How to choose the right section for floor beams?

Competent selection of the cross-section for the floor beams will make the structure strong and reliable. In this article I will tell you how to make error-free calculations and selection.

First of all, the greatest length that can be possible at a certain section is revealed. To find the size, you need some information:

1. The length of the beam (we are talking about the distance between the supporting structures);

2. Length from one beam to another (step);

3. The load on the structure.

It is important to take into account that the load is calculated using a variable and constant indicator. The constant indicator reflects the total weight of beams, insulation, ceiling sheathing and floor. The variable indicator reflects the weight of people and interior items. According to the regulatory documentation for residential structures, it is taken in a coefficient of 150 kg / sq.m. If you are making a ceiling for the attic, then you can take a smaller number. However, I recommend taking this indicator. This will create a margin of safety. It will also provide the ability to convert the attic into an attic without the need to change the supporting structures.

The frame of the beams is calculated according to the following formulas:

M max. = (K * L2) / 8;

· In req. = M max. / 130.

In these formulas, K is the load per square meter of floor. It consists of the mass of the elements and 150 kilograms of the useful coefficient. These indicators must be multiplied with the size of the distance that forms between the beams. This action is required in order to obtain the calculation of the load per running meter, and per square meter. m., as originally calculated. L2 is the square power of the length between the supporting structures holding the purlin.

Knowing B required, you can correctly calculate the size of the section for the floor beams.

B = B * P2 / 6. With a B value, one can quickly form an equation with one unknown value. Here it is required to set only one definition B (section width) or P (its height).

Usually the wood beam is already of a certain width. The easiest way to do it is from a board of 5 or 10 centimeters. Alternatively, you can try using a compound section. It is made from a number of five-centimeter boards. The calculation in this case determines the required height of the structure.

These simple calculations will allow you to accurately select the size of the section for the floor beams.