Advantages And Disadvantages Steel Buildings

Advantages And Disadvantages Steel Buildings

1. The steel structure has light weight and high bearing capacity: it is a lightweight and high-strength material.

2. The steel mouth is close to a homogeneous isotropic body: the steel is divided into small pieces, each piece will have roughly the same mechanical properties, and the properties in all directions are roughly the same, which is the basis of solid mechanics.

3. Good plasticity and toughness of steel: under static load, steel has good plastic deformation ability.


4. Steel has good welding performance: the so-called "good" welding performance refers to the property that the steel can maintain the integrity of the welded part without cracking during and after welding.

5. The steel structure has the characteristics of no leakage: whether it is welded, riveted or bolted, the steel structure can be sealed without leakage.

6. Factory-based steel structure manufacturing and assembly-based construction: light components, convenient construction, small site occupation, short construction period, and easy demolition, reinforcement, reconstruction and expansion.

7. Poor corrosion resistance of steel: steel is easy to rust in environments with high humidity and corrosive media, and the section is constantly weakened, which damages the structure and affects the service life. Therefore, the steel structure needs regular maintenance.

8. The steel structure has good heat resistance, but poor fire resistance: experiments have shown that the performance of the steel does not change much from room temperature to 150 °C. To improve the fire resistance rating of steel structures, the fire resistance limit of steel components is 1.5h when the thickness of the fireproof coating is 15mm.


Application Range of Steel Structure

    Heavy-duty industrial steel workshops: steel crane beams, steel roof trusses, steel columns and other components should be used in workshops with large spans and column distances, or with heavy-duty cranes or large-tonnage cranes or workshops with 2 to 3-story cranes, as well as some high-temperature workshops. even all-steel structure.

2. Large-span structure: when the span of the structure is larger, reducing the weight of the structure will have obvious economic effects The steel structure is mainly used to bear wind loads. In addition to its light weight, it is easy to install and construct, and the small section of the light and high-strength members of the steel reduces the wind load and thus achieves greater economic benefits.

4. Structure subjected to dynamic load: due to the good dynamic performance and toughness of steel, it can be used as a crane beam to directly bear bridge cranes with large lifting weight or large span.

5. Detachable and movable structures: mobile exhibition halls and mobile houses are most suitable for steel structures. Steel structures are light in weight and easy to dismantle. When bolted, they are easy to assemble and disassemble. In order to reduce the weight of the structure, construction machinery must use steel structures.

6. Containers and pipes: Due to the high strength of steel and good airtightness, high-pressure gas pipes, pipes, gas tanks and boilers are all made of steel

7. Light steel structure: Light steel structure composed of single angle steel or thin-walled steel and portal steel structure have the advantages of small self-weight and fast construction and less steel. In recent years, they have been widely used. 8. Other buildings: transport corridor trestle Various pipe supports as well as blast furnace and boiler frameworks are also usually made of steel.

Disadvantages of Steel Structure Building

There are many reasons for the difficulty in guaranteeing the quality of steel structure projects, which are also very complicated, including problems caused by improper process, problems caused by violation of process operations, problems caused by the technical level and sense of responsibility of construction personnel, and problems caused by decision makers. Quality problems caused by mistakes.


(1) Problems existing in the steel itself

When a unit was processing the 1200*1200*60 box-shaped column of a building, it suddenly found that the 60mm thick plate as the web was torn during the welding process. Half, after NDT inspection, it was found that the crack depth occurred at a depth of about 3mm. At the same time, the parts cut from several other plates of the same type and batch number were inspected, and it was found that there were interlayers in the plate, and the poor rolling quality was the main reason for the quality problem. . During the welding process, the material of the interlayer is pulled apart due to the welding stress generated by the welding. As a result, the thick plate is torn in the thickness direction.


Analysis of the reasons: Due to the particularity of the parts used, this part is used as a web in the component, and the parts welded in the vertical and up-down directions are the stiff plates with full penetration grooves in the welding form. delamination, the welding stress caused by welding is released outwardly to tear the plate in the thickness direction.


