Calculation of dynamic assembly and tensioning loads at multiple points of prefabricated structure

Abstract

Prefabricated underground station structure is rapidly assembled on site with modular components manufactured in factory. The longitudinal assembly accuracy of the components along the station’s longitudinal direction determines the construction quality of the station. In order to solve the problems encountered in the longitudinal pre-tensioning and assembly of structural components for a prefabricated station, such as low efficiency of manual operation, difficulty in determining the dynamic tensioning load, and insufficient accuracy of assembly control, a dynamic pre-tensioning load calculation method is proposed. The method, also referred to as centroid tracking pre-tensioning load algorithm, is based on controlling the dynamic relationship among the geometric centroid of rubber gasket, the centroid of multipoint tensioning load and the centroid of the elastic reaction force of rubber gasket. By using the dynamic correspondence between the compression reaction force distribution of the rubber gasket and the seam width under multipoint tensioning load, a loading control strategy is established to realize the balanced compression of the seam width of the prefabricated structure by controlling the load at each tensioning point. Thus, the centroid of the tensioning load continues to track the symmetry point of the centroid of the rubber gasket’s elastic reaction force with the geometric centroid of the rubber gasket as the reference. In this way, the tension value at each point can be precisely configured to improve the assembly accuracy of the components and realize seam width control. Based on the proposed algorithm, a set of tensioning and assembly equipment and control systems for prefabricated components of underground prefabricated structures are developed to carry out the automatic configuration of multipoint tensioning loads. The assembly tests show that the seam gap of assembled components is less than 1 mm. The proposed method demonstrates that the fast and high-precision automated assembly can be achieved and is conducive to improving the construction quality of prefabricated stations.