Cushion blocks shall be placed between the stair beam and the overlap position of the stair segment, and the setting points of the cushion blocks shall be 2.

The thickness of the steel sheet shall be divided into 1mm, 2mm and 5mm, and the elevation error shall not exceed 3mm.

Stair hoisting adjustment 3.

The support points shall not be less than four, and the wooden block shall be placed on the support perpendicular to the long side of the rest platform.

(6) Snap a+1m horizontal line on the precast column and wall, determine the upper surface elevation of the rest platform in advance according to the+1m horizontal line, and make obvious marks.

Lift the rest platform 4.

Gasket elevation adjustment 5 Stair segment lifting 1.

In addition to the steel pipe connection, the embedded reinforcement is also used as the connector on site, as shown in the figure below.

Stair hoisting process hoisting flow chart 1: the positioning line of the rest platform (ladder beam) shall be marked according to the shear wall or column+1m line, and the upper side control line of the rest platform shall be marked according to the reserved hole and the adjacent wall, as shown in the following figure.

(9) Relevant hoisting machinery and equipment have been mobilized and can be used normally after commissioning.

The precast parts are processed, manufactured and maintained to a certain strength in the factory according to the design drawings.

The connection position of the reserved hole between the stair run and the rest platform shall be filled with grout.

The allowable deviation of installation shall comply with the provisions of the following table.

The layout of support points under the rest platform is shown in the figure below.

(5) The specifications of slings, snap rings, rope buckles, etc.

When installing the stair board, pay special attention to the correct elevation, and then unhook after correction.

The outer diameter of the steel pipe is slightly smaller than the hole diameter.

(7) The lifting personnel (5-6 lifting personnel in each group, the number of groups determined according to the schedule requirements) have been trained and in place.

Rest platform installation positioning line 2 The rest platform (ladder beam) support shall be erected according to the lifting position of the rest platform (ladder beam) components.

Preparations before hoisting the precast stair segment of the precast rest platform (1) The on-site technical management personnel and hoisting personnel learn the design drawings and detailed drawings of the stairs, fully understand the design intent, and do a good job in the drawing review of the stairs.

After the installation of the two stair segments of each floor slab, after the position and elevation are checked to be correct, the gap between the rest platform and the stair segment, and between the stair segment and the surrounding wall panels or columns can be formwork erected, and the fine stone concrete can be poured.

(2) Determine the materials and mechanical equipment required for the hoisting of precast stairs, and use tower crane, truck crane or crawler crane according to the project situation.

(8) The concrete pouring at the stair rest platform and the ladder beam has been completed and reached the strength requirements specified in the design, and has been accepted and passed by the construction unit and the supervision unit.

2.

Rest platform support layout drawing 3 Lift the rest platform (ladder beam) Lift the rest platform bottom support after the installation is completed.

During installation, a 2cm gap shall be reserved between the rest platform and stair flight and the connecting wallboard or column to reserve space for the mortar plastering layer.

(3) Prepare the technical scheme of stair hoisting, mainly determining the construction sequence and support arrangement of stair hoisting.

3.

Stair segment lifting: precast stair segments are horizontally lifted.

During lifting, the step plane should be horizontal by adjusting the manual hoist to facilitate positioning.

The gap between the components and between the components and the cast-in-place parts shall be erected and then filled with mortar.

When the rest platform is fully precast, the gap between the rest platform, stairs and the connected wallboard or column shall be cleaned after the lifting of the stairs and rest platform is completed, and then the film shall be laid for protection to prevent the gap from being polluted by other construction processes.

The gap between the stair run and the rest platform shall be filled with C20 fine aggregate concrete and cured.

The precast stairs (PC stairs) are composed of precast stair segments and precast rest platforms.

The lifting sequence shall be reasonably arranged according to the actual situation of the project, and the support arrangement is mainly to determine the support points and the arrangement of the supporting timbers.

The stair segment elevation shall be leveled at the overlap position of the stair segment.

Correction: After the stair is basically in place, use the crowbar to fine-tune the stair segment until the position is correct and the stair is laid flat.

Stair plate in place: when in place, the stair segment shall be lifted from the top to the installation position in a horizontal state, and a slight pause shall be made at about 30cm above the operating floor.

The elevation shall be adjusted through the combination of steel sheets of different thickness to finally meet the requirements of the design elevation.

After the lifting is in place, pull out the embedded parts into the reserved holes of the shear wall (column), and then check and adjust the bottom support according to the marked elevation control line and horizontal control line of the rest platform, as shown in the following figure.

The wooden block section shall not be less than 5cm × 5cm。 Adjust the support height according to the height control line of the rest platform.

The construction personnel shall hold the stair segment to adjust the direction, align the edge line of the stair segment with the placement position line on the rest platform, and when lowering it, it shall be stopped stably and slowly, and it is strictly prohibited to put it fast and violently, so as to avoid the plate surface cracking caused by excessive impact force.

used for hoisting shall be determined according to the calculation, and the technical text data shall be formed.

4.

(4) Before hoisting construction, it is necessary to carry out force calculation for various working conditions during hoisting of precast stair segments and precast rest platforms (precast ladder beams), and the setting of support points also needs to carry out force calculation, and give a reasonable layout plan.

The temporary support under the rest platform shall not be removed before the grouting between the precast rest platform and the joint between the stair segment and the surrounding mechanism is completed to prevent the horizontal position of the rest platform from being offset from the elevation.
.

The bottom elevation of the stair segment shall be leveled at the upper and lower stair beams of the stair segment.

Fixing Socket Angular End

Hinge connection installation: after the correction of the stair segment, connect the reserved hole at the upper opening of the stair segment with the reserved hole at the rest platform with steel pipes, as shown in the following figure.

After the precast stair segments and precast rest platforms are transported to the site, they are hoisted and assembled on the site according to the construction plan; The support poles at the bottom of the precast rest platform are fixed with triangular support frame, the precast rest platform is placed on the shear wall or frame column, and the precast stair segment is placed on the precast rest platform, which is hinged.

Precast stair lifting diagram lifting ring position 2.

The installation quality shall be inspected and accepted after the installation of the stair is completed.