Construction of Long-Span Steel Space Frame Membrane Structure (Part 1)

1.Introduction

With the advancement and rapid development of science and technology, the scope of application of many advanced technologies in various fields is expanding. The application of large-span steel space frame membrane structure technology is not only conducive to reflecting the advantages and characteristics of the application of membrane structure construction technology, but also It can also ensure the improvement of construction quality, prevent the steel structure from being affected by different substances such as rainwater, and provide a guarantee for the stability and reliability of the steel structure.

2. Project Overview

A fully enclosed renovation project of a coal preparation workshop in Shanxi, in which the 1-5 axis is a flat space frame structure, the roof is covered with color steel plates (including the sunshine lighting belt), and the 5-71 axis adopts a floor-to-ceiling arched space frame structure, and the roof is covered with a membrane structure. Closed, the length*width of the partially closed coal yard is 532m*125.4m, the total height is 43.8m, and the total covering film area is about 10,800㎡; the gables at both ends of the coal yard (axis 5 to axis 71) adopt a space frame structure (outer covering film structure). The membrane material is a light-transmitting fabric membrane, and adopts a simple installation method to facilitate installation and maintenance. The membrane material has a certain light transmittance, and the natural lighting is used, and the combustion performance level of the membrane material is B1. According to the characteristics of the pool body of this project and our company’s many years of design experience, this project adopts the form of “anti-hanging membrane”. The steel structure needs to stand on the original pool wall, and the influence of the status quo of the pool body, load, technology and climate should be fully considered in the design. The capping project is mainly divided into embedded parts foundation, supporting structure Q235B material, steel structure surface shot blasting derusting, covering the internationally popular membrane structure anti-hanging membrane form, the membrane material is high-quality double -sided PVDF coating, fire grade B1 special Anti-corrosion film.

3. Application characteristics and advantages of large-span steel space framemembrane structure construction technology

Combined with the current situation of the closed membrane construction of the project, it is mainly based on the space frame structure, with a length and width of 581m and 133m respectively. Corresponding concrete foundations will be set at the lower part of the main structure of the space frame, and corresponding The coal gallery runs through the space frame. According to the basic requirements of the project during construction, at the two ends of the coal yard, the gable surface is covered with a space frame structure, and the upper structure is directly covered with a abrasive film. The fundamental purpose of this is to In order to ensure that the membrane is divided, it can be divided directly according to the spacing of the strings on the space frame. It can be seen from this that the application of the large-span steel space frame membrane structure construction technology not only helps to reflect the aesthetics of the structure, but also has a very strong force transmission performance. The steel structure is severely eroded by rainwater, and the relevant parameters of the specific cover design are shown in Table 1.

Through the application of the large-span steel space frame membrane structure construction technology, it is not difficult to see that this technology has very obvious advantages when applied, especially in terms of convenience in installation. The production of steel structures and the processing of membrane bodies are generally carried out directly in the factory, and the processing quality must be guaranteed. Therefore, the time for installation and processing on site will be greatly shortened, and random occupation of the site can be avoided. All membrane materials are welded by hot-melt method. When installing and processing on-site, the membrane sheets are processed by on-site hot-melt welding, which is not only beneficial to ensure that the cover has good sealing performance, and can also isolate all the internal corrosion gas to avoid adverse effects on the steel structure. Any membrane structure can be opened directly according to the extension requirements, and the on-site hot-melt welding must restore the airtightness in time, so as to form a sealed connection with the on-site equipment pipeline.

The anti-hanging membrane structure supported by the steel structure has all the advantages of the modern membrane structure. It not only has a very beautiful shape, but also has a very strong self-cleaning feature. In particular, the surface of the membrane material has a PVDF self-cleaning coating, which can minimize the adhesion of dust on the surface of the membrane material. Therefore, it is generally directly cleaned and treated through the application of natural rainwater. It has a very strong resistance, especially compared with other traditional covering materials, its advantages and characteristics are more obvious, which can promote its maintenance. Long-term good appearance and optical performance. In terms of fire protection, combined with the current DIN4102 standard requirements, the membrane materials of the project are mainly B1-level fire-resistant materials. The overall structure is located in a relatively open outdoor location with good ventilation, which can meet the basic requirements of fire protection system design. During the design and construction of this project, the cover is processed in the form of a herringbone slope. The height of the cover is generally relatively low. At the same time, the structural form is also characterized by simplicity, which can reduce its air volume. In order to facilitate the layout and utilization of the gas collection pipeline and minimize a series of loss problems along the way, the control of energy consumption can be realized when the odor is collected, which is not only conducive to the large-scale collection and treatment of exhaust gas, but also It also reduces energy consumption. After the construction of this project is completed, all the malodorous gases in the entire factory area can be volatilized and disposed of, which can have a good improvement effect on the overall factory area and the surrounding environment of the factory area, and can also properly deal with ecological environmental problems., in order to achieve the goal of sustainable development.

4. Application of large-span steel space framemembrane structure construction technology

4.1 Membrane capping design scheme

Combined with the construction status and basic requirements of the project, the selected and used membrane materials will directly add anti-ultraviolet or hydrophobic additives in the surface treatment, which can play a good role in anti-ultraviolet aging and avoid the gradual loss of its performance. The application of hydrophobic additives is conducive to promoting the surface of the membrane material to have a very good self-cleaning effect, even after being washed by rain, the surface can still be kept clean and tidy. The design of the membrane structure should consider the effects of dead load, live load, wind load, snow load, pretension, air pressure, temperature change, etc.

Process requirements: In terms of overall shape and appearance, the basic requirements of integrity and unity must be met. Before entering the construction site, all membrane materials must be cut and processed in the factory in advance. The effective connection ensures that the outer sealing position of the membrane material can be crimped in advance. At the same time, the main parts of the steel structure must also be manufactured and pre-assembled inside the factory. A series of anti-corrosion treatments must be done in advance. After entering the construction site, they can be assembled and put in place immediately. Re-cutting and welding, the whole process is relatively simple. In addition, the natural ventilation is used to realize the effective connection between the membrane-enclosed structure and the external ventilation ducts, so as to meet the basic requirements of the indoor workers on the environment as much as possible. During the construction of this project, it is mainly based on the online closed transformation project, so as to avoid the impact on the normal operation of the stacker-reclaimer and belt conveyor, and provide a guarantee for the smoothness of production.

Material technical requirements: The membrane material is made of high-strength polyester fiber substrate, the surface is coated with polyvinyl chloride alloy, and then coated with a poly-anti-corrosion surface treatment layer. The surface cannot be welded with PVDF. Refer to the “Technical Regulations for Membrane Structure” to meet the requirements. Material technical requirements.