The Stability Analysis Of The Bridge Protection Facilities

In recent years, with the development of modern technology, a new, high intensity of light thin structure, widely used in defence and civil industrial fields. Therefore, such as lever, board, shell element in all kinds of such light under loads of stability problems aroused people's attention. Now, with the increase of ship-bridge collision accident, the bridge protect facilities also arises at the historic moment. So similar to the hull,the steel structure stability problem of protection devices is also becoming more and more important.The collision between ship and anti-collision equipment is a complex and a complicated non-linear dynamic response process in a very short time.Because of the complicacy and the uncertain factors in collision process,it is nearly impossible to make theoretic analysis by building up an accurate mathematic model. Therefore, along with the development of the nonlinear finite element technique, and the improvement of computer hardware,numerical simulation by finite element analyses will play a more and more important role in the analysis of collision problems between ship and bridge or equipment for anti-collision..Based on the structural dynamic buckling as the break through point, this paper expounds the dynamic buckling theory of the simple structure, and nonlinear dynamic finite element theory. On the basis of studying and discussing the key technology of computer simulation collision,employing ANSYS/LS-DYNA program,which is the universal nonlinear dynamic analysis software,a collision between a 5000 ton cargo ship and pier protective device designed for one pier of Tianxingzhou Bridge is simulated, the dynamic buckling phenomenon and energy-absorption ability of the structure components was calculated. Present some measures to optimize the structures. The major work in this thesis is listed as follows:1.Basing on the mechanics of colliding between ship and bridge protective device,reviewing the development situation of the dynamic buckling structure, detailing the dynamic buckling theory of the pole and plank in the plate-beam combination structure. 2. Discusses the fundamental theory and pivotal technology in simulation analysis of ship-bridge collision, expounds the basic control equations of the explicit finite theory, researches the basic process of the explicit integrating algorithm and the time step control, examines the applicability of common nonlinear explicit element in a variety of applications, introduces the dynamic characteristics and constitutive model of metal materials under violent shocks, and analyses the main algorithms of contact interface and the calculation of friction.3.By means of the FEM simulation software,calculating the impact process of a ship colliding with the Tianxingzhou Bridge protective device,simulating and studying the dynamic response characteristics of each part of the structure. During simulation, considering the influence of strain rate sensitive and friction,and examines the influence of outcomes by changing the variable parameter of the protective device on this basis.4. According to the calculation results, analyzing the deficiency in the protection devices,proposes improvements.calculates the improved structure using ANSYS/LS-DYNA, discusses the effects of anti-collision function of the device by changing the structure forms.Some measures are proposed about improving structure capability of anti-collision and effect of absorbing energy.