Preliminary Research On Buckling-Restrained Braces In Seismic Design Of Bridge

Comparing to the old seismic specifications for railway, the horizontal seismic force value under seismic design of bridge is highly increased in the new one. In addition, the laying of railway CWR line get a high requirement of the stiffness of bridge piers, which make stiffness of railway bridge pier more higher than before. These factors have made the seismic design of railway bridges more difficult. Buckling-restrained Brace could be introduced to the ductile design of bridge under seismic conditions, which may provide a new approach to bridge seismic design.The Buckling-Restrained Brace (BRB) is a new kind of brace focusing on the solution to the problems associated with buckling. The concept of the BRB is the buckling prevention of the central steel core by encasing it over its length in a steel tube filled with concrete. The compression and tension loads are designed to be carried only by the core by means of unbonded layer to allow the free slip between the core and the surrounding concrete. The BRB can reach and retain fully sectional yielding of the core under compression. And exhibition stable hysteretic behavior when cyclically loaded.Theoretical study is firstly executed to find the rational composition of BRB. Stability analysis is carried out to determined the necessary stiffness and moment resisting capability of the outer tube, as well as other factors governing the mechanical behavior of the BRB.Next, nonlinearity is introduced in the contact analysis by finite element method to precisely simulation the loading progress of the BRB. Numerical Simulation provided by ANSYS is used to test and verify the hysteretic behavior of BRB, which is the foundation of experimental study.