Steel structure engineering, as the name implies, is the structural engineering with steel as the main body. It is composed of steel beams, steel columns, steel trusses, etc. because of the different materials, their connection methods are different, including welds, bolts, rivets, etc.Steel structure engineering includes steel structure canopy, steel structure overpass, spiral stairs, etc. all belong to steel structure. A set of qualified steel structure engineering not only needs construction safety, but also design safety. According to the drawing and ISO9001 standard, construction must be carried out according to specifications, etc. How to make a set of steel structure project safe selection from the beginning to the end is very important, how to distinguish.Whether the steel structure construction team is safe or not, first of all, we must have a standardized construction team, then we must have construction requirements, and finally we must have our own company’s standards for the project.An excellent construction team is the core of a steel structure company, which is also the most basic requirement of a steel structure company. We think that this is not only the core of the company, but also the minimum sense of responsibility for customers. We are more responsible for customers. 

Technical strength of 3D steel structure company

Compared with concrete, steel structure has more advantages, so steel structure is widely used.The instability means that the bearing capacity of the steel structure reaches the limit state and loses its stability.There are many accidents caused by steel structure instability in engineering.In order to fundamentally control the occurrence of steel structure instability accidents, it is necessary to understand the causes of steel structure instability.

 　　1.Instability types and characteristics of steel structures

 Generally speaking, the instability of steel structure can be divided into global and local instability.From the nature, the instability of steel structure can be divided into three categories.

 (1) Equilibrium bifurcation instability.The main problem of equilibrium instability is that the intact axis and the middle plane are affected by external forces, which leads to instability.Equilibrium bifurcation instability, also known as bifurcation instability, is the primary problem in the stability of steel structures. The equilibrium instability also includes cylindrical shells under compression.In the stability problem, there are stable bifurcation instability and unstable bifurcation instability.

 First of all, stable bifurcation instability refers to that the buckling equilibrium configuration of the steel structure is slightly changed when it is close to the critical state.It will increase the load after deformation; secondly, instability bifurcation instability.Buckling of stiffened columns and global shells subjected to uniform external pressure belongs to unstable bifurcation instability, also known as “finite interference buckling”, because they are all transferred from semi buckling equilibrium configuration to non adjacent buckling equilibrium configuration under the action of finite interference.

 (2) The instability of the extreme point.In the instability of steel structure, the instability of extreme point is the second problem.It means that the plastic shape of eccentric compression member of steel structure can not bear its stability when reaching a certain degree.The instability of extreme point also includes biaxial flexural members.The phenomenon of extreme point instability is quite common, for example, some axial compression members appear instability due to initial bending or initial eccentricity.

 (3) Jump instability.For jump instability, there is no equilibrium bifurcation point or extreme point, but there are also instability problems.This kind of structure is mainly a sudden jump from one equilibrium configuration to another, which will lead to some large deformation.In practical engineering, it is necessary to ensure that such deformation can not occur, because large deformation will damage the steel structure.

 　　2.Factors of steel structure accident

 In steel structure, the biggest problem is stability.In some projects, due to the instability of steel structure, a series of instability accidents have occurred, which have paid a heavy price.The instability accidents of steel structure can be global instability and local instability. The following is a detailed analysis of the factors from these two aspects.

 (1) Factors of overall instability accident.1) Design mistakes.The level of designers is directly related to the quality of design.Some designers lack of practical experience and stability concept, are not very familiar with the calculation formula of stability, or only calculate the stability of the basic components, and ignore the stability of the overall structure, thus leading to design errors, and eventually lead to steel structure instability accidents; 2) manufacturing problems.The main problems of fabrication are the initial bending, initial eccentricity and residual deformation caused by welding, which greatly affect the stability bearing capacity of steel structure; 3) the temporary support force is not enough.In the process of steel structure installation, the unformed steel structure can be changed, and the steel structure is not stable at this time.During installation, temporary support points must be set to support the overall stability. If the temporary support points are not set properly and the supporting force is not enough, the components will lose stability, and the whole structure will collapse and the steel structure will lose its stability.

