Large-span roof steel truss hoisting construction method

Abstract

The invention discloses a large-span roof steel truss hoisting construction method which comprises the following steps: determining the foundation bearing capacity of a host installation operation site area, selecting a crane model according to the hoisting height, the operation radius and the weight of a hoisted object, and determining a hoisting scheme according to the site condition after selection; calculating a steel wire rope breaking force, and selecting a steel wire rope model according to the steel wire rope breaking force T; and according to the hoisting scheme and the breaking force T of the steel wire rope, a special construction scheme for steel truss installation operation is formulated, steel truss hoisting work is conducted according to the special construction scheme for steel truss installation operation, and welding and paint repairing are conducted after hoisting is completed. Standardized comprehensive hoisting of the large-span roof steel truss of the high-rise building is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a large-span roof steel truss hoisting construction method. Background Art

[0002] At present, the common construction method of roof steel trusses is: construction preparation → crane inspection → load test → construction measurement → inspection of hoisting equipment and trial lifting → normal lifting and positioning → installation of bolts or welding → inspection and acceptance, exit. The installation and construction of large-span roof steel trusses of high-rise buildings is difficult, and it is necessary to comprehensively consider the construction technology and lifting safety, and formulate a reasonable construction organization design.

[0003] However, this steel truss construction technology is suitable for laying steel trusses on the roofs of low-rise and small-span buildings, but is not suitable for laying steel trusses on the roofs of high-rise buildings and large spans. It cannot guarantee construction safety and quality, and it is difficult to meet the requirements of mechanized construction. Summary of the invention

[0004] The purpose of the present invention is to provide a large-span roof steel truss hoisting construction method, which realizes the standardized comprehensive hoisting of the large-span roof steel truss of a high-rise building.

[0005] To achieve the above objectives, the technical solutions used in the present invention are: The large-span roof steel truss hoisting construction method includes: Determine the foundation bearing capacity PK of the main engine installation site area based on PK=F*K / A, where F is the crane's deadweight, counterweight and maximum weight of the hoisted object, K is the comprehensive influence coefficient, and A is the area occupied by the outriggers; select the crane model based on the hoisting height, operating radius, and weight of the hoisted object, and determine the hoisting plan based on the site conditions after selection; Calculate the breaking tension T of the wire rope according to the formula T=(G*KD*KU / m*sinα)*9.8, where G is the maximum weight of the hanging object, KD is the dynamic load coefficient, KU is the uneven coefficient, m is the number of wire ropes, and α is the angle between the wire rope and the horizontal plane. Select the wire rope model according to the breaking tension T of the wire rope; Formulate a special construction plan for the steel truss installation operation based on the hoisting plan and the breaking tension T of the wire rope. Carry out the steel truss hoisting work in accordance with the special construction plan for the steel truss installation operation. After the hoisting is completed, weld and repaint.

[0006] Furthermore, if the bearing capacity of the foundation is insufficient, the crane leg area needs to be replaced and pressure tested.

[0007] Furthermore, the painting work of the steel trusses is carried out in the workshop, and the temperature in the workshop is kept above 5°C during the spraying period; the on-site fire retardant coating and topcoat coating are arranged according to the temperature conditions, and construction is strictly prohibited when the temperature is below 5°C; the humidity of the coating construction environment is carried out under the condition of relative humidity less than 80%, and the ambient temperature and relative humidity of the air during painting are controlled, and the surface temperature of the steel is more than 3°C higher than the air dew point temperature.

[0008] Furthermore, when the maximum weight of the hoisted object is between 25 and 40 tons, a single main machine is used and the direct lifting method is adopted for hoisting; when the maximum weight of the hoisted object is greater than 40 tons, a double main machine lifting method is adopted and the lifting points of the two cranes are evenly distributed; the load rate of a single main machine ﹤80% meets the hoisting requirements.

