NEW STRUCTURAL SYSTEM FOR COLUMNS OF INFRASTRUCTURES SUBJECTED TO THE ACCIDENTAL LOADING DUE TO NATURAL HAZARDS

摘要

In this paper a new structural system for columns of infrastructures like bridges that are resistant against effects of accidental loading is explained. Accidental loads can occur during the lifetime of an infrastructure like the risk of collision, which may happen during flood or other types of natural disasters. This new structural system consists of different phases. Some phases of the system turns the concentrated force due to the intense loading initial energy to a distributed force effect by absorbing energy in form of large deformations and deconstruction. By absorbing a great amount of the produced energy, this deconstruction provides structural stability, introducing a time lag by which according to the structure's response to the dynamic loading activates other phases of the system afterwards. The analysis method considered in the beginning of the study was structural modelling of single degree of freedom system. This approach has been used to study the influence of the peak pressure on the fundamental mode of vibration. Compared to the SDOF approach, the structural behaviour was simulated by the finite element analyses with strain-rate sensitive material models including non-linear dynamic analysis. Additionally for comparing the results of analytical models some experimental tests have been done. The main purpose of these tests was based on comparing the behaviour of columns designed by available design codes and columns designed by this method. Thereafter, a four span bridge (30 meter) with different column heights (5,7and 9 meters) was analysed and designed with this method and conventional method. Dynamic behaviour of the piers for both systems was compared according to their non-linear behaviour.