In terms of design concept, the Shougang Ski Jumping Platform draws on the flying elements in the Dunhuang murals, so it has the reputation of "snow flying". While people lament its cool and flowing design, it is difficult to imagine the complexity of its construction process and the excellence in the process of material selection. The handling of every detail, the selection of materials, and the solution of difficult problems reflect the wisdom and painstaking efforts of architects, designers, engineers and construction teams.
Recently, this newspaper interviewed Meng Fanxing, deputy chief architect of The Beijing Company of Construction Design, and asked him to decrypt the construction wisdom of "Snow Flying Sky" for us.
In order to make the main structure of the Shougang Ski Jump "Snow Flying" meet the overall shape and aesthetic requirements of the design scheme, what are the considerations in the selection of steel?
Meng Fanxing: First of all, the main structure of the Shougang Ski Jump is about 158m in length, and the slope layer is variable width, from 9.2m at the height to 34.1m at the landing, with a large span, a large load, and a significant temperature load, which puts forward high requirements for the strength of the steel; secondly, in order to achieve the overall shape and aesthetic requirements of the program, two groups of 8 V-shaped columns need to be used directly below the jumping area to avoid the complex structure affecting the lightness of the ribbon curtain wall.
Structural model of the large jump platform Construction design/courtesy of the picture
After computational analysis, conventional steel strength can no longer meet the above design requirements. After comparative demonstration, the final main truss adopts Q345 high construction (GJ) steel. At the same time, in order to meet its inherent slope, the node adopts a fully welded form, which can avoid the deformation superposition that is easy to produce by bolting, and also ensure the beauty of the exposed structure. From the actual completion effect, the rationality of the design has been perfectly reflected.
In addition, in order to improve the anti-snow and water corrosion ability of the large jumping platform panel, Q355NHC weathering steel was selected for construction; in view of the fire protection requirements of the referee room part of the referee tower, the project selected a new type of fire-resistant weathering steel independently developed by Shougang, and passed the special expert demonstration of the material.
In order to present the integration of structure, protection, lighting and architectural effects, "Snow Flying Sky" adopts a glass curtain wall system and a perforated aluminum plate system. Please elaborate on these two systems.
Meng Fanxing: Shougang Ski Jump, like the "Bird's Nest" of the National Stadium, is an outdoor sports venue, using a glass curtain wall as an enclosure structure in the referee room, equipment room, etc., and its glass adopts ultra-white, sandwich, hollow, coating, hot bending, tempering and other advanced production and processing technology.
The most important element of the "Snow Flying Sky" shape is the upper, middle and lower three "ribbons" that surround the departure area, the sides and bottom of the track, and the panel is a 3~4mm thick perforated aluminum plate. Among them, the upper ribbon section is rounded trapezoidal, the curvature at the corner is the largest, the three-dimensional surface is the most, and the plate size change is also the largest; although the curvature of the central ribbon is small, it is a double-layer structure inside and outside, and it is necessary to consider the functional reservation of various equipment and facilities such as hydropower pipelines, snowmelt facilities, flood lighting and race time lighting, safety protection, maintenance channels, and post-race utilization, and at the same time, as the main ribbon, its appearance effect is the highest; the lower ribbon has a twist of nearly 90 °. Through the bim application of the whole process of building plan, construction drawing, curtain wall deepening design, production and construction, and the optimization of multi-round curvature fitting, plate size and node design, the design and construction team finally presented a "snow flying sky" integrating structure, protection, lighting and architectural effects.
How did the track "grasp" 6000 m³ of snow, avoid snow slides and ensure smooth surfaces?
Meng Fanxing: The slope angle between the Shougang Ski Jumping Aid Area and the End Zone is 37°, and the snow must be fixed by snow fixing facilities to stay on the surface of the track without falling. In previous events, the big jumping platforms are temporary structures, and the track panels are wooden boards, which are easier to fix. However, the Shougang Ski Jump track panel is steel, and at the same time, in order to facilitate the use of the big jump after the Olympic Games, it is necessary to ensure that the panel is smooth, and the components cannot be directly welded on the panel to fix the snow. How to fix snow on a steel plate track, there is no precedent in the world. Architects, structural engineers, sports consultants, and snowmaking experts, after many rounds of discussion and testing, took the method of setting a row of fixed points (using high-strength bolts) on the transverse steel beams every 3 m in the direction of the track, and finally solved this problem perfectly. The lateral spacing of the track at the fixed point is not more than 1.2m, and the number is 817 in total. The fixed points are distributed relatively evenly on the surface of the track, so that the sliding force is evenly transmitted to the main structure. In non-race situations, the high-strength bolts, pressure plates and hydrophobic pads are all removed, and the sleeve is closed with stainless steel bolts, thus ensuring the smooth surface of the track during non-race.
Snow fixing point and snow fixing net Construction design /courtesy of the picture
Author: Wang Mengmeng Zhang Weiwei Ding Li Sun Yifan
Editor-in-charge: Ding Tao
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