Abstract:Based on the static load test results of nine externally prestressed concrete beams, a simplified calculation method for the moment, stiffness and stress increment of external tendons at the ultimate state of externally prestressed concrete beams is established. Meanwhile, this method is used to analyze and calculate the test results of a batch of externally prestressed concrete beams abroad, with good results obtained. It is proved that the method has strong generality and good calculation accuracy, and provides a directly usable formula for the research and design of various externally prestressed structures.

Abstract:With the help of domestic and foreign research achievements, this paper expounds the influence of secondary internal forces generated by post-tensioned statically indeterminate structures on the establishment of member section stresses and the internal force redistribution of continuous beams, and puts forward improved suggestions for calculation. Under the two limit states, considering the lag characteristics of the strain increment of bonded and unbonded prestressing, parameters such as the strain lag coefficient are introduced as the basis for calculating the crack width, stiffness and flexural bearing capacity of beam sections, and suggested values of relevant parameters are proposed.

Abstract:The OVM parallel wire strand cable system, a new generation of cables in China developed by the authors together with relevant domestic units, has many advantages and represents a new development trend of cable-stayed bridges in China. It has been successfully used in five bridges such as Liuzhou Fourth Bridge, and is being used in the under-construction Baoshi Bridge. It won the second prize of Science and Technology Progress of the Ministry of Construction in 1996.

Abstract:The west channel bridge of Xiamen Haicang Bridge is the first three-span continuous steel box girder suspension bridge under construction in China. Its anchorage structure is novel, reasonably stressed, economical in materials and magnificent in shape. This paper mainly introduces the design conditions, structural characteristics and construction key points of its anchorage body and prestressed anchorage system.

Abstract:The application of high-strength concrete is a remarkable topic in the field of bridge engineering. This paper introduces the optimization results of section form and dimension, structural ductility detailing measures of bridge deck hollow slab beams after adopting high-strength concrete and high-quality steel strands with high uniform elongation, as well as the technical and economic benefits obtained. The failure test of the 16m-span prototype test slab verifies that all structural mechanical performance indicators meet the design requirements. Thus, an efficient prestressed high-strength concrete hollow slab beam with novel section and excellent economic benefits is obtained. The research results can be extended to other bridge structures.

Abstract:Through load tests, this paper studies the detailing of post-tensioned flat plates without beams, in which unbonded tendons are arranged as banded concentrated bundles in one direction and uniformly dispersed in the other direction, the issue of configuring non-prestressed ordinary steel bars in positive and negative moment zones, the ultimate stress value of unbonded tendons, and the mechanical and deformation performance of unbonded prestressed cantilever slabs.

Abstract:The optimization design problem of cable-prestressed space grid structures with displacement constraints. A two-level optimization algorithm for the optimization problem. From the two examples in this paper, it can be seen that the two-level optimization algorithm is convenient for engineering applications.