Steel structure project - grid hoisting plan?

The following is the relevant content about steel structure engineering brought to you by Zhongda Consulting for your reference.

Project Introduction

This plan is a grid greenhouse project. The roof is a steel grid structure, and the support form is an upper chord support bolt ball node. The materials are mainly steel pipes and bolt balls, which are connected by high-strength bolts. According to the characteristics of this plan, the installation method of the steel grid is: the grid structure is assembled on the ground, using pulling rods and winches as lifting equipment, and using the installation method of block hoisting.

Engineering materials

1. The grid rods are made of high-frequency welded pipes or seamless steel pipes. The materials of rods, supports, steel plates, and ribs are selected from the Q235B material of "Carbon Steel Structural Steel" GB700-88.

2. Welding material matching: Use E43 series electric welding rods, whose quality complies with the national standard "Carbon Steel Welding Rods" GB5117.

3. All materials have quality certification documents (raw material sheet).

Construction deployment

(1) Construction manpower arrangement

In order to ensure that the project is completed on time and with high quality, the construction force of the project is divided into two parts: production and installation. arrange.

Deployment of production force in the factory workshop: For the grid production of this plan, functional teams including material supply, drawing review, sample copying, blanking, cutting, etc. were established to be responsible for production preparation, technical connection, quality monitoring, etc. Manage the entire process and accept supervision from owners, quality supervisors, designers, etc.

(2) Protection measures for transportation of finished grid racks

(1) Storage and protection of parts: parts are stored in a ventilated and dry warehouse. If stored in the open air, precautions should be taken protective measures. Components must be prevented from being deformed and bruised during transportation, loading, unloading, and storage. Components should be stored according to different specifications and model numbers for different projects. And mark it.

(2) Frame transportation protection: Rods are packed and bundled according to numbers before loading and shipped, and bolt balls are shipped in iron cages with numbered numbers. The rods and bolt balls must be lifted into the truck using a forklift or crane. They must be stacked neatly and flatly, and safety must be ensured during transportation.

(3) Construction site protection:

1) After the grid components are transported to the construction site, they should be stacked neatly according to number. The site must be flat and rainproof. , Moisture protection measures.

2) Special personnel must be assigned to take care of the parts at the construction site.

(3) On-site installation force deployment

1. Labor force allocation:

Each construction team will be carried out by the on-site construction project department according to the construction progress requirements. Unify and coordinate to ensure smooth overlapping of processes, and allocate power at any time to avoid work delays.

Selection of installation method

(1) Selection of installation method

This plan includes three parts: 1# greenhouse, 2# greenhouse and 3# greenhouse. In this section, greenhouse 1# is taken as an example for detailed explanation. The 1# greenhouse structure project is divided into two parts: 2-9/B-K and 10-17/B-K. According to the actual site characteristics, the grid area is large and the height is high. Our construction staff initially determined the grid installation as ground assembly and overall hoisting. This method has been used by our company in many projects. Practice has proved that this method has the following advantages:

a. Short construction period , eliminating the cost of vertical transportation of grid components.

b. Workers assemble on the ground and have lower requirements for protective measures when working at heights.

(2) Assembling the grid

(1) Specific assembly of the grid

(a) When splicing the units into a whole, the grid The unit should have sufficient stiffness and ensure its geometric invariance. Otherwise, temporary reinforcement measures should be taken.

(b) The specific assembly of the grid unit is:

The grid unit is assembled from rods, bolt balls and accessories. Our construction workers can assemble the rods, bolt balls and accessories individually on the ground in small units. The installation of the grid unit is extended from the middle position to both sides. The upper and lower chords are installed at the same time, and the installation dimensions are tracked and detected.

After all the rods on each bolt ball are installed, check in time whether the bolts are tightened in place and there should be no looseness or gaps, and make temporary fixing points on the lower chord. Each bolt ball bearing is required to be placed smoothly. When installing the next grid on the grid, recheck whether the high-strength bolts of the previous grid node are tightened in place and must not be loose. After all the grid components are installed, check each bolt ball node, measure the upper and lower chord axes, horizontal elevation and deflection. The deviation must be within the allowable range. Then install the supports and tighten the support bolts. After all is completed, remove the temporary support point and move to the next process. The grid should be marked one by one from production to installation.