The following measures can be taken according to the actual situation:

(1) A large number of interlayers inside the steel belong to the quality problems generated by the steel mill itself during the rolling process, which have exceeded the requirements of national standards and specifications. You can ask the steel mill to send someone to verify it and negotiate with the steel mill to return or exchange goods. deal with;


(2) If the number of interlayers is small, the technical department and the owner can be consulted, the information can be fed back to the steel mill, and construction remedial measures can be taken for the problems that arise. According to the results of non-destructive testing, gouging can be used for all parts with problems. Plane to exceed its own depth, and then fill it with equal-strength welding materials. After completion, the surface is treated, and NDT testing is carried out after the specified time. At the same time, the same components are sampled, and physical and chemical inspections are carried out to meet the design specifications. Continue use;


(3) Under the witness of the supervisor, cut off the parts and replace them with plates that meet the conditions. The replaced parts are used for non-load-bearing and non-important parts or as auxiliary materials. NDT testing, make records.


Problems in the Construction Process

In the process of processing and production, quality problems are more likely to occur and the post-processing is very difficult to deal with mainly special processes and important processes. The proportion of quality problems in general processes is very small. In the above construction process, special processes include welding and painting, and important processes include blanking and assembly.

    Welding process.

This process is a hidden project, and it is also one of the most prone to quality problems. Statistics from a company's product quality report in 2004 show that among the quality problems in this process: the weld repair rate caused by the welding quality is as high as 80%. % or more, followed by welding seam quality problems due to improper operation of the previous process and technical problems of operators, accounting for about 10%. This problem is the main problem that directly affects the quality and quantity of the project, so this type of problem must be handled by professional experts. The inspection company can only detect and judge it by using professional inspection tools. Generally, it can be divided into slag inclusion, unfused, porosity, etc. according to the type of defects in the weld.


2. Coating process. 

This process is also a hidden process, and the impact on the structure is less than the impact on the building function. It is also a process that is more prone to quality problems. The quality problems of the process are mainly manifested in: the paint film on the surface of the component falls off in large areas and locally, the paint film on the surface of the component falls off and sags, the thickness of the paint film is not enough, the thickness of the paint film is unevenly distributed, and the color of the paint film is different. larger.


3. Lofting and blanking process. 

This process belongs to the faucet before the component is processed, and its quality has a direct impact on the next process, and even leads to the scrapping of all parts to be cut. This situation is very common, so before cutting It is very important and necessary to strengthen the quality control of the process. The quality problems caused by this process are mainly manifested in: the deformation of long strip and thin plate type parts is relatively severe during cutting; due to the existence of slag inclusions and uneven distribution of components in the cutting gas or the inside of the plate, the cutting surface appears malformed. The depth of tooth lines, nodules, and cutting marks exceeds the standard; the size of parts that are cut by gas cutting or sawing does not take into account the shrinkage and deformation of the subsequent process, and the size of the parts exceeds the standard; the batch of parts is scrapped due to errors in the preparation of process documents; The size of the blanking cut seriously exceeds the standard requirements.


4. Assembly process. 

This process occupies an important position in the quality of component processing, and its quality is greatly affected by the previous process, so it is very important to strengthen the monitoring of the process before assembly. The production and quality problems of this process are mainly manifested in: the assembled parts are in the wrong position, such as 3450mm assembled into 4350mm; the use of parts is wrong, the 2# parts should have been assembled, but the 3# parts were assembled; , The parts are assembled incorrectly in the correct position. For example, the 45mm hole on the board is originally facing outward, but the 45mm is actually installed inward; the assembly gap of the assembled parts exceeds the requirements of the specifications and technical documents, 3mm gap, 7mm; some zero The parts are assembled without calibration, and the existing deformation cannot be eliminated after the assembly is completed; the operator cuts the part privately to save the trouble, causing the hole position on the part to exceed the standard size; the welding area is not surface and surface treatment; due to the wrong size of the drawings assembly error caused.


(3) Use problems

Due to the non-standard use of foam in steel structure workshops, some manufacturers use low-cost non-flame retardant materials as fillers in order to save costs, which makes steel structure workshops prone to fire-related casualties.