1 Airport Terminal 2 Project Overview
1.1 Airport Project Construction Overview
Nanyang international airport terminal 2 prefabricated large steel structure Installation project has a construction area of 49,000 square meters. It is a concrete frame structure with a structural safety level of first class. The airport terminal building has 3 floors from top to bottom, namely the departure floor, the arrival floor, and the basement floor. The southeast side of the terminal building is the airside apron area of the airport, and the northwest side is the landside elevated connection with the arrival and departure floors of the terminal building. The height of the airport terminal building is 27m, the east-west length is 183.6m, and the north-south width is 75.6m; there are 2 floors above ground and 1 floor underground. It is composed of a conical steel pipe column, single-layer reticulated shell roof, steel canopy, etc. The steel components are mainly made of Q345B, Q390B, and Q390C.
1.2 Roof steel structure of airport terminal 2
The roof is supported by 18 directly welded concrete-filled steel tubular columns, made of Q390B, with 3 columns in the longitudinal direction and 6 columns in the transverse direction. The single-layer reticulated shell structure of the roof consists of vertical and horizontal trusses, skylights, and edge-sealing beams. The roof truss is mainly composed of round pipes, which are connected by intersecting welding, and the trusses are connected by the support of round pipes. The roof is distributed with 9 skylights, each weighing about 22t, and is designed as a double-layer structure: the lower layer is a welded box beam, and the upper layer is a diamond-like structure composed of H-beams, which are assembled and hoisted as a whole.
1.3 Exposed single-layer reticulated shell structure
The exposed single-layer reticulated shell structure is a Q390c welded box beam, located on the northwest side of the steel roof, with a total weight of more than 1000t, and a single maximum weight of 18t. The mesh shell is connected to the bearing platform by four diagonal braces through its own smooth curve, which extends obliquely through the ground finished hinge support, and the nodes between the single-layer shell rods are rigidly connected.
2 Analysis and countermeasures of important and difficult engineering
(1) Due to the complex spatial modeling of the roof steel structure project, it is difficult to locate the rods installed on site. It is necessary to reflect the positioning coordinates of each node in the detailed design drawing, and the precision of the detailed modeling is high.
(2) The main components of the single-layer reticulated shell are box beams. Due to the large section of the box beam, the heavy weight of the components, and the large-span, large-wave, and large-overhanging curved space modeling, the installation is difficult.
(3) The maximum span of the truss is 36m, the highest point is 27m, the space span is large, the height is high, the distribution range of rods is wide, and the changes are large; the welding forms include vertical welding, flat welding, overhead welding and oblique welding. The level is very demanding. Considering the high requirement of detailed modeling accuracy, TeklaStructures special design software is used for model design. At the same time, pay close attention to the detailed design, strictly implement the relevant specifications, and ensure the accuracy of the detailed design of the connection nodes. Due to the difficulty of on-site installation, segmented installation is adopted, that is, supporting tire frames are arranged at the segmented positions, and the tire frames are connected by trusses to form a stable structure, and the total station is used for measurement and positioning to ensure accurate installation and positioning. Considering the difficulty of on-site welding and high-quality requirements, the qualification certificate of the welder and its operating skills shall be reviewed, and the on-site welding procedure examination and evaluation shall be organized.
2 Technical control of roof steel structure installation
3.1 Roof pipe truss pre-assembly
The main purpose of pre-assembly is to check the machining accuracy of the truss, so as to adjust and eliminate the errors in time, so as to ensure that the irregular large components can be smoothly connected during field assembly, thereby reducing the number of adjustments to the components during the high-altitude installation process. Due to the irregular curve structure of the pipe truss, extremely high requirements are placed on the machining and manufacturing accuracy of the components, and pre-assembly is required before leaving the factory.
3.2 On-site assembly of morning cover pipe truss
Before the roof pipe truss is assembled on site, the ground of the site needs to be leveled, and then mechanically compacted in layers to compact, and then poured with plain concrete with a thickness of 100mm as the assembly site to meet the flatness and strength required for the truss assembly. The assembly adopts the multi-section ground continuous horizontal assembly method, and the upper and lower chord segments to be installed are placed in the assembly site in turn. When assembling and positioning, control the size of the groove gap at the chord port and the edge difference of the nozzle of the butt joint, adjust After the rod is positioned, the ear plate can be connected, and tightened with the corresponding specifications of the mounting bolts, and then spot welded for positioning.
3.3 Airport terminal prefabricated roof pipe truss installation
After the concrete pouring in the conical column, the installation of the finished bearing, and the assembly of the section truss are completed, the hoisting and installation link of the roof pipe truss can be entered. Installation sequence: first install the longitudinal and transverse main trusses, then install the secondary trusses, and finally install the scattered parts.
3.4 Airport terminal prefabricated roof skylight installation
The roof skylight is similar in shape to a rhombus. It is a double-layer upper and lower structure, the lower layer is a welded box beam, and the upper layer is a diamond-shaped structure composed of H-shaped steel. The upper and lower layers are connected by skylight columns. 7″ glyph. Installation method of skylight: After the welding of the 4-section “7”-shaped box beam is completed and transported to the site, it is assembled into a lower diamond-shaped skylight, and the whole is hoisted by a car crane.
3.5 Installation of exposed single-layer reticulated shell
The exposed single-layer reticulated shell is composed of square latticed shell structural components welded by box-shaped square tube steel beams. The width of the latticed shell is 180m and the height is 22.1m. The maximum cross-sectional size of a single box-shaped steel beam is 1200mm×600mm×25mm×: 25mm, the largest single steel beam weighs about 17.966t after segmenting, and there are 4 “V”-shaped column foot supports at the bottom connection of the single-layer reticulated shell, and the top is connected with the lower part of the truss, forming a stable reticulated shell structure system.
Nanyang International Airport terminal prefabricated roof steel structure project has large waves, large overhangs, large structural span, complex curved surface modeling, difficult three-dimensional spatial positioning, high component manufacturing standards, and difficult on-site installation. Before the start of construction, repeated analysis and research were carried out on the major and difficult points of the project construction, and feasible construction techniques were put forward.