Response uncertainty under varying orientations of ground motions

![CDATA[Accurate estimation of peak structural response is important in earthquake resistant design. One key issue is the uncertainty of seismic orientation between the directions of ground motion and the structure’s reference axes. Different assumed incident angles of ground motions can result in different peak responses. Therefore, it is important to identify the response uncertainty and suitable response. To explore the stated issues, an evaluation based on relative variation in seismic response quantities of a realistic case study building under the influence of horizontal bi-directional excitation within all possible seismic orientations has been carried out. The investigated results on a realistic case study building demonstrate that (1) excitation applied at structure’s reference axes doesn’t always provide maximum response quantities over all orientations; (2) the uncertainty due to incident angle variability is in the range of 0.16 to 0.30 and cannot be ignored.]]