Design and Construction Optimization for Elevated Long-link Seamless Urban Rail Transit Station with Bridge-building Unified Structure

Abstract

[Objective] The elevated long-link seamless station with bridge-building unified structure integrates building and bridge and enables the station pier column to have stiffness requirements while possessing the characteristics of complex space frame structure system, large volume, and more statically indeterminable times. Therefore, temperature, shrinkage and creep of the concrete structure become the control factors in the design of such station structure. The traditional methods such as setting expansion joint, enlarging pier column section size and strengthening pier column section reinforcement will destroy the integrity of station structure and increase the maintenance and construction cost. It is necessary to optimize the structure of the unified long-link seamless elevated station from the aspects of design and construction. [Method] The island station of Shenzhen Metro Line 6 with 9m width is taken as research object. MIDAS software is used to establish a finite element model for the above station to calculate, analyze and verify the design. The optimization scheme is proposed from the aspects of design and construction respectively, a finite element model of the elevated station is established from the design point of view, and is used to compare and analyze the control bending moment of the pier column. [Result & Conclusion] The calculation results of the finite element model show that the pier columns at both ends of the station are obviously affected by shrinkage, creep and temperature, and the stress and reinforcement are the key control points of the design. Under the condition of ensuring the integrity of the station, three optimization schemes are proposed from the design point of view, such as deepening the buried depth of the cap, adopting double thin wall pier and using hinge connection at the top of the pier column. From the construction point of view, the optimization schemes such as setting up post-grouting belt and adopting modular assembly are put forward. Simulation analysis shows that the control bending moment of the 13th axis at the bottom of the pier can be reduced by about 22% by deepening the pier cap buried depth of 2m and increasing the pier height to reduce the pier stiffness. The stiffness of the pier is greatly reduced by using the double thin-wall pier, and the control bending moment of the 13th axis at the bottom of the pier is reduced by about 46%. The concrete hinge used at the pier top releases the bending moment transmitted from the upper part to the pier column, and reduces the control bending moment of the 13th axis by about 13%.

Keywords

• urban rail transit
• bridge-building unified structure
• elevated station
• long-link seamless structure