Technological Innovation

Research on high formwork construction technology in reinforced concrete frame structure construction

Kou Qian Wenhong

With the improvement of modern science and technology, all industries have witnessed a significant increase in production and manufacturing capacity, especially in the construction industry. At present, many new construction technologies have emerged, promoting the development of the construction industry. In this process, the high formwork construction technology came into being, making the construction of reinforced concrete building frame structure become more horizontal.

1. Technical requirements for high formwork construction in reinforced concrete frame structure

1.1 Pole erection technology for high formwork construction

In the process of high formwork construction, when starting to implement the erection of vertical poles, we should focus on the following points: (1) When setting vertical poles, more cross bridging should be set every four rows to ensure the stability of the overall high formwork; (2) When erecting the pole, the pole must be vertical to the ground, and the distance between poles must be equally divided. If there is vertical deviation, it should be within 1.5 cm, and the distance deviation should be within plus or minus 5 cm; (3) On a plane, the height difference and level difference of the surface of two adjacent crossbars shall not be greater than or equal to 2.9 cm; (4) When selecting the butt joint mode for the longitudinal horizontal bar, its fasteners should be staggered, and they must not be arranged in the same span and synchronization.

1.2 Cross bridging technology in high formwork construction

In the construction of high formwork, the cross bridging technology is one of the key technologies and also a major guarantee to ensure the high stability of high formwork construction. In the layout, care should be taken: first, the external facade along the support must meet the standard requirements set by the full set of diagonal braces; Second, in the middle, the construction should be carried out based on the actual size of the frame. Generally, the corresponding cross bridging should be set every 13 meters, and the width should be up to 5 meters. Third, the bottom of the cross brace should be fully pre tightened with the ground, and the included angle should be kept at 50 degrees. Each cross brace should also have a reasonable included angle deviation, that is, it should be controlled within 10 degrees; (4) When arranging the cross bridging, some parts have been equipped with cross bridging, so it should not be omitted. Instead, a horizontal cross bridging should be arranged based on the cross bridging, so that it is in the middle of each horizontal cross bridging. Based on this, adverse effects of various factors can be avoided and it can be kept stable. In addition, the arrangement of diagonal braces and horizontal diagonal rods in the horizontal layer shall be strengthened along the horizontal structure every 5 meters, and shall be connected with the vertical rods. The number of diagonal rod layers shall be controlled within 33.33% of the total number of horizontal frames.

1.3 Installation technology of high formwork construction

During the construction and installation of high formwork, it is necessary to ensure the accuracy and stability, and grasp every detail of the installation without slack, because if there is any error in the installation process, the high formwork will collapse partially or overall. In order to avoid safety accidents as much as possible, the following should be done during the installation: first, ensure that the specifications of the installation fasteners can be 100% consistent with the outer diameter of the steel pipe and perfectly matched; Second, the tightening torque of the fastener wide bolt must be controlled (55N · m). It cannot be too small or too large. If it is too small, it will make the installation unstable, and if it is too large, it will damage the components. Third, at the position of the main node, the distance between the center points of the rotating fasteners (used for the fixation of the horizontal and longitudinal bars, and the fixation of the diagonal braces) must be less than 150 mm. Fourth, in the process of fastener butt joint, the fastener opening should always face inward or upward, and the bolts should always be in the same direction; Fifthly, anti sliding fasteners must be tightened against each other, and after the installation of fasteners, special personnel shall be arranged to review and accept them.

2. Acceptance of high formwork construction technology

2.1 Inspection of high formwork technical items

In the construction technology of high formwork for large high-rise building projects, inspection is necessary and is the basic condition to ensure the smooth completion of the project, maintain efficiency and safety, so it should be implemented in place. It includes two parts, namely, construction process inspection and acceptance inspection after construction. In the inspection of the construction process, not only the strict supervision and supervision should be made based on the project progress, its standards and professional technical standards, but also the self inspection of the construction team should be deepened. After the construction, the corresponding inspection shall also be carried out, and professional and technical personnel shall be sent to carry out the detailed acceptance, including the strict acceptance of the construction quality of the high formwork and the geometric standard between the upright, the system stability, and the strict acceptance of the support strength. If some problems are found during the inspection, the problems shall be reported in time, and then reliable countermeasures shall be made. The construction can be started only after the rectification is completed and no problems are confirmed.

