How to calculate the length of the negative reinforcement of the support?

Length of negative reinforcement of end support:

The length of the first row of rebars.

This span. Net span length

Anchoring (when the two adjacent spans have negative reinforcement, take the length of the net span.)

anchoring); The length of the second row of reinforcement.

The net span length of this span.

Anchoring (when the two adjacent spans have negative reinforcement, take the length of the net span.)

4+ anchorage).

Note: 1. Anchorage length.

anchorage with the upper part of the beam;

When there are three rows of negative reinforcements on the support of the beam, the length of the third row of reinforcements is calculated as the same as that of the second row.

Length of negative reinforcement of intermediate support:

The length of the first row of rebars.

ln 3 support width;

The length of the second row of reinforcement.

ln 4 support width.

Note: When the sum of the extension lengths of the negative reinforcement of the support at both ends of the middle span is the net span length of the span, its reinforcement length:

The first row is: the span net span length + (ln 3 + front middle support value) + (ln 3 + rear middle support value);

The second row is: the net span length of the span + (ln 4 + front middle support value) + (ln 4 + rear middle support value).

The other reinforcement calculations are the same as the first span reinforcement calculations. ln is the larger value of the span on both sides of the support.

There are two cases about the multiple rows of reinforcement of the beam support, one of which is that when the first row is all long reinforcement, then the second row of reinforcement is l

3, the third row is L

4；In the second case, when the first row is not fully long, the first row is L3 and the second row is L

4. The value of the third row is determined by the designer.

When the upper part of the cantilever beam is provided with a third row of reinforcements, its extension length should be indicated by the designer, and the extension length of the second row is the net length of the pick-out), and the extension length of the third row should be sufficient.

Summary. Calculation method: the length of the negative reinforcement of the end support: the length of the first row of reinforcements = the net span length of the span 3 + anchorage (when the two adjacent spans have negative reinforcement, the net span length of the long span is 3 + anchorage); The length of the second row of reinforcement = the net span length of the local span 4 + anchorage (when the two adjacent spans have negative reinforcement, the net span length of the long span is 4 + anchorage).

Note: 1. The anchorage length is anchored with the upper part of the beam; 2. When there are three rows of negative reinforcement of the supporting reinforcement of the beam, the length of the third row of reinforcement is calculated with the second row. Length of negative reinforcement of intermediate support:

First row reinforcement length = 2 * LN 3 + support width; Second row reinforcement length = 2 * LN 4 + support width. Note: When the sum of the extension lengths of the negative reinforcement of the support at both ends of the middle span is the net span length of the span, its reinforcement length:

The first row is: the span net span length + (ln 3 + front middle support value) + (ln 3 + rear middle support value); The second row is: the net span length of the span + (ln 4 + front middle support value) + (ln 4 + rear middle support value).

The other reinforcement calculations are the same as the first span reinforcement calculations. ln is the larger value of the span on both sides of the support.

Hello, the answer to the problem of eliminating the spike you consulted here is as follows: it refers to the longitudinal stressed steel bar located at the upper part of the beam support to bear the negative moment force, commonly known as the flat bar, the pressure Hu Li Liang Tie Nabu. In some places, this is called a cover bar.

The bearing has negative reinforcement, which is relative, and generally refers to the reinforcement of the supporting part of the beam to offset the negative bending moment, commonly known as the bearing reinforcement.

Calculation method: the length of the negative reinforcement of the end support: the length of the first row of reinforcements = the net span length of the span 3 + anchorage (when the two adjacent spans have negative reinforcement, the net span length of the long span is 3 + anchorage); The length of the second row of reinforcement = the net span length of the local span 4 + anchorage (when the two adjacent spans have negative reinforcement, the net span length of the long span is 4 + anchorage). Note:

1. The anchorage length is anchored with the upper part of the beam; 2. When there are three rows of negative permeability reinforcement on the support of the beam, the length of the third row of reinforcement is calculated as the second row. Length of negative reinforcement of intermediate support: length of first row of reinforcement = 2 * LN 3 + degree of answer of the wide bundle of support; Second row reinforcement length = 2 * LN 4 + support width.

Note: When the sum of the extension lengths of the negative reinforcement of the support at both ends of the middle span is the net span length of the span, its reinforcement length: the first row is:

The span net span length + (ln 3 + front middle support value) + (tan bucket ln 3 + rear middle support value); The second row is: the net span length of the span + (ln 4 + front middle support value) + (ln 4 + rear middle support value). The other reinforcement calculations are the same as the first span reinforcement calculations.

ln is the larger value of the span on both sides of the support.

What is the net span length.

It is the contact area between the reinforcement surface and the reinforcement surface.

