Construction scheme and technical measures for structural reinforcement of residential buildings?
Derived from property documents
Construction scheme and technical measures of residential building structure: steel bar engineering
The rainy season is included in the main construction of this project. Under the interference of various unfavorable factors, at the same time, in order to ensure the construction quality of the project, in the construction stage of the engineering structure, our company focused on technical scheme, material supply, quality inspection, construction technology, finished product protection, safety and environmental protection, etc., and combined with the company's many years of construction experience, dedicated a boutique project for the construction unit.
1 reinforcement works
1. 1 project overview
There are three kinds of steel in this project: HPB235 (Grade I steel), HRB335 (Grade II steel) and HRB400 (Grade III steel). According to the design requirements, there are two ways to connect steel bars: overlapping and mechanical connection. According to the previous construction experience and the use of similar projects, it is suggested that the mechanical connection mode is straight thread+electroslag pressure welding.
1.2 construction preparation
(1) personnel preparation
Because of the straight thread connection, the backstage reinforcement processing personnel are equipped with specially trained personnel in addition to the general processing personnel, and special types of work must hold the employment certificate. Require steel binding skilled, equipped with specially trained threaded sleeve connector.
(2) Mechanical preparation
The backstage processing machinery is debugged in place before reinforcement processing, and it is maintained by technicians full-time to ensure the normal use of machinery and the adjustment of precision; Construction personnel are equipped with steel hooks, crowbars, wrenches, binding frames, wire brushes, chalk, rulers and other gadgets.
For details of reinforcement processing machinery and quantity, please refer to Chapter 6 Mechanical Entry Schedule.
(3) Material preparation
Reinforcement must have factory certificate, heat number and test report when entering the site. Reinforcement must have quality certificate (this part is provided by the material company), and the mechanical properties of reinforcement should be rechecked after entering the site.
(4) Material management
It is difficult to distinguish the secondary and tertiary steel bars in appearance, so when arranging the processing site on the construction site, the secondary and tertiary steel bars shall be stacked, processed and marked separately (see Chapter 7: "Layout of Construction Site" for details). In order to avoid the confusion in stacking and construction of secondary and tertiary steel bars after entering the site, the following measures are taken:
On-site steel yard will pile up secondary and tertiary steel bars separately, and set up steel bar specifications and model identification plates at the site.
When the secondary and tertiary steel bars enter the site, it is forbidden to transport them in the same car.
Steel bars shall be hoisted to the designated place by special personnel and marked clearly. Avoid confusion during transshipment.
The finished steel bars shall be clearly marked with specifications and models in the stacking yard, and identification strips shall be hung on the steel bars during hoisting to ensure that the steel bars can be used correctly in structural construction.
Buy enough plastic cloth or striped cloth at the steel bar stacking site to prevent steel bars from rusting in rainy and snowy weather.
(5) Technical preparation
Before setting out steel bars, technicians and lofting personnel should read the general description of the structure, the description of beams, columns and slabs, design changes and records of the blue prints.the design in detail, and review the drawings in detail. If problems are found, they should be solved through consultation with the design institute in time.
When binding (overlapping) steel bars, the steel bar joints in the tension zone are staggered by 25%, which is located between 1/3- 1/4; The reinforced joints in the compression zone should be staggered by 50%, and the number of reinforced joints in the same section should not be greater than 50%; For straight thread connection, the joint position of reinforcement shall be 50%, and the number of joints in the same section shall not exceed 50%.
The steel bar lofting sheet must be reviewed by the project technician before it can be processed.
1.3 steel bar background processing
(1) steel bar straightening
When straightening steel bar with straightening machine, straightening die and conveying roller should be selected according to the diameter of steel bar, and the compactness of straightening die and roller should be correctly mastered. The offset of straightening die should be determined by experiment according to its wear degree and steel bar variety.
(2) steel derusting
Steel surface should be clean. Oil stains, paint stains, floating skin and rust that can peel off when hammering should be removed before use.
(3) steel cutting
After the project technicians and testers confirm that the steel bar factory certificate and the conclusion of the second interview report meet the design and specification requirements, they shall notify the blanking personnel to carry out steel bar blanking. Before blanking, the professional technicians of the project will give various shapes and reinforcement details of various parts of the structure according to the reinforcement diagram and the divided construction procedures, number them, calculate the blanking length and quantity respectively, fill in the material list and apply for processing.