(2). Grid construction sequence

Bottom chord node→Bottom chord bar→Web bar and top chord node→Top chord→Correction→Tighten the bolts

a. Bottom chord Assembling the rod and ball: The high-strength bolt threads connecting the lower ball and rod are tightened in place at one time.

b. Assembly of the web rod and the upper chord ball: The combination of the web rod and the upper chord ball becomes a downward quadrangular pyramid. The high-strength bolts connecting the web rod and the upper chord ball are all tightened, and the lower end of the web rod is connected to the lower chord. Only one of the three bolts can be tightened, and the other two are loose, mainly for the installation of the upper chord rod.

c. Assembly of upper chord rods: The combination of three upper chord rods forms a downward quadrangular pyramid system. The installation sequence of the upper chord should be from the inside to the outside. Arrange according to the installed web rod body. High-strength bolts are tightened one after another.

d. During acceptance, it should be checked that the vertical and horizontal grids are connected with high-strength bolts, and the bolts should be tightened according to relevant regulations, and should be processed according to the anti-corrosion requirements of steel structures. The side length deviation of the intersection direction, the center deviation and height deviation of the support point.

(3) Inspection and acceptance of completed units

Unit assembly is the basic work of grid installation and the basis of quality assurance. The assembly quality must be strictly controlled to ensure the network Lay the foundation for total frame assembly. The allowable deviations of the grid unit assembly are shown in the table: Allowable deviations of the assembled units.

When the grid unit is assembled, the surfaces of its nodes and rods are clean and there are no obvious scars, sediment and dirt. The grid frame of the assembled unit should be checked and the size of the grid should be within the allowable deviation range.

(4) The specific sequence of installation of the grid

First install the grid on the north side (10-17/B-K axis part). The specific installation is as shown in the figure:

The installation of the grid structure starts from the middle part, spreads to the circumference, and starts installation on three sides at the same time. This installation method can provide multiple construction work surfaces and speed up the installation progress of the grid.

1. Production and installation of grid lifting device

Arrangement of grid lifting device:

(1) Lifting rod arrangement:

The weight of the main body of the grid structure is 67.5 tons. During the construction process, due to the influence of the position of the supports, the upper chords of the side spans and the abdominal rods are not installed and lifted. They will be installed separately after the grid is raised to the in-place elevation, so the lifting weight is far away. Less than the maximum weight of the grid, the maximum lifting weight is calculated to be 62 tons. For this purpose, it is planned to use four φ426×10 one-legged pull-out poles to lift the grid. The calculated length of the grid lifting pull-out poles is considered to be 16.5 meters to meet the construction requirements. According to the architectural form of this plan and the characteristics of the grid design and layout, the lifting rods are arranged and calculated to meet the requirements.

(2) Principles for the arrangement of pull-out poles:

Do not hinder the lifting of the grid; do not hinder the assembly of the grid; the force is uniform; the foundation of the pull-out poles is firm and reliable, and the support system is firm and reliable.

(3) Arrangement of grid lifting points:

In view of the safety of the grid structure during the lifting process, the grid lifting points are tied up by full-time lifting workers, and the responsibility is People are required to tie up one qualified one, and they can only be used after passing the final inspection by the technical staff. For details on the layout of the grid lifting points, please see the grid lifting point layout diagram

(4) Grinding layout:

The overall layout principle is construction safety, unified command is convenient, and the rope guide is smooth. . For details on the layout of the winch and grinding system, please refer to the layout plan of the grid lifting and pulling rod system. The specific layout can be partially adjusted according to site conditions.

(5) Network frame lifting personnel plan:

When the network frame is lifted, 4 winches are needed for 4 pulling rods, and 12 operators are required.

(6) Control of the grid lifting process:

The grid lifting is carried out in three steps. The first lifting height is 1m, and the lifting is stopped after reaching this height. , observe whether the grid is deformed. If there is no deformation or abnormality, you can lift it again. When the lifting height reaches two meters, stop lifting again. After adjusting the grid parallel, observe the deformation of the grid again. If there is no any In case of deformation or abnormality, the grid can be hoisted. The lifting and observation time should be no less than half an hour each time.

2. Grid lifting check

The middle part of the grid is assembled on the ground in the venue. First install the grid on the north side (10-17/B-K axis part). Use the pull rod to lift the grid structure, and lift the grid into place as the lifting height increases. Now use a pull rod to perform lifting calculations.

(1) Weight statistics:

After calculation and analysis, the maximum lifting weight of the pull rod is Q’=15.5T=155KN. Q = Q' (0.5T) Selection:

The index force S at the pulley’s rope end:

S=P/k1=205.59/6.73=30.548KN

k1: Mechanical efficiency of the pulley unit Coefficient, the lifting pulley group adopts "four, four and eight", the number of effective ropes is 8, 1 guide pulley, k1=6.73

Selection of wire rope for the pulley group: the safety factor is K=5.5,

The breaking tension of the steel wire rope is PP=SK=33.572KN×5.5=184.646KN

Select the steel wire rope Φ22-6×37＋IWR tensile strength ≥1770MPa, and its breaking tension is 273.00KN. Selection of winch grinding: One 5T winch grinder.

