Rearch On Behaviors Of R.C. Flyvoer Bridges Subjected To Wartime Loads

Research on behaviors of flyover bridges subjected to war-time loads is the requirement of both making new national defense-related policies and preparing the war under the condition of modern high-technology, which will have a far-reaching influence on improving the economic and military performance of traffic infrastructures. With the development of science and technology, new high-tech weapons have been being invented and continually put into practice, which will come into being a serious threat to the transportation security; The modernization of weapons and accoutrements of PLA are increasingly becoming integrated and large-sized, which are calling for improvements in military transportation; And application of numerous high and new technology in traffic infrastructure will also make full impact on the military transportation. All these changes are calling for making new related technology policies and standards, and are calling for a series of all-round, profound and systemic research on existing related technological policies. One necessary conditions of making these national defence-related policies is conducting a systemic research on the damages of the infrastructures caused by the foreign high-tech weapons and on the applicability of the infrastructures to heavy weapons. The research on behaviors of flyover bridges subjected to war-time loads is an important part of an all-round research on the traffic infrastructure.It is on this background that the research was carried out, and further, this dissertation was written. According to the development of the technology of computer simulation, the author put forward a two-step method in the research: treating the explosive loads and the impacting loads independently; treating the damages of the bridges and the evaluation of these damaged bridges independently. In the phase of feasibility research, the appropriate means can be taken should be given priority to computer simulation.This dissertation is composed of 5 chapters. In Chapter 1, a review of the development of the explosive and impacting dynamics was made, and a summary of the technological features of the R, C. flyover bridges in China was also given. In Chapter 2, by virtue of tensors, the author derived a clear formulation of related nonlinear FEM. In Chapter 3, a detailed analysis of R.C. slab subjected to impacting loads was performed. In Chapter 4, behavioral analyses of R. C. flyover bridges subjected to explosive and impacting loads was carded out. In Chapter 5, based on the analyses in the Chapter 4, evaluations of the damaged flyover bridges were made, a method of grading the damaged flyover bridges was brought forward, and further, according to the various damages, different suggested schemes of rush-repair were presented.The research shows that, irrespective of repeated attacks on the same part of bridges, damage to the bridges subjected to explosive or impacting loads is a limited one, and rush-repair during wartime is possible. Thus it is necessary, according to various situations possibly encountered during potential wars in the future, to carry out a further research on the protection and rush-repair schemes of bridges.