the horn should be placed on the same vertical line, and the components should be prevented from slipping.

17.Before the installation of the steel structure, according to the requirements of negative temperature conditions, the quality of the steel structure shall be re-inspected, and the components that are missed in the production and deformed during transportation and stacking shall be repaired and corrected on the ground.

18.When using steel cables to lift steel components, anti-slip septums should be added, gusset plates that are lifted at the same time as the components, and fixtures and other objects used by installers should be tied firmly with ropes.

19. Prepare the installation sequence chart of steel components according to the temperature conditions, and install them in strict accordance with the prescribed order during construction.

20. Prepare the steel structure installation and welding process, and the two ends of a component shall not be reversed at the same time for welding.

<> key points of winter construction of reinforcement engineering are very important, the formulation of key points is based on the actual situation, and the processing of each detail is very critical, and professional knowledge should be used. Zhongda Consulting will explain to you the key points of winter construction of steel reinforcement projects.

Winters are cold and windy. Under the condition of negative temperature, the mechanical properties of the steel bar change significantly: the yield point and tensile strength increase; Elongation and impact toughness decrease, and brittleness increases.

After the steel joints are welded in the winter travel season, the toughness in the heat-affected zone will also be reduced, and if the welding process is not mastered well, the plasticity and toughness of the steel bars will decrease, and the comprehensive performance will deteriorate; If the welded joint cools too quickly or comes into contact with ice and snow, it will also cause the joint to produce a hardened structure, which will affect the use of steel bar.

The main problem that needs to be considered in the winter construction of steel reinforcement engineering is the negative temperature welding of steel bars.

There are three forms of reinforcement joints in the basement of this project: straight thread connection, welding and lap joint. Under the winter construction conditions, negative temperature welding is particularly important.

The following technical measures are proposed for negative temperature welding of steel bars in this project:

Rebar welding is arranged indoors (rebar butt welding workshop). The steel bar welding workshop is surrounded by Peibu on three sides, and the top is covered with metal tiles, so that it is not only rainproof and snowproof, but also windproof (the gap is the leeward side);

The preheating-flash welding process is used for butt welding of steel bars. Before the flash process begins, the steel bar is touched several times to make the temperature of the steel bar rise, which is conducive to the smooth progress of the flash process. During butt welding, the extension length of the steel bar is increased by 10%, the transformer stage is reduced by one level, the contact pressure during preheating is appropriately increased, and the preheating intermittent time is also appropriately extended;

The joints after butt welding of steel bars are covered with rock wool (or lime powder) to keep them warm and cool slowly to avoid immediately encountering ice and snow;

In the process of processing, transportation and binding of steel bars, attention should be paid to prevent impact and scratches, and damage the original properties of steel bars;

The steel bars stacked in the open air are covered to prevent the surface from freezing. Before pouring concrete, remove snow and ice on the surface of the steel bar; After the steel bar is tied and formed, the construction of the next process will be entered as soon as possible.

1. The steel bars used under negative temperature conditions should be inspected during construction. The steel bar should be protected from impact and scoring during transportation and processing;

2. The mechanical method should be used for the straightening of the steel bar, and the cold drawing method can also be used, and the ambient temperature shall not be lower than -20 when the cold drawing is used; When the temperature is lower, the cold bending operation of HRB335, HRB400 and RRB400 grade steel bars shall not be carried out to avoid strengthening at the bending point of the steel bar, resulting in brittle fracture of the steel bar; The tensile temperature of the prestressed steel bar should not be lower than -15;

3. The negative temperature cold drawing method of steel bar can be controlled by stress control method or cold drawing rate control method. The prestressed tendon used as a prestressed concrete structure should be controlled by the stress control method; The cold drawing of hot-rolled steel bars that cannot be divided into furnace batches should not be used to control the cold drawing rate;

4. Negative temperature welding of steel bars can be welded by flash butt welding, arc welding and pneumatic welding. When the ambient temperature is lower than -20, welding is not suitable.