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TBM steering difficulties. Innovative equipments: Strand jack and self retaining systems
Published in Daniele Peila, Giulia Viggiani, Tarcisio Celestino, Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art, 2020
In the Basci tunnel, the strand jack system was installed on the TBM to compensate the lack of contact force at the tunnel face. The force applied by the strand jack system generates a negative moment, which is opposed to the moments related to the friction force and weigth of the TBM, hereby, it helps to steer the TBM up. The system consists in four hydraulic cylinders installed on the steel thrust structure at the Basci tunnel inlet, appropriately reinforced, steel ropes and four hydraulic cylinders installed on the TBM bulkhead, just behind the cutterhead. In addition, to giving a contribution in terms of upwards rotation of the TBM, it also provides a reduction of the advancing speed, while keeping the same force on thrust cylinders.
TBM steering difficulties. Innovative equipments: Strand jack and self retaining systems
Published in Daniele Peila, Giulia Viggiani, Tarcisio Celestino, Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art, 2019
In the Basci tunnel, the strand jack system was installed on the TBM to compensate the lack of contact force at the tunnel face. The force applied by the strand jack system generates a negative moment, which is opposed to the moments related to the friction force and weigth of the TBM, hereby, it helps to steer the TBM up. The system consists in four hydraulic cylinders installed on the steel thrust structure at the Basci tunnel inlet, appropriately reinforced, steel ropes and four hydraulic cylinders installed on the TBM bulkhead, just behind the cutterhead. In addition, to giving a contribution in terms of upwards rotation of the TBM, it also provides a reduction of the advancing speed, while keeping the same force on thrust cylinders.
Some cases of pathologies in prestressed concrete bridges in Spain. Diagnosis, analysis, and decision making
Published in Joan-Ramon Casas, Dan M. Frangopol, Jose Turmo, Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability, 2022
Ignacio Pulido Sánchez, Francisco Millanes Mato, Beatriz González del Riego, Andrés Hernández Sancho
The tendons replacement wasn’t an easy operation. The free space between end-beams spans was very reduced, around 70 cm, and made the solution and the performance very difficult. This space was totally insufficient to use a multi-strand jack, so a reduced mono strand jack of 30 cm and 45 mm of stroke was designed. In any case, the limited space forced to stress the strands in more than 10 steps.
Innovative Method for the Construction of Cable-Stayed Bridges by Cable Crane
Published in Structural Engineering International, 2018
The bridge stay cables consist of 43 to 83 strands, varying from 103 to 425 m in length. The strands were delivered to the site in compact coils and installed one by one using a winch system, then stressed by a lightweight mono-strand jack at the pylon end individually. For parallel strand stay cables, equal forces in all strands and final tension in the completed stay cable are two major aspects of concern during installation in situ.
Engineering of the National Namaste Signature Bridge Pylon
Published in Structural Engineering International, 2023
Strands in the cables were tensioned using the iso-elongation method. This method utilizes a mono strand jack attached with a load cell, hydraulic pump and dynamometer for calibration of the pump–jack system. For each stressing phase, the strands were first stressed up to 80% of the stressing force.
Roof Design and Construction of the Narendra Modi Stadium—The World’s Largest Cricket Stadium
Published in Structural Engineering International, 2023
Viral Patel, Amol Acharya, Mark Waggoner
The erection of the steel compression ring started after substantial completion of the reinforced concrete bowl. First, a set of V-columns were installed. Because the base of each V-column used pinned connection in the radial direction of the roof, it needed temporary support from the concrete bowl. After two sets of V-columns had been installed with a temporary brace near the top by the bowl structure, a section of the compression ring was secured over the columns. Since the compression ring is a planar truss, the lateral stability had to be provided by temporary steelwork resting on the top of the bowl. Figures 5 and 6 show the schematic installation and photo during the erection of a section of compression ring with temporary supports. Figure 7 shows a partially completed compression ring. The process was repeated until a sufficient length of the partially completed ring was stable without external support from temporary steelwork (Fig. 8). Temporary steelwork used for stability of the planar truss was moved and reused for the new segment of the compression ring until the entire ring was completed. Cable erection started soon after the compression ring was completed. The inner tension ring cables were laid on the previously completed bowl structure with predetermined locations of weldments where radial cables meet (Fig. 8). Radial cables were also connected to weldments at each grid line. The ends of the radial cables were connected to grip devices which were connected to strands. The strands were connected to strand jacks mounded near the pinning locations of the radial cables. The strand jack stressing operation was monitored and coordinated to avoid excessive bending or ovalization of the compression ring. Once all cables had been pinned, a catwalk along the entire inner tension ring with lights for the field of play was installed. Finally, PTFE fabric rolls prepared at the fabrication factory were transported to the site. Fabric rolls were rolled in a pivot-type spindle at the site and lifted by a crane near the tension ring. The fabric was then rolled out and clamped to cables and a compression ring for each panel. The completed roof structure is shown in Fig. 9.