Metal frame

Metal frame

It has the advantage that the construction and implementation of the project is faster and the construction of the structure is finished earlier (about 5-6 months earlier). The price of making a steel frame depends on the current price of iron. The cost of its implementation also depends on several factors, including the infrastructure of the entire project and the type of roof selected. In the implementation of the metal framework, the employer must pay the total amount at once. The distance between the columns in the steel frame can be considered between 6 and 9 meters, depending on the conditions of the structure. The use of wind braces is one of the steps in the construction of Fola buildings, which is used to increase the resistance of these structures against lateral forces such as earthquakes. Among the advantages and disadvantages of steel structures, we can mention good seismic resistance and lack of resistance at temperatures of 500-600 degrees Celsius. But this lack of fire resistance can be solved to a great extent by using glass wool.

Steel structure is a steel structure and one of the main types of building structures whose skeleton is mainly made of steel sections. Metal frame, also known as steel frame or metal structure, refers to a set of load-bearing members in building construction, which are made of building profiles and steel sheet. What is important about metal structures is the connection of the metals and the behavior that the metals show after the connection. The use and implementation of this type of skeleton is very suitable for tall structures. Beams, columns, trusses and other building components are made of black sheet and steel sections. These sections are connected by welding, bolts and rivets. Therefore, the types of steel frame connections are as follows:

1. Welding connection
2. Screw or flange connection
3. Rivet connection (obsolete in almost all parts of the world).

The best way to implement the metal frame to connect the beam to the column is bolts and nuts. The use of the welding connection method in European countries can only be used for buildings with a small size and volume; Because the welding connection has less resistance.

All kinds of steel structures

1. Truss steel structure
2. Suspended steel structure
3. Shell steel structure
4. Steel frame structure

Steel materials

The materials required for the construction of the steel frame of the building include the following sections:

Steel sheet

Construction profile box

belts

Armature

Rivet

bolt and nut

Washer

desire to restrain

Electrode

These materials must be in accordance with the national standards of Iran. If some of the mentioned materials are not made in accordance with Iranian standards, one of the valid international standards, preferably the ISO standard, should be used. According to the regulations, the mechanical specifications of the steels used in the building are according to the following clauses:

• Poisson’s ratio of steel materials is considered 0.3.
• The modulus of elasticity (coefficient of elasticity) of steel materials is considered 106 x 2.1 kg/cm2 (2.05 x 105 N/mm2).
• As far as possible, do not use sheets with a thickness of more than 40 mm. For sheets and sections with a thickness of more than 40 mm, the yield stress should be reduced.

Construction stages of metal frame building

The construction stages of the metal frame building are as follows:

1. Construction of the foundation of the building
2. Placing steel columns in the building site
3. Installation of steel beams and columns
4. Choosing the type of roof.
5. Construction of wind brace or transverse brace
6. Chinese blade
7. Joinery

1- Construction of the foundation of the building

Construction of the foundation is the first step in the construction of the metal frame building. At this stage, the type of foundation is determined based on the bearing capacity of the building soil. If the loads on the foundation are moderate or low, you can use strip or single foundation. If the loads on the foundation of the structure are high and the strength of the soil is low, it is better to use piles or wide foundations. Ribbed rebar is used to reinforce foundation concrete and strengthen tensile strength.

2- Placing steel columns in the building site

Placing steel columns in the construction site is one of the most important steps in the construction of a steel structure. The columns of a metal structure can be beams, hashes, honeycomb beams, cans and studs. The important point in installing the column is the connection between the foundation and the column and the gap between the two. Steel plates are welded to the end of the columns according to the base and connection of the column.

3- Installation of steel beams and columns

For prefabricated beams and columns, beams and hashs, honeycomb beams, profile cans, studs and corners are used. The beam and column are connected by welding or bolts. Beams usually transfer the load from the floor and ceiling to the columns. The size of the span of the beams is usually 3-9 meters. The size of the beams also reaches 18 meters.

4- Choosing the type of roof in steel structures

In Iran, block beam roof and steel deck roof are mainly used. These two types of roofs often transfer the load to the beams in one direction. The roof system supports vertical loads and has the same function as a diaphragm. Yobot roof, chromite beam roof, Rufix roof and waffle roof are other types of slabs that are used in most developed countries.

5- Windshield in metal frame

Wind brace or transverse brace is made to resist the building against lateral forces such as wind and earthquake. To make it, double or single studs or corners are usually used. The duty of the wind brace is to transfer lateral forces to the columns. Braces are made in different shapes: converging, diverging, cross, heptagonal, octagonal and K-shaped. The choice of each of these forms depends on the type and amount of forces acting on the structure. The function of the flange brace is mainly to prevent the instability of the bottom flange of the beam and the inner flange of the column. The brace is connected to the bottom flange of the beam on one side and to the purlin on the other side.

6- Carpentry

Joinery is the last stage of building a building structure. This stage includes insulation, cladding, electrical work, channeling, tiling, stonework and ceramic work, painting, etc.

The distance between the columns in the metal frame

Generally speaking, the most economical distance for columns under standard load is 7.5-9 meters. If this distance is considered more than 9 meters, the consumption of steel in the roof and wall will increase too much and the overall cost will not be affordable. The standard load here is 0.3 KN/m2 for roof (live load) and 0.5 KN/m2 for wind pressure.

For cases where loading is a fundamental and important issue, it is better to reduce the distance between the columns. In such cases, the distance between the columns in the metal frame should be 6-7 meters.

When setting the distance of the columns in the steel frame, if the distance of the columns needs to be unequal, try to set the column distance of the end opening less than the central opening. Because the wind load in the end opening is more than the central opening. Additionally, if you are using a purlin design, end span deflection and mid-span bend should always be considered more than other spans. If smaller end spans are considered, the purlin design will make the roof easier and more economical.

Characteristics of steel structures

The actual performance of steel structures is more consistent with theoretical calculations. Therefore, the resulting structure has higher reliability. Steel has high structural reliability and has very good resistance to impact and dynamic loads and seismic performance. On the other hand, the steel frame is made in the workshop and assembled at the construction site. This causes the accuracy and speed of work to increase and the time period of construction of the structure to be shortened.

Other features of steel structures include the following:

Very good seismic resistance.

Metal frame is suitable for large openings with high height.

The plastic property and suitable malleability of steel and the resulting metal structure

Good homogeneity property and uniform internal structure of steel and as a result the resulting structure

It is resistant to heat but not resistant to fire. Therefore, it is necessary to insulate the skeleton with glass wool.

It is not resistant to corrosion; Wet environments are prone to rust and corrosion. Therefore, stainless steel should be used and either galvanized or painted. For offshore platform structures in seawater, special measures such as “anodic protection of zinc block” are required to prevent corrosion.

benefits

One of the advantages of such structures is its light weight (lightness of the skeleton) and its simple structure. In projects that require high wear resistance, using anti-wear sheet will reduce the weight of the structure more significantly. All components are made in the factory and assembled at the construction site; Easy to assemble on site. The strength and modulus of elasticity of steel is several times higher than that of stone and concrete. As a result, the seismic resistance of an instrument