(4) cut off the quality requirements
There must be no horseshoe-shaped or bending phenomenon in the fracture of steel bar, and there must be no burr and other phenomena in the steel bar with special requirements (such as top die steel bar); The length of reinforcement shall be accurate, with an allowable deviation of 5 mm (except for the ejector pin).
(5) Bending of steel bar
General provisions: when the hook at the end of the first-class steel bar is 180 degrees, the arc bending diameter is controlled at 2.5 times of the steel bar diameter, and the length of the straight part is10d; ; When the secondary and tertiary steel bars need to be bent at 90 degrees or 135 degrees, the bending diameter should be controlled at 5 times of the steel bar diameter, and the straight part should be10d; Bending 135 degrees; The bending radius of the middle bending part of the bending steel bar is 5d.
Bending forming process: according to the requirements of the bill of materials for reinforcement, mark the size of reinforcement on the positioning plate. When the steel bar is bent, draw all bending positions with chalk according to the size of the positioning plate, and deduct the bending adjustment value according to different bending angles. When the steel bar is formed on the bending machine, the axis diameter should be 2.5 times the diameter of the steel bar. The forming shaft is equipped with eccentric shaft sleeve to meet the bending needs of steel bars with different diameters.
After the steel bar is bent and formed, the angle is correct, the hook length meets the requirements, and the stirrup should be square; Similar stirrups should be the same size, hook length and angle, positioning lacing should be packed neatly, and at the same time, identification labels should be attached to indicate the use position and quantity. After the reinforcement of the same specification and size is formed, it is required that the reinforcement length is consistent, the hook length is consistent, and the angle is consistent. After labeling, classification code shall be placed neatly, indicating the use position and quantity.
1.4 Reinforcement installation
(1) Reinforcement binding of the first floor slab
① Process flow:
Draw the rebar position line → tie the bottom layer rebar of the slab → tie the top layer rebar of the slab → tie the top layer rebar of the slab → tie the column rebar → wall rebar.
(2) Key points of construction:
Draw rebar position line: according to the rebar spacing shown in the drawing, completely cover the initial rebar with the thickness of protective layer, and pop up rebar position line (including wall rebar position line). After the rebar is in place, place the rebar according to the rebar position line.
Press the ejected steel.
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Derived from property documents
Construction scheme and technical measures of residential building structure: steel bar project summary: general provisions: when the hook at the end of the first-class steel bar is 180 degrees, its arc bending diameter is controlled at 2.5 times of the steel bar diameter, and the length of the straight part is10d; ; When the secondary and tertiary steel bars need to be bent at 90 degrees or 135 degrees.
Laying floor reinforcement from the rebar locating line on the property paper.
When steel bars are bound, all intersections of steel bars shall be bound, and the bound wire ends shall be pressed on the bottom plate steel bars in the same direction and length, so as to ensure that the binding rules of iron wires and steel bars will not be displaced.
Put marble blocks on the concrete protective layer of the bottom plate. The thickness of the blocks is equal to the thickness of the protective layer, and the spacing is 600*600mm, showing a plum blossom shape. A line is required to be arranged diagonally.
According to the played position line of the wall column, insert the wall column steel dowel into the foundation, and the depth of the inserted foundation should meet the anchoring length, and the upper end of the wall column should be positioned with a horizontal positioning frame. The first horizontal positioning frame is placed at the root of the steel dowel, which is firmly bound with the bottom steel bar, and the second one is placed at the first overlapping position of the steel dowel, which is firmly bound, and the steel dowel is vertical after adjustment.
(2) Wall reinforcement binding
① Process flow:
Vertical steel bar displacement adjustment → binding embedded column steel bar → binding lintel steel bar → binding wall vertical positioning ladder steel bar → binding wall horizontal steel bar → binding hook → adjusting steel bar → acceptance.
(2) Key points of construction:
According to the position line of the played wall and concealed column. When the wall, column and section change, the reinforcement should be adjusted in place according to 1: 6 to meet the requirements of the protective layer and ensure that the wall reinforcement and the concealed column reinforcement are vertical.
Binding embedded column rebar: The process is the same as binding column rebar.
