Hoisting members of steel structure

Hoisting members of steel structure

There shall be a reliable foothold for the suspended work, and protective railings, protective nets or other safety facilities shall be provided as the case may be.

The rigging, scaffold, basket, cage, platform and other equipment used for protective railings shall not be used until they have passed the technical appraisal or verification; the suspended operators must fasten their safety belts. 

For the hoisting of steel structure, the components shall be assembled on the ground as much as possible, and the high-altitude safety measures of temporary fixation, electric welding, high-strength bolt connection and other operation procedures shall be set up. The components shall be installed in place at the same time, and the disassembly of these safety facilities shall be considered.Before hoisting large components at high altitude, safety facilities required for hanging operation shall also be set up.

There are many factors that cause fatigue cracks, which are related to design, manufacture and materials. However, most of the fatigue cracks are closely related to long-term overload use, which is the result of gradual accumulation.With the technological revolution in China’s construction industry, the speed of engineering construction has made rapid progress. The three-day one story building is no longer a myth, and the projects completed in the past few years have become several months.At such a fast pace, we should pay more attention to the standardized operation and maintenance of equipment. On the contrary, the original specialized management organization, equipment department and machinery department, has been optimized and simplified, and their functions have been greatly weakened. Even some companies do not have equipment management departments at all.Moreover, in order to improve the construction speed, it is common for some leaders to adopt the tactics of “resting people without resting horses”.It is not known that “horses” also suffer from tiredness and long illness. If they are not carefully fed and cared for, they will also “stumble”.At first, the fatigue of steel structure is only a small crack, which will lead to accidents when it slowly extends to a certain extent. For example, we often check, find and deal with it in time, which can completely avoid such accidents.The main parts prone to fatigue are: the connection between the foundation joint and the bottom beam, the main leg or connection sleeve weld of the reinforcing joint or standard joint above the diagonal brace, the variable section of the tower body, the upper and lower supports, the rotating tower body, the main leg or ear plate at the lower part of the tower top, etc.

Comments: there are many accidents caused by fatigue of steel structure and welds.There are many accidents due to fatigue of equipment used for many years, many of which are caused by combination of fatigue and illegal operation.

We should not only see the mountains and rivers, but also remember the homesickness… “In the construction of ecological civilization, we should implement the concept of green development, circular development and low-carbon development. We should take multiple measures and take multiple measures to make the green mountains, clear water and air constantly fresh, so that the people can produce and live in a good ecological environment. 

At present, with the rise of the new construction industry represented by steel structure buildings, an ecological civilization advocating energy conservation and environmental protection is setting off a wave of transformation and upgrading of the construction industry.

It is understood that as the main representative of green buildings, steel structure buildings can reduce the use of sand and cement by about 40%; the emission of carbon dioxide is more than 35% lower than that of traditional concrete; it can save resources to the maximum extent, reduce the dust pollution on the construction site, and have little impact on the natural environment.

At the same time, because the steel structure residence is a “whole life cycle” building.From construction to demolition, from demolition to recycling, from recycling to reprocessing, from reprocessing to reconstruction, steel can be fully recycled with low loss.Once mass production, steel structure building can also become “steel storage warehouse”, which is also very consistent with the actual needs of local governments for the development of circular economy, low-carbon economy and ecological economy.

There are many kinds of steel and different resistance. The connection design is usually restricted by the following factors:

1.The source of components: in theory, steel structure components or connecting components have arbitrary machinability, but in each specific project, structural components and connecting components are always restricted by the actual conditions.Experienced designers usually choose the section steel which is easy to obtain and install, and design simple and effective connection methods and components.

2.Restrictions on connection means: one of the construction features of steel structure is factory processing and field assembly.This is different from the traditional masonry method and produces a large number of joints.There are three main methods of connection between various sections of steel: riveting, welding and bolting.In the early stage of steel structure building, riveting is often used. The construction is simple, but it needs to dig holes in the components to reduce the section performance, which is easy to generate concentrated stress at the nodes. Recently, it is rarely used.The welded joint is simple in appearance and continuous in load transfer efficiency, but it requires high construction work.The later high-strength bolt connection can also meet the strength requirements of similar welding, which is widely used in modern steel structures.

3.The connection components are hierarchical: there is a complex and logical hierarchical relationship between the structural systems of steel structures. At the connection level, this hierarchical relationship is reflected in the difference between component size and installation sequence.The purpose of connection is to realize the hierarchical transformation, and it is also the key to realize the transformation of force from three-dimensional to two-dimensional, and ultimately to one-dimensional components.The complex connection is usually completed by the combination of three-dimensional connection components and plane connection components.

4.The plane of the connecting member: two linear structural members are always in a plane, which is the plane of the member stress. In order to effectively resist the stress, bending moment or shear force in this plane, the connecting member is often designed in this plane, such as the steel pipe and the cable’s welding piece are always in the plane of the two; in the case of multiple members’ connection, the combined plane.The face component can correspond to the stress of the solid.

Post time: Jun-04-2020