implementation effect
it is suitable for the template construction of cast-in-place reinforced concrete structure stairs with various specifications, which has a tight construction period, high quality requirements and high requirements for template universality.
process principle
The formwork made of steel plate, channel steel, angle steel and other materials has high strength and good rigidity. According to different stair tread design parameters, the optimal stair tread variation range is determined, and the position of each tread baffle can be adjusted up and down and back and meet each tread variation range through slotting and hole formation at the joint of each component; By instrumentalizing all parts, the nonstandard parts are expanded based on the standard stairs; Bolt connection is used instead of welding technology, and the stairs can be assembled and disassembled flexibly, and the general stair specifications are applicable; After assembly, the tower crane can be used for vertical transportation, integral lifting and integral dismantling. Ensure the accurate location and achieve the purpose of construction and design requirements.
construction process flow and key points of operation
1. process flow
tool-type adjustable stair steel formwork design → formwork processing and production → stair bottom formwork and steel bar installation → bolt connection and assembly of formwork components → adjustment and finalization according to stair design conditions → hoisting and fixing in place → installation of stair side formwork → inspection and acceptance → pouring concrete → formwork removal and cleaning for standby.
2. Key points of operation
Design of adjustable steel formwork for stairs
The formwork mainly uses six kinds of raw materials: steel plate, channel steel, angle steel, bolts, steel pipes and fine-tuning screws.
(1) Tool-based design
The problem that the positions of various components are relatively fixed due to the welding and setting of stair formwork is solved by using profile processing and bolt connection. 16# channel steel is used as formwork support, and the ends of both sides are bolted with the transverse short channel steel support through 1mm-thick L-shaped connecting plates to form the formwork support structure. The functional parts of the stair steel formwork are as follows (① ~ ⑥), in which the formwork support parts are connected with the step baffle parts by using 8.8-grade bolts with a length of 4mm, so that the stair formwork can be assembled into a whole on the operation surface one by one and disassembled into individual parts for handling; It can also be assembled on site before use, and then hoisted and dismantled as a whole, thus realizing the tool of stair steel formwork.
(2) Adjustable design
Movable grooves for adjusting the position of bolts are arranged on the formwork support parts, so as to realize the adjustable spacing of step baffles; The unequal angle steel L1X63X7 is used to connect the stair step baffle with the bracket. The 1mm wide angle steel is used to increase the distance between the two connecting bolts, which is beneficial to balance the lateral pressure generated in the concrete pouring process of the step. Open a movable groove with a length of 1mm on the short side of the baffle connecting angle steel to give the bolt a movable range with adjustable position; Open three rows of holes on the long side of the baffle connecting angle steel, with a row spacing of 65mm and an included angle of 151 (with the oblique angle of stairs) to increase the adjustment ability. According to the different height and width of stair tread, the adjustability of stair steel formwork is realized by adjusting the spacing and height between stair tread baffles and adjusting the slope of stairs to meet the requirements of different specifications of stair formwork construction.
(3) Extension of step baffle
Panel: 8-thick steel plate is selected.
back stare blankly: 1# channel steel, with 42X1 holes at the bottom of the fixing place, which is convenient for bolts to penetrate.
the back edge is connected with the panel by welding, and the welding deformation should be reduced. The welding seam length is 15@15, and the flatness of the panel should be polished and corrected.
the connection between the stare blankly and the panel is welded. In order to reduce the welding deformation of the panel, the weld length is 1@1, and the panel should be polished and corrected for flatness. The positioning of the back-stare channel steel is designed to increase the operating space for concrete leveling and surface closing of stair treads.
according to the different widths of the stairs, the minimum tread width (e.g. 15mm wide) is taken as the standard, and the tread baffle fittings are made. The bolts are used to connect the extension, and the ports are blocked by extruded polystyrene board, so that the stair construction with different widths (e.g. 155mm and 18mm wide) can be met, and the extension of the width of the stair steel formwork can be realized.
(4) Extension of stair length
According to the stair design, the stairs with different specifications are selected as the standard stair template. In this project, 12 steps are used as the standard stair template, support fittings and step baffles are added, and the end of the standard template is replaced. The project is extended to 14 steps and 16 steps respectively by connecting plates with a thickness of 1mm; N-step stair template can be used for both N-step and n-1-step stair template construction. When the number of steps differs greatly, the extension of the length of the stair steel template is realized by adding accessories to meet the construction needs.
Tool-type adjustable stair steel formwork processing
Entrust a professional steel structure manufacturing factory to process various parts of the formwork with raw materials of section steel and steel plate.
slotting: mechanical holes are positioned at both ends, and slots are automatically cut between holes.
hole: it is a mechanical hole, and the positioning deviation of the hole is 1 mm.
welding: the channel steel is welded manually, and the weld height hf is 5mm, and the allowable deviation is +1mm.
post-treatment: mechanical derusting and two coats of yellow antirust paint.
according to the template processing drawing, cut the steel plate by stepping kick, with the deviation of width dimension, length dimension and flatness of the plate surface of 1 mm; Angle steel blanking, length dimension deviation -5mm, vertical angle steel length deviation plus or minus 2 mm; The inclination angle of the end of channel steel joint must be strictly controlled, and its allowable error is .1 degrees.
