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Engineering safety accidents happen frequently
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Scaffold is the most important safety protection facility in all construction sites! Especially bridge engineering
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According to the standards and specifications to build a good scaffold, do a good job in life protection, no delay! The following bridge construction scaffolding operation points, we must take a good look! 1
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Before the scaffold is erected, the foundation plane shall be checked and leveled by means of pulling wires to ensure that the scaffold is supported in the same horizontal plane and the stress of the scaffold is uniform
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During the construction, the tight placement of each connection point shall be ensured, and false connection is strictly prohibited
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2
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In order to prevent the concentrated load transmitted by the outrigger from cracking the cushion concrete, square timber is laid on it with the thickness of not less than 5cm and the width of not less than 20cm
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3
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The adjustable base is set under the base mounting vertical pole, the screw rod and nut kneading length shall not be less than 5 buckles, and the extension length shall not exceed 30cm, and the length inserted into the vertical pole shall not be less than 30cm
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The base of the vertical pole and the square timber, the square timber and the hardened ground shall be closely attached, and there shall be no void or looseness
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4
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The erection of vertical pole shall be arranged according to the design scheme
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The extension of vertical pole with bearing capacity must be butted, and overlapping is not allowed
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Except that the top step of the top layer can be overlapped, the joints of other layers must be butted with butt fasteners
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The butt fastener on the vertical pole should be staggered, the joints of two adjacent vertical poles should not be set in the synchronous, the staggered distance of two separated joints separated from a vertical pole in the synchronous direction should not be less than 50cm, and the distance between the joint center and the main node should not be greater than 1 / 3 of the step distance
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As shown in the figure: when the vertical pole h ≤ 20m, the deviation is not greater than h ／ 200 (mm)
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When h ≥ 20m, the deviation is not more than h ／ 300 (mm), and the vertical deviation of total height is not more than 100 mm
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5
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For each layer of vertical pole erected, the horizontal pole and longitudinal pole shall be erected after passing the inspection
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According to the design requirements, the cross bar and longitudinal bar must be set up horizontally
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If it is a fastener scaffold, each node of the horizontal bar and vertical bar of the longitudinal and transverse bars shall be fastened with fasteners, and it is strictly forbidden to fail to buckle or fail to buckle
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A transverse horizontal bar must be set at the main node, which shall be connected with right angle fastener and shall not be removed
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The center distance of two right angle fasteners at the main node shall not be greater than 150 mm
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6
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The angle of diagonal bracing is 45 ° to 60 ° and the length shall not be less than 6m
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Each diagonal bracing shall span no less than 4 pieces
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The diagonal bar of the cross bracing shall be fixed on the extension end of the vertical bar or the transverse horizontal bar intersected with it by the rotary fastener, and the distance from the center line of the rotary fastener to the main node shall not be greater than 15cm
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The bottom of the cross brace must fall to the ground
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The nodes are not parallelogram
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The overlapping length of scissors shall be greater than 1m, and double fasteners shall be used for fastening
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7
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The setting of cross bracing – longitudinal, transverse, horizontal 8, longitudinal and transverse sweeping poles
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It is fixed on the vertical pole with right angle fastener, and the distance from the base is not more than 20cm
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The horizontal sweeping pole shall also be fixed on the vertical pole close to the bottom of the longitudinal sweeping pole with right angle fasteners
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When the vertical pole foundation is not at the same height, the vertical sweeping pole at the high place must be extended to the low place for two spans and fixed with the vertical pole
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The height difference shall not be more than 1m, and the distance between the vertical pole axis above the slope and the slope shall not be less than 50cm
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Setting of sweeping pole 9
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Laying of scaffold board: according to article 6.2.4 in Chapter 6 of scaffold specification, ① the operation layer shall be fully, stably and solidly paved; ② wooden scaffold board and bamboo scaffold board shall be set on three horizontal poles
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When the length of the scaffold board is less than 2m, it can be supported by two horizontal bars, but both ends of the scaffold board should be fixed with the horizontal bar to prevent overturning
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The scaffold board shall be laid by butting or overlapping
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During butt joint laying, two horizontal bars shall be set at the joint, the overhanging length of scaffold board shall be 13cm ~ 15cm, and the sum of overhanging length of two scaffold boards shall not be greater than 30cm; during erection laying, the joint shall be supported on the horizontal bar, and the overlapping length shall not be less than 20cm
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The extension length of the horizontal bar should not be less than 10 cm
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③ The probe length of the scaffold board at the end of the floor should be 15cm, and both ends of the board should be fixed on the supporting rod
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10
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Article 9.0.11 in Chapter 9 of the code for setting flat net of scaffold stipulates that the scaffold board shall be laid firmly and tightly, and the bottom shall be covered with double layers of safety net
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The safety net shall be used to seal every 10 meters below the construction layer
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11
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According to article 9.0.12 of Chapter 9 of the scaffold specification, single row scaffold, double row scaffold and cantilever scaffold shall be fully enclosed with dense mesh safety net along the periphery of the scaffold
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The dense mesh safety net shall be set inside the outer pole of the scaffold and shall be firmly bound with the scaffold
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12
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The upper bracket is set at the top of the support, the rotation height of the upper bracket is not more than 30cm, and the length of the cantilever end of the upper part of the vertical pole is not more than 60cm; 13
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The longitudinal beam is set with wooden square as the longitudinal beam, which is installed on the adjustable top bracket
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The dimension of timber is determined according to the calculated strength and deflection, and the jacking needs to be leveled
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14
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Other control points: ① for the beam slab on the circular curve with small radius, the layout form of support scaffold shall be adjusted according to the design principle and the actual construction situation
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When the number of small cross bars does not meet the construction requirements, the steel pipe and fastener of Φ 48mm shall be used instead, and it is strictly prohibited to remove the setting of small cross bars
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② After the scaffold is erected, the plane position, top elevation, node connection and vertical and horizontal stability of the scaffold shall be comprehensively inspected
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Before concrete pouring, the upper and lower supports of the scaffold shall be tightened again to ensure close contact with the square timber and prevent settlement and deformation of the scaffold during concrete pouring
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③ The tightening torque of fastener bolts after installation shall be checked by torque wrench, and the sampling method shall be carried out according to the principle of random distribution
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The tightening torque of fastener bolt shall not be less than 40kN · m and not more than 60kn · M
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④ Construction joints shall be set at both ends of segmental pouring
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When the tension grouting of the middle section is completed, the bottom support scaffold shall be removed, but the support system at the cantilever end shall not be removed before the construction of the whole beam section is completed
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⑤ Lightning protection and grounding: the scaffold with a height of more than 20m must be provided with lightning protection and grounding
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⑥ Power line: when the power line contacts the frame, the hook with insulating sleeve shall be used
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The distance from overhead transmission line shall not be less than 3m
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⑦ Professional tools shall be used for the erection of scaffold: level ruler shall be used to correct the perpendicularity of vertical rod and the levelness of horizontal rod; meter ruler shall be used to control the step distance, longitudinal distance and transverse distance
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⑧ The probe length of the bar and springboard at the end of the frame should be no more than 20cm, and the probe length should be unified
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⑨ The transmission material shall not damage the dense mesh
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⑩ According to article 9.0.15 of Chapter 9 of the code for installation of cable wind rope scaffold, temporary anti overturning fixing measures shall be taken during the installation of full scaffold and full support frame
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