Fixation of the winch grinder: The rear part of the winch grinder frame is fixed with a steel wire rope, and the steel wire rope and the steel column foundation are fixed.

(4) Calculation of the pull rod base:

Vertical pressure of the pull rod support: Pc=P Pt×Sin30° G T S where:

Pulley group Force P=205.59KN

Cable wind rope force Pt=3.891KN

Pull rod gravity G=16.5M×102.59Kg/M=16.927KN

The pre-tension force of the wind rope gives vertical pressure to the pulling rod:

T=(n-1)×t×Sin30°=(4-1)×3.891×50×0.5=2.918KN

In the above formula, t is the pre-tension force of the wind rope, take 30%-50% of the maximum tension of the wind rope, and the rope end tension S=33.572KN

Pc=205.59KN 3.891KN×0.5 16.927KN 2.918KN 33.572KN=260.952KN

Calculation of the ground bearing capacity at the bottom of the pull rod: Pc/A≤[R]

In the formula: Pc - vertical pressure on the ground

A - Pressure area of ??the ground

[R] - Allowable bearing capacity of the ground, take 160KN/m?

A≥Pc/[R]=260.952/160=1.631 m? That is, the area of ??the pull-out rod base should be ≥ 1.631m?

(5) Checking the strength and stability of the pull-out rod:

The middle section of the pull-up rod has the largest deflection. Generally, only steel pipe pull-out rods have the largest deflection. Perform stability check

The positive pressure P in the middle part = Pc-G G Z = 260.952-16.927 16.927/2 = 269.41KN

The bending moment M in the middle = ( S P)×e?-Pt(l/2×Sin30° e1×Sin30°)=(33.572 225.94)×0.3-3.891(20/2×0.866 0.2×0.5)=43.768KN〃M

Mechanical properties of steel pipe Φ426×10: W=2656.08CM?, Fm=130.69CM?

Rotation radius r=0.25×√(D? d?)=0.25×√(42.6? 40.6?)=14.7 CM

In the formula: D is the outer diameter of the steel pipe and d is the inner diameter of the steel pipe

Slenderness ratio λ=l/r=2000CM/14.7CM=136.05

Stable The coefficient is found to be Φ=0.402

Stable calculation σ=M in/W P in/ΦFm

=43768/2656.08 274635/(0.402×13069)=68.753MPalt; [σ] =162MPa

The calculation of the pulling rod meets the requirements.

(6) Selection of lifting lock:

F=P/(4×cosβ)=205.59KN/ (4×cos45)=72.687KN,

In the formula: F-the force on the sling, P-the force on the pulley 205.59KN,

β-the angle between the sling and the vertical line Take 45 degrees

Choose a steel wire rope Φ18-6×37+IWR with tensile strength ≥1770MPa. Its breaking tension is 182.00KN, and the two strands can withstand at least 364KN.

β is less than or equal to 45 degrees, that is, h is greater than or equal to 1875mm.

3. Production and installation of lifting rods:

(1) Treatment and reinforcement of the bottom of the lifting rods:

According to the actual ground conditions at the construction site, it is not necessary to The bottom of the pull rod needs to be processed.

(2) The structure of the pull rod:

The one-legged pull rod consists of an independent steel pipe, base, pulley group and winch. The pulling rod is made of steel pipe, and the top wind rope is fixed on the frame beam and column. All wind ropes must be tightened. A pulley block and a guide pulley block are respectively provided at the top and bottom of the pull rod, and a winch is used to lift heavy objects. The cable wind rope and pulley train unit wire rope need to be calculated and determined.

The number of pulleys: 4 movable pulleys, 4 fixed pulleys, and the pulling force of the winching rope is 5 tons. A head steel plate with holes is welded to the top of the pull-out rod, and a clamping plate is provided for attaching the cable wind rope. A cantilever plate is installed close to the top to hang the lifting tackle. The lower part of the pulling rod is supported on the square wood and must be anchored with ropes to prevent displacement.

(3) Production of pull-out rods:

Transport the steel pipes used for lifting the pull-out rods to the construction site, select an assembly site, and measure the length and appearance of the steel pipes. Start assembly and welding of the pull rod. Use brightly colored paint to number and mark the pulling rods to facilitate unified management. After re-testing and correcting the assembled pull-out rod, install the pulley block and threaded wire rope, pay attention to the direction of the rope running, and install and arrange the cable wind rope at the same time. After all assembled pull-out rods are inspected and found to be correct, they can be put into place.