 (2) Local instability accident factors.The consequence of local instability is relatively small for the overall instability, but it can not be ignored, otherwise it will cause accidents.The main causes of local instability are as follows.

 　　1）The design is unreasonable.If the designer’s calculation method is not correct, the width thickness ratio and height thickness ratio of the component may deviate from the standard value, which may lead to local instability.

 　　2）The structure is unreasonable.In the construction of local components, stiffening ribs should be set in the parts with large concentrated force.In addition, in order to keep the components from deformation during operation, diaphragms should be set in the members.But in some projects, the common problems are that the number of stiffeners is too small and the structure is unreasonable. 

Processing design of steel components in steel structure engineering

　　3）The position of the lifting point.In the hoisting of steel structure components, it is very important to select the appropriate lifting point position for the stability of the whole component. The stress state of the component is determined by the position of the lifting point. If the internal force of the component is too large, it will lead to local instability of the component.

 　　3.Measures to deal with steel structure accidents

 In engineering construction, if the instability of steel structure occurs, it may lead to the collapse of the whole structure and cause serious instability accidents.After the accident, the most common way to deal with it is to investigate the responsibility, which is not of much significance.Therefore, in order to avoid the occurrence of accidents caused by the instability of steel structure, the whole project should do a good job of prevention, reinforce or replace the plate to fix the components, so as to make them more stable, so as to reduce the occurrence of instability accidents.

 (1) Improve the professional quality of designers.The designer should be responsible for the instability accident of steel structure.Therefore, it is necessary for engineering units to improve the professional quality of designers, and to improve the design concept of designers, we should start from several negative aspects.First, the designer should have the overall consciousness, in the overall layout design of the structure, the factors affecting its stability should be considered from all aspects, especially the design of the support points; second, in the design of the stability of the steel structure, the relevant calculation formula will be involved. Therefore, when calculating the stability of the steel structure, the designer should fully consider its actual bearing capacity, especially pay attention to the supportThirdly, when considering the stability problem, we should consider not only the overall stability factor, but also the local influence factor, and combine the two to consider the calculation, so as to reduce the occurrence of steel structure instability accidents.

 (2) Reduce defects in steel structure.In the influencing factors of steel structure instability, initial bending, initial eccentricity and other problems are relatively common, but also the larger impact factors, so the relevant units must control these defects at the source, adopt reasonable technology to ensure the quality of steel structure, so as to reduce the instability accidents.

 (3) The construction unit should pay attention to safety.Security is an issue that everyone should be concerned about.In the construction process, the construction unit must have a reasonable hoisting scheme, carefully design the whole construction, and pay attention to the overall safety; the setting of temporary support points should be scientific and reasonable, and ensure the safety of the steel structure installation process, and do a good job in the prevention measures of steel structure instability, so as to reduce the occurrence of steel structure instability accidents.

 (4) Use steel structure correctly.It is inevitable that there will be some damage to the steel structure in the storage process. Therefore, the engineering unit should regularly inspect and repair the steel structure, so as to avoid some damaged steel structure being used in the construction, thus causing the steel structure instability accident.At the same time, the bearing capacity of the steel structure can not be changed by itself, and it must be discussed with professionals before appropriate changes can be made.

 　　4.Conclusion

 Through the above analysis, we can see that in order to fundamentally control the occurrence of instability accidents, we must do a good job in the prevention of instability of steel structures, set reasonable support points, improve stability, so as to reduce the occurrence of accidents.

Hebei Hongjishunda Steel Structure Co., Ltd. is engaged in steel structure engineering, construction engineering, steel member processing and export, steel structure workshop construction design and other types of engineering.Three dimensional steel structure is a company with more than ten years of steel structure engineering experience. It is a set of steel structure design, processing, installation, maintenance, anti-corrosion, and other aspects in one, to provide you with one-stop construction services.Professionals to do professional work has always been the purpose of three-dimensional, will be able to build high-quality building steel structure engineering.