Installation of stair step bottom formwork and steel bar
At the scene, the stair step bottom formwork and floor support frame are set up at the same time, and the beam and stair steel bar in the stairwell are installed in advance, and the formwork is hoisted in place after acceptance.
bolt connection and assembly of formwork components
Prepare for assembly
According to the stair design drawing, draw the formwork assembly working condition diagram, with two workers for each run. Erection of stair steel formwork to assemble the jig frame requires that the jig frame is reliable and has enough strength to make the formwork stable, easy to operate and easy to lift after being placed; The inclination of the template placed on the jig frame is the same as that in actual work, so it is convenient to check the size, spacing and angle, and it is convenient to brush the release agent or clean up after use.
Assemble stairs
Place the formwork support on the jig frame, fix the middle baffle with the central bolt, fix each baffle up and down according to the step width respectively, adjust the vertical position of each step according to the step height, and brush the release agent for lifting after inspection and acceptance.
Adjust and finalize the design according to the stair design conditions
When transferring between different stairs, adjust and finalize the design. According to the stair design conditions to be used and the number of runs n, select the stair with the highest frequency of use. Based on the n/2nd step baffle of the running, start to adjust the step position evenly upward and downward respectively, and select the middle step to adjust to both ends, such as starting at the seventh step. This adjustment method improves the adjustable range of stair formwork, reduces errors and improves efficiency.
Hoisting in place and fixing
From safely lifting the formwork on the jig frame to manually fitting in place on the stair working face, the supports at both ends are padded with self-made concrete blocks with a thickness of 1X (thickness -2)X (thickness -2), and the elevation of the stair formwork is adjusted by screws. A horizontal steel pipe is set at the channel end of the platform steel formwork at the lower end of the stairs, and one end of the steel pipe is propped up.
Install stair side formwork
Install wooden side formworks on both sides of stairs, and fix them directly on the steel formwork by "step by step", and the side formworks are tightly sealed to prevent quality defects caused by slurry leakage.
side formwork fixing
pedal pendant installation
After the stairs are hoisted and fixed in place, the L-shaped stair steel pedal pendant is placed on the steel formwork to be used as a passage for people to get up and down. Pay attention to that when erecting the frame of the bottom formwork, the uprights should be separated on both sides, leaving a passage to avoid the erection of the track, thus avoiding important safety hazards.
inspection and acceptance
recheck the elevation, positioning size and flat-fell seam of bottom formwork, and comprehensively check the straightness and tightness of side formwork lines, the positioning, step height, step width and length of step steel formwork and the docking with the end wooden formwork. Only after the formwork is qualified and meets the design requirements can it enter the next working procedure.
pouring concrete
when pouring stair concrete from top to bottom, the stair tread height is calculated by the difference between the lower edges of the front and rear step baffles, so the lower edges of the baffles are flush, and the stair tread surface is leveled.
template removal and cleaning for standby
when the concrete strength reaches 1.2Mpa, and the edges and corners will not be damaged due to removal, the template steel template and side plates can be removed. The horizontal support and other supporting facilities at the bottom of the steel formwork should be dismantled first, and then an appropriate amount of horizontal thrust should be applied at the upper end to loosen the formwork with a slight pry from the lower part with a crowbar. After the template is loose, use the tower crane to transfer from the operation surface.
the removed formwork shall be cleaned in time, coated with release agent, and placed on the specially-built jig frame for next use.
Problems to be solved
In public buildings, stair designs are diverse and have different specifications. Stair step templates usually use wooden templates or steel templates. However, due to the limited physical properties of wood materials, it takes a lot of manpower to manufacture and install, which is not suitable for quality assurance and wastes wood. The steel stair template is welded and cannot be adjusted, and the scope of application is relatively simple, which can't meet the mutual call of various stairs. In the construction, each stair needs to be configured separately, which not only costs a lot, but also has low utilization efficiency of ordinary steel stair template.
Value
In the technical field of stair formwork, the steel welding formwork was improved and innovatively designed by using bolt technology instead of welding technology. The steel plate, channel steel, angle steel and bolt were made into various functional parts, and the stair formwork with different specifications and sizes was assembled by parts, combined with common tools on site, to meet the construction requirements of cast-in-place stairs. The adjustable steel stair template has many advantages, such as high rigidity, many turnover times, convenient construction, one-time integral lifting and dismantling, and can be assembled and dismantled on site for special parts. It is designed as a tool-type assembly template, which can adjust the width, length, height and steps of stairs, so it has a wide application range. The use of this template can improve the surface visual quality of stair concrete members and effectively control the construction error; Can save wood and improve the efficacy; Good applicability, reduced input cost and high application and popularization value.
for more information about the engineering/service/procurement bidding, and to improve the winning rate, you can click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd