The main construction methods and technical measures of scaffolding works
6.7.1 Overview of scaffolding works.
This project is a large commercial project, with a building height of 238m consideration, so the underground part -2F 1F adopts floor scaffolding, and the embedded components are used during the construction of plus or minus zero, the part above 2F adopts cantilevered scaffolding, and the tower part adopts climbing frame. Outside the floor scaffolding is shown in Figure 67-1.
Figure 67-1 Schematic diagram of floor-mounted steel pipe scaffolding.
6.7.2. Construction and erection of scaffolding.
1.Construction and erection of double-row floor scaffolding.
1) The structure of double-row floor scaffolding.
Double row floor scaffolding with 48 3The steel pipe erection of 5 is erected, and the maximum height of erection is 24m, and the vertical distance of the vertical rod is 15m, pole row spacing 105m, large crossbar step distance 18m, the inner row of poles is 0 from the wall3m。The bottom of the floor scaffold is compacted, the 100mm thick C15 concrete cushion is cast-in-place, the root of the vertical pole is laid with a long scaffold board, and the longitudinal and transverse sweeping rod is set 200mm above the ground. Bamboo fences are laid on the small crossbar of each step, and a skirting bar is arranged on the outside of each small crossbar at a height of 250mm, and two handrail bars are arranged at 600mm and 1200mm. A green mesh safety net is hung on the outside. Set the 180mm high foot plate in the top three steps. The scaffold tie is set up according to two steps and three spans, and is connected by double fasteners, and the connection mode is shown in Figure 67-2。
2) The erection process of floor scaffolding is shown in Figure 6 below7-3：
Figure 67-3 Flow chart of floor scaffolding erection.
1) In the erection, the joint position of the adjacent vertical rod should be staggered and arranged in different steps, and the distance between the adjacent large crossbar is not more than one-third of the step distance, and the vertical rod and the large crossbar must be fastened with right-angle fasteners, and shall not be set or omitted in each step. In addition to the lap connection at the top of the top layer, the joints of each step of the rest of the layers are connected by butt fasteners. The distance from the edge of the end fastener cover plate to the end of the rod is not less than 100mm, and the vertical deviation of the vertical rod should not be greater than 1 300 of the frame height, and the absolute deviation of the rod is controlled at the same time is not more than 50mm.
2) The large crossbar is arranged on the inside of the vertical rod, and the length of a single rod shall not be less than 3 spans. The large crossbar is arranged according to the layer height, and each layer is provided with a two-step frame, and the setting spacing is not more than 1500mm, and meets the design requirements, and the rods are connected by butt joints, and lap joints can also be used. When erection, the joint position of the crossbar should be staggered and arranged in different vertical rod longitudinal distances, the staggered distance should not be less than 500mm, and the lap length of the rod should not be less than 1m. The distance from the adjacent upright is not greater than 1 3 of the longitudinal distance.
3) Arranged close to the pole, erected on the large crossbar and fastened with right-angle fasteners. A small crossbar must be set at the main node, which is fastened with a right-angle fastener and is strictly forbidden to be removed. The center distance between the two right-angle fasteners at the main node should not be greater than 150mm. The length of the side of the small crossbar stretched out of the outer pole shall not be of different lengths, and it is best to control it at about 150 300mm, which is convenient for the hanging of the dense safety net and ensures the façade effect of the entire outer frame. The overhang length of the end of the small crossbar against the wall shall not be less than 100mm and shall not be greater than 300mm, and the distance from one end of the small crossbar against the wall to the decorative surface shall not be greater than 100mm. The small crossbar at the non-main node on the working layer should be set at an equal distance according to the needs of the supporting scaffold board, and the maximum spacing should not be greater than 1 2 of the vertical distance of the vertical rod. Between the adjacent poles, add 1 2 small crossbars as needed. Under no circumstances shall the small crossbars, which are members of the basic frame structure, be removed.
