This technical standard is applicable to the reinforcement binding of reinforced concrete floors and walls in basements.
2 Construction preparation
2. 1 Materials and main machines:
2. 1. 1 steel bar: It shall have the factory certificate and conduct the mechanical properties re-inspection as required. When special circumstances such as brittle fracture occur during processing, it is necessary to carry out chemical composition inspection. Steel bars shall be free of old rust and oil stain.
2. 1.2 iron wire: No.20 ~ No.22 iron wire (burning wire) or galvanized iron wire (lead wire) can be used. The cutting length of iron wire should meet the use requirements.
2. 1.3 mortar pad, plastic card, various hooks or poles for controlling concrete protective layer.
2. 1.4 Tools: steel hook, crowbar, wrench, binding frame, wire brush, trolley, chalk, ruler, etc.
2.2 Operating conditions:
2.2. 1 according to the location specified in the construction site plan, clean and level the steel yard. Prepare stow-wood, pile it up in the order of steel binding, and clean up the corrosion.
2.2.2 Check whether the grade, model, shape, size and quantity of reinforcement are consistent with the design drawings and the processing ingredient list.
2.2.3 When the underground water level in the construction site is high, there must be drainage and precipitation measures.
2.2.4 Be familiar with the drawings, determine the order in which steel bars are inserted in place, coordinate with related jobs, such as shuttering, pipeline construction and steel bar binding, determine the construction method, and make technical disclosure.
2.2.5 According to the basement waterproof construction scheme (using internal sticking method or external sticking method), the waterproof layer and protective layer under the floor should be completed before the floor reinforcement binding; After the formwork is supported around the bottom plate (or after the protective wall is built, the waterproof layer is made). When the basement exterior wall waterproof is constructed by internal sticking method, the protective wall should be built before binding the wall reinforcement, and the waterproof layer and protective layer should be completed.
3 operation process
3. 1 process flow:
Draw the reinforcement position line → transport the reinforcement to the use position → bind the floor and beam reinforcement → bind the wall reinforcement.
3.2 Drawing reinforcement position line: According to the reinforcement spacing shown in the drawing, calculate the actual number of reinforcement required for the bottom plate. Generally, the rebar near the template edge of the bottom plate is 5cm away from the template edge, and the rebar position line (including the rebar position line of the foundation beam) pops up on the bottom plate.
3.3 Binding foundation slab and foundation beam reinforcement
3.3. 1 According to the pop-up reinforcement position line, the lower floor reinforcement shall be laid first. According to the stress of the bottom plate, decide which direction the lower reinforcement is below. Generally, short tendons are laid first, and then long tendons are laid.
3.3.2 When steel bars are bound, every point near the intersection of the outer two rows of steel bars shall be bound, and the intersection of the middle part can be staggered and bound at intervals, and all the steel bars under two-way stress must be bound at the intersection of steel bars. If a straight buckle is used, the direction should be staggered, and a splayed buckle can also be used, but the reinforcement shall not be displaced.
3.3.3 Place the mortar pad for the concrete protective layer of the bottom plate. The thickness of the pad is equal to the thickness of the protective layer, and it is placed in a quincunx shape every1m. If the foundation slab is thick or the amount of steel used for foundation beams and slabs is large, the placement distance can be reduced, and even the mortar pad can be replaced by iron.
3.3.4 When there is a foundation beam on the bottom plate, it can be bound and shaped in sections, and then installed in place, or bound and shaped in situ according to the beam position line.
3.3.5 When the foundation slab adopts double-layer reinforcement, after the lower reinforcement is bound, a reinforced horse stool or a reinforced bracket (the spacing should be about 1m) should be placed on the horse stool, and positioning reinforcement in both vertical and horizontal directions should be placed on the horse stool. The up-and-down order and fastening method of reinforcement are the same as those of the lower reinforcement of the plate.
3.3.6 When there is a binding joint for the bottom steel bar, the lap length and lap position of the steel bar should meet the requirements of construction specifications, and the lap joint of the steel bar should be fastened with iron wire at the middle and both ends. If welded joints are used, in addition to sampling according to welding regulations, joint treatment should also comply with the provisions of construction specifications.
3.3.7 Due to the particularity of the stress on the foundation slab and foundation beam, the positions of the upper and lower bars should meet the design requirements.
3.3.8 According to the played position line of the wall column, the steel dowel inserted into the foundation of the wall column shall be firmly bound, the depth of the inserted foundation shall meet the design requirements, and the length of the sling shall not be too long. Measures should be taken to ensure that the sling is vertical and will not be skewed, dumped or displaced.
3.4 wall reinforcement assembling:
3.4. 1 Pop up the position lines of the wall and the openings of doors and windows on the floor concrete, and correct the embedded steel dowel again. If there is any displacement, it will be dealt with seriously according to the negotiation regulations. Wall formwork should adopt "jumping formwork" to facilitate steel bar construction.
3.4.2 First, tie 2 ~ 4 vertical bars, and draw the horizontal bar classification mark, then tie two horizontal bars horizontally at the lower part and chest, and draw the vertical bar classification mark. Generally, the transverse reinforcement is on the outside and the vertical reinforcement is on the inside, so tie the vertical reinforcement first, and then tie the transverse reinforcement. The spacing and position of horizontal and vertical bars shall meet the design requirements.
3.4.3 Wall reinforcement is a bi-directional reinforced bar, and all steel bar intersections should be bound point by point, and the lap length and position should meet the requirements of design drawings and construction specifications.
3.4.4 Double-row steel bars shall be supported by spacing or tied by lacing to fix the spacing of steel bars. Brace or brace can be made of φ6 or φ8 steel bars, and the spacing is about 1m to ensure the spacing of double-row steel bars.
