Design and Physical Detection of Bridge Tower and Externally Prestressing Cable for Existing Bridge Strengthened by A Cable-Stayed System

With the continuous development of economy, the increasing traffic volume has brought greater burden to highway bridges. In this paper, a Yellow River Bridge is taken as an example. The cracking and deflection of the box girder of the main bridge have affected the structural performance requirements of the bridge operation. Based on this situation, the cable-stayed system is used to reinforce the bridge, and the construction process of bridge tower, cable saddle, steel anchor box and external beam is described in detail. The theoretical calculation and practice show that this method can effectively strengthen the bridge structure, and the cable-stayed system reinforcement method, as a mature, reasonable and operable construction technology, provides relevant reference for the reinforcement research of similar bridges.

Experimental Study on the Mechanical Property of SMA Externally Prestressed Concrete Box Beam

This paper conducted an experiment to research flexural property of SMA unbounded prestressed box beam ,which applied the Shape Memory Alloy (SMA) at martensite state as externally prestressing tendons, and then through heating the SMA bars fully anchored on the beam with cracks by electrifying motivation, drove SMA to produce the “recovery stress” because of transformation, to study the effects of this stress on the deflection and crack width of concrete box-beam on work ,to study the recovery ability of SMA bars ,and to provide basis for the application of the SMA bars to bridge strengthening.

Experimental Investigation on Steel H-Beam Prestressed with Externally High Strength Steel Bars

The external post-tensioning technique has been commonly used in the construction field because it facilitates the analysis of structures and is widely applicable for many types of structures. In this research, 12 steel H-beams were built and tested in terms of the amount of tendon or prestressing force. The results show that the externally prestressing method can increase ultimate bearing capacity of the beams. The prestressing force is the significant factor that influence the strengthening of steel H-beams. However, the amount of deviators cannot significantly influence the bearing capacity.

Deflection Calculation on Reinforced Concrete Beams Strengthened by Externally Prestressing Transverse Tensioning Method

Eight reinforced concrete beams (six externally reinforced and two contrast beams) were tested under primary or secondary load experiment. According to the test results, the existing specifications were applied to make calculations on short-term deflection which leaded to a large error. The secondary effect should be considered on calculating the deflection. Therefore, comparisons were made between the improved calculated value and test value on deflections of reinforced concrete beams strengthened by externally prestressed transverse tensioning method and they are in good agreement.

Crack Analysis on Reinforced Concrete Beams Strengthened by Externally Prestressing Vertical Tensioning Method

In this paper, seven reinforced concrete beams (two contrast beams and five externally reinforced beams) were tested. The crack regularity under different tension stresses was analyzed through experimental data. Taking the stress mode under pressure for the triangle area, in the tension zone in the shape of a trapezoid , the crack resistance equation of externally prestressing reinforced rectangle beam is derived from balance method of the internal forces and moment, and the results coincide with the experiment results well.