Column edge to column edge, or axis-to-axis length.

Axis to axis.

1. The length of the negative reinforcement of the end support:

The length of the first row of reinforcement = the net span length of the local span 3 + anchorage (when the two adjacent spans have negative reinforcement, the net span length of the long span is 3 + anchorage).

The length of the second row of reinforcement = the length of the net span of the current span 4 + anchorage (when the two adjacent spans have negative reinforcement, the length of the net span is 4 + anchorage).

Note: The anchorage length is anchored with the upper part of the beam; When there are three rows of negative reinforcements on the support of the beam, the length of the third row of reinforcements is calculated as the same as that of the second row.

2. The length of the negative reinforcement of the middle support:

First row reinforcement length = 2 * LN 3 + support width;

Second row reinforcement length = 2 * LN 4 + support width.

Note: When the sum of the extension lengths of the negative reinforcement of the support at both ends of the middle span is the net span length of the span, its reinforcement length:

The first row is: the span net span length + (ln 3 + front middle support value) + (ln 3 + rear middle support value);

The second row is: the net span length of the span + (ln 4 + front middle support value) + (ln 4 + rear middle support value).

The calculation of other reinforcements is the same as that of the first span reinforcement, and ln is the larger value of the spans on both sides of the support.

Dear, hello, I am glad to answer for youAnswer: the negative reinforcement of the lower part of the beam is calculated in this way The length of the first row of reinforcement = the net span length of this span 3 + anchorage (when the adjacent two spans have negative reinforcement, the net span length of the long span is 3 + anchorage); The length of the second row of reinforcement = the net span length of the local span 4 + anchorage (when the two adjacent spans have negative reinforcement, the net span length of the long span is 4 + anchorage). Note:

1. The anchorage length is the same as that of the upper part of the Minming beam; 2. When there are three rows of negative reinforcement of the supporting reinforcement of the beam, the length of the third row of reinforcement is calculated with the second row. Length of negative reinforcement of intermediate support: length of first row of reinforcement = 2 * LN 3 + width of support; Second row reinforcement length = 2 * LN 4 + support width.

Note: When the sum of the extension lengths of the negative reinforcement of the support at both ends of the middle span is the net span length of the span, the length of the reinforcement bar is: the first row is:

The span net span length + (ln 3 + front intermediate support value) + (ln 3 + rear middle support value); The second row is: the net span length of the span + (ln 4 + front middle support value) + (ln 4 + rear middle support value). The other reinforcement calculations are the same as the first span reinforcement calculations.

ln is the larger value of the span on both sides of the support.

In the design, the 1 4 of the net span in the direction of the short span is generally taken as the length of the negative reinforcement of the floor support. As shown in the figure below:

The short plate span shown in the above figure is 3800, then 1 4 is 950, and the module of 50 is generally taken; But this 950 is counted from the side of the beam or the wall.

Of course, if the adjacent floor slab span is not the same, then the 1 4 of the larger span of the adjacent two spans should be taken as the length of the negative reinforcement of the support, and the length of the negative reinforcement of the support is the same on both sides. That's how it's generally handled in design.

Summary. Hello dear, 1, is the net span of 1 3, plus 5d in the column, plus 15d of the bent anchor. As you asked, the 5d in the bar is a bit of a problem.

According to the requirements of the bending anchor, it should be extended to the inner side of the side column reinforcement of the column and be larger, not the requirement of 5d in the column. 5d in the column is the requirement of the straight anchor, and at the same time the requirement is greater than the net span of 1 3, which is calculated according to the net span of the adjacent two large spans 1 3, so there is no problem with the answer.

The calculation method of the negative reinforcement of the support is that you have a good pro, 1, is the net span of 1 3, plus 5d in the column, plus 15d of the bent anchor. As you asked, the 5d in the column is a bit of a problem. According to the requirements of the bending anchor, it should be extended to the inner side of the side column reinforcement of the column and be larger, not the requirement of 5d in the column.

5d in the column is the requirement of the straight anchor, and at the same time the round car 1 3 that is required to be greater than the net span is calculated according to the net span 1 3 of the large span of the adjacent two sides, so there is no problem with the answer.

The approach is different! We can roughly categorize the following three algorithms: Method 1:

The distribution bar and the negative bar are overlapped to a certain length, such as mm method 2: the length of the distribution bar = the length of the axis method 3: the length of the lead blind division of the barn = calculated according to the layout range of the negative bar.

2. What is the formula for calculating the reinforcement under method 3? Method 1: 150mm length of the lap of the distribution bar and the negative bar = the length of the axis - the length of the negative bar * 2 + the length of the uneven * 2 support Chaye negative bar and the top of the plate through the bar.