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Method for calculating steel strands

Method for calculating steel strands
1. Concept

1. The term “root” (or “wire”) refers to a steel wire.2. Strand: a strand composed of several steel wires;3. Bundle: the number of strand bundles visible in the prestressed member’s section, each with two anchors;4. Beam length: one tension’s length;

.XX bundles per ton: the number of bundles of steel strands folded per ton within the standard tensile length.So it doesn’t have to be an integer.

2. Steel strand specifications

1. What does 15s15.2 stand for?

s stands for steel strand.

15 represents a group anchor with 15 holes; that is, 15 steel strands are arranged in one hole at the same time.

15.2 is the specification of the steel strand, indicating that the nominal diameter is 15.2mm.

2. What does 17 in 17-j15.2 represent? 15.2 What exactly does it mean?

17. This means that there are 17 strands in a bundle;

15.2 indicates the diameter of the steel strand, and each linear meter of the steel strand can be directly checked without calculation.

3. What does the steel strand 5s15.2 and the anchor BM15-5 mean?

5s15.2 is 5 groups of steel strands with a nominal diameter of 15.2, and its theoretical weight is 1.101 kg per meter. Anchor BM15 is a type of flat anchor. -5 means five holes.

3. Steel strand weight calculation

1,calculation formula

2. How do I determine the theoretical weight of a steel strand?

The square of the single diameter (mm)*0.785*number of roots*1.0186 (twisting coefficient)*7.8

The unit is kg/km.

Fourth, the selection and adjustment of the steel strand quota

1. The length of the beam and the number of holes should conform to the actual tension length and the number of anchor holes in the design or construction plan.

2. Calculate the number of bundles of the designed steel strand: the weight/length given in the drawing = the number of bundles, and apply a similar quota according to the number of bundles calculated. If the number of bundles calculated is different from the number of bundles in the quota, you need to adjust the quota.

3. The number of bundles per ton should be adjusted to the number of bundles given in the design drawings. For example, a steel strand with a length of 16m is designed, and a steel strand with a diameter of 15.24mm (75) and a 7-hole anchorage is used. The steel strand unit If the weight is 1.102Kg/m, then: 1000Kg/(7*16*1.102)=8.102 bundles, apply the quota of 4068022 (strand bundle length 20m7 holes per t11.65 bundles), 11.65-8.102 =3.448 bundles, so it is necessary to set the quota adjusted to: 4068022-4068023*3.448;

4. The longitudinal prestressed steel strands of the box girder of the X bridge are  15.24-19, that is, 19 strands per bundle, 7 wires per share, and a total of 240 bundles. The total length is 8106.2m and the total weight is 169419.6Kg. Then the steel strand per ton is 240 bundles/169.42 tons = 1.417 bundles/ton. The average design bundle length is 8106/240 = 33.775m. Considering the construction tension length, the selected quota is : 4068036 (strand wire bundle length 40m, 19 holes per t2.05 bundle). The adjustment of the quota is: 2.05-1.42 = 0.63. The adjustment of the quota is: 4068036-4068037*0.63.

Given the number of steel strands and anchors in the general bidding documents, it is easy to calculate:

The number of steel strand bundles per t = anchor bundle (set)/2/steel strand (t), and then set the quota.

A bridge adopts the post-tensioning method to prefabricate the prestressed T beam, and the number of anchors and steel strands used is as follows:

It can be seen that the common steel strand is 65237.3kg, the diameter of the steel wire is 15.2mm, and the 5-hole anchorage

Number of beams per t=480/2/65.2373=3.68 beams/t

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