[0009] The technical effects of the present invention include: The present invention adopts mechanized construction, realizes the standardized comprehensive hoisting of the large-span roof steel trusses of high-rise buildings, and is conducive to large-scale promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the direct lifting method for a single main engine in the present invention; Figure 2 It is a schematic diagram of the direct lifting method for double main machines in the present invention. DETAILED DESCRIPTION

[0011] The following description sufficiently illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce the invention.

[0012] The large-span roof steel truss hoisting construction method includes the following steps: Step 1: Determine the foundation bearing capacity PK of the main engine installation site area based on PK=F*K / A, where F is the crane's deadweight, counterweight and maximum weight of the hoisted object, K is the comprehensive influence coefficient, and A is the area occupied by the outriggers; select the crane model based on the hoisting height, operating radius, and weight of the hoisted object, and after selection, determine the hoisting plan based on the site conditions; If the bearing capacity of the foundation is insufficient, the crane leg area needs to be replaced and a pressure test performed.

[0013] Step 2: Calculate the breaking force T of the wire rope according to the formula T=(G*KD*KU / m*sinα)*9.8, where G is the maximum weight of the hanging object, KD is the dynamic load coefficient, KU is the uneven coefficient, m is the number of wire ropes, and α is the angle between the wire rope and the horizontal plane. Select the wire rope model according to the breaking force T of the wire rope; The dynamic load coefficient KD is taken as 1.1, the unevenness coefficient KU is taken as 1.1, and m is the number of steel wire ropes.

[0014] Step 3: According to the lifting plan and the breaking tension T of the wire rope, a special construction plan for the steel truss installation operation is formulated, and the steel truss is lifted according to the special construction plan. After the lifting is completed, welding and repainting are performed.

[0015] 1. Construction preparation The embedded plate is completed, the positioning points are re-measured, the elevation and axis are reported to the supervisor for inspection, the preparation of the crane is completed one day in advance, all parts of the crane are comprehensively inspected, and the preparations before lifting are completed.

[0016] 2. Steel truss hoisting and alignment Lift the trusses in sequence, focusing on protecting personnel working at height.

[0017] 3. Steel beam welding and inspection In this stage, shielding and protection measures should be taken to prevent welding sparks from falling to the ground. After the on-site welding is completed, non-destructive testing of the welds shall be carried out as required.

[0018] 4. Paint coating It is mainly about repainting the weld area and cleaning the exterior of the steel beam and applying the final coat of paint. Example

[0019] Taking QAY650A lifting equipment as an example, relevant lifting calculations are performed as follows: 1. PK of foundation bearing capacity in the host installation operation site The QAY650A truck crane has a deadweight of about 161 tons (including superlift), a counterweight of 197 tons, and a roadbed of 4.4*2.4m under each leg during hoisting.

[0020] PK=F*K / A determines the foundation bearing capacity PK of the main engine installation site, where F is the crane's own weight, counterweight and maximum load weight, K is the comprehensive influence coefficient, which is 1.5, and A is the footing area.

[0021] When the maximum load is 50 tons, PK=F*K / A=(161+197+50)*1.5 / (4*4.4*2.4)=14.5t / ㎡ Therefore, the foundation bearing capacity is required to reach above 14.5t / ㎡, and 15t / ㎡ is taken for safety reasons.

[0022] If conditions permit, use ground bearing capacity tester for inspection, which requires more than 15 tons per square meter. You can also use crane counterweight test, which requires 20 tons per square meter, and the settlement under pressure for 24 hours is qualified if it is no more than 50mm.

[0023] If the foundation test results do not meet the bearing capacity requirements, it is necessary to deep dig the crane leg area and use subsequent crushed stone replacement treatment. The replacement area at each leg is 6m×4m, and the replacement depth is not less than 1.5m. After the replacement is completed, the crushed stone is leveled and the above-mentioned ground endurance test is repeated. Only after passing the test can the lifting construction be carried out.