2.2 Acceptance of high formwork technology project

Strict acceptance shall be made for the high formwork technology project, so that the technical practice can have a reasonable ending. That is, the high formwork construction shall be confirmed according to the construction inspection process after it is clear that the high formwork construction is completed, so as to facilitate the subsequent process. The acceptance criteria have been mentioned in the previous section. In addition, many items should be prohibited, such as the following conditions should not occur during the acceptance, otherwise the acceptance cannot be carried out:

First, the connection with the upper and lower upright rods must be achieved by lapping; Second, on the horizontal bar, the fastening mode is the rotary fastening with insufficient stability; Third, change or reduce the horizontal bar structure at will; Fourthly, the column cannot be kept stable on the ground; Fifth, the strength of the supporting material is relatively low; All the above situations will affect the support strength and stability of high formwork construction. Once the above five situations are found, they should be handled in a timely manner.

2.3 High formwork removal technology and safety construction measures

2.31 Removal process of high formwork

Before removal, the sundries and obstacles in the high formwork shall be completely cleaned, and they shall be transported to a specific place. It is strictly prohibited to place them on the ground at will, and it is strictly prohibited to throw them at random from high altitude;

When demolishing the wall connecting rod and scaffold, they must be demolished synchronously and layer by layer. One item cannot be demolished first, and then another item cannot be demolished; When removing the cable wind rope, it shall be removed at the same time with the scaffold, and the pace shall be consistent.

Before demolition, special personnel shall be dispatched again to evaluate the overall structural stability, so as to ensure that the high formwork can be demolished only when it is still stable, and it shall be reinforced when it is unstable.

2.32 High formwork safety construction technology

During the construction, we must maintain the level of high formwork safety construction technology, and implement the high formwork construction in this process. In addition, we should also establish a complete set of safety assurance system and supervision system to ensure effective project construction management and implement the project. The technical standards and requirements for the safe construction of high formwork are as follows: first, determine the relevant responsible personnel in the safe production, determine the posts and corresponding responsibilities, and assign special posts and responsibilities, so that they can really devote themselves to the supervision and management of the overall safety in the construction process; Secondly, before the actual high formwork construction, safety education and professional management training should be carried out for the high formwork construction personnel to ensure that they can always pay attention to safety and obey the command and management of the person in charge of safety during the construction process. Third, we must strictly select the on-site construction personnel with strong technical level, and implement the comprehensive disclosure of safety technology before the erection and removal of formwork and the pouring of concrete; Fourth, scaffold erection workers must hold special certificates before taking up their posts. Those who are not of this type of work are strictly prohibited from engaging in scaffold erection operations, and must meet the assessment requirements of this type of work. They must accept necessary inspections before specific construction operations. At the same time, they should strengthen their safety awareness and prevent them from taking up their posts without certificates; Fifth, construction personnel and other relevant personnel must wear safety helmets before entering. For personnel working at heights, they must wear safety belts and put connectors into tool bags to prevent them from falling, and they are responsible for their own safety and the safety of others; Sixth, in the process of construction, the construction personnel must keep their attention focused, and should meticulously carry out the installation and erection of high formwork, and can take turns to avoid safety risks; Seventh, in case of severe weather, such as heavy rain or super wind weather, high-altitude operations cannot be carried out, and the erection and removal of formwork supports must not be carried out in this weather;

In a word, in the construction of reinforced concrete frame structure, the construction of high formwork should be put into place. This paper has made a specific analysis and research on the construction technology of high formwork in order to help the relevant personnel to implement the effect of project construction and ensure the construction quality of reinforced concrete frame structure.