Study On Prestressed Reinforcement Line Cables Of Frame Spandrel Beams Considering The Combined Effect Of Bending-shear-torsion

With the wide application of prestressed technology in engineering structure, a lot of researches and analysis about performance of all aspects of components have been done, and many research achievements have been made. The achievements mostly concentrated in the analysis of influence on torsional property and shearing property which was caused by the prestress and pure pre-axial force, in the research of destructive form of prestressed component under the composite force, and in the establishment of the corresponding formulas. But the researches on resolving the bending-shear-torsion problem about composite components by configuring some appropriate form of prestressed tendons were very few.Based on the basic principles of generalized prestress and the fundamental character of equivalent load, a new type of prestressed tendons form has been presented and put into the frame spandrel main beams. The research work on optimizing the tendons form in the frame spandrel main beams has been developed. The novelty of this study is that the form of the spiral broken line cables has been improved, thus the prestressed tendons which resist moment formerly can stand torsion simultaneously. At the same time the effect of resisting torsion has been achieved by changing the trends and forms of the long-pass tendon at the top and bottom of the beam, the purpose that one kind of tendons can stand the bending-shear-torsion effect has been achieved, the steel has been saved, and the structure scheme has been optimized. Comparing the simulation analysis of the frame spandrel beams with spiral broken line cables to the one of the frame spandrel beams with line cables of new forms, analyzing data has been got, and the rationality and progressiveness of this new forms line layout cables have been proved.By analyzing the ANSYS equivalence chart of the three pieces of frame spandrel beams, the relationship between loads and the stress, strain of the concrete, prestressed tendons can been seen clearly in the whole phase when prestressed concrete bending-shear-torsion component standing the force. The deformation, the formation and development of the cracks, and the whole destroy process can also be seen. Data results showed that ultimate bearing capacity of the frame spandrel beams with the recommended cables has increased without adding the cross-sectional area of prestressed tendon, while this new type of cables can also save the cross-sectional area of the non-prestressed tendons. Imagining if the recommended form of tendons was configured in a larger cross section of the components (such as box girder), prestressed tendons can get greater inclination angle and the arm of inner force, and a larger pre-torsion, pre-shear and pre-moments can be got, which would be benefit for prestressed tendons playing their role. Based on the two phases work principle of the prestressed tendons, the bearing capacity formula applied for the rectangular cross-section shear-torsion components with new type of prestressed tendons has been proposed. The conclusions obtained in this paper have a certain importance and broad application prospects in the actual project.