(4) Installation of the pull rod:

Place square wood at the bottom of the pull rod. The pull-out rod can be lifted and placed at the designated position using a truck crane, and the corresponding cable wind rope is tensioned and fixed at the same time. The lower end of the cable wind rope is fixed on the steel column to ensure that the position is correct, the direction is clear, and the fixation is firm. The lower part of the pull-out rod is added with a bottom tie rope corresponding to the upper part, and the outer end is tied to the surrounding steel column to firmly connect and fix the bottom of the pull-out rod to prevent horizontal and lateral movement.

(5) Take protective measures at the connection between the steel wire rope and the building. First, cut the 89mm diameter steel pipe into three sections, and then place the cut steel pipe at the corners of the building to protect the building from damage and the wire rope from damage due to broken wires. There should be no less than four fixed buckles of the wire rope, which must be firm and reliable without loosening.

4. Installation of the winch grinder

Based on the actual conditions of the construction site, select the location of the winch grinder. After the pull-out rod is installed, the installation of the winch grinder can be started. Use a wire rope to fix the winch on the frame column of the building, and wrap the lifting rope around the rolling shaft of the winch. At the same time, install the start switch. After the power is turned on, the winch for grid lifting is ready. Installation completed.

5. Reinforcement of the grid

The load bearing capacity of the grid should consider the grid's own weight, live load, and wind load. Use SFCAD design software to re-analyze the stress of the grid. On-site reinforcement measures are taken for the chords at the lifting points to ensure the overall stability of the grid hoisting and the safety of the grid structure. The reinforcement plan is to use two 8# channel steels to be welded to the grid chords and increase the net size. The effective cross-sectional area of ??the rack rods ensures that the rack rods will not bend or deform during the hoisting process.

Construction Safety Guarantee Measures

(1) Production Safety Guarantee Measures:

1. The safety department shall formulate safety management systems for departments at all levels and relevant responsible persons in accordance with relevant national, provincial and municipal safety regulations, so that tasks are clear and there are rules to follow. Each economic contract has clear safety indicators and guarantee measures including rewards and punishments, and responsibility certificates are signed at all levels to achieve strict discipline, clear rewards and punishments, and ensure production safety.

2． Provide safety education to all construction personnel entering the site, establish the idea of ????safety first, and strictly implement various rules and regulations. There should be clear safety placards on site, safety responsibility systems at all levels should be implemented, and assessments should be conducted.

3． Enclosure and isolation measures will be taken around the construction site to ensure the safety and smooth flow of surrounding roads and sites to ensure the safe construction of adjacent projects and the safe and smooth flow of roads.

4. Establish full-time safety personnel in the project department for this plan to ensure the implementation of the system.

5. On-site construction workers have complete safety protection equipment. They wear safety helmets when entering the site and wear safety belts when working at heights. High-altitude safety protection facilities are complete and effective.

6． Facilities and lines that meet the requirements must be set up for on-site electricity use. It is strictly forbidden to mess around and run lines anywhere to eliminate hidden dangers.

7. According to the construction site management regulations, a regional responsibility system is implemented, and targeted warning signs are hung at dangerous parts and locations.

8. Strictly implement the construction site safety protection regulations of the construction authorities, formulate targeted safety technical measures and disclose them in writing before construction operations.

9. "Four Ports" protection is carried out in accordance with strict safety operating procedures. All personnel entering the site must wear safety helmets, and those working at heights must wear safety belts and non-slip shoes.

10． The distribution box is a rainproof and dustproof mobile switch box made of iron welded, and is arranged in three levels: main distribution box, distribution box and switch box. The main distribution box is equipped with a main automatic switch, the power and lighting circuits are branched, the distribution box and switch box are equipped with leakage protectors, and each switch box is equipped with a zero line connection and zero protection terminal.

11. The construction site must have a strict work-by-piece and individual job responsibility system. The site must be clean, materials and components must be neatly stacked, and materials that are afraid of moisture, water, and sunlight must have moisture-proof and covering measures.

12． Workers must keep their feet clear when working, clean up materials after work, and remove garbage and dirt in the building in a timely manner.

13. Pay attention to safety during construction and wear safety helmets at the construction site. Slippers, high heels and plastic shoes are not allowed to be worn for work. Transferring items and tools must be packed in tool bags, and special passages must be used to get up and down the platform. Keep away from flammable and explosive materials when welding. Prevent accidents such as falling, knocking, smashing, bumping, and falling from high altitudes.

