In order to further grasp the structural reliability under earthquake

the effect of seismic duration and safety bound on structural seismic reliability are studied in this paper.Using MATLAB the random responses under the earthquake ground motion model of Gauss filtered white noise（Kanai-Tajimi spectrum）is analyzed.Then the exceeding probability of random response process is calculated using Poisson process method and Markov process method and Rayleigh extreme value distribution method.The calculation results of the three methods are similar

which show the change law of the structural dynamic reliability.The calculation results show that the structural dynamic reliability decreases when the excitation time increases.When the safety bound is greater than a certain value

the relationship between the dynamic reliability and the excitation time is close to linear.When the safety bound is less than that value

the relationship between the dynamic reliability and the excitation time is quadratically nonlinear.The structural dynamic reliability increases with the increasing of safety bound.The longer the excitations time

the steeper the curve between dynamic reliability and safety bound will be.The shorter the excitation time

the more smooth the curve between dynamic reliability and safety bound will be.