Ground motion generation of nonstationary both in amplitude and frequency content based on frequency adjustment

Dynamic time-history analysis method is an effective way to study the structural response under the action of the earthquake.The precision of the input ground motion time-history has a major impact on the calculation results.The actual ground motions are non-stationary both in amplitude and frequency con tent,but currently the artificial wave used for dynamic time-history analysis is stationary ground motion in frequency content.In this paper,an improved earthquake model as the product of a constant intensity pro cess having time-varying frequency content and a deterministic intensity function is proposed.The new mod el is achieved by adding frequency adjustment to the traditional triangular series model.The fully nonstation ary ground motion generated by the new model is not only closer to the real earthquake records but also can fit the target response spectrum better,so it will be of great significance for the engineering practice.