[0024] When the maximum load weight is 100 tons, PK=F*K / A=(161+197+100)*1.5 / (4*4.4*2.4)=16.2t / ㎡ Therefore, the bearing capacity of the foundation is required to reach above 16.2t / ㎡. For safety reasons, 16.5t / ㎡ is taken. Other factors remain the same as above.

[0025] 2. Confirmation of hoisting plan like Figure 1 The figure shows a schematic diagram of the direct lifting method for a single main engine in the present invention.

[0026] For the hoisting of large-span steel trusses of high-rise buildings, the lifting equipment adopts 88.1m main arm, operating radius of 40m, super-lifting counterweight of 197t. According to the parameters of QAY650A lifting equipment, the rated lifting capacity Q=37.3t.

[0027] When the maximum load weight is 25 tons, use a single main engine and adopt direct lifting method for lifting; Load rate µ=G / Q×100%=25 / 37.3×100%=67%﹤80%, which meets the lifting requirements.

[0028] Among them: G is the lifting weight of the truck crane, 25t; Q is the rated lifting weight of the truck crane, 37.3t.

[0029] like Figure 2 The figure shows a schematic diagram of the direct lifting method for the dual-host cranes in the present invention.

[0030] When the maximum weight of the hoisted object is 40 tons, the double-machine lifting method is adopted, and the lifting points of the two cranes are evenly distributed; the load rate of crane A µ=G / Q×100%=20 / 37.3×100%=53%﹤80%, which meets the requirements of double-machine lifting.

[0031] The load rate of crane B µ=G / Q×100%=20 / 37.3×100%=53%﹤80%, which meets the requirements for double-crane lifting.

[0032] Among them: G is the lifting weight of a single truck crane, 25t; Q is the rated lifting weight of the truck crane, 37.3t; When the maximum load weight is 40 tons and the operating radius is 28m, according to the parameters of the QAY650A lifting equipment, the rated load Q=55.3t, with a single main machine, the direct lifting method is adopted for lifting; Load rate µ=G / Q×100%=40 / 55.3×100%=72%﹤80%, which meets the lifting requirements.

[0033] Among them: G is the lifting weight of the truck crane, 40t; Q is the rated lifting weight of the truck crane, 55.3t.

[0034] 3. Wire rope calculation Taking the maximum load weight of 50 tons as an example, the breaking force T of a single wire rope is calculated as: T=(G*KD*KU / m*sinα)*9.8, = 50.00×1.10×1.10 / (4.00×sin60.00) × 9.8 = 171.16 kN Where G is the maximum weight of the load, KD is the dynamic load coefficient which is 1.1, KU is the unevenness coefficient which is 1.1, m is the number of wire ropes, and α is the angle between the wire rope and the horizontal plane which is 60 degrees.

[0035] Wire rope strength capacity Pn: According to the mechanical properties of the wire rope, the wire rope model 6X37+FC is selected, with a tensile strength of 1770.00MPa, a nominal diameter of 48.00mm, a single minimum breaking force of 1350.00kN, 1.00 strands of wire rope bending, and a wire rope winding diameter of 100.00mm.

[0036] Pn=nP =1.00×1350.00 =1350.00 kN Where: n—the number of bent strands of the wire rope is 1.00, P—the breaking force of a single wire rope (t) = 1350.00, the actual safety factor of the wire rope is K, K = Pn / T = 1350.00 / 171.16 = 7.88; K =7.88 > allowable safety factor 6.00, the selected wire rope meets the standard requirements.

[0037] 4. Construction machinery requirements (1) The performance parameters of the construction machinery meet the construction requirements, and the crane must obtain the safety inspection certificate issued by the government competent department in accordance with the regulations. Within the validity period, a 650t truck crane is selected as the main crane according to the actual project, and the 650t truck crane is inspected and accepted before entering the site. It can only enter the site after passing the inspection; (2) Carry out a comprehensive inspection and trial operation of the electrical system and hydraulic system of the lifting machinery, and conduct static and dynamic load tests to ensure that the performance of the lifting machinery is intact; (3) Large lifting machinery must be fully insured, have complete and effective safety protection devices, good performance, all kinds of certificates, and complete safety technical files; the factory service life of the main crane rented out shall not exceed 5 years, and the rented machinery must have signed an installation / disassembly project safety agreement.

