Study on Decision-Making Method of Lifting Space Frame in Maintenance Hangar (Part 1)

In 2021, the Two Sessions proposed a grand blueprint for China’s civil aviation industry based on the 14th Five-Year Plan and the 2035 long-term goal outline : the implementation of Guangzhou, Shenzhen, Kunming, Xi’an, Chongqing, Urumqi, Harbin and other international hub airports and Hangzhou, Hefei, Jinan, Changsha, Nanning and other regional hub airport reconstruction and expansion projects, and build new airports in Xiamen, Dalian and Sanya. Build Shuozhou, Jiaxing, Ruijin, Qianbei, Alar and other regional airports, and add more than 30 civil transport airports. The further development of civil aviation airport construction has enriched my country’s air routes, but also put forward more efficient, accurate and fast requirements for the maintenance of spacecraft. Among them, the maintenance hangar, as the construction of the infrastructure for spacecraft maintenance, is undoubtedly the top priority.

The roof of the maintenance hangar often adopts a spherical space frame structure, and a multi-layer truss structure is used at the warehouse door. Construction requirements often have the characteristics of large span, high height, small deformation requirements, and difficult construction. Taking into account factors such as high-altitude operations, construction costs, construction progress, and construction difficulty, it is often adopted to upgrade the ground to the design elevation after the overall assembly and welding of the ground is completed.

1、Overview of categories of maintenance hangars and space frames

Maintenance hangars are generally divided into wide-body machine hangars and narrow-body machine hangars in terms of service objects ; in terms of the number of service objects, they are generally divided into single-position hangars, double-position hangars and multi-position hangars ; The layout of the hall and maintenance auxiliary rooms is generally divided into surround type and front-to-back type; from the structural point of view, the general maintenance hangar column adopts the column form, the maintenance hangar roof adopts a spherical space frame structure, and the maintenance hangar door head A local truss structure is adopted.

The main limitation affecting the selection of the maintenance hangar lifting scheme is the span and depth of the maintenance hangar itself. Generally, the span ranges from 70 to 150m, and the depth is generally controlled at 60 to 90m ; the height of the space frame is generally determined by the calculation of the structural design after being determined by the first two, and the common ones are single-layer space frame or double-layer space frame. The lifting height of the space frame is generally between 24 and 35m.

2、Common lifting methods for maintenance hangar space frames

According to the different spans and depths of maintenance hangar space frames, different construction conditions, differences in construction quality and cost factors, generally the main hangar space frame lifting schemes include lifting and jacking; different lifting methods are considered The support carrier can be divided into two types: in-situ lifting using the original structure and new point lifting of newly built lattice columns.

2.1、The in-situ hoisting technology of the maintenance hangar space frame The core of the in-situ hoisting technology is to use the originally designed structural column, arrange the hoisting oil pump on the top of the structural column, and synchronously lift the ground-assembled space frame to the top of the structural column through multi-stranded steel cables Design elevation. In this construction process, most of the force of the lifting space frame is borne by the main structure columns, which has great requirements on the main structure itself. The program has been practiced in the construction of the space frame structure of the maintenance hangar of Wuhan Eastern Airlines, and has great reference value in terms of overall project economy.

2.2、Upgrading technology for new points in the maintenance hangar

The core of Xindian’s lifting technology is to build a number of lattice columns slightly higher than the structural columns in the hangar hall according to the calculation, and install a lifting oil pump above the lattice columns, and synchronously lift the space frame assembled on the ground through multi-stranded steel cables. to the design level. During this process, the force of the space frame itself falls entirely on the newly-built lattice columns, without any impact on the original structural system.

This scheme has been successfully practiced in the construction of the space frame structure of the new hangar of Beijing Eastern Airlines, and has accumulated a lot of experience.

2.3、Hangar space frame lifting technology

The core of the space frame lifting technology is to build multiple jacking nodes in the hangar hall according to the calculation, and further subdivide the one-time space frame lifting according to the lattice column modulus, and carry out through multiple lifting rounds: jack “jacking “Liter” – add “standard section” – oil return climbing jack of pumping station – after fixing the force parts of the jack, raise the maintenance hangar space frame to the target design elevation.

This scheme has been successfully practiced in the construction of the maintenance hangar space frame structure of China Eastern Airlines in Qingdao New Airport, and has accumulated a lot of experience.

3、Decision-making analysis of space frame lifting methods

3.1、Conditions and advantages and disadvantages analysis of three space frame lifting schemes

(1) Conditions and advantages and disadvantages analysis of the in-situ lifting scheme. Since the in-situ lifting scheme arranges the oil pump and the lifting device on the original structural column, the reserved load requirements for the structural column are much higher than the normal working conditions of the column. At the same time, in order to facilitate the construction and later repair welding of the space frame, the lifting point is generally cantilevered at a distance of 1~2m outside the structural column, and the force on the column is eccentrically compressed. Therefore, in addition to recalculating the compressive load during structural design, a special recalculation or reservation should be made for the bending and shearing capacity of the column (especially the middle part of the column).

In addition, due to the layout of the original structural system and the load limit of the construction equipment, the in-situ lifting scheme has certain restrictions on the lifting of the large-span two-position or even three-position wide-body machine hangar space frame. Lifting lattice columns are added in the centralized area or the hangar door area to assist in the lifting.

Compared with the other two lifting schemes, economy is the biggest advantage of the in-situ lifting scheme. This scheme can maximize the use of the original structural system without the need for new lattice columns or jacking columns and the lower foundation and cast-in-situ piles, which makes this scheme have a greater advantage in cost sharing.

The second is to improve quality control. The in-situ lifting is carried out synchronously through the computer and the mechanical oil pump after the first leveling of the hangar structural column top after the first installation. Therefore, the construction quality is less subject to human interference, and the construction quality is more reliable.

Relatively speaking, the in-situ lifting scheme has higher requirements on the vertical accuracy of the original structural column. The reason is that when the entire structural system is stressed, the structural column is deformed under force, and the elastic deformation will further aggravate its eccentric compression, thereby further aggravating the overall risk to the original structural system. In other words, in-situ lifting has relatively high requirements for the unit that compiles the construction plan and the unit that designed the original structure. On the other hand, the in-situ lifting scheme requires that the construction of the original structural column be completed and the concrete curing be completed before construction. This will bring more organizational requirements to the construction process and construction schedule.