4) The scissor braces on the façade of the scaffold are continuously set and set continuously from the bottom to the top. The scissor brace must be erected synchronously with the vertical pole, longitudinal and transverse horizontal rods, etc. The oblique rod of the scissor brace is fixed with a rotating fastener outside the vertical rod or large crossbar fastening that intersects it, and the distance from the center of the rotating fastener to the main node is not more than 150mm. The angle between the scissor brace oblique rod and the ground is 45 60 degrees, and the scissor brace oblique rod should be reliably connected with the basic frame member of the scaffolding. The connection of the nodes is reliable. The fastener bolt tightening torque is 40Nm～ 65n.m。
5) The verticality deviation of the scaffold pole should be L 300, and the maximum verticality deviation value of the scaffold should be controlled at the same time: not more than 50mm.
6) The deviation of the horizontal rod of the scaffold should be 1 250, and the horizontal deviation value of the full length of the scaffolding: should not be greater than 50mm.
7) When the scaffold is in use, it needs to be re-inspected before it is allowed to be put into use: continuous use for 6 months;If it is stopped for more than 15 days in the middle of construction, it should be checked before it can be usedAfter being subjected to strong factors such as storms, heavy rains, etc.;In the process of use, it is found that there are significant deformations, settlements, removal of rods and ties, and the existence of potential safety hazards.
8) Hang the safety net with the lifting of the outer frame, and the safety net is fixed on the steel pipe with nylon rope and shall not be loosened at will.
2.Structural design and material selection of unloading platform.
1) Structural design of unloading platform.
In order to ensure the turnover and reversal of materials, the above-ground structure construction is provided with a discharging platform from the second floor upwards on each floor, the plane size of the unloading platform is 5000mm 3000mm, the bottom adopts I-beam steel as the main beam structure of the receiving platform, the spacing is 1500mm, the angle steel is used as a support between the I-beams, the spacing is 500mm, the angle steel and the I-beam are welded into a whole, and the surface is paved with wood plywood. On the I-beams on both sides at a distance of 800mm from the outer end of the receiving table, a steel plate is welded for threading the wire rope. Steel pipes with a height of 1200mm and a spacing of 1500mm are welded on the I-beams on both sides as handrails.
2) Material selection.
Pick beam: the selection of I-beam specifications 126 74 50；
Angle steel: 50 6 angle steel is selected;
Wire rope: 6 19 wire rope with a diameter of 185mm, the total breaking tension of the wire rope is 1800kn (according to the nominal tensile strength of steel wire 1400n mm2);
Beam screw: 20 round steel processing;
Connecting steel plate: select a steel plate with a thickness of 20mm, 3) installation, acceptance and use of the unloading platform.
1) When the unloading platform is installed, the angle steel is welded with the unloading platform on the outside of the floor slab to prevent the receiving table from sliding inward due to axial pressure. The unloading platform is 300mm overlapping with the floor slab. A hole with a diameter of 250mm is reserved on the top beam of the floor, and the beam screw is fixed in the reserved hole during installation, and the receiving table and the bolt are connected with the selected steel plate and wire rope, and the wire rope is at an angle of 45° with the receiving table.
The wire rope of the unloading platform adopts 19 wire ropes, totaling 4, of which 2 are safety ropes, and the wire rope is adjusted by flower basket bolts to ensure that the wire rope is evenly stressed. The wire rope connection adopts rope clamp, and each wire rope is not less than 6. The platform is enclosed on three sides with a height of 1200mm. With 48 35. The steel pipe is welded, and the safety mesh is hung inside. The unloading platform shall not be connected with the outer scaffolding.
2) the unloading platform can be hoisted after the experience is qualified, the hook of the four corners is hung up when hoisting, and the initial signal is transmitted, but the platform can only be slightly lifted, and the cable-stayed wire rope can be officially hoisted, and the four lead ropes of the hook should be of equal length, so as to ensure that the platform is stable in the lifting process. After hoisting to the predetermined position, the platform I-beam and embedded parts are fixed, and then the wire rope is fixed, the nut and the wire rope clamp are fastened, and the tower crane hook can be loosened after completion.