[0038] 5. Requirements for construction equipment, tools and materials (1) Before installation, the crane components must be inspected and accepted, and the main engine must be self-checked. The oil, coolant, etc. must meet the operating requirements; the specifications and quantity of the assembled parts must meet the crane installation conditions and the requirements of the manual; (2) During the assembly process, the components should be cleaned, lubricated, rust-proofed, tightened, adjusted and other maintenance work should be done; (3) All components must be inspected and necessary maintenance must be performed in accordance with the requirements of the Maintenance Manual, and the maintenance of auxiliary machinery must also be done well; (4) The lifting slings and other equipment used for lifting should be inspected and accepted to meet the use requirements; (5) The communication equipment used for lifting (mainly walkie-talkies) has good performance and meets the construction communication requirements.

[0039] 6. Construction environment requirements (1) Level the work site according to the construction site layout, and ensure that there are no obstacles around. The area and flatness of the hoisting site meet the construction requirements. The site flatness does not exceed 0.5%. There are no slopes around or there is a sufficient safety distance from the slopes and trenches. There are no holes, ancient tombs, or pipelines that affect construction under the main machine installation and disassembly station and the auxiliary crane station; (2) The foundation bearing capacity requirement of the main engine installation site is not less than 15t / m2; and it must be tested by a third party to meet the construction requirements. There must be no obstacles within the range where the crane needs to rotate; (3) There are no idle personnel at the construction site. Cordons and warning signs have been set up in the construction area. Safety personnel are on site for supervision and non-operating personnel are not allowed to enter. (4) The crane operation range does not affect construction work; (5) Consult the local meteorological department in advance about the weather conditions during lifting.

[0040] 7. On-site painting construction (1) Acceptance of on-site anti-corrosion coatings According to the painting plan, the primer, intermediate paint and topcoat of the steel structure are painted in the factory. Before the steel structure is processed and manufactured, the paint used should be inspected and accepted. The paint used on site should be the same batch of materials used in the factory. The factory warehouse should directly ship it to the construction site for painting. When the paint is brought to the site, the variety, specification and performance of the paint, diluent and curing agent should comply with national product standards and design requirements. The product factory certificate, Chinese mark and inspection report should be fully checked.

[0041] (2) Technical preparation 1) Ambient temperature The requirements of the coating product manual should be followed; All painting work must be carried out in the workshop, and the temperature in the workshop must be kept above 5°C during spraying; On-site fire retardant paint and topcoat application should be arranged according to the temperature conditions, and construction is strictly prohibited when the temperature is below 5℃.

[0042] 2) Ambient humidity The humidity of the paint construction environment should generally be kept at a relative humidity of less than 80%, and the paint product manual should also be referred to.

[0043] 3) Control the surface temperature and dew point temperature of steel Controlling the ambient temperature and relative humidity of the air during painting cannot fully indicate the dryness or wetness of the steel surface. The steel surface temperature must be at least 3°C ​​higher than the air dew point temperature.

[0044] (3) Repair of anti-corrosion paint The coating of steel structure components may be damaged during transportation and on-site installation. Therefore, the damaged coating of the components needs to be repaired on-site before and after installation. Only after repair can the topcoat be applied.

[0045] 8. Safety command measures at the lifting site (1) Preparation. Before carrying out the lifting operation with two cranes, some preparation work needs to be done first, including inspecting the environment of the lifting site, clarifying the operation steps and requirements, and preparing the necessary safety equipment and protective measures.

