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Steel structure installation(1)

Jun 27, 2018

1.Installation sequence of steel columns:

 1 basic laying out, 2 bandages, 3 hoisting, 4 Correction, 5 final fixation.

2.steel column installation method

  (1)Discharge line

A. Elevation control: in this project, according to the depth of concrete cup mouth, the elevation of steel column bottom, the embedded elevation of concrete foundation in the middle of the bottom of cup mouth, the steel parts and "middle reinforcement" (φ 30 steel bar) are controlled, and the top elevation of "middle reinforcement" is based on the elevation of steel column bottom, The elevation error of iron parts is controlled within ±1mm. To ensure that the steel column is placed accurately and firmly on the pre-buried φ 30 "middle reinforcement" in the foundation, weld a steel plate of 20 thickness at the bottom of the H-section column, as shown in the following figure

Steel structure installation.jpg

When the steel column is installed, the foundation cup is cleaned up first, and the actual height of the "middle reinforcement" (φ 30 steel bar) which is controlled by the embedded elevation in the foundation is checked. Because the elevation of the "middle steel bar", which is pre-buried during the foundation construction, has been accurately controlled, No more padded iron. With this method, the treatment of steel column foot is simple, fast and efficient. The construction is fast and the force is reasonable. When the columns are hoisted, they can be adjusted freely in several directions when the elevation is unchanged.

B. Before installation, the vertical and horizontal axis datum of the foundation plane is placed on the top of the cup with the woodworking ink bucket as the steel column installation and positioning line.

(2) Steel column binding and hoisting

A the steel column is placed in accordance with the position of the lifting plan after entering the field, and check the type and number of the steel column is correct. The plane position of the steel column after entering the field is shown in the following figure.

Steel structure installation.jpg

B before the post is hoisted, the horizontal line should be aligned with red paint from the bottom of the column up to the 2300mm, so that it can be used as a recheck plane elevation benchmark before and after the installation of the fixed post.

C column installation is vertical hoisting, in order to keep the suspended column droop, easy to position, determine the binding point in the lower part of the corbel. In order to prevent the sharp edge of the column angle, in the hoisting damage rope, with the old car rubber belt separated, set in the corner hanging rope. Note that the binding is firm and easy to remove.

D steel column to tie up the temporary steel ladder, high strength bolts to install the working platform of the clamp.

E in order to avoid the free swing of the suspended post, the upper part of the column should be tied with hemp rope, which can be used as the pulling rope to adjust the direction

F the rotation method is used to hoist according to the situation of the site:

After the preparation work before hoisting is ready, first test hoisting, steel column hoisting from the ground height of 200mm should stop to check whether the rigging is firm, whether the crane is stable. After confirming that there is no problem, the crane can only be slowly lifted up, rotated to the top of the cup, and then slowly decreased. When the base line between the column bottom and the foundation is adjusted to the exact position when the distance between the pillar bottom and the design position is 40~100mm, the crane can be directed to descend into position. And with steel wedge (or wood wedge block), wind rope will be temporarily fixed pillars, to achieve safety can remove the hook. Key points of the rotation method: the method of lifting the column by rotating the hooks around the foot of the column is called the rotation method, as shown in figure a below. In order to improve the lifting efficiency, when lifting the columns by rotating method, when the steel columns enter the field, the three points of binding point, the center of the foot of the column and the center of the cup foundation should be made, and the center of the pillar should be centered at the stop point of the crane. The distance from the stop point to the binding point (that is, the radius of rotation of the hanging column) is on the arc of radius (3.1 arc for short), as shown in figure b below.

Steel structure installation.jpg

The steel column hoisting is shown in the following figure:

Steel column hoisting.jpg

(3) initial correction of the column: the correction of the column should first correct the side with large deviation, then the side with small deviation.

A. The correction work of the column generally includes three contents: the plane position, the elevation and the perpendicularity.

B. When the steel column is hoisted in position, it belongs to the primary alignment, and generally does not need to be recorrected in the plane. For the elevation of the column, because of the φ 30 pre-buried "middle reinforcement" to accurately control the elevation before hoisting, generally only need to check, no need to be corrected. Therefore, the correction of steel column is mainly to correct the verticality and check the elevation.

C. The post correction work needs to be carried out simultaneously with measuring tools. In this project, the vertical degree of the column is observed and the correction is measured with two theodolites. 

First, place the theodolite on one side of the column so that the longitudinal wire is aligned with the base line of the post seat, and then fix the screws of the horizontal plate. Measure the centerline of the column and observe from the bottom up. If the centerline is aligned, that is, the column is vertical, the criteria need to adjust the column until the alignment of the theodolite longitudinal wire. Measure the horizontal line in the same way so that the center line on the other side of the column is perpendicular to the baseline horizontal axis. After the column is positioned accurately, the column can be fixed. Steel column verticality correction: adopt pitch adjusting wire rod and steel wedge, because the long side contact surface of the column is small, the cushion plate is set in construction, details are as follows.

QQ截图20180626111329.jpg

Steel wedge dimensions as shown below

QQ截图20180626112751.jpg

(4) final correction and fixation of steel columns

After the steel column is hoisted and in place, the post correction work is mainly to adjust the elevation and the verticality; the calibration method can be selected as wind rope, Jack, crowbar and steel wedge (or wood wedge), etc. Apply vertical force and lateral force to the steel column such as pull, top, brace and pry. Adjust the vertical degree of the column, positioning axis, elevation. After confirmation, the gap between the steel column and the base cup is compacted with C40 fine stone concrete. The expansion high strength grouting material is preferred