3) When the unloading platform is used, hang a weight limit card in a conspicuous position near the platform, and it shall not be used in excess of weight.
6.7.3 Safety technical requirements for scaffolding.
1.Safety technical requirements for scaffolding erection and use.
1) The steel pipe frame should be provided with lightning rods, which are placed on the corner poles of the outer frame, and connected with large crossbars to form a lightning protection network, and the detection grounding resistance is not greater than 30.
2) Regularly inspect the scaffolding, find problems and hidden dangers, and repair and reinforce it in time before construction operations to achieve firmness and stability and ensure construction safety.
3) Outer scaffolding erectors must be certified to work, and correctly use safety helmets, safety belts, and wear non-slip shoes.
4) It is strictly forbidden to have a probe board on the scaffold board, and when laying the scaffold board and multi-layer operation, the construction load should be balanced as much as possible.
5) Ensure the integrity of the scaffolding body, and shall not pull the knot together with the lift, and shall not cut off the scaffolding body.
6) The scaffolding outside the structure is built on one floor each, and after the support is completed, it can be used only after the safety officer of the project department has passed the acceptance. No team leader or individual shall arbitrarily dismantle scaffolding components without consent.
7) Strictly control the construction load, the scaffold board shall not be concentrated and loaded, and the construction load shall not be greater than 3kn m2 to ensure a large safety reserve.
8) During the construction of the structure, it is not allowed to operate multiple layers at the same time, and the number of simultaneous operation layers does not exceed two layers during decoration construction, and the number of simultaneous operation layers of the temporary cantilever does not exceed the heavy layer.
9) When the working floor is higher than the wall piece under it 3When it is more than 0m and there is no wall connection on it, appropriate temporary support measures should be taken.
10) Set up a reliable protective fence between each working layer to prevent falling objects from injuring people.
11) A drainage ditch should be dug on the outside of the scaffolding pole foundation to prevent rainwater from soaking the foundation.
2.Safety technical requirements for scaffolding removal.
1) Before dismantling, comprehensively inspect the scaffolding to be dismantled, according to the inspection results, draw up an operation plan, report for approval, and only allow work after technical disclosure.
2) When dismantling the frame, the operation area should be divided, rope fences should be set up around it or warning signs should be erected, and a special person should be set up on the ground to command, and non-operators should be prohibited from entering.
3) The dismantling procedure should comply with the principle of top-down, first erection and then dismantling, that is, first dismantling the tie rod, scaffold board, scissor brace, diagonal brace, and then dismantling the small crossbar, large crossbar, vertical bar, etc., and proceed in turn according to the principle of one step and one clear. It is strictly forbidden to dismantle the rack at the same time.
4) When dismantling the pole, you should first hold the pole and then disassemble the last two buckles, and when removing the large crossbar, diagonal brace and scissor brace, you should first remove the middle fastener, then hold the middle, and then untie the end buckle.
5) The connecting wall rod (tie point) should be dismantled layer by layer with the demolition progress, and when the brace is dismantled, it should be supported by a temporary brace before it can be removed.
6) When dismantling, it is necessary to unify the command, echo up and down, coordinate the action, and notify the other party first when untying the knot related to another person to prevent falling.
7) When dismantling the frame, it is not allowed to change people halfway, if it is necessary to replace people, the dismantling situation can be explained clearly before leaving.
8) The dismantled materials should be transported slowly, and it is strictly forbidden to throw them. The materials transported to the ground shall be dismantled and transported at the designated place, classified and stacked, and cleared on the same day.
9) When leaving the post on the same day, strengthen the part that has not been dismantled in time to prevent man-made accidents caused by hidden dangers after resuming work.
10) In case of strong wind, rain, snow and other special climates, the scaffolding will not be dismantled, and it is strictly forbidden to dismantle at night.