[0046] (2) Arrange the operators. The operation of two cranes requires professional operators, and the responsibilities of the person in charge, signalman and safety officer need to be clearly defined to ensure the smooth progress of the collaborative operation.

[0047] (3) Confirm the lifting position. Confirming the lifting position is an important step in the lifting operation of two cranes. It is necessary to ensure that the crane is in the correct position and the lifting chain or other lifting device can normally contact the center of mass of the lifting object.

[0048] (4) Install the outrigger pads. After confirming the hoisting position, it is necessary to install the foundation, that is, install the hoisting frame facilities to ensure its support capacity and stability.

[0049] (5) Two cranes are used for lifting operations. Before the two cranes are used for lifting operations, it is necessary to communicate the lifting signals. The signalman needs to cooperate with the signalman of the other crane to convey various signal instructions to other staff members. During operation, pay attention to the control of the crane's lifting height, lifting angle, lifting span and operating speed to ensure the coordinated operation between the two cranes.

[0050] (6) Compress the construction time at the same construction site and within the same working hours, control the scope of the construction site, and ensure the safety of lifting.

[0051] (7) Arrange full-time safety personnel at the lifting site to promptly detect and technically deal with safety hazards.

[0052] (8) Emphasize safety measures, steps and methods to ensure the safety of workers. When two cranes are lifting, they must coordinate and clarify the responsible parties, unify the number and working positions of the two cranes, take safety precautions, and coordinate with other construction units.

[0053] (9) At least two signal commanders shall be provided. The ground signalman shall be responsible for overall command during the lifting and hoisting process. The hoisting design shall set up a signal commander to be responsible for commanding the descent and precise positioning of the hoisted components. The commanders shall strengthen communication with each other.

[0054] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the attached claims.

Claims

1. A method for hoisting and constructing a large-span roof steel truss, characterized in that: include: Determine the foundation bearing capacity PK of the main engine installation site area based on PK=F*K / A, where F is the crane's deadweight, counterweight and maximum weight of the hoisted object, K is the comprehensive influence coefficient, and A is the area occupied by the outriggers; select the crane model based on the hoisting height, operating radius, and weight of the hoisted object, and determine the hoisting plan based on the site conditions after selection; Calculate the breaking tension T of the wire rope according to the formula T=(G*KD*KU / m*sinα)*9.8, where G is the maximum weight of the hanging object, KD is the dynamic load coefficient, KU is the uneven coefficient, m is the number of wire ropes, and α is the angle between the wire rope and the horizontal plane. Select the wire rope model according to the breaking tension T of the wire rope; Formulate a special construction plan for the steel truss installation operation based on the hoisting plan and the breaking tension T of the wire rope. Carry out the steel truss hoisting work in accordance with the special construction plan for the steel truss installation operation. After the hoisting is completed, weld and repaint.

2. The method for hoisting and constructing a large-span roof steel truss according to claim 1, characterized in that: If the bearing capacity of the foundation is insufficient, the crane leg area needs to be replaced and a pressure test performed.

3. The method for hoisting and constructing a large-span roof steel truss according to claim 1, characterized in that: The painting work of steel trusses is carried out in the workshop, and the temperature in the workshop is kept above 5°C during spraying; the on-site fire retardant coating and topcoat coating are arranged according to the temperature conditions, and construction is strictly prohibited when the temperature is below 5°C; the humidity of the coating construction environment is carried out under the condition of relative humidity less than 80%, and the ambient temperature and relative humidity of the air are controlled during painting, and the surface temperature of the steel is more than 3°C higher than the air dew point temperature.

4. The method for hoisting and constructing a large-span roof steel truss according to claim 1, characterized in that: When the maximum weight of the hoisted object is between 25 and 40 tons, a single main machine is used and the direct lifting method is adopted for hoisting; when the maximum weight of the hoisted object is greater than 40 tons, a double main machine lifting method is adopted and the lifting points of the two cranes are evenly distributed; the load rate of a single main machine ﹤80% meets the hoisting requirements.

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