Abstract:With the continuous development of bridge engineering in our country, the durability and safety of bridge structure have gradually developed into the key issues. This paper mainly analyzes the problems and countermeasures of these two aspects. Among them, the durability of bridge structure is mainly reflected in the cracking of concrete cable-stayed bridge, the deflection of concrete beam bridge and the fatigue crack of orthotropic steel bridge deck. The durability design practice mainly involves the cracking resistance of concrete beam, the improvement of orthotropic steel bridge deck and the durability guarantee of large Bridges. Based on the statistics of bridge failure accidents at home and abroad in recent years and the analysis of the causes of bridge failure, the main problems of bridge structure safety are expounded.

Abstract:Bridge robustness is the overall stability of the structure under accidental action. The aim of the research is to avoid collapse. Structural robustness will be involved in seismic and disaster repair of Bridges and sudden cable breakage of Bridges. After an overview of bridge robustness, the approaches to achieve bridge robustness are discussed, such as redundancy technology, multi-channel force transmission, improving ductility, etc., as well as an example analysis based on robustness theory.

Abstract:Long-span downwarping and beam cracking are common diseases of long-span concrete Bridges. The external prestressing technology has clear and safe force, which can play an obvious role in restraining mid-span downwarping and controlling cracks. Based on the summary of strengthening practice of two rigid frame Bridges with main span over 200m, some suggestions on improvement and application of prestressed system are put forward for reference.

Abstract:In this paper, the mechanical properties of a new type of high damping rubber isolation bearing and the isolation properties of this bearing on Bridges are studied experimentally. The mechanical properties of the new high-damping rubber isolation bearings are studied by sine-wave experiments. The experimental results show that the new high-damping rubber isolation bearings are velocity dependent bearings, and the loading frequency has great influence on the equivalent horizontal stiffness, but little influence on the equivalent damping coefficient. However, the loading experience has a great influence on the equivalent horizontal stiffness and equivalent damping coefficient of the new high damping rubber isolation bearing. At the same time, the seismic isolation effect of the new high damping rubber bearing on the bridge is verified precisely and quantitatively by numerical analysis.

Abstract:The over-limit of transverse amplitude of bridge has always been an important problem in railway Bridges. In the overall speed of the national railway environment, this problem is more and more prominent, the increase of train speed is bound to cause greater lateral displacement of the bridge, and then have an adverse impact on traffic safety. The traditional bridge lateral vibration control method is mainly to reduce the bridge vibration response by changing the bridge stiffness, but the cost is high and the economy is poor. The idea of energy dissipation and vibration reduction provides a new idea for transverse vibration control of Bridges, which is to reinforce Bridges with dampers. The installation of the damper can convert the input energy of the bridge into the hysteretic energy of the damper, and consume the input energy before the structure through the reciprocating loading and unloading cycle of the damper. The advantage of this method is that it is economical and easy to replace, but there is a lack of this type of damper products and related application research in China. It is this new type of damper that is studied in this paper.

Abstract:This paper introduces the basic meaning of bridge health monitoring, the urgency and significance of research and development, summarizes the research status and existing problems, and prospects the further research.

Abstract:This paper mainly introduces a kind of electrically insulated prestressed anchorage system used in post-tensioned prestressed Bridges. The main difference between this anchoring system and common anchorage system is that electrically insulated anchor plate is used. The plate consists of a circular pressure plate and a plastic horn, while the middle of the pressure plate is a traditional cast iron core surrounded by ultra-high strength concrete that is nearly insulated. By embedding the electrically insulated anchor plate and using plastic bellows, the prestressed tendons and anchors are isolated from the surrounding concrete insulation, which can not only protect the prestressed tendons well, but also measure the impedance between them at any time by using impedance meters. According to foreign research results, the impedance value reflects the degree of corrosion of prestressed tendons. In this way, the non-destructive testing system can be formed by monitoring the dynamic impedance value, and the safety and durability of prestressed concrete structures can be effectively improved.

Abstract:With the wide application of prestressed technology and the continuous improvement of the application level, China's prestressed machinery industry has also been greatly developed. This paper summarizes the problems existing in the development of prestressed machinery in China in the past 20 years and the future development direction, and puts forward some suggestions for the development of prestressed machinery industry.