Binding lintel reinforcement: When binding lintel reinforcement, level it with a spirit level. Stirrups should be evenly distributed and perpendicular to the main reinforcement of the beam. The first starting reinforcement is 50mm away from the external reinforcement in the column, and the second reinforcement is 50mm away from the main reinforcement outside the column.
Binding wall reinforcement: firstly, bind the vertical positioning ladder reinforcement of the wall, and the spacing of the vertical positioning ladder reinforcement is 1200- 1500mm, which is evenly arranged. When the spacing of concealed columns is small, it can be placed between two concealed columns according to the situation, and the spacing of spacers is the same as that of horizontal steel bars. The top die supports the upper, middle and lower parts and is painted with antirust paint, which is 2mm smaller than the wall thickness and 65438+ smaller on each side. The height of stirrup of ladder is required to be consistent. The spacing of horizontal reinforcement in the binding wall should be bound according to the vertical positioning of ladder reinforcement, and the first starting reinforcement should be 50mm away from the roof. At the same time, it should be ensured that there are three horizontal bars in the lap section, and the length of the binding line is consistent without burr. When binding wire, it should be bound from the opposite side to ensure that the wire head is in the wall reinforcement. Finally, add a horizontal positioning frame at the top of the wall: the spacing between the positioning frames is the same as the spacing between the vertical bars of the wall.
See the above figure for the overlapping form of vertical reinforcement of the wall:
Support spacing of 600mm plum blossom arrangement;
With plastic cushion blocks, the distance between the inner and outer walls is 600×600, which is arranged in a plum blossom shape. Outside the external wall, mortar pads with a thickness of 50×50× 15mm and a spacing of 600×600 are used, which are arranged in a plum blossom shape. The spacer blocks are evenly spaced and are all in a straight line.
(3) Column rebar binding
(1) technological process of frame column:
Binding column stirrups → Uniform vertical reinforcement (messenger wire binding) → Delineating stirrup spacing → Binding stirrups.
(2) Process key points:
Binding column stirrups: according to the spacing required by the drawings, calculate the number of stirrups for each column. Put the stirrups on the connecting steel bars protruding from the lower layer first, and then reinforce the columns. Steel bars are connected with straight bars, and each joint is tightened with a wrench.
Connection and binding of vertical reinforced bar: After the main bar of column is erected, the connection position of reinforced bar must be more than 500mm from the ground, and the hanging line should ensure that the main bar of column is vertical to the ground.
Draw the stirrup spacing line: draw the stirrup spacing line with chalk on the vertical bar of the column that has been erected.
Column stirrup binding:
1) Move the group of stirrups upward according to the stirrup position line, tie them from top to bottom, tie them with positive and negative buttons, and tie the wire around the column.
2) Stirrup and main reinforcement should be vertical, the intersection of stirrup corner and main reinforcement should be bound, and the non-corner part of main reinforcement and stirrup should be bound by positive and negative buttons.
3) Stirrup hook lap along the column vertical reinforcement staggered by 50%, and binding firmly.
4) The end of column stirrup is bent into 135 degrees, and the length of straight part is 10d(d is the diameter of steel bar).
5) Column rebar cover thickness requirements: main rebar: not less than 25mm, and larger than the diameter of main rebar. The pad is tied to the column stirrup, with the minimum thickness of 15mm, which can ensure the protective layer of the main reinforcement, with the size of 50×50mm and the spacing of 600× 600 mm.
6) At the joint of beam and column, ensure the section size of column.
(4) the roof steel binding
① Process flow:
Draw the position line of plate steel bar → tie the lower steel bar of bottom iron → tie the upper steel bar of bottom iron → add a horse stool pad → tie the lower steel bar of bottom iron on the pull-through line → tie the upper steel bar of bottom iron on the pull-through line → adjust the position of wall steel bar → clean it up → apply for inspection and supervision.
② Key points of construction
When binding steel bars, all steel bar intersections must be bound, and the steel bars shall not be displaced. Within the overlapping range of steel bars, three threads should be added for binding except the intersection;
Top caving pad, thickness 15mm, put a quincunx every 800 mm, after putting the pad, make sure that there is a line horizontally, vertically and obliquely.
The roof reinforcement is anchored in the wall or beam; The anchorage length meets the design and specification requirements;
After the binding of roof reinforcement, adjust the vertical reinforcement of the wall, and place the ladder reinforcement horizontally to ensure that the protective layer of the reinforcement is correct and the reinforcement does not shift or exceed the height.