3.4.5 Tie mortar pad with iron wire on the outside of wall reinforcement to ensure the thickness of protective layer.
3.4.6 In order to ensure the correct elevation position of doors and windows, draw elevation lines on the vertical bars of the hole. Doors and windows openings shall be bound with lintel reinforcement according to the design requirements, and the length of anchorage into the wall shall meet the design requirements.
3.4.7 The seismic structural reinforcement and anchorage length of each connection point shall be bound according to the design requirements. For example, the longitudinal stress reinforcement of the first column extends to the depth of the basement wall; Attention should be paid to the anchorage length of reinforcement at the junction of wall end and internal and external wall.
3.4.8 Cooperate with other types of work to install embedded pipe fittings and reserve holes. , its position and elevation should meet the design requirements.
4 quality standards
4. 1 guarantee project:
4. 1. 1 The variety and quality of reinforcement, the brand and performance of covered electrode and flux, and the steel plate used must meet the design requirements and the provisions of relevant standards. Before welding imported steel bars, welding tests must be carried out to check the chemical composition, and welding can only be carried out after meeting the relevant regulations.
4. 1.2 The surface of steel bar must be clean, and the steel bar with granular or flaky old rust and pits after rust removal should be used in strict accordance with the original specifications.
4. 1.3 The specification, shape, size, quantity, spacing, anchorage length and joint setting of reinforcement must meet the design requirements and construction specifications.
4. 1.4 The mechanical properties of welded joints must conform to the special provisions of the rebar welding code.
4.2 Basic items:
4.2. 1 The number of missing buckles and loose buckles of binding reinforcement shall not exceed 10% of the number of binding buckles, and shall not be concentrated.
4.2.2 The hook is in the right direction, the binding joint conforms to the provisions of the construction specification, and the lap length is not less than the specified value.
4.2.3 The number of stirrups made of Grade I steel bars shall meet the design requirements, and the hook angle and straight length shall comply with the provisions of construction specifications.
4.2.4 Butt joint has no transverse cracks and burns, and the welding package is uniform. The bending at the joint is not more than 4, and the axis deviation of steel bar at the joint is not more than 0. 1d and not more than 2mm.
4.2.5 The weld surface of the arc welding joint shall be smooth, free from sag and flash, and free from cracks, pores, dust accumulation and undercut at the joint. The allowable deviation of joint size shall not exceed the following provisions:
4.2.5. 1 The longitudinal displacement of the binding belt along the center of the joint is not more than 0.5d, and the bending of the joint is not more than 4.
The deviation of steel bar axis at 4.2.5.2 joint is not more than 0. 1d and not more than 3mm.
4.2.5.3 weld thickness is not less than 0.05 micron.
The weld width of 4.2.5.4 is not less than 0.1d.
4.2.5.5 weld length is not less than 0.5d 。
4.2.5.6 joint bending is not more than 4.
4.3 See Table 4-6 for allowable deviation items.
Table 4-6 Allowable deviation values of rebar installation and embedded parts position
Inspection method of allowable deviation (mm) of the project: 1 mesh size, three consecutive steps of welding 10 foot, take its maximum value, tie the width and height of 202 skeleton, check the spacing between 3 skeleton lengths 104 stirrups and structural steel bars, and take its maximum value to tie the steel bar spacing. The displacement of the bending starting point of steel bar is 20 7. The center line of welded embedded parts is displaced by 5 feet. Check the level difference +3-0 8. Check 10 foot foundation reinforcement cover. Check beams, columns, walls and slabs.
5 finished product protection
5. 1 Molded steel bars shall be stacked in the designated place, and placed neatly with stow-wood to prevent steel bars from deformation, corrosion and oil pollution.
5.2 When binding the wall reinforcement, a temporary shelf shall be erected, and the reinforcement shall not be trampled.
5.3 properly protect the exposed waterproof layer around the foundation to avoid being damaged by steel bars.
5.4 When binding the upper and lower steel bars on the bottom plate, the supporting horse stool should be fastened to prevent the deformation during operation.
5.5 It is forbidden to cut steel bars at will.
6 Quality problems that should be paid attention to
6. 1 Displacement of embedded steel bars in walls and columns: The steel dowel of the main reinforcement of walls and columns should be firmly fixed and bound with the upper and lower steel bars of the bottom plate to ensure the accurate position. If necessary, additional steel bars can be securely welded by electric welding. Before concrete pouring, there should be special personnel for inspection and maintenance.
6.2 rebar exposure: add cement mortar pads (or plastic cards) with binding wires to the wall and column rebar every 1m or so.
6.3 Insufficient lap length: When binding, measure each joint to check whether the lap length meets the design and specification requirements.
6.4 Incorrect position of steel bar joints: When there are many steel bar joints in beams, columns and walls, the construction sample diagram should be drawn in advance according to the drawings, indicating the collocation order of various steel bars, and avoiding the maximum bending moment of the stressed steel bars.
6.5 Binding joint and butt joint are not open properly: when binding and welding steel bars on site, butt joints should be staggered. Therefore, when processing blanking, there must be no butt welding head within the lap length of the steel bar end.
7 quality records
This process standard should have the following quality records:
7. 1 ex-factory quality certificate or inspection report of reinforcement.
7.2 Rebar mechanical properties retest report.
7.3 Imported steel bars shall have chemical composition inspection report and weldability test report. In case of brittle fracture, poor welding performance and obvious abnormal mechanical properties of domestic steel bars during processing, there should be a chemical composition inspection report.
7.4 Test report of welded joints of steel bars.
7.5 covered electrode, flux factory certificate.
7.6 steel component project quality inspection and evaluation data.
7.7 Acceptance record of concealed works of steel members.
For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd