Progress of research on connection of high-strength structural steel

With the development of building structures towards higher and larger spans, the application of high-strength structural steel is becoming more and more widespread, and the research on its connection technology is becoming more and more important.

In terms of welding connection, high strength structural steel welding faces many challenges. Due to its high strength and high alloying element content, welding cracks and heat-affected zone performance degradation are prone to occur during welding. In recent years, research has focused on optimising welding process parameters, such as welding current, voltage, welding speed, etc., to control heat input and reduce the impact on the properties of the base material. The use of advanced welding methods, such as laser welding and electron beam welding, which have a small heat-affected zone and small welding deformation, can effectively improve the quality of welded joints. At the same time, the development of new welding materials, so that its chemical composition and mechanical properties of high-strength structural steel to match, enhance the strength and toughness of welded joints. For example, for Q690 high-strength steel, the development of special welding wire, significantly improving the comprehensive performance of welded joints.

Bolt connections are also critical for high-strength structural steel. High-strength bolted joints have the advantages of easy construction and removability. Research has focused on improving the performance of high-strength bolts and optimising the connection design. New high-strength bolt materials continue to emerge, and their tensile strength and shear strength are further improved, which can be better adapted to the needs of high-strength structural steel connections. In the connection design, through finite element analysis and other means to study the arrangement of the bolt form, the preload size of the impact on the connection performance. For example, in the large-span steel structure node, a reasonable bolt arrangement can make the force uniformly transmitted and improve the node bearing capacity and stability. In addition, the slip performance and fatigue performance of bolted connections are also more deeply understood, which provides a basis for the application of high-strength structural steel bolted connections in dynamic loaded structures.

For the bolted-welded hybrid connection, the advantages of welded and bolted connections are combined. The research focuses on the synergistic working mechanism and reliability of the bolted-welded connection. Determine the reasonable proportion and sequence of welding and bolting connections, so that both can give full play to their respective strengths when subjected to loads, and jointly undertake the role of shear force, tension and so on. For example, in the beam-column connection of some high-rise steel structures, the bolted-welded hybrid connection is adopted, which not only ensures the integrity and strength of the connection, but also facilitates the construction and later maintenance. Through a large number of tests and numerical simulations, the mechanical model of bolted-welded hybrid connection is established to accurately predict its performance under different loading conditions, so as to provide scientific guidance for engineering design.

In the research on the seismic performance of connection nodes, considering that high-strength structural steel is mostly used in structures with high seismic requirements, the seismic performance of connection nodes under seismic action is investigated. The energy dissipation mechanism and ductile deformation capacity of connection nodes under seismic action are explored in depth. The seismic toughness of the connection nodes is improved by adding energy-dissipating elements, such as dampers and energy-dissipating angles, so that the structure can effectively dissipate energy in an earthquake and avoid brittle damage. At the same time, the study of the damage evolution law of the connection node under repeated loads provides technical support for the reinforcement and repair of the node.

In conclusion, the research of high-strength structural steel connection technology is constantly deepening and expanding, and progress has been made from welding, bolting, bolted-welded hybrid connection, etc., which lays a solid foundation for the wide application of high-strength structural steel in building structures, and also promotes the field of building structures towards a safer, more efficient, and sustainable direction.