(5) Beam steel binding
Clean up the shavings, wood chips, wire tubes and other sundries on the template. After the upper surface of the formwork is brushed with release agent, the positioning sideline of the axis and superstructure is released. Draw the main reinforcement on the template, distribute the reinforcement spacing, use red ink lines to pop up every two main reinforcement lines, and tie the reinforcement according to the lines.
According to the pop-up spacing line, put the main reinforcement first and then the distribution reinforcement. Embedded parts, electrical conduits and reserved holes shall be installed in time.
The short-span upper main reinforcement of the floor slab should be placed above the long-span upper main reinforcement, and the short-span lower main reinforcement should be placed below the long-span lower main reinforcement.
Joint position of longitudinal reinforcement in the beam: the lower reinforcement should be at the bearing, and the upper reinforcement should be within the clear distance of mid-span 1/3;
Beam stirrups are added with plastic locating clips to ensure the thickness of protective layer of beam reinforcement.
(6) Stair steel binding
① Process flow:
Draw the position line → tie the reinforcement → tie the distribution reinforcement → tie the step reinforcement.
(2) Key points of construction:
Draw the position lines of main reinforcement and distribution reinforcement on the stair board.
According to the direction of beam reinforcement, main reinforcement and distribution reinforcement in the design drawings, when binding the stair beam, the beam should be tied first and then the plate. Plate reinforcement should be anchored into the beam, then the main reinforcement should be bound and the distribution reinforcement should be bound, and each intersection should be bound. Rest platform construction joints must be added with a horse stool, and the foot of the horse stool should be padded; Stair beams are supported by top beams.
Tie the iron bars, tie the stepping steel bars, and then support the stepping template.
1.5 straight thread technology
(1) construction preparation
Steel bar connection adopts the construction method of straight thread connection, off-site sleeve prefabrication and on-site connection, and all steel bars are processed in the field. Require on-site processing personnel who enter the site to receive training. After completion, the workers will be assessed on site, qualified personnel will be issued with work permits, and construction personnel will hold relevant certificates. Operation by non-professionals is strictly prohibited.
(2) Process flow and operation points
① Process flow:
Blanking → set of wires → 10% sampling inspection → (after passing the inspection) wear plastic protective caps → classify and pile them up → transport them to the site for standby → connect the steel bars with the sleeve → tighten the positioning with movable hands → check that the exposed buckles at both ends of the sleeve are not more than one complete buckle → conduct on-site inspection and record.
② Key points of operation:
Steel blanking requires a straight end and cannot be horseshoe-shaped.
Set of silk workers should be relatively fixed, and hold relevant certificates after training. The threader shall visually check the threading quality one by one, and randomly check the 10% thread head, and check with the thread gauge.
When setting silk
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Derived from property documents
Construction scheme and technical measures of residential building structure: steel bar project summary: general provisions: when the hook at the end of the first-class steel bar is 180 degrees, its arc bending diameter is controlled at 2.5 times of the steel bar diameter, and the length of the straight part is10d; ; When the secondary and tertiary steel bars need to be bent at 90 degrees or 135 degrees.
The paper provided by the property must be coated with lubricant.
Check the diameter and length of the machined steel wire head with a thread gauge and keep it within the specified fluctuation range.
When connecting steel bars on site, the steel bars at both ends of the sleeve should be pressed against each other, and the central position of the sleeve should be maintained. The exposed buckles at both ends should not exceed a complete thread.
(3) Reinforcement connection
Check whether the model of casing and steel bar is consistent, check whether the thread is in good condition and clean, and remove impurities and rust. When reinforcing bars are connected, pay attention to the jacking of two reinforcing bars, so that the exposed tooth profile does not exceed a complete thread. After the construction is completed, the joints that pass the acceptance shall be marked with red paint.
50% lap joint shall be considered for the connection of bottom plate reinforcement, and the position of lower iron joint shall avoid the maximum bending moment of bearing as far as possible; Try to avoid the maximum bending moment in the middle of the span when the upper iron is lapped; After the joint connection is completed, the joint inspection shall be carried out by special personnel.
