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Typical steel structure connections


What does the steel arch bridge structure include?The connection plays a crucial role in the project working process for steel structures. In this article, BMB Steel will introduce to you current structural steel connections and steel arch bridge structures.

1. Welding connection:

Welding is the use of heat (fire or electric arc) to make the metal melt and mix, and when cooled, it solidifies to form a weld.


  • Electric arc welding: It is a commonly used welding method. It is divided into types: manual welding, automatic welding, and semi-automatic welding.
An illustration of electric arc welding
An illustration of electric arc welding
  • Steam welding: Rarely used.

Welding methods in steel structures

  • Manual electric arc welding is a molten electric welding process that uses an electrode in the form of a welding rod; the temperature can be up to more than 20000 C. Usually, there is a coating layer 1 - 1.5mm thick, which is a mixture of stone powder and metals. The welder performs all operations (arcing, moving the welding rod, replacing the welding rod, etc.) manually. The metal in the solder can increase the strength of the weld.
  • Automatic electric arc welding: Before welding, spread a layer of solder on the weld, then plug one end of the bare welding coil into the solder water to contact with the steel to create an electric arc. Welding has done by an automatic machine.
  • Semi-automatic welding: This method is similar to automatic welding because the welding machine is moved by hand; it can have welded in tight, vertical places, etc.
  • Steam welding: using the heat generated when burning C2H2, CH4, C6H6, or H2 with oxygen to melt metal. The most common is oxy-Acetylene gas welding because the heat generated by the combustion reaction of these two gasses is large, forming a flame with a high temperature (the most elevated area is up to 3200 oC); In contrast, the flame between oxygen and other combustible gasses has a temperature of 2000-2200oC.

2. Bolt connections

Bolt connections are very popular in the construction of pre-engineered steel buildings
Bolt connections are very popular in the construction of pre-engineered steel buildings


  • Coarse bolt: manufactured from carbon steel by forging, stamping, and low precision.
  • Fine bolt: made from carbon steel, low alloy steel by turning, high precision.
  • High strength bolts: made from alloy steel and then heat processed to achieve the required tightening and pulling force, very high bearing capacity.
  • Foundation anchor bolts: designed and manufactured according to the engineers’ drawings to ensure bearing capacity, used to connect the foundation and columns of pre-engineered steel buildings.
  • Stainless steel bolts: used in many outdoor mounting positions, both to ensure the corrosion resistance as well as the bearing capacity of the connection to ensure the aesthetics of the joint.
  • Expansion bolts: applied in joints between concrete columns and rafters or joints of concrete to steel or concrete columns to any structure.
  • Galvanized roofing screws: commonly, galvanized roofing screws can be used to reduce construction costs with good corrosion resistance. It can be used for work near the sea. However, it is costly to invest.

Types of steel structures that need bolting

Overlapping connections (Actual bolts need to be increased by 10%):

  • Link overlapping 2 steel plates
  • The joint connection between angle steel and steel plate

Connection with joints:

  • Connect 2 joints using 1 or 2 joints (need to arrange the number of bolts to 10%)
  • Connect between 2 sections (no need to increase the number of bolts by 10% because the stiffness of the members is large)

3. Steel arch bridge structure

Concrete-filled steel pipe structure is a system of main bearing factors: round or square steel pipes; the inside of which fill with high-strength concrete.

An application of steel arch structure
An application of steel arch structure

Unlike standard steel pipes, concrete-filled steel pipes only work effectively under compression.

This type of steel pipe arch bridge filled with concrete with ropes suspended vertically with the arch structure bearing the main force, the horizontal force generated at the arch foot is transmitted chiefly to the beam. The bridge girder acts as a tension rod attached to the arch rim. The suspension system is subjected to concentrated tensile forces with this arch due to the structure's own and live loads. The steel pipes are light in weight, so they are easy to transport and assemble. With high aesthetics, this structure is relatively popularly applied to urban bridges.

The entire content of steel structure connections and steel arch bridges has shown in the above article. Hopefully, we have brought you valuable information. See more articles about steel structures and pre-engineered steel buildings at BMB Steel.

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