Optimization Scheme for the Zigzag Prestressing Construction with Pretension Method
Currently,the majority of existing pretensioning pedestals in China are used for the production of straight prestressed precast beams with medium and small spans.They are generally designed to withstand significant shear forces in the direction of prestress but can not resist large overturning moments.When producing higher zigzag prestressed beams,the risk of overturning and strength failure of the pedestal increases due to the raised center of prestress force.This paper proposes a zigzag prestress construction scheme based on actual engineering projects and conducts a comparative study with two common zigzag prestressing construction schemes.Research and engineering practice show that the scheme proposed in this paper can effectively lower the center of combined forces at the pedestal in zigzag prestressing,thereby reducing the overturning moment and the base bending moment generated on the pedestal during prestress tensioning,significantly improving the safety of prestress construction.The actual camber of the prestressed beams produced using the proposed scheme is closer to the design value,meeting engineering requirements.Based on the scheme proposed in this paper,when precast plants use existing pedestals for the production of zigzag prestressed beams,the cost of pedestal modifications can be significantly reduced,offering notable economic benefits.