The upper iron is connected with the beam reinforcement of the mid-span section of 1/3, and the lower iron is connected with the load-bearing section of 1/3; After the connection is completed, someone will check it.
Column rebar connection: the position of column rebar connection joint is more than 500mm from the ground, and the positions of two joints are staggered by 35d. After the reinforcement is connected, there will be someone to check it.
Steel joint test should be sampled on site, and the sampling quality and representativeness should be guaranteed. The qualified rate of the joint is 100%.
(4) Quality standards
The variety and quality of steel bars must meet the design requirements and the current national standards. Inspection method: factory certificate and inspection report must be available.
Requirements for sleeve:
There are no defects such as cracks on the surface of the sleeve;
Overall dimensions, including internal thread diameter and sleeve length, meet the product design requirements;
Plastic protective caps should be added at both ends of the casing.
Requirements for threaded head:
Steel wire heads shall be covered with plastic protective caps as soon as possible after passing the inspection, and shall be neatly stacked according to the specifications;
In case of rain or long-term stacking, the thread head should be covered for rust prevention;
The thread head should be properly protected during transportation to avoid rain and mechanical damage.
The strength of joints must be qualified. Less than 500 joints are taken as a batch, and 3 specimens are made for tensile test in each batch. Inspection method: Check the tensile test report of the joint.
The specification of steel bar, joint position and the percentage of steel bar area with joint in the same section should not be greater than 50%. Inspection method: field observation and statistics.
(5) Quality problems that should be paid attention to
Before setting out, the specifications and appearance quality of steel bars must be checked. If the ends of steel bars are found to be bent, they must be straightened first.
Steel wire sleeve: before operation, adjust the position of the positioning ruler according to the specifications of steel bars, and match it with the corresponding processing guide sleeve. For large-diameter steel bars, the specified size should be turned several times to ensure the thread accuracy.
1.6 electroslag pressure welding head
(1) The process is as follows:
Cutting steel bar → polishing the end face of steel bar → putting the steel bar into the lifting frame and tightening it → putting the flux into the flux box after drying → turning on the power supply to strike the arc → starting the motor to pressurize the joint, making the joint pier thick → removing the fixture, removing the electroslag → quality inspection.
(2) Electroslag pressure welding operation shall meet the following requirements:
1) Before welding, the rust and oil stain within the range of 120mm shall be removed, and the rebar ends shall be leveled with gas cutting tools when necessary.
2) Steel bars shall be installed in the jaws of the fixture for pre-clamping, and the axes of upper and lower steel bars shall be kept in a straight line.
3) The location of steel bar joints in the same component shall comply with the design requirements or relevant specifications, and the welded joints shall be considered when making steel bars.
4) Close the flux box and inject the required flux. Before use, the flux must be baked in an oven at 250℃ for 65438±0-2h.
5) When manual electroslag pressure welding is adopted, the direct arc initiation method can be adopted, so that the upper steel bar contacts with the lower steel bar first, and after the welding power supply is connected, the upper steel bar is raised by 2-4 mm immediately to ignite the arc; Then continue to slowly lift the steel bar for several millimeters to make the arc burn stably. Then, with the melting of the steel bar, it is gradually sent down and transferred to the electroslag process. After the steel bar melts to a certain extent, when cutting off the welding power supply, the jacking should be carried out quickly, and the operating rod can be loosened after a few seconds to avoid the joint deflection or uncertain combination. The speed of lifting and sending steel bars should be determined by trial welding to prevent open circuit or short circuit.
6) The gap between the lower reinforcement and the flux box must be plugged with asbestos cloth to prevent flux leakage.
7) When welding, the voltage shall be stable, and the voltage shall not be lower than 365V.
(3) Before welding, try to weld three joints, and after the appearance inspection is qualified, the welding parameters can be selected. Every time a batch of steel bars is replaced, the welding parameters should be readjusted.
(4) Visual inspection
1) The welding package of steel bar joint shall be uniform, full and smooth, free of cracks, collapse, undercut and slag inclusion, and the surface of steel bar shall be free of obvious burns and other defects.
2) The deviation of rebar axis at the joint shall not be greater than110 rebar diameter, and shall not be greater than 2mm at the same time.
3) The bending of the joint shall not be greater than 4.
4) The joints that fail to pass the visual inspection shall be removed and re-welded.