(2) Construction safety production management measures:

1. Establish and improve the safety management organization, set up a safety management team headed by the project manager, equip safety management personnel, and implement a management system that combines dedicated management and group management.

2． Before construction, the safety management team should conduct hazard identification and evaluation and formulate corresponding preventive measures.

3． Establish various safety management systems with the safety production responsibility system as the core. It mainly includes the safety production responsibility system for all types of personnel at all levels, the safety production target management system, the safety inspection system, the safety education system, the safety technical measures planning system, the safety disclosure system, the special operations personnel management system, the safety acceptance system, and team safety activities. system, accident reporting and investigation and handling system, safety reward and punishment system, etc. The safety production responsibility objectives are broken down layer by layer, implemented to each person, strictly assessed, and the assessment results are linked to the economy.

4. Strengthen safety education and strengthen personnel management. Strengthen the safety awareness of on-site managers so that every manager can care about safety work and insist on putting safety first in actual management work and conscientiously perform their duties. Strictly implement the three-level safety education and safety clarification system, and personnel who have not been educated and clarified are not allowed to work. Adhere to regular education and educate employees to change from "I want safety" to "I want safety."

5. Special operations personnel must hold valid operating certificates to work. Strict personnel management, standardized employment, serious investigation and punishment of violations, patient persuasion and education, and elimination of illegal commands, illegal operations and violations of labor disciplines, so that employees will not harm themselves, harm others, or be harmed by others. A safety helmet must be worn when entering the construction site, and a safety belt must be worn when working at heights. The safety belt should be worn high and low.

6． Strict supervision and inspection to eliminate hidden dangers of accidents. The project department conducts regular inspections every ten days; the project manager and safety officers insist on daily safety inspections. For accident hazards discovered during inspections, rectification will be carried out by designated persons, time and measures, so that no accident hazards are left behind. Scaffolding, construction electricity, mechanical equipment, protective facilities, etc. must be inspected and accepted before they can be put into use.

7. Actively carry out pre-shift safety activities, carry out extensive publicity on production safety, promote advanced experience in production safety, promote construction safety management, and ensure construction safety.

(3) Safety assurance measures for network frame improvement:

1. A grid improvement leading group was established on site, with the on-site upgrade commander as the team leader. According to the main links and positions, four team members are responsible for observing and reporting in a timely manner and accepting unified command. The lifting operators are divided into four groups of three people each. The control switch of the grinding mill is handled by one person.

2． Make material preparations based on important aspects and positions during the construction process, as well as links prone to problems. For example, there are 4 spare steel hooks and horse bolts, 4 50m steel wire ropes, 30 buckles, several square logs, 15 ropes, and 1 electric winch.

3． During the grid lifting operation, the on-site commander is responsible for the lifting command.

4. Participants must concentrate and are not allowed to leave their posts without permission, play or play, and pedestrians or people standing under the grid are strictly prohibited during the lifting process.

5. Safety warning tapes are set up around the lifting work area, and non-construction personnel are strictly prohibited from entering. Set up 2 inspectors to conduct inspections around the building.

6. Before lifting operations, carefully check whether the lifting equipment is operating normally, and then lift after confirming that it is correct.

7. Lifting rigging, electrical equipment and tools must be inspected before work, especially if problems are found with slings, they should be dealt with promptly to eliminate safety hazards.

8. During lifting operations, no lifting is allowed if the command signal is unclear; no lifting is allowed if there is someone on the lifting object; no lifting is allowed if the safety device of the mechanism fails or someone is sick; no lifting is allowed if the lighting at the site is dark and the lifting points of the lifting object cannot be clearly seen; Level 5 The above strong winds are not allowed to rise.

9. Special personnel are assigned to monitor all ground anchors. If any problems are found, they will be reported immediately and the lifting operation will be stopped and re-reinforced.

10． All rope fastening parts should be monitored by dedicated personnel and any loose or damaged parts should be replaced immediately.

11. Each pull-out pole is supervised by a dedicated person. If tilt is found, the lifting should be stopped immediately and adjusted to the vertical position. If the lifting rope is out of synchronization, it should be adjusted in time. Adjustment should be made when the height difference of the scales on each pull-out pole exceeds 250px.

12. When the grid is lifted, support frames or square timbers are set up at both ends to support it as the grid is lifted to prepare for problems.

13． The brake of the winch grinder must be flexible and effective. If a problem occurs, brake immediately. In case of power outage, brake and lock immediately, and support the grid firmly.

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