Assessment of Higher Modes Effects in the Steel Moment Resisting Frames under the Far and Near Fault Earthquakes Using the DAP Method

In this research using the DAP method, the higher modes effects under the far and near -fault earthquakes are investigated. For this purpose 5 intermediate (ductility) steel moment resisting frames with 4, 7, 10, 15, and 20 stories have been investigated. The results show that in all the structures being investigated, the higher modes effects under the far fault earthquakes are greater with respect to the near- fault earthquakes. Also, by increase in the structure's height, the effects of higher modes increase. The base shear resulting from the near- fault earthquakes, considering the higher modes effects, has the negligible difference with the base shear resulting from the first mode of the structures.