1.7 quality standard for steel bar forming
The variety and quality of steel bars must comply with the design and relevant standards.
Steel surface must be clean. After derusting, the steel bars with granular and flaky old rust and pits should be used in strict accordance with the original specifications. Steel surface should be kept clean.
The specification, shape, size, quantity, anchorage length and joint position of reinforcement must meet the requirements of design and construction specifications.
No missing, loose or missing buttons are allowed.
Hook orientation should be correct, and lap length should meet the requirements.
Stirrup spacing should comply with the design requirements. The initial reinforcement is 50mm (the intersection with horizontal reinforcement can be adjusted to 30mm), the hook angle is 135 degrees, the hook straight line length is 10d, the hook direction is consistent, the angle is consistent, the straight line length is consistent, and the stirrup spacing is consistent.
The position and spacing of horizontal bars do not meet the requirements: the starting bar of the wall is 50mm, and when it conflicts with the stirrup, the stirrup drops to 30mm from the ground; Simple scaffolding should be used when binding wall reinforcement, and construction personnel should not trample on wall reinforcement to avoid horizontal reinforcement displacement.
The binding of the wall reinforcement protruding from the lower floor slab and the vertical reinforcement does not meet the requirements: when binding, the reinforcement protruding from the lower floor slab should be straightened first, and the protective layer should be adjusted according to 1: 6 (when the horizontal section is 1, the vertical bending section is 6) before binding.
The position and size of steel bars at the openings of doors and windows do not meet the requirements: before binding, the position of steel bars should be adjusted according to the edges of the openings, and the steel bars should be aligned with hanging wires when binding.
The anchorage length of horizontal bar of shear wall does not meet the requirements: study the drawings carefully. Reinforcement anchorage in corners, intersection nodes, end points, coupling beams and other parts must meet the requirements.
The lap length must meet the requirements, and the lap position of reinforcement must be highly consistent.
Reinforced protective layer must comply with the design requirements, and the allowable deviation is 65438 0 mm.
1.8 finished product protection measures
No trampling is allowed after the column reinforcement is bound, and no welding is allowed on the column main reinforcement.
After the floor negative reinforcement is tied, it is not allowed to walk on it. After the steel bars are bound and formed, a springboard is set for the construction personnel to walk around. When pouring concrete, assign rebar workers to repair it to ensure the correctness of the negative bending rebar position.
When binding reinforcement, it is forbidden to touch the embedded parts and the template of the hole.
Don't pollute the steel bar when applying isolation agent in the formwork.
When installing electric conduits, heating pipes or other facilities, steel bars shall not be cut and moved at will.
Before semi-finished steel bars enter the binding site, take rust prevention measures; Corroded steel bars should be cleaned up in the background first, and can enter the binding site only after preview;
Before rebar binding, the rebar worker should check whether the specifications and dimensions of rebar processing meet the requirements of drawings, including
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Derived from property documents
Construction scheme and technical measures of residential building structure: steel bar project summary: general provisions: when the hook at the end of the first-class steel bar is 180 degrees, its arc bending diameter is controlled at 2.5 times of the steel bar diameter, and the length of the straight part is10d; ; When the secondary and tertiary steel bars need to be bent at 90 degrees or 135 degrees.
When the property paper is in doubt, report it to the relevant personnel of the project in time, and then check the appearance quality of steel bar processing and whether there is any damage during transportation. If yes, report it to relevant personnel in time.
In the process of steel binding, erection of binding frame, one-time binding in place; After the steel bar is formed, it is forbidden to trample;
In the process of hydropower construction, it is forbidden to step on steel bars, and the construction must be put on airs. When the steel bar is damaged, the civil construction team has the right to stop it and feed it back to the project department, which will punish the relevant teams;
During hydropower construction, it is forbidden to weld the main reinforcement and burn the reinforcement at will. When the casing is worn, the steel bar will be adjusted in time after displacement.
After concrete pouring, the reinforcement shall be cleaned and adjusted in time.
Ensure that the position of the embedded electric conduit is accurate, etc. If there is any conflict, the vertical reinforcement can be bent left and right along the plane, and the horizontal reinforcement can be bent up and down, bypassing the embedded pipe. But be sure to ensure the thickness of the protective layer of steel bar, and it is forbidden to cut steel bar arbitrarily.
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Derived from property documents
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