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Shotcrete application
Published in Dudley Robert (‘Rusty’) Morgan, Marc Jolin, Shotcrete, 2022
Dudley Robert (‘Rusty’) Morgan, Marc Jolin
Stiff plastic conduit pipe has been widely used as screed pipe for control of line and grade and tolerance for curved structures such as circular water tanks, tunnel shafts (Zhang et al., 2018) and bobsleigh/luge tracks (ASA, 2008). Similar to pencil rods, when bent it forms a perfect arc. Figure 9.16 shows plastic conduit pipe installed on a mock-up for shotcrete construction of the Alpensia Sliding Centre bobsleigh/luge track for the 2018 Winter Olympics at PyeongChang in South Korea. The plastic conduit screed pipe was tied to the outer layer of reinforcing steel to very exacting tolerances using plastic clip ties. After the shotcrete had been placed, screeded and finished, the plastic clip tires were cut, and the ties and screed pipe removed. Wet-mix shotcrete material was hand placed to fill the void left by the screed pipe as part of the final finishing operations. The same method was used for construction of the 2010 Whistler Winter Olympics bobsleigh/luge track (ASA, 2008) and the Beijing 2022 Winter Olympics bobsleigh/luge track. In structures with less exacting tolerances, structures with multiple curvatures, such as skate parks, can be constructed using curved guide strips.
3D printing technologies and implications for sport management
Published in Cheryl Mallen, Emerging Technologies in Sport, 2019
Intriguingly, 3D printed sports equipment was used at the 2018 PyeongChang Winter Olympics. The Chinese short track speed skating delegation wore 3D printed gloves that helped them win gold medals.37 Each team member had their gloves fitted specifically for their finger size and were manufactured with titanium alloy fingertips.38 The glove tips were an innovation that replaced the usual resin or types of gel materials used to tip the fingers in the gloves.39 The fingertips on the gloves are placed on the ice to assist the skaters as they lean into the corners to complete a lap on the short track course. This technology was noted as providing an advantage for the athletes with respect to the drag created by the hands during the turns.40 Gloves for other sports are sure to follow. Further, the 2018 Olympic gold medallist in the men’s biathlon event used a personalized 3D printed gun.41 And, the US luge team used a 3D printer to generate their streamlined sled.42
Design and Construction of China’s National Sliding Center
Published in Structural Engineering International, 2023
Xiaomeng Zhang, Qingying Ren, Wenting Liu, Zheng Li, Xiang Liu, Ziqi Liu
The bobsleigh-luge track’s structural system must consider the influence of the main load, which consists of the dead weight of the structure, the dynamic load of the bobsleigh and luge, or the temperature load under the action of thermal expansion and cold contraction. If the joints are connected using cast-in-place concrete, they will be rigid and so can easily undergo failure. Different from the frame structures used in ordinary buildings, the pendulum column structure takes the fixed column in the center as the fixed support. This is the main bearer of the bending moment, shear force and axial force, while the upper and lower parts of each pair of columns at the two ends transfer the vertical and shear force through the rubber pads and steel bars. When the pendulum column structure is used, the rubber bearing not only bears the load but also reduces the stress generated by friction, vibration and thermal expansion and contraction-induced displacement.
Step characteristics of international-level skeleton athletes in the starting phase of official races
Published in Sports Biomechanics, 2021
Takahisa Oguchi, Michiyoshi Ae, Hermann Schwameder
The significant correlation between the sled speed at the 2nd step and the start time indicated that pushing the sled quickly just after leaving the starting block should not be negligible for gaining a shorter start time. Running while pushing the sled is one of the features of the skeleton starting motion. In sled sports such as the bobsleigh, luge, the coefficient of friction between the blade and ice, air resistance, and system mass (i.e., total mass of the athlete and equipment) are additional factors that contribute to the competition result. Baumann (1973) reported that a 10 kg increase in luge mass reduced the finish time by 0.25 to 0.35 s, revealing that the system mass was one of the factors determining luge performance. According to the International Bobsleigh & Skeleton Federation regulations, the total mass of the athlete and equipment (i.e., the sled and gear) must be within 120 kg and the maximum mass of the sled must be no more than 45 kg for men (International Bobsleigh & Skeleton Federation, 2018b). Although the mass of the sled and equipment (helmet, wear, shoes, etc.) varied according to an athlete, the estimated mass in this study was around 35 kg based on the mean mass (78.9 ± 8.0 kg) of the athletes and equipment (5 kg, estimated). Therefore, another feature of the skeleton is that athletes must push forward a heavy sled to gain a high sled speed in the first few steps. The 1st step of most athletes was on the same side as the sled (i.e., the ipsi-type), resulting in a higher sled speed compared with the contra-type athletes. The arm swing in normal walking and running is reciprocal to the leg motion so that the right arm swings forward when the left leg does and vice versa (Pontzer et al., 2009). Based on our observation, the ipsilateral motion can be seen in various sports, such as a pass in fencing, a forefist punch in karate, and a thrust in sumo. Whether such ipsilateral motions were more faster and powerful than contralateral motions have not been clarified, but this speculation may be partially supported by the fact that the sled speed and SL index in the 1st step of the ipsi-type athletes were significantly greater than those of the contra-type athletes. Such motion, hereinafter the ‘ipsi-type starting technique’ might help push the sled forward strongly and swing the leg further forward in the 1st step. As a result, most athletes in the present study likely used the ipsi-type starting technique and gained a higher sled speed in the 1st step.